2018-09-03 16:34:18 +00:00
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/* SPDX-License-Identifier: GPL-2.0 */
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linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
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#ifndef __LINUX_COMPILER_TYPES_H
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#define __LINUX_COMPILER_TYPES_H
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#ifndef __ASSEMBLY__
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2022-03-10 21:16:55 +00:00
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#if defined(CONFIG_DEBUG_INFO_BTF) && defined(CONFIG_PAHOLE_HAS_BTF_TAG) && \
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__has_attribute(btf_type_tag)
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# define BTF_TYPE_TAG(value) __attribute__((btf_type_tag(#value)))
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#else
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# define BTF_TYPE_TAG(value) /* nothing */
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#endif
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2022-03-23 23:05:32 +00:00
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/* sparse defines __CHECKER__; see Documentation/dev-tools/sparse.rst */
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linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
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#ifdef __CHECKER__
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2020-08-12 01:34:26 +00:00
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/* address spaces */
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linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
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# define __kernel __attribute__((address_space(0)))
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sparse: use identifiers to define address spaces
Currently, address spaces in warnings are displayed as '<asn:X>' with
'X' being the address space's arbitrary number.
But since sparse v0.6.0-rc1 (late December 2018), sparse allows you to
define the address spaces using an identifier instead of a number. This
identifier is then directly used in the warnings.
So, use the identifiers '__user', '__iomem', '__percpu' & '__rcu' for
the corresponding address spaces. The default address space, __kernel,
being not displayed in warnings, stays defined as '0'.
With this change, warnings that used to be displayed as:
cast removes address space '<asn:1>' of expression
... void [noderef] <asn:2> *
will now be displayed as:
cast removes address space '__user' of expression
... void [noderef] __iomem *
This also moves the __kernel annotation to be the first one, since it is
quite different from the others because it's the default one, and so:
- it's never displayed
- it's normally not needed, nor in type annotations, nor in cast
between address spaces. The only time it's needed is when it's
combined with a typeof to express "the same type as this one but
without the address space"
- it can't be defined with a name, '0' must be used.
So, it seemed strange to me to have it in the middle of the other
ones.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-17 22:02:26 +00:00
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# define __user __attribute__((noderef, address_space(__user)))
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# define __iomem __attribute__((noderef, address_space(__iomem)))
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2020-08-12 01:34:26 +00:00
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# define __percpu __attribute__((noderef, address_space(__percpu)))
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# define __rcu __attribute__((noderef, address_space(__rcu)))
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2020-08-28 08:53:01 +00:00
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static inline void __chk_user_ptr(const volatile void __user *ptr) { }
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static inline void __chk_io_ptr(const volatile void __iomem *ptr) { }
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2020-08-12 01:34:26 +00:00
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/* context/locking */
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linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
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# define __must_hold(x) __attribute__((context(x,1,1)))
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# define __acquires(x) __attribute__((context(x,0,1)))
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sparse: introduce conditional lock acquire function attribute
The kernel tends to try to avoid conditional locking semantics because
it makes it harder to think about and statically check locking rules,
but we do have a few fundamental locking primitives that take locks
conditionally - most obviously the 'trylock' functions.
That has always been a problem for 'sparse' checking for locking
imbalance, and we've had a special '__cond_lock()' macro that we've used
to let sparse know how the locking works:
# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
so that you can then use this to tell sparse that (for example) the
spinlock trylock macro ends up acquiring the lock when it succeeds, but
not when it fails:
#define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock))
and then sparse can follow along the locking rules when you have code like
if (!spin_trylock(&dentry->d_lock))
return LRU_SKIP;
.. sparse sees that the lock is held here..
spin_unlock(&dentry->d_lock);
and sparse ends up happy about the lock contexts.
However, this '__cond_lock()' use does result in very ugly header files,
and requires you to basically wrap the real function with that macro
that uses '__cond_lock'. Which has made PeterZ NAK things that try to
fix sparse warnings over the years [1].
To solve this, there is now a very experimental patch to sparse that
basically does the exact same thing as '__cond_lock()' did, but using a
function attribute instead. That seems to make PeterZ happy [2].
Note that this does not replace existing use of '__cond_lock()', but
only exposes the new proposed attribute and uses it for the previously
unannotated 'refcount_dec_and_lock()' family of functions.
For existing sparse installations, this will make no difference (a
negative output context was ignored), but if you have the experimental
sparse patch it will make sparse now understand code that uses those
functions, the same way '__cond_lock()' makes sparse understand the very
similar 'atomic_dec_and_lock()' uses that have the old '__cond_lock()'
annotations.
Note that in some cases this will silence existing context imbalance
warnings. But in other cases it may end up exposing new sparse warnings
for code that sparse just didn't see the locking for at all before.
This is a trial, in other words. I'd expect that if it ends up being
successful, and new sparse releases end up having this new attribute,
we'll migrate the old-style '__cond_lock()' users to use the new-style
'__cond_acquires' function attribute.
The actual experimental sparse patch was posted in [3].
Link: https://lore.kernel.org/all/20130930134434.GC12926@twins.programming.kicks-ass.net/ [1]
Link: https://lore.kernel.org/all/Yr60tWxN4P568x3W@worktop.programming.kicks-ass.net/ [2]
Link: https://lore.kernel.org/all/CAHk-=wjZfO9hGqJ2_hGQG3U_XzSh9_XaXze=HgPdvJbgrvASfA@mail.gmail.com/ [3]
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Aring <aahringo@redhat.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-06-30 16:34:10 +00:00
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# define __cond_acquires(x) __attribute__((context(x,0,-1)))
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linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
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# define __releases(x) __attribute__((context(x,1,0)))
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# define __acquire(x) __context__(x,1)
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# define __release(x) __context__(x,-1)
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# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
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2020-08-12 01:34:26 +00:00
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/* other */
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# define __force __attribute__((force))
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# define __nocast __attribute__((nocast))
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# define __safe __attribute__((safe))
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linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
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# define __private __attribute__((noderef))
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# define ACCESS_PRIVATE(p, member) (*((typeof((p)->member) __force *) &(p)->member))
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#else /* __CHECKER__ */
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2020-08-12 01:34:26 +00:00
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/* address spaces */
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# define __kernel
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linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
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# ifdef STRUCTLEAK_PLUGIN
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2020-08-12 01:34:26 +00:00
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# define __user __attribute__((user))
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
# else
|
2022-03-10 21:16:55 +00:00
|
|
|
# define __user BTF_TYPE_TAG(user)
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
# endif
|
|
|
|
# define __iomem
|
2022-03-10 21:16:55 +00:00
|
|
|
# define __percpu BTF_TYPE_TAG(percpu)
|
2020-08-12 01:34:26 +00:00
|
|
|
# define __rcu
|
|
|
|
# define __chk_user_ptr(x) (void)0
|
|
|
|
# define __chk_io_ptr(x) (void)0
|
|
|
|
/* context/locking */
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
# define __must_hold(x)
|
|
|
|
# define __acquires(x)
|
sparse: introduce conditional lock acquire function attribute
The kernel tends to try to avoid conditional locking semantics because
it makes it harder to think about and statically check locking rules,
but we do have a few fundamental locking primitives that take locks
conditionally - most obviously the 'trylock' functions.
