Commit Graph

142 Commits

Author SHA1 Message Date
Chris Down 3370155737 printk: Userspace format indexing support
We have a number of systems industry-wide that have a subset of their
functionality that works as follows:

1. Receive a message from local kmsg, serial console, or netconsole;
2. Apply a set of rules to classify the message;
3. Do something based on this classification (like scheduling a
   remediation for the machine), rinse, and repeat.

As a couple of examples of places we have this implemented just inside
Facebook, although this isn't a Facebook-specific problem, we have this
inside our netconsole processing (for alarm classification), and as part
of our machine health checking. We use these messages to determine
fairly important metrics around production health, and it's important
that we get them right.

While for some kinds of issues we have counters, tracepoints, or metrics
with a stable interface which can reliably indicate the issue, in order
to react to production issues quickly we need to work with the interface
which most kernel developers naturally use when developing: printk.

Most production issues come from unexpected phenomena, and as such
usually the code in question doesn't have easily usable tracepoints or
other counters available for the specific problem being mitigated. We
have a number of lines of monitoring defence against problems in
production (host metrics, process metrics, service metrics, etc), and
where it's not feasible to reliably monitor at another level, this kind
of pragmatic netconsole monitoring is essential.

As one would expect, monitoring using printk is rather brittle for a
number of reasons -- most notably that the message might disappear
entirely in a new version of the kernel, or that the message may change
in some way that the regex or other classification methods start to
silently fail.

One factor that makes this even harder is that, under normal operation,
many of these messages are never expected to be hit. For example, there
may be a rare hardware bug which one wants to detect if it was to ever
happen again, but its recurrence is not likely or anticipated. This
precludes using something like checking whether the printk in question
was printed somewhere fleetwide recently to determine whether the
message in question is still present or not, since we don't anticipate
that it should be printed anywhere, but still need to monitor for its
future presence in the long-term.

This class of issue has happened on a number of occasions, causing
unhealthy machines with hardware issues to remain in production for
longer than ideal. As a recent example, some monitoring around
blk_update_request fell out of date and caused semi-broken machines to
remain in production for longer than would be desirable.

Searching through the codebase to find the message is also extremely
fragile, because many of the messages are further constructed beyond
their callsite (eg. btrfs_printk and other module-specific wrappers,
each with their own functionality). Even if they aren't, guessing the
format and formulation of the underlying message based on the aesthetics
of the message emitted is not a recipe for success at scale, and our
previous issues with fleetwide machine health checking demonstrate as
much.

This provides a solution to the issue of silently changed or deleted
printks: we record pointers to all printk format strings known at
compile time into a new .printk_index section, both in vmlinux and
modules. At runtime, this can then be iterated by looking at
<debugfs>/printk/index/<module>, which emits the following format, both
readable by humans and able to be parsed by machines:

    $ head -1 vmlinux; shuf -n 5 vmlinux
    # <level[,flags]> filename:line function "format"
    <5> block/blk-settings.c:661 disk_stack_limits "%s: Warning: Device %s is misaligned\n"
    <4> kernel/trace/trace.c:8296 trace_create_file "Could not create tracefs '%s' entry\n"
    <6> arch/x86/kernel/hpet.c:144 _hpet_print_config "hpet: %s(%d):\n"
    <6> init/do_mounts.c:605 prepare_namespace "Waiting for root device %s...\n"
    <6> drivers/acpi/osl.c:1410 acpi_no_auto_serialize_setup "ACPI: auto-serialization disabled\n"

This mitigates the majority of cases where we have a highly-specific
printk which we want to match on, as we can now enumerate and check
whether the format changed or the printk callsite disappeared entirely
in userspace. This allows us to catch changes to printks we monitor
earlier and decide what to do about it before it becomes problematic.

There is no additional runtime cost for printk callers or printk itself,
and the assembly generated is exactly the same.

Signed-off-by: Chris Down <chris@chrisdown.name>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kees Cook <keescook@chromium.org>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Tested-by: Petr Mladek <pmladek@suse.com>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Jessica Yu <jeyu@kernel.org> # for module.{c,h}
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/e42070983637ac5e384f17fbdbe86d19c7b212a5.1623775748.git.chris@chrisdown.name
2021-07-19 11:57:48 +02:00
Ard Biesheuvel 3cce9d4432 ARM: 9044/1: vfp: use undef hook for VFP support detection
Commit f77ac2e378 ("ARM: 9030/1: entry: omit FP emulation for UND
exceptions taken in kernel mode") failed to take into account that there
is in fact a case where we relied on this code path: during boot, the
VFP detection code issues a read of FPSID, which will trigger an undef
exception on cores that lack VFP support.

So let's reinstate this logic using an undef hook which is registered
only for the duration of the initcall to vpf_init(), and which sets
VFP_arch to a non-zero value - as before - if no VFP support is present.

