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Subject[PATCH v2]: perf/x86: store user space frame-pointer value on a sample
Date

Store user space frame-pointer value (BP register) into Perf trace
on a sample for a process so the value becomes available when
unwinding call stacks for functions gaining event samples.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
---
arch/x86/kernel/perf_regs.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
index e47b2dbbdef3..8d68658eff7f 100644
--- a/arch/x86/kernel/perf_regs.c
+++ b/arch/x86/kernel/perf_regs.c
@@ -156,7 +156,13 @@ void perf_get_regs_user(struct perf_regs *regs_user,
* Most system calls don't save these registers, don't report them.
*/
regs_user_copy->bx = -1;
- regs_user_copy->bp = -1;
+ /*
+ * Store user space frame-pointer value on sample
+ * to facilitate stack unwinding for cases when
+ * user space executable code has such support
+ * enabled at compile time;
+ */
+ regs_user_copy->bp = user_regs->bp;
regs_user_copy->r12 = -1;
regs_user_copy->r13 = -1;
regs_user_copy->r14 = -1;
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