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From: Nathan Chancellor <natechancellor@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	clang-built-linux@googlegroups.com,
	Nathan Chancellor <natechancellor@gmail.com>,
	stable@vger.kernel.org
Subject: [PATCH v2] powerpc: Handle .text.{hot,unlikely}.* in linker script
Date: Mon,  4 Jan 2021 13:59:53 -0700	[thread overview]
Message-ID: <20210104205952.1399409-1-natechancellor@gmail.com> (raw)
In-Reply-To: <20210104204850.990966-1-natechancellor@gmail.com>

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
-- 
2.30.0


  parent reply	other threads:[~2021-01-04 23:52 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-04 20:48 [PATCH] " Nathan Chancellor
2021-01-04 20:55 ` Sedat Dilek
2021-01-04 20:57   ` Nathan Chancellor
2021-01-04 20:59 ` Nathan Chancellor [this message]
2021-01-15 12:23   ` [PATCH v2] " Michael Ellerman
2021-01-16 18:44   ` Segher Boessenkool
2021-01-16 18:52     ` Nathan Chancellor

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