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 v2: 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. 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/irqflags.h | 2 +- arch/x86/kernel/Makefile | 1 + arch/x86/kernel/irqflags.S | 26 ++++++++++++++++++++++++++ include/linux/compiler-gcc.h | 19 +++++++++++++------ 4 files changed, 41 insertions(+), 7 deletions(-) create mode 100644 arch/x86/kernel/irqflags.S -- 2.17.1.1185.g55be947832-goog -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
