| Message ID | 20200319214530.2046-1-ilie.halip@gmail.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 6f5459da2b8736720afdbd67c4bd2d1edba7d0e3 |
| Headers | show |
| Series | arm64: alternative: fix build with clang integrated assembler | expand |
On Thu, Mar 19, 2020 at 2:45 PM Ilie Halip <ilie.halip@gmail.com> wrote: > > Building an arm64 defconfig with clang's integrated assembler, this error > occurs: > <instantiation>:2:2: error: unrecognized instruction mnemonic > _ASM_EXTABLE 9999b, 9f > ^ > arch/arm64/mm/cache.S:50:1: note: while in macro instantiation > user_alt 9f, "dc cvau, x4", "dc civac, x4", 0 > ^ > > While GNU as seems fine with case-sensitive macro instantiations, clang > doesn't, so use the actual macro name (_asm_extable) as in the rest of > the file. > > Also checked that the generated assembly matches the GCC output. > > Fixes: 290622efc76e ("arm64: fix "dc cvau" cache operation on errata-affected core") > Link: https://github.com/ClangBuiltLinux/linux/issues/924 > Signed-off-by: Ilie Halip <ilie.halip@gmail.com> > --- > arch/arm64/include/asm/alternative.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h > index 324e7d5ab37e..5e5dc05d63a0 100644 > --- a/arch/arm64/include/asm/alternative.h > +++ b/arch/arm64/include/asm/alternative.h > @@ -221,7 +221,7 @@ alternative_endif > > .macro user_alt, label, oldinstr, newinstr, cond > 9999: alternative_insn "\oldinstr", "\newinstr", \cond > - _ASM_EXTABLE 9999b, \label > + _asm_extable 9999b, \label > .endm Testing a -next defconfig build, if I apply this, apply fixes for https://github.com/ClangBuiltLinux/linux/issues/913, then disable CONFIG_KVM, I can assemble (with Clang's integrated assembler) and boot an aarch64 kernel. I think that's a first for Clang. Wow. For CONFIG_KVM, I see: arch/arm64/kvm/hyp/entry.S:112:87: error: too many positional arguments alternative_insn nop, .inst (0xd500401f | ((0) << 16 | (4) << 5) | ((!!1) << 8)), 4, 1 ^ which also uses `alternative_insn`, but not `user_alt`, so another bug for us to look into, filed: https://github.com/ClangBuiltLinux/linux/issues/939 Looks like `_asm_extable` itself is a macro, defined in arch/arm64/include/asm/assembler.h on line 125. It's probably easy to fix this in clang, but from a consistency with the rest of the file (arch/arm64/include/asm/alternative.h) this patch should be accepted. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Should be easy to fix in Clang, too. Filed: https://bugs.llvm.org/show_bug.cgi?id=45257 Thanks for the patch!
On Thu, Mar 19, 2020 at 04:43:56PM -0700, Nick Desaulniers wrote: > On Thu, Mar 19, 2020 at 2:45 PM Ilie Halip <ilie.halip@gmail.com> wrote: > > > > Building an arm64 defconfig with clang's integrated assembler, this error > > occurs: > > <instantiation>:2:2: error: unrecognized instruction mnemonic > > _ASM_EXTABLE 9999b, 9f > > ^ > > arch/arm64/mm/cache.S:50:1: note: while in macro instantiation > > user_alt 9f, "dc cvau, x4", "dc civac, x4", 0 > > ^ > > > > While GNU as seems fine with case-sensitive macro instantiations, clang > > doesn't, so use the actual macro name (_asm_extable) as in the rest of > > the file. > > > > Also checked that the generated assembly matches the GCC output. > > > > Fixes: 290622efc76e ("arm64: fix "dc cvau" cache operation on errata-affected core") > > Link: https://github.com/ClangBuiltLinux/linux/issues/924 > > Signed-off-by: Ilie Halip <ilie.halip@gmail.com> > > --- > > arch/arm64/include/asm/alternative.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h > > index 324e7d5ab37e..5e5dc05d63a0 100644 > > --- a/arch/arm64/include/asm/alternative.h > > +++ b/arch/arm64/include/asm/alternative.h > > @@ -221,7 +221,7 @@ alternative_endif > > > > .macro user_alt, label, oldinstr, newinstr, cond > > 9999: alternative_insn "\oldinstr", "\newinstr", \cond > > - _ASM_EXTABLE 9999b, \label > > + _asm_extable 9999b, \label > > .endm > > Testing a -next defconfig build, if I apply this, apply fixes for > https://github.com/ClangBuiltLinux/linux/issues/913, then disable > CONFIG_KVM, I can assemble (with Clang's integrated assembler) and > boot an aarch64 kernel. I think that's a first for Clang. Wow. > > For CONFIG_KVM, I see: > arch/arm64/kvm/hyp/entry.S:112:87: error: too many positional arguments > alternative_insn nop, .inst (0xd500401f | ((0) << 16 | (4) << 5) | > ((!!1) << 8)), 4, 1 > > ^ > which also uses `alternative_insn`, but not `user_alt`, so another bug > for us to look into, filed: > https://github.com/ClangBuiltLinux/linux/issues/939 > > Looks like `_asm_extable` itself is a macro, defined in > arch/arm64/include/asm/assembler.h on line 125. It's probably easy to > fix this in clang, but from a consistency with the rest of the file > (arch/arm64/include/asm/alternative.h) this patch should be accepted. > > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Tested-by: Nick Desaulniers <ndesaulniers@google.com> Thanks, I'll pick this up as a fix. Will
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h index 324e7d5ab37e..5e5dc05d63a0 100644 --- a/arch/arm64/include/asm/alternative.h +++ b/arch/arm64/include/asm/alternative.h @@ -221,7 +221,7 @@ alternative_endif .macro user_alt, label, oldinstr, newinstr, cond 9999: alternative_insn "\oldinstr", "\newinstr", \cond - _ASM_EXTABLE 9999b, \label + _asm_extable 9999b, \label .endm /*
Building an arm64 defconfig with clang's integrated assembler, this error occurs: <instantiation>:2:2: error: unrecognized instruction mnemonic _ASM_EXTABLE 9999b, 9f ^ arch/arm64/mm/cache.S:50:1: note: while in macro instantiation user_alt 9f, "dc cvau, x4", "dc civac, x4", 0 ^ While GNU as seems fine with case-sensitive macro instantiations, clang doesn't, so use the actual macro name (_asm_extable) as in the rest of the file. Also checked that the generated assembly matches the GCC output. Fixes: 290622efc76e ("arm64: fix "dc cvau" cache operation on errata-affected core") Link: https://github.com/ClangBuiltLinux/linux/issues/924 Signed-off-by: Ilie Halip <ilie.halip@gmail.com> --- arch/arm64/include/asm/alternative.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)