On Thu, Mar 18, 2021 at 10:11 AM Sami Tolvanen <samitolvanen@xxxxxxxxxx> wrote: > > CONFIG_CFI_CLANG_SHADOW assumes the __cfi_check() function is page > aligned and at the beginning of the .text section. While Clang would > normally align the function correctly, it fails to do so for modules > with no executable code. > > This change ensures the correct __cfi_check() location and > alignment. It also discards the .eh_frame section, which Clang can > generate with certain sanitizers, such as CFI. > > Link: https://bugs.llvm.org/show_bug.cgi?id=46293 > Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx> > --- > scripts/module.lds.S | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/scripts/module.lds.S b/scripts/module.lds.S > index 168cd27e6122..93518579cf5d 100644 > --- a/scripts/module.lds.S > +++ b/scripts/module.lds.S > @@ -3,10 +3,19 @@ > * Archs are free to supply their own linker scripts. ld will > * combine them automatically. > */ > +#include <asm/page.h> > + > +#ifdef CONFIG_CFI_CLANG > +# define ALIGN_CFI ALIGN(PAGE_SIZE) > +#else > +# define ALIGN_CFI > +#endif > + > SECTIONS { > /DISCARD/ : { > *(.discard) > *(.discard.*) > + *(.eh_frame) Do we want to unconditionally discard this section from modules for all arches/configs? I like how we conditionally do so on SANITIZER_DISCARDS in include/asm-generic/vmlinux.lds.h for example. > } > > __ksymtab 0 : { *(SORT(___ksymtab+*)) } > @@ -40,7 +49,14 @@ SECTIONS { > *(.rodata..L*) > } > > - .text : { *(.text .text.[0-9a-zA-Z_]*) } > + /* > + * With CONFIG_CFI_CLANG, we assume __cfi_check is at the beginning > + * of the .text section, and is aligned to PAGE_SIZE. > + */ > + .text : ALIGN_CFI { > + *(.text.__cfi_check) > + *(.text .text.[0-9a-zA-Z_]* .text..L.cfi*) > + } > } > > /* bring in arch-specific sections */ > -- > 2.31.0.291.g576ba9dcdaf-goog > -- Thanks, ~Nick Desaulniers