Fixes: f77ac2e378 ("ARM: 9030/1: entry: omit FP emulation for UND ...")
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2020-12-21 11:19:19 +00:00
Ard Biesheuvel f77ac2e378 ARM: 9030/1: entry: omit FP emulation for UND exceptions taken in kernel mode
There are a couple of problems with the exception entry code that deals
with FP exceptions (which are reported as UND exceptions) when building
the kernel in Thumb2 mode:
- the conditional branch to vfp_kmode_exception in vfp_support_entry()
  may be out of range for its target, depending on how the linker decides
  to arrange the sections;
- when the UND exception is taken in kernel mode, the emulation handling
  logic is entered via the 'call_fpe' label, which means we end up using
  the wrong value/mask pairs to match and detect the NEON opcodes.

Since UND exceptions in kernel mode are unlikely to occur on a hot path
(as opposed to the user mode version which is invoked for VFP support
code and lazy restore), we can use the existing undef hook machinery for
any kernel mode instruction emulation that is needed, including calling
the existing vfp_kmode_exception() routine for unexpected cases. So drop
the call to call_fpe, and instead, install an undef hook that will get
called for NEON and VFP instructions that trigger an UND exception in
kernel mode.

While at it, make sure that the PC correction is accurate for the
execution mode where the exception was taken, by checking the PSR
Thumb bit.

Cc: Dmitry Osipenko <digetx@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Fixes: eff8728fe6 ("vmlinux.lds.h: Add PGO and AutoFDO input sections")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2020-12-08 10:15:00 +00:00
Stefan Agner 2cbd1cc3dc ARM: 8991/1: use VFP assembler mnemonics if available
The integrated assembler of Clang 10 and earlier do not allow to access
the VFP registers through the coprocessor load/store instructions:
arch/arm/vfp/vfpmodule.c:342:2: error: invalid operand for instruction
        fmxr(FPEXC, fpexc & ~(FPEXC_EX|FPEXC_DEX|FPEXC_FP2V|FPEXC_VV|FPEXC_TRAP_MASK));
        ^
arch/arm/vfp/vfpinstr.h:79:6: note: expanded from macro 'fmxr'
        asm("mcr p10, 7, %0, " vfpreg(_vfp_) ", cr0, 0 @ fmxr   " #_vfp_ ", %0"
            ^
<inline asm>:1:6: note: instantiated into assembly here
        mcr p10, 7, r0, cr8, cr0, 0 @ fmxr      FPEXC, r0
            ^

This has been addressed with Clang 11 [0]. However, to support earlier
versions of Clang and for better readability use of VFP assembler
mnemonics still is preferred.

Ideally we would replace this code with the unified assembler language
mnemonics vmrs/vmsr on call sites along with .fpu assembler directives.
The GNU assembler supports the .fpu directive at least since 2.17 (when
documentation has been added). Since Linux requires binutils 2.21 it is
safe to use .fpu directive. However, binutils does not allow to use
FPINST or FPINST2 as an argument to vmrs/vmsr instructions up to
binutils 2.24 (see binutils commit 16d02dc907c5):
arch/arm/vfp/vfphw.S: Assembler messages:
arch/arm/vfp/vfphw.S:162: Error: operand 0 must be FPSID or FPSCR pr FPEXC -- `vmsr FPINST,r6'
arch/arm/vfp/vfphw.S:165: Error: operand 0 must be FPSID or FPSCR pr FPEXC -- `vmsr FPINST2,r8'
arch/arm/vfp/vfphw.S:235: Error: operand 1 must be a VFP extension System Register -- `vmrs r3,FPINST'
arch/arm/vfp/vfphw.S:238: Error: operand 1 must be a VFP extension System Register -- `vmrs r12,FPINST2'

Use as-instr in Kconfig to check if FPINST/FPINST2 can be used. If they
can be used make use of .fpu directives and UAL VFP mnemonics for
register access.

This allows to build vfpmodule.c with Clang and its integrated assembler.

[0] https://reviews.llvm.org/D59733

Link: https://github.com/ClangBuiltLinux/linux/issues/905

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2020-07-21 16:33:39 +01:00
Stefan Agner a6c30873ee ARM: 8989/1: use .fpu assembler directives instead of assembler arguments
Explicit FPU selection has been introduced in commit 1a6be26d5b
("[ARM] Enable VFP to be built when non-VFP capable CPUs are selected")
to make use of assembler mnemonics for VFP instructions.

However, clang currently does not support passing assembler flags
like this and errors out with:
clang-10: error: the clang compiler does not support '-Wa,-mfpu=softvfp+vfp'

Make use of the .fpu assembler directives to select the floating point
hardware selectively. Also use the new unified assembler language
mnemonics. This allows to build these procedures with Clang.

Link: https://github.com/ClangBuiltLinux/linux/issues/762

Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2020-07-21 16:33:37 +01:00
Thomas Gleixner d2912cb15b treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500
Based on 2 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation #

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 4122 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-19 17:09:55 +02:00
Thomas Gleixner ec8f24b7fa treewide: Add SPDX license identifier - Makefile/Kconfig
Add SPDX license identifiers to all Make/Kconfig files which:

 - Have no license information of any form

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-21 10:50:46 +02:00
Linus Torvalds e2f8b472a7 Merge branch 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm
Pull ARM fix from Russell King:
 "It was noticed that one of Julien's patches contained an error, this
  fixes that up"

* 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 8810/1: vfp: Fix wrong assignement to ufp_exc
2018-11-14 13:40:22 -06:00
Julien Thierry 5df7a99bdd ARM: 8810/1: vfp: Fix wrong assignement to ufp_exc
In vfp_preserve_user_clear_hwstate, ufp_exc->fpinst2 gets assigned to
itself. It should actually be hwstate->fpinst2 that gets assigned to the
ufp_exc field.

