x86/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.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 9304570 ("kernel/kexec_file.c: split up __kexec_load_puragory")
Signed-off-by: Ricardo Ribalda <[email protected]>
Cc: <[email protected]>
Cc: Albert Ou <[email protected]>
Cc: Baoquan He <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Christophe Leroy <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dave Young <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Palmer Dabbelt <[email protected]>
Cc: Paul Walmsley <[email protected]>
Cc: Philipp Rudo <[email protected]>
Cc: Ross Zwisler <[email protected]>
Cc: Simon Horman <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Rix <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

arch/x86/purgatory/Makefile

@@ -14,6 +14,11 @@ $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE
 
 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