| Message ID | 214134496.67043.1623317284090@office.mailbox.org |
|---|---|
| State | Accepted |
| Commit | 2398ce80152aae33b9501ef54452e09e8e8d4262 |
| Headers | show |
| Series | x86/Makefile: make -stack-alignment conditional on LLD < 13.0.0 | expand |
Hi Tor, On 6/10/2021 2:28 AM, torvic9@mailbox.org wrote: > Since LLVM commit 3787ee4, the '-stack-alignment' flag has been dropped [1], > leading to the following error message when building a LTO kernel with > Clang-13 and LLD-13: > > ld.lld: error: -plugin-opt=-: ld.lld: Unknown command line argument > '-stack-alignment=8'. Try 'ld.lld --help' > ld.lld: Did you mean '--stackrealign=8'? > > It also appears that the '-code-model' flag is not necessary anymore starting > with LLVM-9 [2]. > > Drop '-code-model' and make '-stack-alignment' conditional on LLD < 13.0.0. > > This is for linux-stable 5.12. > Another patch will be submitted for 5.13 shortly (unless there are objections). This patch needs to be accepted into mainline first before it can go to stable so this line needs to be removed. The rest of the description looks good to me, good job on being descriptive! > Discussion: https://github.com/ClangBuiltLinux/linux/issues/1377 > [1]: https://reviews.llvm.org/D103048 > [2]: https://reviews.llvm.org/D52322 As Greg's auto-response points out, there needs to be an actual Cc: stable@vger.kernel.org here in the patch, rather than just cc'ing stable@vger.kernel.org through email. > Signed-off-by: Tor Vic <torvic9@mailbox.org> The actual patch itself looks good and I have verified that it fixes the build error. On the resend with the above fixed, please feel free to add: Reviewed-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> > --- > arch/x86/Makefile | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index 1f2e5bf..2855a1a 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -192,8 +192,9 @@ endif > KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE) > > ifdef CONFIG_LTO_CLANG > -KBUILD_LDFLAGS += -plugin-opt=-code-model=kernel \ > - -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) > +ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0) > +KBUILD_LDFLAGS += -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) > +endif > endif > > ifdef CONFIG_X86_NEED_RELOCS > Cheers, Nathan
On Thu, Jun 10, 2021 at 11:39 AM Tor Vic <torvic9@mailbox.org> wrote: > > Hi Nathan, > > On 10.06.21 16:42, Nathan Chancellor wrote: > > As Greg's auto-response points out, there needs to be an actual > > > > Cc: stable@vger.kernel.org > > > > here in the patch, rather than just cc'ing stable@vger.kernel.org > > through email. > > > > Yes I misinterpreted this in the sense of "put stable mail in CC". > So if I get this right, I should NOT put stable email in CC, but only > add the "Cc: stable@vger.kernel.org" tag above the "Signed-off-by"? Yep, just above the Link: tags would be perfect. Don't worry, you'll get the hang of it.
On Thu, Jun 10, 2021 at 2:28 AM <torvic9@mailbox.org> wrote: > > Since LLVM commit 3787ee4, the '-stack-alignment' flag has been dropped [1], > leading to the following error message when building a LTO kernel with > Clang-13 and LLD-13: > > ld.lld: error: -plugin-opt=-: ld.lld: Unknown command line argument > '-stack-alignment=8'. Try 'ld.lld --help' > ld.lld: Did you mean '--stackrealign=8'? > > It also appears that the '-code-model' flag is not necessary anymore starting > with LLVM-9 [2]. > > Drop '-code-model' and make '-stack-alignment' conditional on LLD < 13.0.0. Please include this additional context in v2: ``` These flags were necessary because these flags were not encoded in the IR properly, so the link would restart optimizations without them. Now there are properly encoded in the IR, and these flags exposing implementation details are no longer necessary. ``` That way it doesn't sound like we're not using an 8B stack alignment on x86; we very much are so; AMDGPU GPFs without it! Cut the below paragraph out on v2. Thanks for the patch and keep up the good work! > > This is for linux-stable 5.12. > Another patch will be submitted for 5.13 shortly (unless there are objections). > > Discussion: https://github.com/ClangBuiltLinux/linux/issues/1377 > [1]: https://reviews.llvm.org/D103048 > [2]: https://reviews.llvm.org/D52322 > > Signed-off-by: Tor Vic <torvic9@mailbox.org> > --- > arch/x86/Makefile | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index 1f2e5bf..2855a1a 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -192,8 +192,9 @@ endif > KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE) > > ifdef CONFIG_LTO_CLANG > -KBUILD_LDFLAGS += -plugin-opt=-code-model=kernel \ > - -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) > +ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0) > +KBUILD_LDFLAGS += -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) > +endif > endif > > ifdef CONFIG_X86_NEED_RELOCS > -- > 2.32.0
