linux-kernel - [PATCH v7 4/4] riscv/purgatory: Remove PGO flags

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Message-Id: <20230321-kexec_clang16-v7-4-b05c520b7296@chromium.org>
Date:   Fri, 19 May 2023 16:47:39 +0200
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Eric Biederman <ebiederm@...ssion.com>,
        Philipp Rudo <prudo@...ux.vnet.ibm.com>,
        Dave Young <dyoung@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Tom Rix <trix@...hat.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>
Cc:     Baoquan He <bhe@...hat.com>, Philipp Rudo <prudo@...hat.com>,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Ross Zwisler <zwisler@...gle.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Simon Horman <horms@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        llvm@...ts.linux.dev, linuxppc-dev@...ts.ozlabs.org,
        linux-riscv@...ts.infradead.org,
        Ricardo Ribalda <ribalda@...omium.org>, stable@...r.kernel.org,
        Palmer Dabbelt <palmer@...osinc.com>
Subject: [PATCH v7 4/4] riscv/purgatory: Remove PGO flags

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

Cc: stable@...r.kernel.org
Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory")
Acked-by: Palmer Dabbelt <palmer@...osinc.com>
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 arch/riscv/purgatory/Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
index 5730797a6b40..bd2e27f82532 100644
--- a/arch/riscv/purgatory/Makefile
+++ b/arch/riscv/purgatory/Makefile
@@ -35,6 +35,11 @@ CFLAGS_sha256.o := -D__DISABLE_EXPORTS
 CFLAGS_string.o := -D__DISABLE_EXPORTS
 CFLAGS_ctype.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

-- 
2.40.1.698.g37aff9b760-goog