Fixes commit 3aa2df6ec2 ("ARM: 8791/1:
vfp: use __copy_to_user() when saving VFP state").

Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-11-12 10:51:01 +00:00
Linus Torvalds ba9f6f8954 Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull siginfo updates from Eric Biederman:
 "I have been slowly sorting out siginfo and this is the culmination of
  that work.

  The primary result is in several ways the signal infrastructure has
  been made less error prone. The code has been updated so that manually
  specifying SEND_SIG_FORCED is never necessary. The conversion to the
  new siginfo sending functions is now complete, which makes it
  difficult to send a signal without filling in the proper siginfo
  fields.

  At the tail end of the patchset comes the optimization of decreasing
  the size of struct siginfo in the kernel from 128 bytes to about 48
  bytes on 64bit. The fundamental observation that enables this is by
  definition none of the known ways to use struct siginfo uses the extra
  bytes.

  This comes at the cost of a small user space observable difference.
  For the rare case of siginfo being injected into the kernel only what
  can be copied into kernel_siginfo is delivered to the destination, the
  rest of the bytes are set to 0. For cases where the signal and the
  si_code are known this is safe, because we know those bytes are not
  used. For cases where the signal and si_code combination is unknown
  the bits that won't fit into struct kernel_siginfo are tested to
  verify they are zero, and the send fails if they are not.

  I made an extensive search through userspace code and I could not find
  anything that would break because of the above change. If it turns out
  I did break something it will take just the revert of a single change
  to restore kernel_siginfo to the same size as userspace siginfo.

  Testing did reveal dependencies on preferring the signo passed to
  sigqueueinfo over si->signo, so bit the bullet and added the
  complexity necessary to handle that case.

  Testing also revealed bad things can happen if a negative signal
  number is passed into the system calls. Something no sane application
  will do but something a malicious program or a fuzzer might do. So I
  have fixed the code that performs the bounds checks to ensure negative
  signal numbers are handled"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (80 commits)
  signal: Guard against negative signal numbers in copy_siginfo_from_user32
  signal: Guard against negative signal numbers in copy_siginfo_from_user
  signal: In sigqueueinfo prefer sig not si_signo
  signal: Use a smaller struct siginfo in the kernel
  signal: Distinguish between kernel_siginfo and siginfo
  signal: Introduce copy_siginfo_from_user and use it's return value
  signal: Remove the need for __ARCH_SI_PREABLE_SIZE and SI_PAD_SIZE
  signal: Fail sigqueueinfo if si_signo != sig
  signal/sparc: Move EMT_TAGOVF into the generic siginfo.h
  signal/unicore32: Use force_sig_fault where appropriate
  signal/unicore32: Generate siginfo in ucs32_notify_die
  signal/unicore32: Use send_sig_fault where appropriate
  signal/arc: Use force_sig_fault where appropriate
  signal/arc: Push siginfo generation into unhandled_exception
  signal/ia64: Use force_sig_fault where appropriate
  signal/ia64: Use the force_sig(SIGSEGV,...) in ia64_rt_sigreturn
  signal/ia64: Use the generic force_sigsegv in setup_frame
  signal/arm/kvm: Use send_sig_mceerr
  signal/arm: Use send_sig_fault where appropriate
  signal/arm: Use force_sig_fault where appropriate
  ...
2018-10-24 11:22:39 +01:00
Russell King 3e98d24098 Merge branches 'fixes', 'misc' and 'spectre' into for-next 2018-10-10 13:53:33 +01:00
Julien Thierry 3aa2df6ec2 ARM: 8791/1: vfp: use __copy_to_user() when saving VFP state
Use __copy_to_user() rather than __put_user_error() for individual
members when saving VFP state.
This has the benefit of disabling/enabling PAN once per copied struct
intead of once per write.

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-10-05 10:51:15 +01:00
Eric W. Biederman b059454846 signal/arm: Use send_sig_fault where appropriate
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-09-27 21:57:40 +02:00
Russell King c61b466d4f Merge branches 'fixes', 'misc' and 'spectre' into for-linus
Conflicts:
	arch/arm/include/asm/uaccess.h

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-08-13 16:28:50 +01:00
Russell King 42019fc50d ARM: vfp: use __copy_from_user() when restoring VFP state
__get_user_error() is used as a fast accessor to make copying structure
members in the signal handling path as efficient as possible.  However,
with software PAN and the recent Spectre variant 1, the efficiency is
reduced as these are no longer fast accessors.

In the case of software PAN, it has to switch the domain register around
each access, and with Spectre variant 1, it would have to repeat the
access_ok() check for each access.