That has always been a problem for 'sparse' checking for locking
imbalance, and we've had a special '__cond_lock()' macro that we've used
to let sparse know how the locking works:
# define __cond_lock(x,c) ((c) ? ({ __acquire(x); 1; }) : 0)
so that you can then use this to tell sparse that (for example) the
spinlock trylock macro ends up acquiring the lock when it succeeds, but
not when it fails:
#define raw_spin_trylock(lock) __cond_lock(lock, _raw_spin_trylock(lock))
and then sparse can follow along the locking rules when you have code like
if (!spin_trylock(&dentry->d_lock))
return LRU_SKIP;
.. sparse sees that the lock is held here..
spin_unlock(&dentry->d_lock);
and sparse ends up happy about the lock contexts.
However, this '__cond_lock()' use does result in very ugly header files,
and requires you to basically wrap the real function with that macro
that uses '__cond_lock'. Which has made PeterZ NAK things that try to
fix sparse warnings over the years [1].
To solve this, there is now a very experimental patch to sparse that
basically does the exact same thing as '__cond_lock()' did, but using a
function attribute instead. That seems to make PeterZ happy [2].
Note that this does not replace existing use of '__cond_lock()', but
only exposes the new proposed attribute and uses it for the previously
unannotated 'refcount_dec_and_lock()' family of functions.
For existing sparse installations, this will make no difference (a
negative output context was ignored), but if you have the experimental
sparse patch it will make sparse now understand code that uses those
functions, the same way '__cond_lock()' makes sparse understand the very
similar 'atomic_dec_and_lock()' uses that have the old '__cond_lock()'
annotations.
Note that in some cases this will silence existing context imbalance
warnings. But in other cases it may end up exposing new sparse warnings
for code that sparse just didn't see the locking for at all before.
This is a trial, in other words. I'd expect that if it ends up being
successful, and new sparse releases end up having this new attribute,
we'll migrate the old-style '__cond_lock()' users to use the new-style
'__cond_acquires' function attribute.
The actual experimental sparse patch was posted in [3].
Link: https://lore.kernel.org/all/20130930134434.GC12926@twins.programming.kicks-ass.net/ [1]
Link: https://lore.kernel.org/all/Yr60tWxN4P568x3W@worktop.programming.kicks-ass.net/ [2]
Link: https://lore.kernel.org/all/CAHk-=wjZfO9hGqJ2_hGQG3U_XzSh9_XaXze=HgPdvJbgrvASfA@mail.gmail.com/ [3]
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Alexander Aring <aahringo@redhat.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-06-30 16:34:10 +00:00
|
|
|
# define __cond_acquires(x)
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
# define __releases(x)
|
2020-08-12 01:34:26 +00:00
|
|
|
# define __acquire(x) (void)0
|
|
|
|
# define __release(x) (void)0
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
# define __cond_lock(x,c) (c)
|
2020-08-12 01:34:26 +00:00
|
|
|
/* other */
|
|
|
|
# define __force
|
|
|
|
# define __nocast
|
|
|
|
# define __safe
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
# define __private
|
|
|
|
# define ACCESS_PRIVATE(p, member) ((p)->member)
|
2020-08-12 01:34:26 +00:00
|
|
|
# define __builtin_warning(x, y...) (1)
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
#endif /* __CHECKER__ */
|
|
|
|
|
|
|
|
/* Indirect macros required for expanded argument pasting, eg. __LINE__. */
|
|
|
|
#define ___PASTE(a,b) a##b
|
|
|
|
#define __PASTE(a,b) ___PASTE(a,b)
|
|
|
|
|
|
|
|
#ifdef __KERNEL__
|
|
|
|
|
Compiler Attributes: use feature checks instead of version checks
Instead of using version checks per-compiler to define (or not)
each attribute, use __has_attribute to test for them, following
the cleanup started with commit 815f0ddb346c
("include/linux/compiler*.h: make compiler-*.h mutually exclusive"),
which is supported on gcc >= 5, clang >= 2.9 and icc >= 17.
In the meantime, to support 4.6 <= gcc < 5, we implement
__has_attribute by hand.
All the attributes that can be unconditionally defined and directly
map to compiler attribute(s) (even if optional) have been moved
to a new file include/linux/compiler_attributes.h
In an effort to make the file as regular as possible, comments
stating the purpose of attributes have been removed. Instead,
links to the compiler docs have been added (i.e. to gcc and,
if available, to clang as well). In addition, they have been sorted.
Finally, if an attribute is optional (i.e. if it is guarded
by __has_attribute), the reason has been stated for future reference.
