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Subject[PATCH] x86/sev: Disable ftrace branch profiling in SEV startup code
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From: Ard Biesheuvel <ardb@kernel.org>

Ftrace branch profiling inserts absolute references to its metadata at
call sites, and this implies that this kind of instrumentation cannot be
used while executing from the 1:1 mapping of memory.

Therefore, disable ftrace branch profiling in the SEV startup routines,
by disabling it for the entire SEV core source file.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501072244.zZrx9864-lkp@intel.com/
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/x86/coco/sev/core.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index 86898547056e..b5c6c4afd1cc 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -9,6 +9,8 @@

#define pr_fmt(fmt) "SEV: " fmt

+#define DISABLE_BRANCH_PROFILING
+
#include <linux/sched/debug.h> /* For show_regs() */
#include <linux/percpu-defs.h>
#include <linux/cc_platform.h>
--
2.47.1.613.gc27f4b7a9f-goog

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