Use __copy_from_user() rather than __get_user_err() for individual
members when restoring VFP state.

Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-08-02 17:41:37 +01:00
Masahiro Yamada 35f5a6acfb ARM: 8782/1: vfp: clean up arch/arm/vfp/Makefile
Since commit 799c434154 ("kbuild: thin archives make default for
all archs"), $(AR) is used instead of $(LD) to combine object files.

The following code in arch/arm/vfp/Makefile:

  LDFLAGS         +=--no-warn-mismatch

... is no longer used.

Also, arch/arm/Makefile already guards arch/arm/vfp/ by a boolean
symbol, CONFIG_VFP, like this:

  core-$(CONFIG_VFP)              += arch/arm/vfp/

So, $(CONFIG_VFP) is always evaluated to y in arch/arm/vfp/Makefile.
There is no point to use pseudo object, vfp.o, which never becomes
a module.  Add all objects to obj-y directly.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-07-30 11:45:50 +01:00
Linus Torvalds 93e95fa574 Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull siginfo updates from Eric Biederman:
 "This set of changes close the known issues with setting si_code to an
  invalid value, and with not fully initializing struct siginfo. There
  remains work to do on nds32, arc, unicore32, powerpc, arm, arm64, ia64
  and x86 to get the code that generates siginfo into a simpler and more
  maintainable state. Most of that work involves refactoring the signal
  handling code and thus careful code review.

  Also not included is the work to shrink the in kernel version of
  struct siginfo. That depends on getting the number of places that
  directly manipulate struct siginfo under control, as it requires the
  introduction of struct kernel_siginfo for the in kernel things.

  Overall this set of changes looks like it is making good progress, and
  with a little luck I will be wrapping up the siginfo work next
  development cycle"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits)
  signal/sh: Stop gcc warning about an impossible case in do_divide_error
  signal/mips: Report FPE_FLTUNK for undiagnosed floating point exceptions
  signal/um: More carefully relay signals in relay_signal.
  signal: Extend siginfo_layout with SIL_FAULT_{MCEERR|BNDERR|PKUERR}
  signal: Remove unncessary #ifdef SEGV_PKUERR in 32bit compat code
  signal/signalfd: Add support for SIGSYS
  signal/signalfd: Remove __put_user from signalfd_copyinfo
  signal/xtensa: Use force_sig_fault where appropriate
  signal/xtensa: Consistenly use SIGBUS in do_unaligned_user
  signal/um: Use force_sig_fault where appropriate
  signal/sparc: Use force_sig_fault where appropriate
  signal/sparc: Use send_sig_fault where appropriate
  signal/sh: Use force_sig_fault where appropriate
  signal/s390: Use force_sig_fault where appropriate
  signal/riscv: Replace do_trap_siginfo with force_sig_fault
  signal/riscv: Use force_sig_fault where appropriate
  signal/parisc: Use force_sig_fault where appropriate
  signal/parisc: Use force_sig_mceerr where appropriate
  signal/openrisc: Use force_sig_fault where appropriate
  signal/nios2: Use force_sig_fault where appropriate
  ...
2018-06-04 15:23:48 -07:00
Russell King 92d44a42af ARM: fix kill( ,SIGFPE) breakage
Commit 7771c66457 ("signal/arm: Document conflicts with SI_USER and
SIGFPE") broke the siginfo structure for userspace triggered signals,
causing the strace testsuite to regress.  Fix this by eliminating
the FPE_FIXME definition (which is at the root of the breakage) and
use FPE_FLTINV instead for the case where the hardware appears to be
reporting nonsense.

Fixes: 7771c66457 ("signal/arm: Document conflicts with SI_USER and SIGFPE")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-05-19 18:49:43 +01:00
Eric W. Biederman 3eb0f5193b signal: Ensure every siginfo we send has all bits initialized
Call clear_siginfo to ensure every stack allocated siginfo is properly
initialized before being passed to the signal sending functions.

Note: It is not safe to depend on C initializers to initialize struct
siginfo on the stack because C is allowed to skip holes when
initializing a structure.

The initialization of struct siginfo in tracehook_report_syscall_exit
was moved from the helper user_single_step_siginfo into
tracehook_report_syscall_exit itself, to make it clear that the local
variable siginfo gets fully initialized.

In a few cases the scope of struct siginfo has been reduced to make it
clear that siginfo siginfo is not used on other paths in the function
in which it is declared.

Instances of using memset to initialize siginfo have been replaced
with calls clear_siginfo for clarity.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-04-25 10:40:51 -05:00
Fabio Estevam 1328f02005 ARM: 8746/1: vfp: Go back to clearing vfp_current_hw_state[]
Commit 384b38b669 ("ARM: 7873/1: vfp: clear vfp_current_hw_state
for dying cpu") fixed the cpu dying notifier by clearing
vfp_current_hw_state[]. However commit e5b61bafe7 ("arm: Convert VFP
hotplug notifiers to state machine") incorrectly used the original
vfp_force_reload() function in the cpu dying notifier.

Fix it by going back to clearing vfp_current_hw_state[].