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # on top of v4.19-rc5, clang 7
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
2018-08-30 18:36:59 +00:00
|
|
|
/* Attributes */
|
|
|
|
#include <linux/compiler_attributes.h>
|
|
|
|
|
2020-10-19 07:35:39 +00:00
|
|
|
/* Builtins */
|
|
|
|
|
|
|
|
/*
|
|
|
|
* __has_builtin is supported on gcc >= 10, clang >= 3 and icc >= 21.
|
|
|
|
* In the meantime, to support gcc < 10, we implement __has_builtin
|
|
|
|
* by hand.
|
|
|
|
*/
|
|
|
|
#ifndef __has_builtin
|
|
|
|
#define __has_builtin(x) (0)
|
|
|
|
#endif
|
|
|
|
|
2018-08-22 23:37:24 +00:00
|
|
|
/* Compiler specific macros. */
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
#ifdef __clang__
|
|
|
|
#include <linux/compiler-clang.h>
|
2018-08-22 23:37:24 +00:00
|
|
|
#elif defined(__INTEL_COMPILER)
|
|
|
|
#include <linux/compiler-intel.h>
|
|
|
|
#elif defined(__GNUC__)
|
|
|
|
/* The above compilers also define __GNUC__, so order is important here. */
|
|
|
|
#include <linux/compiler-gcc.h>
|
|
|
|
#else
|
|
|
|
#error "Unknown compiler"
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
#endif
|
|
|
|
|
2018-08-20 22:36:17 +00:00
|
|
|
/*
|
|
|
|
* Some architectures need to provide custom definitions of macros provided
|
|
|
|
* by linux/compiler-*.h, and can do so using asm/compiler.h. We include that
|
|
|
|
* conditionally rather than using an asm-generic wrapper in order to avoid
|
|
|
|
* build failures if any C compilation, which will include this file via an
|
|
|
|
* -include argument in c_flags, occurs prior to the asm-generic wrappers being
|
|
|
|
* generated.
|
|
|
|
*/
|
|
|
|
#ifdef CONFIG_HAVE_ARCH_COMPILER_H
|
|
|
|
#include <asm/compiler.h>
|
|
|
|
#endif
|
|
|
|
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
struct ftrace_branch_data {
|
|
|
|
const char *func;
|
|
|
|
const char *file;
|
|
|
|
unsigned line;
|
|
|
|
union {
|
|
|
|
struct {
|
|
|
|
unsigned long correct;
|
|
|
|
unsigned long incorrect;
|
|
|
|
};
|
|
|
|
struct {
|
|
|
|
unsigned long miss;
|
|
|
|
unsigned long hit;
|
|
|
|
};
|
|
|
|
unsigned long miss_hit[2];
|
|
|
|
};
|
|
|
|
};
|
|
|
|
|
|
|
|
struct ftrace_likely_data {
|
|
|
|
struct ftrace_branch_data data;
|
|
|
|
unsigned long constant;
|
|
|
|
};
|
|
|
|
|
2018-12-14 14:14:31 +00:00
|
|
|
#if defined(CC_USING_HOTPATCH)
|
|
|
|
#define notrace __attribute__((hotpatch(0, 0)))
|
2019-06-05 20:32:21 +00:00
|
|
|
#elif defined(CC_USING_PATCHABLE_FUNCTION_ENTRY)
|
|
|
|
#define notrace __attribute__((patchable_function_entry(0, 0)))
|
2018-12-14 14:14:31 +00:00
|
|
|
#else
|
|
|
|
#define notrace __attribute__((__no_instrument_function__))
|
|
|
|
#endif
|
|
|
|
|
|
|
|
/*
|
|
|
|
* it doesn't make sense on ARM (currently the only user of __naked)
|
|
|
|
* to trace naked functions because then mcount is called without
|
|
|
|
* stack and frame pointer being set up and there is no chance to
|
|
|
|
* restore the lr register to the value before mcount was called.
|
|
|
|
*/
|
|
|
|
#define __naked __attribute__((__naked__)) notrace
|
|
|
|
|
|
|
|
/*
|
|
|
|
* Prefer gnu_inline, so that extern inline functions do not emit an
|
|
|
|
* externally visible function. This makes extern inline behave as per gnu89
|
|
|
|
* semantics rather than c99. This prevents multiple symbol definition errors
|
|
|
|
* of extern inline functions at link time.
|
|
|
|
* A lot of inline functions can cause havoc with function tracing.
|
|
|
|
*/
|
2020-04-07 03:09:33 +00:00
|
|
|
#define inline inline __gnu_inline __inline_maybe_unused notrace
|
2018-12-14 14:14:31 +00:00
|
|
|
|
2019-09-12 22:19:24 +00:00
|
|
|
/*
|
|
|
|
* gcc provides both __inline__ and __inline as alternate spellings of
|
|
|
|
* the inline keyword, though the latter is undocumented. New kernel
|
|
|
|
* code should only use the inline spelling, but some existing code
|
|
|
|
* uses __inline__. Since we #define inline above, to ensure
|
|
|
|
* __inline__ has the same semantics, we need this #define.
|
|
|
|
*
|
|
|
|
* However, the spelling __inline is strictly reserved for referring
|
|
|
|
* to the bare keyword.
|
|
|
|
*/
|
2018-12-14 14:14:31 +00:00
|
|
|
#define __inline__ inline
|
|
|
|
|
kbuild: allow Clang to find unused static inline functions for W=1 build
GCC and Clang have different policy for -Wunused-function; GCC does not
warn unused static inline functions at all whereas Clang does if they
are defined in source files instead of included headers although it has
been suppressed since commit abb2ea7dfd82 ("compiler, clang: suppress
warning for unused static inline functions").
We often miss to delete unused functions where 'static inline' is used
in *.c files since there is no tool to detect them. Unused code remains
until somebody notices. For example, commit 075ddd75680f ("regulator:
core: remove unused rdev_get_supply()").
Let's remove __maybe_unused from the inline macro to allow Clang to
start finding unused static inline functions. For now, we do this only
for W=1 build since it is not a good idea to sprinkle warnings for the
normal build (e.g. 35 warnings for arch/x86/configs/x86_64_defconfig).
My initial attempt was to add -Wno-unused-function for no W= build
(https://lore.kernel.org/patchwork/patch/1120594/)
Nathan Chancellor pointed out that would weaken Clang's checks since
we would no longer get -Wunused-function without W=1. It is true GCC
would catch unused static non-inline functions, but it would weaken
Clang as a standalone compiler, at least.
Hence, here is a counter implementation. The current problem is, W=...
only controls compiler flags, which are globally effective. There is
no way to address only 'static inline' functions.
This commit defines KBUILD_EXTRA_WARN[123] corresponding to W=[123].
When KBUILD_EXTRA_WARN1 is defined, __maybe_unused is omitted from
the 'inline' macro.
The new macro __inline_maybe_unused makes the code a bit uglier, so I
hope we can remove it entirely after fixing most of the warnings.
If you contribute to code clean-up, please run "make CC=clang W=1"
and check -Wunused-function warnings. You will find lots of unused
functions.
