On Thu, May 14, 2020 at 03:07:08PM +0200, Marco Elver wrote: > On Thu, 14 May 2020 at 14:27, Peter Zijlstra <pet...@infradead.org> wrote: > > > > On Thu, May 14, 2020 at 01:01:04PM +0100, Will Deacon wrote: > > > > > > +#if __has_feature(undefined_sanitizer) > > > > > > Hmm, this might want to be __has_feature(undefined_behavior_sanitizer) > > > (and damn is that hard for a Brit to type out!) > > > > (I know right, it should be behaviour, dammit!) > > > > I tried without the condition, eg.: > > > > +#define __no_sanitize_undefined \ > > + __attribute__((no_sanitize("undefined"))) > > > > and it still generated UBSAN gunk. > > Which ubsan calls are left? I'm trying to reproduce.
To be more precise, the patches were on top of: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git entry-v5-the-rest $ grep ubsan poke_int3_handler-clang10.asm 0074 74: R_X86_64_PLT32 __ubsan_handle_load_invalid_value-0x4 0083 83: R_X86_64_PLT32 __ubsan_handle_load_invalid_value-0x4 01c5 1c5: R_X86_64_PLT32 __ubsan_handle_builtin_unreachable-0x4 I think the config was defconfig_x86-64 inspired with KASAN+UBSAN enabled. So I build with: touch arch/x86/kernel/alterantive.c; make CC=clang-10 V=1 O=defconfig-build/ arch/x86/kernel/alterantive.o And then dump the output with: ./objdump-func.sh defconfig-build/arch/x86/kernel/alterantive.o poke_int3_handler $ # cat objdump-func.sh #!/bin/bash objdump -dr $1 | awk "/^\$/ { P=0; } /$2[^>]*>:\$/ { P=1; O=strtonum(\"0x\" \$1); } { if (P) { o=strtonum(\"0x\" \$1); printf(\"%04x \", o-O); print \$0; } }" Hope that is enough to reproduce.