Fixes: e5b61bafe7 ("arm: Convert VFP hotplug notifiers to state machine")
Cc: linux-stable <stable@vger.kernel.org>
Reported-by: Kohji Okuno <okuno.kohji@jp.panasonic.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-03-24 14:27:48 +00:00
Eric W. Biederman 7771c66457 signal/arm: Document conflicts with SI_USER and SIGFPE
Setting si_code to 0 results in a userspace seeing an si_code of 0.
This is the same si_code as SI_USER.  Posix and common sense requires
that SI_USER not be a signal specific si_code.  As such this use of 0
for the si_code is a pretty horribly broken ABI.

Further use of si_code == 0 guaranteed that copy_siginfo_to_user saw a
value of __SI_KILL and now sees a value of SIL_KILL with the result
that uid and pid fields are copied and which might copying the si_addr
field by accident but certainly not by design.  Making this a very
flakey implementation.

Utilizing FPE_FIXME, siginfo_layout will now return SIL_FAULT and the
appropriate fields will be reliably copied.

Possible ABI fixes includee:
- Send the signal without siginfo
- Don't generate a signal
- Possibly assign and use an appropriate si_code
- Don't handle cases which can't happen

Cc: Russell King <rmk@flint.arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Ref: 451436b7bbb2 ("[ARM] Add support code for ARM hardware vector floating point")
History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2018-01-12 14:21:05 -06:00
Ingo Molnar 3f07c01441 sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h>
We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:29 +01:00
Thomas Gleixner 73c1b41e63 cpu/hotplug: Cleanup state names
When the state names got added a script was used to add the extra argument
to the calls. The script basically converted the state constant to a
string, but the cleanup to convert these strings into meaningful ones did
not happen.

Replace all the useless strings with 'subsys/xxx/yyy:state' strings which
are used in all the other places already.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Link: http://lkml.kernel.org/r/20161221192112.085444152@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2016-12-25 10:47:44 +01:00
Nicolas Pitre a85b2257a5 ARM: 8629/1: vfp: properly tag assembly function declarations in C code
This is good for consistency even if there is no difference in compiled
code. LTO might rely on this eventually. No need to preserve the extern
attribute as it is the default with function prototypes.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2016-11-22 11:45:09 +00:00
Thomas Gleixner e5b61bafe7 arm: Convert VFP hotplug notifiers to state machine
Straight forward conversion plus commentary why code which is executed
in hotplug callbacks needs to be invoked before installing them.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160713153335.713612993@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-15 10:40:22 +02:00
Jiri Slaby e64646946e exit_thread: accept a task parameter to be exited
We need to call exit_thread from copy_process in a fail path.  So make it
accept task_struct as a parameter.

[v2]
* s390: exit_thread_runtime_instr doesn't make sense to be called for
  non-current tasks.
* arm: fix the comment in vfp_thread_copy
* change 'me' to 'tsk' for task_struct
* now we can change only archs that actually have exit_thread

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Howells <dhowells@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-05-20 17:58:30 -07:00
Florian Fainelli 7d7d7a413c ARM: vfp: Add vfp_disable for problematic platforms
Some platforms might not be able to fully utilize VFP when e.g: one CPU
out of two in a SMP complex lacks a VFP unit. Adding code to migrate
task to the CPU which has a VFP unit would be cumbersome and not
performant, instead, just add the ability to disable VFP.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
2015-05-20 15:07:00 -07:00
Russell King 4ed89f2228 ARM: convert printk(KERN_* to pr_*
Convert many (but not all) printk(KERN_* to pr_* to simplify the code.
We take the opportunity to join some printk lines together so we don't
split the message across several lines, and we also add a few levels
to some messages which were previously missing them.

Tested-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-11-21 15:24:50 +00:00
Stephen Boyd 2b94fe2ac9 ARM: 8215/1: vfp: Silence mvfr0 variable unused warning
Stephen Rothwell reports that commit 3f4c9f8f0a20 ("ARM: 8197/1:
vfp: Fix VFPv3 hwcap detection on CPUID based cpus") introduced a
variable unused warning.

arch/arm/vfp/vfpmodule.c: In function 'vfp_init':
arch/arm/vfp/vfpmodule.c:725:6: warning: unused variable 'mvfr0'
[-Wunused-variable]
  u32 mvfr0;

Silence this warning by using IS_ENABLED instead of ifdefs.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-11-21 15:24:44 +00:00
Stephen Boyd 6c96a4a6e2 ARM: 8197/1: vfp: Fix VFPv3 hwcap detection on CPUID based cpus
The subarchitecture field in the fpsid register is 7 bits wide on
ARM CPUs using the CPUID identification scheme, spanning bits 22
to 16. The topmost bit is used to designate that the
subarchitecture designer is not ARM when it is set to 1. On
non-CPUID scheme CPUs the subarchitecture field is only 4 bits
wide and the higher bits are used to indicate no double precision
support (bit 20) and the FTSMX/FLDMX format (bits 21-22).