Some of them are false-positives because the call-sites are disabled
by #ifdef. I do not like to abuse the inline keyword for suppressing
unused-function warnings because it is intended to be a hint for the
compiler optimization. I prefer #ifdef around the definition, or
__maybe_unused if #ifdef would make the code too ugly.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
2019-09-07 02:52:36 +00:00
|
|
|
/*
|
|
|
|
* GCC does not warn about unused static inline functions for -Wunused-function.
|
|
|
|
* Suppress the warning in clang as well by using __maybe_unused, but enable it
|
|
|
|
* for W=1 build. This will allow clang to find unused functions. Remove the
|
|
|
|
* __inline_maybe_unused entirely after fixing most of -Wunused-function warnings.
|
|
|
|
*/
|
|
|
|
#ifdef KBUILD_EXTRA_WARN1
|
|
|
|
#define __inline_maybe_unused
|
|
|
|
#else
|
|
|
|
#define __inline_maybe_unused __maybe_unused
|
|
|
|
#endif
|
|
|
|
|
2018-12-14 14:14:31 +00:00
|
|
|
/*
|
|
|
|
* Rather then using noinline to prevent stack consumption, use
|
|
|
|
* noinline_for_stack instead. For documentation reasons.
|
|
|
|
*/
|
|
|
|
#define noinline_for_stack noinline
|
|
|
|
|
2020-05-21 14:20:47 +00:00
|
|
|
/*
|
|
|
|
* Sanitizer helper attributes: Because using __always_inline and
|
|
|
|
* __no_sanitize_* conflict, provide helper attributes that will either expand
|
|
|
|
* to __no_sanitize_* in compilation units where instrumentation is enabled
|
|
|
|
* (__SANITIZE_*__), or __always_inline in compilation units without
|
|
|
|
* instrumentation (__SANITIZE_*__ undefined).
|
|
|
|
*/
|
|
|
|
#ifdef __SANITIZE_ADDRESS__
|
2020-05-21 14:20:46 +00:00
|
|
|
/*
|
|
|
|
* We can't declare function 'inline' because __no_sanitize_address conflicts
|
|
|
|
* with inlining. Attempt to inline it may cause a build failure.
|
|
|
|
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67368
|
|
|
|
* '__maybe_unused' allows us to avoid defined-but-not-used warnings.
|
|
|
|
*/
|
|
|
|
# define __no_kasan_or_inline __no_sanitize_address notrace __maybe_unused
|
|
|
|
# define __no_sanitize_or_inline __no_kasan_or_inline
|
|
|
|
#else
|
|
|
|
# define __no_kasan_or_inline __always_inline
|
|
|
|
#endif
|
|
|
|
|
|
|
|
#ifdef __SANITIZE_THREAD__
|
kcsan: Support WEAK_MEMORY with Clang where no objtool support exists
Clang and GCC behave a little differently when it comes to the
__no_sanitize_thread attribute, which has valid reasons, and depending
on context either one could be right.
Traditionally, user space ThreadSanitizer [1] still expects instrumented
builtin atomics (to avoid false positives) and __tsan_func_{entry,exit}
(to generate meaningful stack traces), even if the function has the
attribute no_sanitize("thread").
[1] https://clang.llvm.org/docs/ThreadSanitizer.html#attribute-no-sanitize-thread
GCC doesn't follow the same policy (for better or worse), and removes
all kinds of instrumentation if no_sanitize is added. Arguably, since
this may be a problem for user space ThreadSanitizer, we expect this may
change in future.
Since KCSAN != ThreadSanitizer, the likelihood of false positives even
without barrier instrumentation everywhere, is much lower by design.
At least for Clang, however, to fully remove all sanitizer
instrumentation, we must add the disable_sanitizer_instrumentation
attribute, which is available since Clang 14.0.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-11-30 11:44:33 +00:00
|
|
|
/*
|
|
|
|
* Clang still emits instrumentation for __tsan_func_{entry,exit}() and builtin
|
|
|
|
* atomics even with __no_sanitize_thread (to avoid false positives in userspace
|
|
|
|
* ThreadSanitizer). The kernel's requirements are stricter and we really do not
|
|
|
|
* want any instrumentation with __no_kcsan.
|
|
|
|
*
|
|
|
|
* Therefore we add __disable_sanitizer_instrumentation where available to
|
|
|
|
* disable all instrumentation. See Kconfig.kcsan where this is mandatory.
|
|
|
|
*/
|
|
|
|
# define __no_kcsan __no_sanitize_thread __disable_sanitizer_instrumentation
|
2020-06-02 15:04:03 +00:00
|
|
|
# define __no_sanitize_or_inline __no_kcsan notrace __maybe_unused
|
kcsan: Support WEAK_MEMORY with Clang where no objtool support exists
Clang and GCC behave a little differently when it comes to the
__no_sanitize_thread attribute, which has valid reasons, and depending
on context either one could be right.
Traditionally, user space ThreadSanitizer [1] still expects instrumented
builtin atomics (to avoid false positives) and __tsan_func_{entry,exit}
(to generate meaningful stack traces), even if the function has the
attribute no_sanitize("thread").
[1] https://clang.llvm.org/docs/ThreadSanitizer.html#attribute-no-sanitize-thread
GCC doesn't follow the same policy (for better or worse), and removes
all kinds of instrumentation if no_sanitize is added. Arguably, since
this may be a problem for user space ThreadSanitizer, we expect this may
change in future.
Since KCSAN != ThreadSanitizer, the likelihood of false positives even
without barrier instrumentation everywhere, is much lower by design.
At least for Clang, however, to fully remove all sanitizer
instrumentation, we must add the disable_sanitizer_instrumentation
attribute, which is available since Clang 14.0.
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-11-30 11:44:33 +00:00
|
|
|
#else
|
|
|
|
# define __no_kcsan
|
2020-05-21 14:20:46 +00:00
|
|
|
#endif
|
|
|
|
|
|
|
|
#ifndef __no_sanitize_or_inline
|
|
|
|
#define __no_sanitize_or_inline __always_inline
|
|
|
|
#endif
|
|
|
|
|
2020-06-02 16:47:11 +00:00
|
|
|
/* Section for code which can't be instrumented at all */
|
|
|
|
#define noinstr \
|
2020-06-04 05:58:11 +00:00
|
|
|
noinline notrace __attribute((__section__(".noinstr.text"))) \
|
Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:
"190 patches.
