linux-kernel - [PATCH 5.4 51/92] powerpc: Handle .text.{hot,unlikely}.* in linker script

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Date:   Mon, 11 Jan 2021 14:01:55 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Nathan Chancellor <natechancellor@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 5.4 51/92] powerpc: Handle .text.{hot,unlikely}.* in linker script

From: Nathan Chancellor <natechancellor@...il.com>

commit 3ce47d95b7346dcafd9bed3556a8d072cb2b8571 upstream.

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

Fixes: 83a092cf95f2 ("powerpc: Link warning for orphan sections")
Cc: stable@...r.kernel.org
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Link: https://github.com/ClangBuiltLinux/linux/issues/1218
Link: https://lore.kernel.org/r/20210104205952.1399409-1-natechancellor@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/kernel/vmlinux.lds.S |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -98,7 +98,7 @@ 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