The VFP support code only looks at bits 19-16 to determine the
VFP version. On Qualcomm's processors (Krait and Scorpion) we
should see that we have HWCAP_VFPv3 but we don't because bit 22
is set to 1 to indicate that the subarchitecture is not
implemented by ARM and the rest of the bits are left as 0 because
this is the first subarchitecture that Qualcomm has designed.
Unfortunately we can't just widen the FPSID subarchitecture
bitmask to consider all the bits on a CPUID scheme because there
may be CPUs without the CPUID scheme that have VFP without double
precision support and then the version would be a very wrong and
large number. Instead, update the version detection logic to
consider if the CPU is using the CPUID scheme.

If the CPU is using CPUID scheme, use the MVFR registers to
determine what version of VFP is supported. We already do this
for VFPv4, so do something similar for VFPv3 and look for single
or double precision support in MVFR0. Otherwise fall back to
using FPSID to detect VFP support on non-CPUID scheme CPUs. We
know that VFPv3 is only present in CPUs that have support for the
CPUID scheme so this should be equivalent.

Tested-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-11-21 15:24:43 +00:00
Stepan Moskovchenko 1ca8bf6f7b ARM: 8195/1: vfp: Bounce undefined instructions in vectored mode
Certain ARM CPU implementations (e.g. Cortex-A15) may not raise a
floating- point exception whenever deprecated short-vector VFP
instructions are executed. Instead these instructions are treated
as UNALLOCATED. Change the VFP exception handling code to emulate
short-vector instructions even if FPEXC exception bits are not
set.

Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Tested-by: Will Deacon <will.deacon@arm.com>
Tested-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-11-17 20:53:57 +00:00
Russell King 6ebbf2ce43 ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+
ARMv6 and greater introduced a new instruction ("bx") which can be used
to return from function calls.  Recent CPUs perform better when the
"bx lr" instruction is used rather than the "mov pc, lr" instruction,
and this sequence is strongly recommended to be used by the ARM
architecture manual (section A.4.1.1).

We provide a new macro "ret" with all its variants for the condition
code which will resolve to the appropriate instruction.

Rather than doing this piecemeal, and miss some instances, change all
the "mov pc" instances to use the new macro, with the exception of
the "movs" instruction and the kprobes code.  This allows us to detect
the "mov pc, lr" case and fix it up - and also gives us the possibility
of deploying this for other registers depending on the CPU selection.

Reported-by: Will Deacon <will.deacon@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S
Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385
Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci
Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M
Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-07-18 12:29:04 +01:00
Russell King 1fb333489f Merge branches 'alignment', 'fixes', 'l2c' (early part) and 'misc' into for-next 2014-06-05 12:35:52 +01:00
Catalin Marinas 1417a6b8dc ARM: 8036/1: Enable IRQs before attempting to read user space in __und_usr
The Undef abort handler in the kernel reads the undefined instruction
from user space. If the page table was modified from another CPU, the
user access could fail and do_page_fault() will be executed with
interrupts disabled. This can potentially deadlock on ARM11MPCore or on
Cortex-A15 with erratum 798181 workaround enabled (both implying IPI for
TLB maintenance with page table lock held).

This patch enables the IRQs in __und_usr before attempting to read the
instruction from user space.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Arun KS <getarunks@gmail.com>
Cc: Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Ryan Mallon <rmallon@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-04-25 12:06:38 +01:00
Jay Foad 244b478386 ARM: 8026/1: Fix emulation of multiply accumulate instructions
The emulation for single and double precision multiply accumulate
instructions correctly normalised any denormal values in the operand
registers, but failed to normalise the destination (accumulator)
register.

This fixes https://bugzilla.kernel.org/show_bug.cgi?id=70501

Signed-off-by: Jay Foad <jay.foad@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-04-14 23:28:24 +01:00
Catalin Marinas 0b1f68e836 ARM: 8018/1: Add {inc,dec}_preempt_count asm macros
The patch adds asm macros for inc_preempt_count and dec_preempt_count_ti
(which also gets the current thread_info) instead of open-coding them in
arch/arm/vfp/*.S files.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Arun KS <getarunks@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-04-09 13:08:08 +01:00
Catalin Marinas 39ad04ccd6 ARM: 8017/1: Move asm macro get_thread_info to asm/assembler.h
asm/assembler.h is a better place for this macro since it is used by
asm files outside arch/arm/kernel/

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Arun KS <getarunks@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2014-04-09 13:08:07 +01:00
Yuanyuan Zhong 384b38b669 ARM: 7873/1: vfp: clear vfp_current_hw_state for dying cpu
The CPU_DYING notifier is called by cpu stopper task which
does not own the context held in the VFP hardware. Calling
vfp_force_reload() has no effect.
Replace it with clearing vfp_current_hw_state.

Signed-off-by: Yuanyuan Zhong <zyy@motorola.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-10-30 22:10:10 +00:00
Ard Biesheuvel 73c132c15d ARM: add support for kernel mode NEON
In order to safely support the use of NEON instructions in
kernel mode, some precautions need to be taken:
- the userland context that may be present in the registers (even
  if the NEON/VFP is currently disabled) must be stored under the
  correct task (which may not be 'current' in the UP case),
- to avoid having to keep track of additional vfpstates for the
  kernel side, disallow the use of NEON in interrupt context
  and run with preemption disabled,
- after use, re-enable preemption and re-enable the lazy restore
  machinery by disabling the NEON/VFP unit.

