Messages in this thread | | | Subject | Re: [PATCH] x86/process: Silence KASAN warnings in get_wchan() | From | Andrey Ryabinin <> | Date | Wed, 7 Oct 2015 12:11:05 +0300 |
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On 10/07/2015 11:54 AM, Andrey Ryabinin wrote: > On 10/06/2015 09:11 PM, Andy Lutomirski wrote: >> >> But what's wrong with the GCC attribute mechanism? Surely GCC ought >> to be able to generate the code, at least in the simple cases, and the >> attribute already exists. The attribute and READ_ONCE_NOCHECK seem >> like the least messy in the C code. > > The problem with 'no_sanitize_address' attribute is incompatibility with inlining. > GCC can't inline function with that attribute into function without it. > And the contrary is also true - GCC can't inline function without attribute into function with such attribute. > > Failure to inline always_inline function leads to build failure. > And under CONFIG_OPTIMIZE=n 'inline' means 'always_inline'. > > include/linux/compiler-gcc.h: > > #if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \ > !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) > #define inline inline __attribute__((always_inline)) notrace >
Huh, 'inline' effectively means 'always_inline' on every arch, except x86. This looks like a bug IMO. Allowing gcc to uninline functions marked 'inline' could be beneficial for some arches/configs.
$ git grep ARCH_SUPPORTS_OPTIMIZED_INLINING arch/tile/Kconfig:config ARCH_SUPPORTS_OPTIMIZED_INLINING arch/x86/Kconfig:config ARCH_SUPPORTS_OPTIMIZED_INLINING include/linux/compiler-gcc.h:#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
$ git grep OPTIMIZE_INLINING arch/x86/Kconfig.debug:config OPTIMIZE_INLINING arch/x86/configs/i386_defconfig:CONFIG_OPTIMIZE_INLINING=y arch/x86/configs/x86_64_defconfig:CONFIG_OPTIMIZE_INLINING=y arch/x86/entry/vdso/vdso32/vclock_gettime.c:#undef CONFIG_OPTIMIZE_INLINING include/linux/compiler-gcc.h: !defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4) kernel/configs/tiny.config:CONFIG_OPTIMIZE_INLINING=y
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