On 6/10/2021 1:16 PM, Tor Vic wrote: > > > On 10.06.21 19:20, Nick Desaulniers wrote: >> On Thu, Jun 10, 2021 at 2:28 AM <torvic9@mailbox.org> wrote: >>> >>> Since LLVM commit 3787ee4, the '-stack-alignment' flag has been dropped [1], >>> leading to the following error message when building a LTO kernel with >>> Clang-13 and LLD-13: >>> >>> ld.lld: error: -plugin-opt=-: ld.lld: Unknown command line argument >>> '-stack-alignment=8'. Try 'ld.lld --help' >>> ld.lld: Did you mean '--stackrealign=8'? >>> >>> It also appears that the '-code-model' flag is not necessary anymore starting >>> with LLVM-9 [2]. >>> >>> Drop '-code-model' and make '-stack-alignment' conditional on LLD < 13.0.0. >> >> Please include this additional context in v2: >> ``` >> These flags were necessary because these flags were not encoded in the >> IR properly, so the link would restart optimizations without them. Now >> there are properly encoded in the IR, and these flags exposing >> implementation details are no longer necessary. >> ``` >> That way it doesn't sound like we're not using an 8B stack alignment >> on x86; we very much are so; AMDGPU GPFs without it! >> > > Will do so. > Does this have to be a v2 (with a "changes from v1" info) or just a > resend? It is based on mainline now and the line numbers have changed. Yes, this should be a v2 because the commit message changed. It would be considered a resend if nothing changed and the patch just needed to be picked up rather than re-reviewed. Cheers, Nathan
From: Nick Desaulniers > Sent: 10 June 2021 20:21 > > On Thu, Jun 10, 2021 at 2:28 AM <torvic9@mailbox.org> wrote: > > > > Since LLVM commit 3787ee4, the '-stack-alignment' flag has been dropped [1], > > leading to the following error message when building a LTO kernel with > > Clang-13 and LLD-13: > > > > ld.lld: error: -plugin-opt=-: ld.lld: Unknown command line argument > > '-stack-alignment=8'. Try 'ld.lld --help' > > ld.lld: Did you mean '--stackrealign=8'? > > > > It also appears that the '-code-model' flag is not necessary anymore starting > > with LLVM-9 [2]. > > > > Drop '-code-model' and make '-stack-alignment' conditional on LLD < 13.0.0. > > Please include this additional context in v2: > ``` > These flags were necessary because these flags were not encoded in the > IR properly, so the link would restart optimizations without them. Now > there are properly encoded in the IR, and these flags exposing > implementation details are no longer necessary. > ``` > That way it doesn't sound like we're not using an 8B stack alignment > on x86; we very much are so; AMDGPU GPFs without it! Actually, give that LTO is still 'experimental' is it worth just removing the flags and requiring clang-13 for LTO builds? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 1f2e5bf..2855a1a 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -192,8 +192,9 @@ endif KBUILD_LDFLAGS += -m elf_$(UTS_MACHINE) ifdef CONFIG_LTO_CLANG -KBUILD_LDFLAGS += -plugin-opt=-code-model=kernel \ - -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) +ifeq ($(shell test $(CONFIG_LLD_VERSION) -lt 130000; echo $$?),0) +KBUILD_LDFLAGS += -plugin-opt=-stack-alignment=$(if $(CONFIG_X86_32),4,8) +endif endif ifdef CONFIG_X86_NEED_RELOCS
Since LLVM commit 3787ee4, the '-stack-alignment' flag has been dropped [1], leading to the following error message when building a LTO kernel with Clang-13 and LLD-13: ld.lld: error: -plugin-opt=-: ld.lld: Unknown command line argument '-stack-alignment=8'. Try 'ld.lld --help' ld.lld: Did you mean '--stackrealign=8'? It also appears that the '-code-model' flag is not necessary anymore starting with LLVM-9 [2]. Drop '-code-model' and make '-stack-alignment' conditional on LLD < 13.0.0. This is for linux-stable 5.12. Another patch will be submitted for 5.13 shortly (unless there are objections). Discussion: https://github.com/ClangBuiltLinux/linux/issues/1377 [1]: https://reviews.llvm.org/D103048 [2]: https://reviews.llvm.org/D52322 Signed-off-by: Tor Vic <torvic9@mailbox.org> --- arch/x86/Makefile | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)