| Message ID | 20200729215152.662225-1-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 966a0acce2fca776391823381dba95c40e03c339 |
| Headers | show |
| Series | arm64/alternatives: move length validation inside the subsection | expand |
On Wed, Jul 29, 2020 at 02:51:52PM -0700, Sami Tolvanen wrote: > Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement > sequences") breaks LLVM's integrated assembler, because due to its > one-pass design, it cannot compute instruction sequence lengths before the > layout for the subsection has been finalized. This change fixes the build > by moving the .org directives inside the subsection, so they are processed > after the subsection layout is known. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1078 > Cc: <stable@vger.kernel.org> # 4.14+ Commit f7b93d42945c went in 5.8-rc4. Why is this cc stable from 4.14? If Will picks it up for 5.8, it doesn't even need a cc stable. Please add a Fixes: tag as well.
On Thu, Jul 30, 2020 at 5:22 AM Catalin Marinas <catalin.marinas@arm.com> wrote: > > On Wed, Jul 29, 2020 at 02:51:52PM -0700, Sami Tolvanen wrote: > > Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement > > sequences") breaks LLVM's integrated assembler, because due to its > > one-pass design, it cannot compute instruction sequence lengths before the > > layout for the subsection has been finalized. This change fixes the build > > by moving the .org directives inside the subsection, so they are processed > > after the subsection layout is known. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1078 > > Cc: <stable@vger.kernel.org> # 4.14+ > > Commit f7b93d42945c went in 5.8-rc4. Why is this cc stable from 4.14? If > Will picks it up for 5.8, it doesn't even need a cc stable. Greg or Sasha can probably answer why, but this patch is in 4.14.189, 4.19.134, 5.4.53, and 5.7.10, which ended up breaking some downstream Android kernel builds. > Please add a Fixes: tag as well. Sure, I'll send v2 shortly with the tag. Thanks. Sami
On Thu, Jul 30, 2020 at 08:13:05AM -0700, Sami Tolvanen wrote: > On Thu, Jul 30, 2020 at 5:22 AM Catalin Marinas <catalin.marinas@arm.com> wrote: > > > > On Wed, Jul 29, 2020 at 02:51:52PM -0700, Sami Tolvanen wrote: > > > Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement > > > sequences") breaks LLVM's integrated assembler, because due to its > > > one-pass design, it cannot compute instruction sequence lengths before the > > > layout for the subsection has been finalized. This change fixes the build > > > by moving the .org directives inside the subsection, so they are processed > > > after the subsection layout is known. > > > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1078 > > > Cc: <stable@vger.kernel.org> # 4.14+ > > > > Commit f7b93d42945c went in 5.8-rc4. Why is this cc stable from 4.14? If > > Will picks it up for 5.8, it doesn't even need a cc stable. > > Greg or Sasha can probably answer why, but this patch is in 4.14.189, > 4.19.134, 5.4.53, and 5.7.10, which ended up breaking some downstream > Android kernel builds. I see but I don't think we need the explicit cc stable for 4.14. That's why the Fixes tag is important. If a patch was back-ported, the subsequent fixes should be picked by the stable maintainers as well.