This patch adds the functions kernel_neon_begin() and
kernel_neon_end() which take care of the above. It also adds
the Kconfig symbol KERNEL_MODE_NEON to enable it.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
2013-07-08 22:08:51 +01:00
Ard Biesheuvel ab3da15643 ARM: be strict about FP exceptions in kernel mode
The support code in vfp_support_entry does not care whether the
exception that caused it to be invoked occurred in kernel mode or
in user mode. However, neither condition that could trigger this
exception (lazy restore and VFP bounce to support code) is
currently allowable in kernel mode.

In either case, print a message describing the condition before
letting the undefined instruction handler run its course and trigger
an oops.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
2013-07-08 22:07:38 +01:00
Ard Biesheuvel 0773d73d81 ARM: move VFP init to an earlier boot stage
In order to use the NEON unit in the kernel, we should
initialize it a bit earlier in the boot process so NEON users
that like to do a quick benchmark at load time (like the
xor_blocks or RAID-6 code) find the NEON/VFP unit already
enabled.

Replaced late_initcall() with core_initcall().

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
2013-07-08 18:22:19 +01:00
Will Deacon f27d6e1723 ARM: 7729/1: vfp: ensure VFP_arch is non-zero when VFP is not supported
Commit d3f79584a8 ("ARM: cleanup undefined instruction entry code")
improved the register scheduling when handling undefined instructions.
A side effect of this is that r5 is now used as a temporary, whilst the
VFP probing code relies on r5 containing a non-zero value when VFP is
not supported.

This patch fixes the VFP detection code so that we don't rely on the
contents of r5. Without this patch, Linux dies loudly on CPUs without
VFP support.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-05-22 22:01:37 +01:00
Russell King ded3ef0fa7 ARM: Fix broken commit 0cc41e4a21 corrupting kernel messages
Commit 0cc41e4a21 (arch: remove direct definitions of KERN_<LEVEL>
uses) is broken - not enough thought was put into changing:

	.asciz	"string"

to

	.asciz	"string1" "string2"

The problem is that each string gets _separately_ NUL terminated, so
the result is a string containing:

	"string1\0string2\0"

rather than:

	"string1string2\0"

With our new printk levels, this ends up as - eg, KERN_DEBUG "string":

	0x01 0x00 0x07 0x00 "string" 0x00

which produces lots of \x01 in the kernel log.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-03-01 21:09:59 +00:00
Russell King 5e4ba617c1 ARM: VFP: fix emulation of second VFP instruction
Martin Storsjö reports that the sequence:

        ee312ac1        vsub.f32        s4, s3, s2
        ee702ac0        vsub.f32        s5, s1, s0
        e59f0028        ldr             r0, [pc, #40]
        ee111a90        vmov            r1, s3

on Raspberry Pi (implementor 41 architecture 1 part 20 variant b rev 5)
where s3 is a denormal and s2 is zero results in incorrect behaviour -
the instruction "vsub.f32 s5, s1, s0" is not executed:

        VFP: bounce: trigger ee111a90 fpexc d0000780
        VFP: emulate: INST=0xee312ac1 SCR=0x00000000
        ...

As we can see, the instruction triggering the exception is the "vmov"
instruction, and we emulate the "vsub.f32 s4, s3, s2" but fail to
properly take account of the FPEXC_FP2V flag in FPEXC.  This is because
the test for the second instruction register being valid is bogus, and
will always skip emulation of the second instruction.

Cc: <stable@vger.kernel.org>
Reported-by: Martin Storsjö <martin@martin.st>
Tested-by: Martin Storsjö <martin@martin.st>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-02-25 16:09:12 +00:00
Stephen Boyd 568dca15aa ARM: 7627/1: Predicate preempt logic on PREEMP_COUNT not PREEMPT alone
Patrik Kluba reports that the preempt count becomes invalid due
to the preempt_enable() call being unbalanced with a
preempt_disable() call in the vfp assembly routines. This happens
because preempt_enable() and preempt_disable() update preempt
counts under PREEMPT_COUNT=y but the vfp assembly routines do so
under PREEMPT=y. In a configuration where PREEMPT=n and
DEBUG_ATOMIC_SLEEP=y, PREEMPT_COUNT=y and so the preempt_enable()
call in VFP_bounce() keeps subtracting from the preempt count
until it goes negative.

