Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM change [1].
After another LLVM change [2], these sections are seen in some PowerPC builds, where there is a orphan section warning then build failure:
$ make -skj"$(nproc)" \ ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- LLVM=1 O=out \ distclean powernv_defconfig zImage.epapr ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.' ... ld.lld: warning: address (0xc000000000009314) of section .text is not a multiple of alignment (256) ... ERROR: start_text address is c000000000009400, should be c000000000008000 ERROR: try to enable LD_HEAD_STUB_CATCH config option ERROR: see comments in arch/powerpc/tools/head_check.sh ...
Explicitly handle these sections like in the main linker script so there is no more build failure.
Cc: stable@vger.kernel.org Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections") Link: https://github.com/ClangBuiltLinux/linux/issues/1218 Signed-off-by: Nathan Chancellor natechancellor@gmail.com --- arch/powerpc/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 0318ba436f34..8e0b1298bf19 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -85,7 +85,7 @@ SECTIONS ALIGN_FUNCTION(); #endif /* careful! __ftr_alt_* sections need to be close to .text */ - *(.text.hot TEXT_MAIN .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text); + *(.text.hot .text.hot.* TEXT_MAIN .text.fixup .text.unlikely .text.unlikely.* .fixup __ftr_alt_* .ref.text); #ifdef CONFIG_PPC64 *(.tramp.ftrace.text); #endif
base-commit: d8a4f20584d5906093a8fc6aa06622102a501095
On Mon, Jan 4, 2021 at 9:49 PM Nathan Chancellor natechancellor@gmail.com wrote:
Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM change [1].
After another LLVM change [2], these sections are seen in some PowerPC builds, where there is a orphan section warning then build failure:
Looks like you forgot to add your references/links to [1] and [2].
Might be good to mention...?
With CONFIG_LD_ORPHAN_WARN=y is enabled
- Sedat
$ make -skj"$(nproc)" \ ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- LLVM=1 O=out \ distclean powernv_defconfig zImage.epapr ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.' ... ld.lld: warning: address (0xc000000000009314) of section .text is not a multiple of alignment (256) ... ERROR: start_text address is c000000000009400, should be c000000000008000 ERROR: try to enable LD_HEAD_STUB_CATCH config option ERROR: see comments in arch/powerpc/tools/head_check.sh ...
Explicitly handle these sections like in the main linker script so there is no more build failure.
Cc: stable@vger.kernel.org Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections") Link: https://github.com/ClangBuiltLinux/linux/issues/1218 Signed-off-by: Nathan Chancellor natechancellor@gmail.com
arch/powerpc/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 0318ba436f34..8e0b1298bf19 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -85,7 +85,7 @@ SECTIONS ALIGN_FUNCTION(); #endif /* careful! __ftr_alt_* sections need to be close to .text */
*(.text.hot TEXT_MAIN .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text);
*(.text.hot .text.hot.* TEXT_MAIN .text.fixup .text.unlikely .text.unlikely.* .fixup __ftr_alt_* .ref.text);#ifdef CONFIG_PPC64 *(.tramp.ftrace.text); #endif
base-commit: d8a4f20584d5906093a8fc6aa06622102a501095
2.30.0
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On Mon, Jan 04, 2021 at 09:55:20PM +0100, Sedat Dilek wrote:
On Mon, Jan 4, 2021 at 9:49 PM Nathan Chancellor natechancellor@gmail.com wrote:
Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM change [1].
After another LLVM change [2], these sections are seen in some PowerPC builds, where there is a orphan section warning then build failure:
Looks like you forgot to add your references/links to [1] and [2].
Indeed, thank you for pointing that out! v2 coming shortly.
Might be good to mention...?
With CONFIG_LD_ORPHAN_WARN=y is enabled
Since this symbol is not user selectable, I do not really think it is worth mentioning, plus PowerPC has had this enabled for a while :)
Cheers, Nathan
Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM change [1].
