On 13/06/18 23:05, Nick Desaulniers wrote: > paravirt depends on a custom calling convention (callee saved), but > expects this from a static inline function that it then forces to be > outlined. This is problematic because different compilers or flags can > then add a stack guard that violates the calling conventions. > > Uses extern inline with the out-of-line definition in assembly to > prevent compilers from adding stack guards to the outlined version. > > Other parts of the codebase overwrite KBUILD_CFLAGS, which is *extremely > problematic* for extern inline, as the sematics are completely the > opposite depending on what C standard is used. > http://blahg.josefsipek.net/?p=529 > > Changes since v4: > Take Arnd's and hpa's suggestions properly feature detect gnu_inline > attribute to support gcc 4.1. > > Changes since v3: > Take Joe's suggestion to hoist __inline__ and __inline out of > conditional block. > > Changes since v2: > Take hpa's _ASM_ARG patch into the set in order to simplify cross > 32b/64b x86 assembly and rebase my final patch to use it. Apply > Sedat's typo fix to commit message and sign off on it. Take Joe's > suggestion to simplify __inline__ and __inline. Add Arnd to list of > folks who made helpful suggestions. > > Changes since v1: > Prefer gnu_inline function attribute instead of explicitly setting C > standard compiler flag in problematic Makefiles. We should instead > carefully evaluate if those Makefiles should be overwriting > KBUILD_CFLAGS at all. Dropped the previous first two patches and added > a new first patch. > > H. Peter Anvin (1): > x86/asm: add _ASM_ARG* constants for argument registers to <asm/asm.h> > > Nick Desaulniers (2): > compiler-gcc.h: add gnu_inline to all inline declarations > x86: paravirt: make native_save_fl extern inline > > arch/x86/include/asm/asm.h | 59 +++++++++++++++++++++++++++++++++ > arch/x86/include/asm/irqflags.h | 2 +- > arch/x86/kernel/Makefile | 1 + > arch/x86/kernel/irqflags.S | 26 +++++++++++++++ > include/linux/compiler-gcc.h | 29 ++++++++++++---- > 5 files changed, 109 insertions(+), 8 deletions(-) > create mode 100644 arch/x86/kernel/irqflags.S > For the series: Acked-by: Juergen Gross <jgross@xxxxxxxx> Juergen -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