Fix this by always using PREEMPT_COUNT to decided when to update
preempt counts in the ARM assembly code.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reported-by: Patrik Kluba <pkluba@dension.com>
Tested-by: Patrik Kluba <pkluba@dension.com>
Cc: <stable@vger.kernel.org> # 2.6.30
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2013-01-16 16:51:10 +00:00
Paul Walmsley 39141ddfb6 ARM: 7566/1: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set
After commit 846a136881 ("ARM: vfp: fix
saving d16-d31 vfp registers on v6+ kernels"), the OMAP 2430SDP board
started crashing during boot with omap2plus_defconfig:

[    3.875122] mmcblk0: mmc0:e624 SD04G 3.69 GiB
[    3.915954]  mmcblk0: p1
[    4.086639] Internal error: Oops - undefined instruction: 0 [#1] SMP ARM
[    4.093719] Modules linked in:
[    4.096954] CPU: 0    Not tainted  (3.6.0-02232-g759e00b #570)
[    4.103149] PC is at vfp_reload_hw+0x1c/0x44
[    4.107666] LR is at __und_usr_fault_32+0x0/0x8

It turns out that the context save/restore fix unmasked a latent bug
in commit 5aaf254409 ("ARM: 6203/1: Make
VFPv3 usable on ARMv6").  When CONFIG_VFPv3 is set, but the kernel is
booted on a pre-VFPv3 core, the code attempts to save and restore the
d16-d31 VFP registers.  These are only present on non-D16 VFPv3+, so
this results in an undefined instruction exception.  The code didn't
crash before commit 846a136 because the save and restore code was
only touching d0-d15, present on all VFP.

Fix by implementing a request from Russell King to add a new HWCAP
flag that affirmatively indicates the presence of the d16-d31
registers:

   http://marc.info/?l=linux-arm-kernel&m=135013547905283&w=2

and some feedback from Måns to clarify the name of the HWCAP flag.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Martin <dave.martin@linaro.org>
Cc: Måns Rullgård <mans.rullgard@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-10-29 10:04:05 +00:00
Will Deacon 3d9fb0038a ARM: 7483/1: vfp: only advertise VFPv4 in hwcaps if CONFIG_VFPv3 is enabled
VFPv4 support depends on the VFPv3 context save/restore code, so only
advertise support in the hwcaps if the kernel can actually handle it.

Cc: <stable@vger.kernel.org> # 3.1+
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-08-11 09:15:57 +01:00
Linus Torvalds 9a2533c3eb Merge branch 'fixes' of git://git.linaro.org/people/rmk/linux-arm
Pull ARM fixes from Russell King:
 "This fixes various issues found during July"

* 'fixes' of git://git.linaro.org/people/rmk/linux-arm:
  ARM: 7479/1: mm: avoid NULL dereference when flushing gate_vma with VIVT caches
  ARM: Fix undefined instruction exception handling
  ARM: 7480/1: only call smp_send_stop() on SMP
  ARM: 7478/1: errata: extend workaround for erratum #720789
  ARM: 7477/1: vfp: Always save VFP state in vfp_pm_suspend on UP
  ARM: 7476/1: vfp: only clear vfp state for current cpu in vfp_pm_suspend
  ARM: 7468/1: ftrace: Trace function entry before updating index
  ARM: 7467/1: mutex: use generic xchg-based implementation for ARMv6+
  ARM: 7466/1: disable interrupt before spinning endlessly
  ARM: 7465/1: Handle >4GB memory sizes in device tree and mem=size@start option
2012-08-01 16:30:45 -07:00
Russell King 15ac49b650 ARM: Fix undefined instruction exception handling
While trying to get a v3.5 kernel booted on the cubox, I noticed that
VFP does not work correctly with VFP bounce handling.  This is because
of the confusion over 16-bit vs 32-bit instructions, and where PC is
supposed to point to.

The rule is that FP handlers are entered with regs->ARM_pc pointing at
the _next_ instruction to be executed.  However, if the exception is
not handled, regs->ARM_pc points at the faulting instruction.

This is easy for ARM mode, because we know that the next instruction and
previous instructions are separated by four bytes.  This is not true of
Thumb2 though.

Since all FP instructions are 32-bit in Thumb2, it makes things easy.
We just need to select the appropriate adjustment.  Do this by moving
the adjustment out of do_undefinstr() into the assembly code, as only
the assembly code knows whether it's dealing with a 32-bit or 16-bit
instruction.

Cc: <stable@vger.kernel.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-07-31 12:04:30 +01:00
Colin Cross 24b35521b8 ARM: 7477/1: vfp: Always save VFP state in vfp_pm_suspend on UP
vfp_pm_suspend should save the VFP state in suspend after
any lazy context switch.  If it only saves when the VFP is enabled,
the state can get lost when, on a UP system:
  Thread 1 uses the VFP
  Context switch occurs to thread 2, VFP is disabled but the
     VFP context is not saved
  Thread 2 initiates suspend
  vfp_pm_suspend is called with the VFP disabled, and the unsaved
     VFP context of Thread 1 in the registers

Modify vfp_pm_suspend to save the VFP context whenever
vfp_current_hw_state is not NULL.

Includes a fix from Ido Yariv <ido@wizery.com>, who pointed out that on
SMP systems, the state pointer can be pointing to a freed task struct if
a task exited on another cpu, fixed by using #ifndef CONFIG_SMP in the
new if clause.

Cc: Barry Song <bs14@csr.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ido Yariv <ido@wizery.com>
Cc: Daniel Drake <dsd@laptop.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-07-31 10:30:43 +01:00