Subsystems affected by this patch series: mm (hugetlb, userfaultfd,
vmscan, kconfig, proc, z3fold, zbud, ras, mempolicy, memblock,
migration, thp, nommu, kconfig, madvise, memory-hotplug, zswap,
zsmalloc, zram, cleanups, kfence, and hmm), procfs, sysctl, misc,
core-kernel, lib, lz4, checkpatch, init, kprobes, nilfs2, hfs,
signals, exec, kcov, selftests, compress/decompress, and ipc"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (190 commits)
ipc/util.c: use binary search for max_idx
ipc/sem.c: use READ_ONCE()/WRITE_ONCE() for use_global_lock
ipc: use kmalloc for msg_queue and shmid_kernel
ipc sem: use kvmalloc for sem_undo allocation
lib/decompressors: remove set but not used variabled 'level'
selftests/vm/pkeys: exercise x86 XSAVE init state
selftests/vm/pkeys: refill shadow register after implicit kernel write
selftests/vm/pkeys: handle negative sys_pkey_alloc() return code
selftests/vm/pkeys: fix alloc_random_pkey() to make it really, really random
kcov: add __no_sanitize_coverage to fix noinstr for all architectures
exec: remove checks in __register_bimfmt()
x86: signal: don't do sas_ss_reset() until we are certain that sigframe won't be abandoned
hfsplus: report create_date to kstat.btime
hfsplus: remove unnecessary oom message
nilfs2: remove redundant continue statement in a while-loop
kprobes: remove duplicated strong free_insn_page in x86 and s390
init: print out unknown kernel parameters
checkpatch: do not complain about positive return values starting with EPOLL
checkpatch: improve the indented label test
checkpatch: scripts/spdxcheck.py now requires python3
...
2021-07-02 19:08:10 +00:00
|
|
|
__no_kcsan __no_sanitize_address __no_profile __no_sanitize_coverage
|
2020-06-02 16:47:11 +00:00
|
|
|
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
#endif /* __KERNEL__ */
|
|
|
|
|
2018-08-22 23:37:24 +00:00
|
|
|
#endif /* __ASSEMBLY__ */
|
|
|
|
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
/*
|
2018-08-22 23:37:24 +00:00
|
|
|
* The below symbols may be defined for one or more, but not ALL, of the above
|
|
|
|
* compilers. We don't consider that to be an error, so set them to nothing.
|
|
|
|
* For example, some of them are for compiler specific plugins.
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
*/
|
|
|
|
#ifndef __latent_entropy
|
|
|
|
# define __latent_entropy
|
|
|
|
#endif
|
|
|
|
|
2022-05-03 20:55:00 +00:00
|
|
|
#if defined(RANDSTRUCT) && !defined(__CHECKER__)
|
|
|
|
# define __randomize_layout __designated_init __attribute__((randomize_layout))
|
|
|
|
# define __no_randomize_layout __attribute__((no_randomize_layout))
|
|
|
|
/* This anon struct can add padding, so only enable it under randstruct. */
|
|
|
|
# define randomized_struct_fields_start struct {
|
|
|
|
# define randomized_struct_fields_end } __randomize_layout;
|
|
|
|
#else
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
# define __randomize_layout __designated_init
|
|
|
|
# define __no_randomize_layout
|
|
|
|
# define randomized_struct_fields_start
|
|
|
|
# define randomized_struct_fields_end
|
|
|
|
#endif
|
|
|
|
|
2020-04-27 16:00:07 +00:00
|
|
|
#ifndef __noscs
|
|
|
|
# define __noscs
|
|
|
|
#endif
|
|
|
|
|
add support for Clang CFI
This change adds support for Clang’s forward-edge Control Flow
Integrity (CFI) checking. With CONFIG_CFI_CLANG, the compiler
injects a runtime check before each indirect function call to ensure
the target is a valid function with the correct static type. This
restricts possible call targets and makes it more difficult for
an attacker to exploit bugs that allow the modification of stored
function pointers. For more details, see:
https://clang.llvm.org/docs/ControlFlowIntegrity.html
Clang requires CONFIG_LTO_CLANG to be enabled with CFI to gain
visibility to possible call targets. Kernel modules are supported
with Clang’s cross-DSO CFI mode, which allows checking between
independently compiled components.
With CFI enabled, the compiler injects a __cfi_check() function into
the kernel and each module for validating local call targets. For
cross-module calls that cannot be validated locally, the compiler
calls the global __cfi_slowpath_diag() function, which determines
the target module and calls the correct __cfi_check() function. This
patch includes a slowpath implementation that uses __module_address()
to resolve call targets, and with CONFIG_CFI_CLANG_SHADOW enabled, a
shadow map that speeds up module look-ups by ~3x.
Clang implements indirect call checking using jump tables and
offers two methods of generating them. With canonical jump tables,
the compiler renames each address-taken function to <function>.cfi
and points the original symbol to a jump table entry, which passes
__cfi_check() validation. This isn’t compatible with stand-alone
assembly code, which the compiler doesn’t instrument, and would
result in indirect calls to assembly code to fail. Therefore, we
default to using non-canonical jump tables instead, where the compiler
generates a local jump table entry <function>.cfi_jt for each
address-taken function, and replaces all references to the function
with the address of the jump table entry.
Note that because non-canonical jump table addresses are local
to each component, they break cross-module function address
equality. Specifically, the address of a global function will be
different in each module, as it's replaced with the address of a local
jump table entry. If this address is passed to a different module,
it won’t match the address of the same function taken there. This
may break code that relies on comparing addresses passed from other
components.
CFI checking can be disabled in a function with the __nocfi attribute.
Additionally, CFI can be disabled for an entire compilation unit by
filtering out CC_FLAGS_CFI.
By default, CFI failures result in a kernel panic to stop a potential
exploit. CONFIG_CFI_PERMISSIVE enables a permissive mode, where the
kernel prints out a rate-limited warning instead, and allows execution
to continue. This option is helpful for locating type mismatches, but
should only be enabled during development.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210408182843.1754385-2-samitolvanen@google.com
2021-04-08 18:28:26 +00:00
|
|
|
#ifndef __nocfi
|
|
|
|
# define __nocfi
|
|
|
|
#endif
|
|
|
|
|
2021-04-08 18:28:27 +00:00
|
|
|
#ifndef __cficanonical
|
|
|
|
# define __cficanonical
|
|
|
|
#endif
|
|
|
|
|
Compiler Attributes: add __alloc_size() for better bounds checking
GCC and Clang can use the "alloc_size" attribute to better inform the
results of __builtin_object_size() (for compile-time constant values).
