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689b097a06
The kernel supports a minimum GCC version of 5.1.0 for building. However,
the "__diag_ignore_all" directive only suppresses the
"-Wmissing-prototypes" warning for GCC versions >= 8.0.0. As a result, when
building the kernel with older GCC versions, warnings may be triggered. The
example below illustrates the warnings reported by the kernel test robot
using GCC 7.5.0:
compiler: gcc-7 (Ubuntu 7.5.0-6ubuntu2) 7.5.0
All warnings (new ones prefixed by >>):
kernel/bpf/helpers.c:1893:19: warning: no previous prototype for 'bpf_obj_new_impl' [-Wmissing-prototypes]
__bpf_kfunc void *bpf_obj_new_impl(u64 local_type_id__k, void *meta__ign)
^~~~~~~~~~~~~~~~
kernel/bpf/helpers.c:1907:19: warning: no previous prototype for 'bpf_percpu_obj_new_impl' [-Wmissing-prototypes]
__bpf_kfunc void *bpf_percpu_obj_new_impl(u64 local_type_id__k, void *meta__ign)
[...]
To address this, we should also suppress the "-Wmissing-prototypes" warning
for older GCC versions. "#pragma GCC diagnostic push" is supported as
of GCC 4.6, and both "-Wmissing-prototypes" and "-Wmissing-declarations"
are supported for all the GCC versions that we currently support.
Therefore, it is reasonable to suppress these warnings for all supported
GCC versions.
With this adjustment, it's important to note that after implementing
"__diag_ignore_all", it will effectively suppress warnings for all the
supported GCC versions.
In the future, if you wish to suppress warnings that are only supported on
higher GCC versions, it is advisable to explicitly use "__diag_ignore" to
specify the GCC version you are targeting.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311031651.A7crZEur-lkp@intel.com/
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20231106031802.4188-1-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
147 lines
4.1 KiB
C
147 lines
4.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_COMPILER_TYPES_H
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#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
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#endif
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/*
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* Common definitions for all gcc versions go here.
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*/
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#define GCC_VERSION (__GNUC__ * 10000 \
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+ __GNUC_MINOR__ * 100 \
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+ __GNUC_PATCHLEVEL__)
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/*
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* This macro obfuscates arithmetic on a variable address so that gcc
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* shouldn't recognize the original var, and make assumptions about it.
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*
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* This is needed because the C standard makes it undefined to do
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* pointer arithmetic on "objects" outside their boundaries and the
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* gcc optimizers assume this is the case. In particular they
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* assume such arithmetic does not wrap.
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*
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* A miscompilation has been observed because of this on PPC.
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* To work around it we hide the relationship of the pointer and the object
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* using this macro.
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*
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* Versions of the ppc64 compiler before 4.1 had a bug where use of
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* RELOC_HIDE could trash r30. The bug can be worked around by changing
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* the inline assembly constraint from =g to =r, in this particular
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* case either is valid.
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*/
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#define RELOC_HIDE(ptr, off) \
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({ \
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unsigned long __ptr; \
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__asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
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(typeof(ptr)) (__ptr + (off)); \
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})
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#ifdef CONFIG_RETPOLINE
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#define __noretpoline __attribute__((__indirect_branch__("keep")))
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#endif
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#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
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#define __latent_entropy __attribute__((latent_entropy))
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#endif
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/*
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* calling noreturn functions, __builtin_unreachable() and __builtin_trap()
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* confuse the stack allocation in gcc, leading to overly large stack
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* frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
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*
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* Adding an empty inline assembly before it works around the problem
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*/
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#define barrier_before_unreachable() asm volatile("")
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/*
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* Mark a position in code as unreachable. This can be used to
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* suppress control flow warnings after asm blocks that transfer
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* control elsewhere.
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*/
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#define unreachable() \
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do { \
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annotate_unreachable(); \
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barrier_before_unreachable(); \
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__builtin_unreachable(); \
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} while (0)
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#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
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#define __HAVE_BUILTIN_BSWAP32__
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#define __HAVE_BUILTIN_BSWAP64__
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#define __HAVE_BUILTIN_BSWAP16__
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#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
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#if GCC_VERSION >= 70000
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#define KASAN_ABI_VERSION 5
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#else
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#define KASAN_ABI_VERSION 4
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#endif
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#ifdef CONFIG_SHADOW_CALL_STACK
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#define __noscs __attribute__((__no_sanitize__("shadow-call-stack")))
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#endif
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#define __no_sanitize_address __attribute__((__no_sanitize_address__))
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#if defined(__SANITIZE_THREAD__)
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#define __no_sanitize_thread __attribute__((__no_sanitize_thread__))
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#else
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#define __no_sanitize_thread
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#endif
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#define __no_sanitize_undefined __attribute__((__no_sanitize_undefined__))
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/*
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* Only supported since gcc >= 12
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*/
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#if defined(CONFIG_KCOV) && __has_attribute(__no_sanitize_coverage__)
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#define __no_sanitize_coverage __attribute__((__no_sanitize_coverage__))
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#else
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#define __no_sanitize_coverage
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#endif
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/*
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* Treat __SANITIZE_HWADDRESS__ the same as __SANITIZE_ADDRESS__ in the kernel,
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* matching the defines used by Clang.
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*/
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#ifdef __SANITIZE_HWADDRESS__
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#define __SANITIZE_ADDRESS__
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#endif
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/*
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* GCC does not support KMSAN.
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*/
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#define __no_sanitize_memory
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#define __no_kmsan_checks
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/*
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* Turn individual warnings and errors on and off locally, depending
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* on version.
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*/
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#define __diag_GCC(version, severity, s) \
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__diag_GCC_ ## version(__diag_GCC_ ## severity s)
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/* Severity used in pragma directives */
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#define __diag_GCC_ignore ignored
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#define __diag_GCC_warn warning
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#define __diag_GCC_error error
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#define __diag_str1(s) #s
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#define __diag_str(s) __diag_str1(s)
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#define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
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#if GCC_VERSION >= 80000
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#define __diag_GCC_8(s) __diag(s)
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#else
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#define __diag_GCC_8(s)
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#endif
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#define __diag_ignore_all(option, comment) \
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__diag(__diag_GCC_ignore option)
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/*
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* Prior to 9.1, -Wno-alloc-size-larger-than (and therefore the "alloc_size"
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* attribute) do not work, and must be disabled.
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*/
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#if GCC_VERSION < 90100
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#undef __alloc_size__
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#endif
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