Messages in this thread | | | From | Nick Desaulniers <> | Date | Fri, 10 Dec 2021 15:58:10 -0800 | Subject | Re: [PATCH] x86/extable: Fix extable_type_reg macro with Clang LTO |
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On Fri, Dec 10, 2021 at 3:51 PM Nathan Chancellor <nathan@kernel.org> wrote: > > When building x86_64_defconfig + CONFIG_LTO_CLANG_FULL=y after > commit a90a845d94b4 ("x86/extable: Extend extable functionality"), the > build fails during linking: > > ld.lld: error: <inline asm>:64:2: macro 'extable_type_reg' is already defined > .macro extable_type_reg type:req reg:req > ^ > > The build failures happens because the definition of extable_type_reg > happens in every source file that includes asm.h, which all get combined > together during LTO. > > Commit be604c616ca7 ("arm64: sysreg: Make mrs_s and msr_s macros work > with Clang and LTO") ran into a similar issue and the solution was to > define, use, then undefine the macro within each inline asm block it was > needed in. > > Break apart the inline asm macro definition into two macros > ({,UN}DEFINE_EXTABLE_TYPE_REG) and use them in _ASM_EXTABLE_TYPE so > there is no more error with LTO. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1513 > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Thanks for coming up with a fix.
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com>
> --- > > I expect this to be squashed into commit a90a845d94b4 ("x86/extable: > Extend extable functionality") in Peter's x86/wip.extable branch to > avoid bisect issues. The description and link are there for archaeology.
SGTM; feel free to carry over my tested by tag in that case.
> > arch/x86/include/asm/asm.h | 52 ++++++++++++++++++++------------------ > 1 file changed, 28 insertions(+), 24 deletions(-) > > diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h > index 95bb23082b87..c878fed3056f 100644 > --- a/arch/x86/include/asm/asm.h > +++ b/arch/x86/include/asm/asm.h > @@ -152,30 +152,32 @@ > > #else /* ! __ASSEMBLY__ */ > > -asm( > -" .macro extable_type_reg type:req reg:req\n" > -" .set found, 0\n" > -" .set regnr, 0\n" > -" .irp rs,rax,rcx,rdx,rbx,rsp,rbp,rsi,rdi,r8,r9,r10,r11,r12,r13,r14,r15\n" > -" .ifc \\reg, %\\rs\n" > -" .set found, found+1\n" > -" .long \\type + (regnr << 8)\n" > -" .endif\n" > -" .set regnr, regnr+1\n" > -" .endr\n" > -" .set regnr, 0\n" > -" .irp rs,eax,ecx,edx,ebx,esp,ebp,esi,edi,r8d,r9d,r10d,r11d,r12d,r13d,r14d,r15d\n" > -" .ifc \\reg, %\\rs\n" > -" .set found, found+1\n" > -" .long \\type + (regnr << 8)\n" > -" .endif\n" > -" .set regnr, regnr+1\n" > -" .endr\n" > -" .if (found != 1)\n" > -" .error \"extable_type_reg: bad register argument\"\n" > -" .endif\n" > -" .endm\n" > -); > +# define DEFINE_EXTABLE_TYPE_REG \ > + ".macro extable_type_reg type:req reg:req\n" \ > + ".set found, 0\n" \ > + ".set regnr, 0\n" \ > + ".irp rs,rax,rcx,rdx,rbx,rsp,rbp,rsi,rdi,r8,r9,r10,r11,r12,r13,r14,r15\n" \ > + ".ifc \\reg, %%\\rs\n" \ > + ".set found, found+1\n" \ > + ".long \\type + (regnr << 8)\n" \ > + ".endif\n" \ > + ".set regnr, regnr+1\n" \ > + ".endr\n" \ > + ".set regnr, 0\n" \ > + ".irp rs,eax,ecx,edx,ebx,esp,ebp,esi,edi,r8d,r9d,r10d,r11d,r12d,r13d,r14d,r15d\n" \ > + ".ifc \\reg, %%\\rs\n" \ > + ".set found, found+1\n" \ > + ".long \\type + (regnr << 8)\n" \ > + ".endif\n" \ > + ".set regnr, regnr+1\n" \ > + ".endr\n" \ > + ".if (found != 1)\n" \ > + ".error \"extable_type_reg: bad register argument\"\n" \ > + ".endif\n" \ > + ".endm\n" > + > +# define UNDEFINE_EXTABLE_TYPE_REG \ > + ".purgem extable_type_reg\n" > > # define _ASM_EXTABLE_TYPE(from, to, type) \ > " .pushsection \"__ex_table\",\"a\"\n" \ > @@ -190,7 +192,9 @@ asm( > " .balign 4\n" \ > " .long (" #from ") - .\n" \ > " .long (" #to ") - .\n" \ > + DEFINE_EXTABLE_TYPE_REG \ > "extable_type_reg reg=" __stringify(reg) ", type=" __stringify(type) " \n"\ > + UNDEFINE_EXTABLE_TYPE_REG \ > " .popsection\n" > > /* For C file, we already have NOKPROBE_SYMBOL macro */ > > base-commit: fa04e38818aeac177f730cfeadfbdb6f7c25f5b4 > -- > 2.34.1 > >
-- Thanks, ~Nick Desaulniers
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