Clang can additionally use alloc_size to inform the results of
__builtin_dynamic_object_size() (for run-time values).
Because GCC sees the frequent use of struct_size() as an allocator size
argument, and notices it can return SIZE_MAX (the overflow indication),
it complains about these call sites overflowing (since SIZE_MAX is
greater than the default -Walloc-size-larger-than=PTRDIFF_MAX). This
isn't helpful since we already know a SIZE_MAX will be caught at
run-time (this was an intentional design). To deal with this, we must
disable this check as it is both a false positive and redundant. (Clang
does not have this warning option.)
Unfortunately, just checking the -Wno-alloc-size-larger-than is not
sufficient to make the __alloc_size attribute behave correctly under
older GCC versions. The attribute itself must be disabled in those
situations too, as there appears to be no way to reliably silence the
SIZE_MAX constant expression cases for GCC versions less than 9.1:
In file included from ./include/linux/resource_ext.h:11,
from ./include/linux/pci.h:40,
from drivers/net/ethernet/intel/ixgbe/ixgbe.h:9,
from drivers/net/ethernet/intel/ixgbe/ixgbe_lib.c:4:
In function 'kmalloc_node',
inlined from 'ixgbe_alloc_q_vector' at ./include/linux/slab.h:743:9:
./include/linux/slab.h:618:9: error: argument 1 value '18446744073709551615' exceeds maximum object size 9223372036854775807 [-Werror=alloc-size-larger-than=]
return __kmalloc_node(size, flags, node);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/slab.h: In function 'ixgbe_alloc_q_vector':
./include/linux/slab.h:455:7: note: in a call to allocation function '__kmalloc_node' declared here
void *__kmalloc_node(size_t size, gfp_t flags, int node) __assume_slab_alignment __malloc;
^~~~~~~~~~~~~~
Specifically:
'-Wno-alloc-size-larger-than' is not correctly handled by GCC < 9.1
https://godbolt.org/z/hqsfG7q84 (doesn't disable)
https://godbolt.org/z/P9jdrPTYh (doesn't admit to not knowing about option)
https://godbolt.org/z/465TPMWKb (only warns when other warnings appear)
'-Walloc-size-larger-than=18446744073709551615' is not handled by GCC < 8.2
https://godbolt.org/z/73hh1EPxz (ignores numeric value)
Since anything marked with __alloc_size would also qualify for marking
with __malloc, just include __malloc along with it to avoid redundant
markings. (Suggested by Linus Torvalds.)
Finally, make sure checkpatch.pl doesn't get confused about finding the
__alloc_size attribute on functions. (Thanks to Joe Perches.)
Link: https://lkml.kernel.org/r/20210930222704.2631604-3-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dwaipayan Ray <dwaipayanray1@gmail.com>
Cc: Joe Perches <joe@perches.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Alexandre Bounine <alex.bou9@gmail.com>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jing Xiangfeng <jingxiangfeng@huawei.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-11-05 20:36:19 +00:00
|
|
|
/*
|
|
|
|
* Any place that could be marked with the "alloc_size" attribute is also
|
|
|
|
* a place to be marked with the "malloc" attribute. Do this as part of the
|
|
|
|
* __alloc_size macro to avoid redundant attributes and to avoid missing a
|
|
|
|
* __malloc marking.
|
|
|
|
*/
|
|
|
|
#ifdef __alloc_size__
|
|
|
|
# define __alloc_size(x, ...) __alloc_size__(x, ## __VA_ARGS__) __malloc
|
|
|
|
#else
|
|
|
|
# define __alloc_size(x, ...) __malloc
|
|
|
|
#endif
|
|
|
|
|
2018-10-31 19:39:01 +00:00
|
|
|
#ifndef asm_volatile_goto
|
|
|
|
#define asm_volatile_goto(x...) asm goto(x)
|
|
|
|
#endif
|
|
|
|
|
2019-09-12 22:19:25 +00:00
|
|
|
#ifdef CONFIG_CC_HAS_ASM_INLINE
|
|
|
|
#define asm_inline asm __inline
|
|
|
|
#else
|
|
|
|
#define asm_inline asm
|
|
|
|
#endif
|
|
|
|
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
/* Are two types/vars the same type (ignoring qualifiers)? */
|
2018-08-22 23:37:24 +00:00
|
|
|
#define __same_type(a, b) __builtin_types_compatible_p(typeof(a), typeof(b))
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
|
READ_ONCE: Drop pointer qualifiers when reading from scalar types
Passing a volatile-qualified pointer to READ_ONCE() is an absolute
trainwreck for code generation: the use of 'typeof()' to define a
temporary variable inside the macro means that the final evaluation in
macro scope ends up forcing a read back from the stack. When stack
protector is enabled (the default for arm64, at least), this causes
the compiler to vomit up all sorts of junk.
Unfortunately, dropping pointer qualifiers inside the macro poses quite
a challenge, especially since the pointed-to type is permitted to be an
aggregate, and this is relied upon by mm/ code accessing things like
'pmd_t'. Based on numerous hacks and discussions on the mailing list,
this is the best I've managed to come up with.
Introduce '__unqual_scalar_typeof()' which takes an expression and, if
the expression is an optionally qualified 8, 16, 32 or 64-bit scalar
type, evaluates to the unqualified type. Other input types, including
aggregates, remain unchanged. Hopefully READ_ONCE() on volatile aggregate
pointers isn't something we do on a fast-path.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Will Deacon <will@kernel.org>
2019-12-19 14:22:31 +00:00
|
|
|
/*
|
|
|
|
* __unqual_scalar_typeof(x) - Declare an unqualified scalar type, leaving
|
|
|
|
* non-scalar types unchanged.
|
compiler_types.h: Optimize __unqual_scalar_typeof compilation time
If the compiler supports C11's _Generic, use it to speed up compilation
times of __unqual_scalar_typeof(). GCC version 4.9 or later and
all supported versions of Clang support the feature (the oldest
supported compiler that doesn't support _Generic is GCC 4.8, for which
we use the slower alternative).