After another LLVM change [2], these sections are seen in some PowerPC builds, where there is a orphan section warning then build failure:
$ make -skj"$(nproc)" \ ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- LLVM=1 O=out \ distclean powernv_defconfig zImage.epapr ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.' ... ld.lld: warning: address (0xc000000000009314) of section .text is not a multiple of alignment (256) ... ERROR: start_text address is c000000000009400, should be c000000000008000 ERROR: try to enable LD_HEAD_STUB_CATCH config option ERROR: see comments in arch/powerpc/tools/head_check.sh ...
Explicitly handle these sections like in the main linker script so there is no more build failure.
[1]: https://reviews.llvm.org/D79600 [2]: https://reviews.llvm.org/D92493
Cc: stable@vger.kernel.org Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections") Link: https://github.com/ClangBuiltLinux/linux/issues/1218 Signed-off-by: Nathan Chancellor natechancellor@gmail.com ---
v1 -> v2:
* Add missing [1] and [2] references in commit message. Thanks to Sedat Dilek for pointing it out!
arch/powerpc/kernel/vmlinux.lds.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 0318ba436f34..8e0b1298bf19 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -85,7 +85,7 @@ SECTIONS ALIGN_FUNCTION(); #endif /* careful! __ftr_alt_* sections need to be close to .text */ - *(.text.hot TEXT_MAIN .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text); + *(.text.hot .text.hot.* TEXT_MAIN .text.fixup .text.unlikely .text.unlikely.* .fixup __ftr_alt_* .ref.text); #ifdef CONFIG_PPC64 *(.tramp.ftrace.text); #endif
base-commit: d8a4f20584d5906093a8fc6aa06622102a501095
On Mon, 4 Jan 2021 13:59:53 -0700, Nathan Chancellor wrote:
Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM change [1].
After another LLVM change [2], these sections are seen in some PowerPC builds, where there is a orphan section warning then build failure:
[...]
Applied to powerpc/fixes.
[1/1] powerpc: Handle .text.{hot,unlikely}.* in linker script https://git.kernel.org/powerpc/c/3ce47d95b7346dcafd9bed3556a8d072cb2b8571
cheers
Hi!
Very late of course, and the patch is fine, but:
On Mon, Jan 04, 2021 at 01:59:53PM -0700, Nathan Chancellor wrote:
Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM change [1].
After another LLVM change [2], these sections are seen in some PowerPC builds, where there is a orphan section warning then build failure:
$ make -skj"$(nproc)" \ ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- LLVM=1 O=out \ distclean powernv_defconfig zImage.epapr ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.'
Is the section really called ".text.unlikely.", i.e. the name ending in a dot? How very unusual, is there some bug elsewhere?
Segher
On Sat, Jan 16, 2021 at 12:44:38PM -0600, Segher Boessenkool wrote:
Hi!
Very late of course, and the patch is fine, but:
On Mon, Jan 04, 2021 at 01:59:53PM -0700, Nathan Chancellor wrote:
Commit eff8728fe698 ("vmlinux.lds.h: Add PGO and AutoFDO input sections") added ".text.unlikely.*" and ".text.hot.*" due to an LLVM change [1].
After another LLVM change [2], these sections are seen in some PowerPC builds, where there is a orphan section warning then build failure:
$ make -skj"$(nproc)" \ ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- LLVM=1 O=out \ distclean powernv_defconfig zImage.epapr ld.lld: warning: kernel/built-in.a(panic.o):(.text.unlikely.) is being placed in '.text.unlikely.'
Is the section really called ".text.unlikely.", i.e. the name ending in a dot? How very unusual, is there some bug elsewhere?
No, this was an intention change done by LLVM: https://reviews.llvm.org/D79600
Cheers, Nathan
linux-stable-mirror@lists.linaro.org
-
Michael Ellerman -
Nathan Chancellor -
Sedat Dilek -
Segher Boessenkool