On Thu, Jul 30, 2020 at 04:23:31PM +0100, Catalin Marinas wrote: > On Thu, Jul 30, 2020 at 08:13:05AM -0700, Sami Tolvanen wrote: > > On Thu, Jul 30, 2020 at 5:22 AM Catalin Marinas <catalin.marinas@arm.com> wrote: > > > > > > On Wed, Jul 29, 2020 at 02:51:52PM -0700, Sami Tolvanen wrote: > > > > Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement > > > > sequences") breaks LLVM's integrated assembler, because due to its > > > > one-pass design, it cannot compute instruction sequence lengths before the > > > > layout for the subsection has been finalized. This change fixes the build > > > > by moving the .org directives inside the subsection, so they are processed > > > > after the subsection layout is known. > > > > > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1078 > > > > Cc: <stable@vger.kernel.org> # 4.14+ > > > > > > Commit f7b93d42945c went in 5.8-rc4. Why is this cc stable from 4.14? If > > > Will picks it up for 5.8, it doesn't even need a cc stable. > > > > Greg or Sasha can probably answer why, but this patch is in 4.14.189, > > 4.19.134, 5.4.53, and 5.7.10, which ended up breaking some downstream > > Android kernel builds. > > I see but I don't think we need the explicit cc stable for 4.14. That's > why the Fixes tag is important. If a patch was back-ported, the > subsequent fixes should be picked by the stable maintainers as well. If you know it ahead of time, the explict "# kernel.version" hint is always nice to have as it ensures I will try to backport it that far, and if I have problems, I will ask for help. thanks, greg k-h
On Fri, Jul 31, 2020 at 08:49:15AM +0200, Greg Kroah-Hartman wrote: > On Thu, Jul 30, 2020 at 04:23:31PM +0100, Catalin Marinas wrote: > > On Thu, Jul 30, 2020 at 08:13:05AM -0700, Sami Tolvanen wrote: > > > On Thu, Jul 30, 2020 at 5:22 AM Catalin Marinas <catalin.marinas@arm.com> wrote: > > > > > > > > On Wed, Jul 29, 2020 at 02:51:52PM -0700, Sami Tolvanen wrote: > > > > > Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement > > > > > sequences") breaks LLVM's integrated assembler, because due to its > > > > > one-pass design, it cannot compute instruction sequence lengths before the > > > > > layout for the subsection has been finalized. This change fixes the build > > > > > by moving the .org directives inside the subsection, so they are processed > > > > > after the subsection layout is known. > > > > > > > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1078 > > > > > Cc: <stable@vger.kernel.org> # 4.14+ > > > > > > > > Commit f7b93d42945c went in 5.8-rc4. Why is this cc stable from 4.14? If > > > > Will picks it up for 5.8, it doesn't even need a cc stable. > > > > > > Greg or Sasha can probably answer why, but this patch is in 4.14.189, > > > 4.19.134, 5.4.53, and 5.7.10, which ended up breaking some downstream > > > Android kernel builds. > > > > I see but I don't think we need the explicit cc stable for 4.14. That's > > why the Fixes tag is important. If a patch was back-ported, the > > subsequent fixes should be picked by the stable maintainers as well. > > If you know it ahead of time, the explict "# kernel.version" hint is > always nice to have as it ensures I will try to backport it that far, > and if I have problems, I will ask for help. Good to know. Thanks for the clarification.
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h index 12f0eb56a1cc..619db9b4c9d5 100644 --- a/arch/arm64/include/asm/alternative.h +++ b/arch/arm64/include/asm/alternative.h @@ -77,9 +77,9 @@ static inline void apply_alternatives_module(void *start, size_t length) { } "663:\n\t" \ newinstr "\n" \ "664:\n\t" \ - ".previous\n\t" \ ".org . - (664b-663b) + (662b-661b)\n\t" \ - ".org . - (662b-661b) + (664b-663b)\n" \ + ".org . - (662b-661b) + (664b-663b)\n\t" \ + ".previous\n" \ ".endif\n" #define __ALTERNATIVE_CFG_CB(oldinstr, feature, cfg_enabled, cb) \
Commit f7b93d42945c ("arm64/alternatives: use subsections for replacement sequences") breaks LLVM's integrated assembler, because due to its one-pass design, it cannot compute instruction sequence lengths before the layout for the subsection has been finalized. This change fixes the build by moving the .org directives inside the subsection, so they are processed after the subsection layout is known. Link: https://github.com/ClangBuiltLinux/linux/issues/1078 Cc: <stable@vger.kernel.org> # 4.14+ Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- arch/arm64/include/asm/alternative.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) base-commit: 6ba1b005ffc388c2aeaddae20da29e4810dea298