The non-_Generic variant relies on multiple expansions of
__pick_integer_type -> __pick_scalar_type -> __builtin_choose_expr,
which increases pre-processed code size, and can cause compile times to
increase in files with numerous expansions of READ_ONCE(), or other
users of __unqual_scalar_typeof().
Summary of compile-time benchmarking done by Arnd Bergmann:
<baseline normalized time> clang-11 gcc-9
this patch 0.78 0.91
ideal 0.76 0.86
See https://lkml.kernel.org/r/CAK8P3a3UYQeXhiufUevz=rwe09WM_vSTCd9W+KvJHJcOeQyWVA@mail.gmail.com
Further compile-testing done with:
gcc 4.8, 4.9, 5.5, 6.4, 7.5, 8.4;
clang 9, 10.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lkml.kernel.org/r/20200527103236.148700-1-elver@google.com
Link: https://lkml.kernel.org/r/CAK8P3a0RJtbVi1JMsfik=jkHCNFv+DJn_FeDg-YLW+ueQW3tNg@mail.gmail.com
[will: tweak new macros to make them a bit more readable]
Signed-off-by: Will Deacon <will@kernel.org>
2020-05-27 10:32:36 +00:00
|
|
|
*/
|
|
|
|
/*
|
2020-07-08 17:48:35 +00:00
|
|
|
* Prefer C11 _Generic for better compile-times and simpler code. Note: 'char'
|
compiler_types.h: Optimize __unqual_scalar_typeof compilation time
If the compiler supports C11's _Generic, use it to speed up compilation
times of __unqual_scalar_typeof(). GCC version 4.9 or later and
all supported versions of Clang support the feature (the oldest
supported compiler that doesn't support _Generic is GCC 4.8, for which
we use the slower alternative).
The non-_Generic variant relies on multiple expansions of
__pick_integer_type -> __pick_scalar_type -> __builtin_choose_expr,
which increases pre-processed code size, and can cause compile times to
increase in files with numerous expansions of READ_ONCE(), or other
users of __unqual_scalar_typeof().
Summary of compile-time benchmarking done by Arnd Bergmann:
<baseline normalized time> clang-11 gcc-9
this patch 0.78 0.91
ideal 0.76 0.86
See https://lkml.kernel.org/r/CAK8P3a3UYQeXhiufUevz=rwe09WM_vSTCd9W+KvJHJcOeQyWVA@mail.gmail.com
Further compile-testing done with:
gcc 4.8, 4.9, 5.5, 6.4, 7.5, 8.4;
clang 9, 10.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Tested-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lkml.kernel.org/r/20200527103236.148700-1-elver@google.com
Link: https://lkml.kernel.org/r/CAK8P3a0RJtbVi1JMsfik=jkHCNFv+DJn_FeDg-YLW+ueQW3tNg@mail.gmail.com
[will: tweak new macros to make them a bit more readable]
Signed-off-by: Will Deacon <will@kernel.org>
2020-05-27 10:32:36 +00:00
|
|
|
* is not type-compatible with 'signed char', and we define a separate case.
|
|
|
|
*/
|
|
|
|
#define __scalar_type_to_expr_cases(type) \
|
|
|
|
unsigned type: (unsigned type)0, \
|
|
|
|
signed type: (signed type)0
|
|
|
|
|
|
|
|
#define __unqual_scalar_typeof(x) typeof( \
|
|
|
|
_Generic((x), \
|
|
|
|
char: (char)0, \
|
|
|
|
__scalar_type_to_expr_cases(char), \
|
|
|
|
__scalar_type_to_expr_cases(short), \
|
|
|
|
__scalar_type_to_expr_cases(int), \
|
|
|
|
__scalar_type_to_expr_cases(long), \
|
|
|
|
__scalar_type_to_expr_cases(long long), \
|
|
|
|
default: (x)))
|
READ_ONCE: Drop pointer qualifiers when reading from scalar types
Passing a volatile-qualified pointer to READ_ONCE() is an absolute
trainwreck for code generation: the use of 'typeof()' to define a
temporary variable inside the macro means that the final evaluation in
macro scope ends up forcing a read back from the stack. When stack
protector is enabled (the default for arm64, at least), this causes
the compiler to vomit up all sorts of junk.
Unfortunately, dropping pointer qualifiers inside the macro poses quite
a challenge, especially since the pointed-to type is permitted to be an
aggregate, and this is relied upon by mm/ code accessing things like
'pmd_t'. Based on numerous hacks and discussions on the mailing list,
this is the best I've managed to come up with.
Introduce '__unqual_scalar_typeof()' which takes an expression and, if
the expression is an optionally qualified 8, 16, 32 or 64-bit scalar
type, evaluates to the unqualified type. Other input types, including
aggregates, remain unchanged. Hopefully READ_ONCE() on volatile aggregate
pointers isn't something we do on a fast-path.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Will Deacon <will@kernel.org>
2019-12-19 14:22:31 +00:00
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linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
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/* Is this type a native word size -- useful for atomic operations */
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2018-08-22 23:37:24 +00:00
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#define __native_word(t) \
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(sizeof(t) == sizeof(char) || sizeof(t) == sizeof(short) || \
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sizeof(t) == sizeof(int) || sizeof(t) == sizeof(long))
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2020-07-21 08:54:15 +00:00
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#ifdef __OPTIMIZE__
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# define __compiletime_assert(condition, msg, prefix, suffix) \
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do { \
|
2021-10-14 13:23:31 +00:00
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/* \
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* __noreturn is needed to give the compiler enough \
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* information to avoid certain possibly-uninitialized \
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* warnings (regardless of the build failing). \
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*/ \
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__noreturn extern void prefix ## suffix(void) \
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__compiletime_error(msg); \
|
2020-07-21 08:54:15 +00:00
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if (!(condition)) \
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prefix ## suffix(); \
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} while (0)
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#else
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# define __compiletime_assert(condition, msg, prefix, suffix) do { } while (0)
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#endif
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#define _compiletime_assert(condition, msg, prefix, suffix) \
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__compiletime_assert(condition, msg, prefix, suffix)
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/**
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* compiletime_assert - break build and emit msg if condition is false
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* @condition: a compile-time constant condition to check
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* @msg: a message to emit if condition is false
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*
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* In tradition of POSIX assert, this macro will break the build if the
|
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* supplied condition is *false*, emitting the supplied error message if the
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* compiler has support to do so.
