+ x86-purgatory-remove-pgo-flags.patch added to mm-hotfixes-unstable branch

+ x86-purgatory-remove-pgo-flags.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: x86/purgatory: remove PGO flags
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     x86-purgatory-remove-pgo-flags.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-purgatory-remove-pgo-flags.patch

This patch will later appear in the mm-hotfixes-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Ricardo Ribalda <ribalda@chromium.org>
Subject: x86/purgatory: remove PGO flags
Date: Fri, 19 May 2023 16:47:37 +0200

If profile-guided optimization is enabled, the purgatory ends up with
multiple .text sections.  This is not supported by kexec and crashes the
system.

Link: https://lkml.kernel.org/r/20230321-kexec_clang16-v7-2-b05c520b7296@chromium.org
Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory")
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Cc: <stable@vger.kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Ross Zwisler <zwisler@google.com>
Cc: Simon Horman <horms@kernel.org>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Rix <trix@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/purgatory/Makefile |    5 +++++
 1 file changed, 5 insertions(+)

--- a/arch/x86/purgatory/Makefile~x86-purgatory-remove-pgo-flags
+++ a/arch/x86/purgatory/Makefile
@@ -14,6 +14,11 @@ $(obj)/sha256.o: $(srctree)/lib/crypto/s
 
 CFLAGS_sha256.o := -D__DISABLE_EXPORTS
 
+# When profile-guided optimization is enabled, llvm emits two different
+# overlapping text sections, which is not supported by kexec. Remove profile
+# optimization flags.
+KBUILD_CFLAGS := $(filter-out -fprofile-sample-use=% -fprofile-use=%,$(KBUILD_CFLAGS))
+
 # When linking purgatory.ro with -r unresolved symbols are not checked,
 # also link a purgatory.chk binary without -r to check for unresolved symbols.
 PURGATORY_LDFLAGS := -e purgatory_start -z nodefaultlib
_

Patches currently in -mm which might be from ribalda@chromium.org are

kexec-support-purgatories-with-texthot-sections.patch
x86-purgatory-remove-pgo-flags.patch
powerpc-purgatory-remove-pgo-flags.patch
riscv-purgatory-remove-pgo-flags.patch