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*/
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#define compiletime_assert(condition, msg) \
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_compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
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#define compiletime_assert_atomic_type(t) \
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compiletime_assert(__native_word(t), \
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"Need native word sized stores/loads for atomicity.")
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2018-08-22 23:37:24 +00:00
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/* Helpers for emitting diagnostics in pragmas. */
|
kbuild: add macro for controlling warnings to linux/compiler.h
I have occasionally run into a situation where it would make sense to
control a compiler warning from a source file rather than doing so from
a Makefile using the $(cc-disable-warning, ...) or $(cc-option, ...)
helpers.
The approach here is similar to what glibc uses, using __diag() and
related macros to encapsulate a _Pragma("GCC diagnostic ...") statement
that gets turned into the respective "#pragma GCC diagnostic ..." by
the preprocessor when the macro gets expanded.
Like glibc, I also have an argument to pass the affected compiler
version, but decided to actually evaluate that one. For now, this
supports GCC_4_6, GCC_4_7, GCC_4_8, GCC_4_9, GCC_5, GCC_6, GCC_7,
GCC_8 and GCC_9. Adding support for CLANG_5 and other interesting
versions is straightforward here. GNU compilers starting with gcc-4.2
could support it in principle, but "#pragma GCC diagnostic push"
was only added in gcc-4.6, so it seems simpler to not deal with those
at all. The same versions show a large number of warnings already,
so it seems easier to just leave it at that and not do a more
fine-grained control for them.
The use cases I found so far include:
- turning off the gcc-8 -Wattribute-alias warning inside of the
SYSCALL_DEFINEx() macro without having to do it globally.
- Reducing the build time for a simple re-make after a change,
once we move the warnings from ./Makefile and
./scripts/Makefile.extrawarn into linux/compiler.h
- More control over the warnings based on other configurations,
using preprocessor syntax instead of Makefile syntax. This should make
it easier for the average developer to understand and change things.
- Adding an easy way to turn the W=1 option on unconditionally
for a subdirectory or a specific file. This has been requested
by several developers in the past that want to have their subsystems
W=1 clean.
- Integrating clang better into the build systems. Clang supports
more warnings than GCC, and we probably want to classify them
as default, W=1, W=2 etc, but there are cases in which the
warnings should be classified differently due to excessive false
positives from one or the other compiler.
- Adding a way to turn the default warnings into errors (e.g. using
a new "make E=0" tag) while not also turning the W=1 warnings into
errors.
This patch for now just adds the minimal infrastructure in order to
do the first of the list above. As the #pragma GCC diagnostic
takes precedence over command line options, the next step would be
to convert a lot of the individual Makefiles that set nonstandard
options to use __diag() instead.
[paul.burton@mips.com:
- Rebase atop current master.
- Add __diag_GCC, or more generally __diag_<compiler>, abstraction to
avoid code outside of linux/compiler-gcc.h needing to duplicate
knowledge about different GCC versions.
- Add a comment argument to __diag_{ignore,warn,error} which isn't
used in the expansion of the macros but serves to push people to
document the reason for using them - per feedback from Kees Cook.
- Translate severity to GCC-specific pragmas in linux/compiler-gcc.h
rather than using GCC-specific in linux/compiler_types.h.
- Drop all but GCC 8 macros, since we only need to define macros for
versions that we need to introduce pragmas for, and as of this
series that's just GCC 8.
- Capitalize comments in linux/compiler-gcc.h to match the style of
the rest of the file.
- Line up macro definitions with tabs in linux/compiler-gcc.h.]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Tested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Tested-by: Stafford Horne <shorne@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2018-06-19 20:14:56 +00:00
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#ifndef __diag
|
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#define __diag(string)
|
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|
#endif
|
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|
|
#ifndef __diag_GCC
|
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|
|
#define __diag_GCC(version, severity, string)
|
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|
|
#endif
|
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|
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|
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|
|
#define __diag_push() __diag(push)
|
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|
|
#define __diag_pop() __diag(pop)
|
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|
|
#define __diag_ignore(compiler, version, option, comment) \
|
|
|
|
__diag_ ## compiler(version, ignore, option)
|
|
|
|
#define __diag_warn(compiler, version, option, comment) \
|
|
|
|
__diag_ ## compiler(version, warn, option)
|
|
|
|
#define __diag_error(compiler, version, option, comment) \
|
|
|
|
__diag_ ## compiler(version, error, option)
|
|
|
|
|
2022-03-04 22:46:43 +00:00
|
|
|
#ifndef __diag_ignore_all
|
|
|
|
#define __diag_ignore_all(option, comment)
|
|
|
|
#endif
|
|
|
|
|
linux/compiler.h: Split into compiler.h and compiler_types.h
linux/compiler.h is included indirectly by linux/types.h via
uapi/linux/types.h -> uapi/linux/posix_types.h -> linux/stddef.h
-> uapi/linux/stddef.h and is needed to provide a proper definition of
offsetof.
Unfortunately, compiler.h requires a definition of
smp_read_barrier_depends() for defining lockless_dereference() and soon
for defining READ_ONCE(), which means that all
users of READ_ONCE() will need to include asm/barrier.h to avoid splats
such as:
In file included from include/uapi/linux/stddef.h:1:0,
from include/linux/stddef.h:4,
from arch/h8300/kernel/asm-offsets.c:11:
include/linux/list.h: In function 'list_empty':
>> include/linux/compiler.h:343:2: error: implicit declaration of function 'smp_read_barrier_depends' [-Werror=implicit-function-declaration]
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
^
A better alternative is to include asm/barrier.h in linux/compiler.h,
but this requires a type definition for "bool" on some architectures
(e.g. x86), which is defined later by linux/types.h. Type "bool" is also
used directly in linux/compiler.h, so the whole thing is pretty fragile.
This patch splits compiler.h in two: compiler_types.h contains type
annotations, definitions and the compiler-specific parts, whereas
compiler.h #includes compiler-types.h and additionally defines macros
such as {READ,WRITE.ACCESS}_ONCE().
uapi/linux/stddef.h and linux/linkage.h are then moved over to include
linux/compiler_types.h, which fixes the build for h8 and blackfin.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1508840570-22169-2-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-10-24 10:22:46 +00:00
|
|
|
#endif /* __LINUX_COMPILER_TYPES_H */
|