Implement perf_callchain_user using the unwind_user_frame
method, allow up to PAGE_SIZE / 4 instructions to be checked.
Signed-off-by: Holger Freyther <holger@xxxxxxxxxxxxxxxx>
---
arch/mips/kernel/perf_event.c | 14 ++++++++++++++
1 files changed, 14 insertions(+), 0 deletions(-)
diff --git a/arch/mips/kernel/perf_event.c b/arch/mips/kernel/perf_event.c
index 0aee944..7ea4d3c 100644
--- a/arch/mips/kernel/perf_event.c
+++ b/arch/mips/kernel/perf_event.c
@@ -540,6 +540,20 @@ handle_associated_event(struct cpu_hw_events *cpuc,
void perf_callchain_user(struct perf_callchain_entry *entry,
struct pt_regs *regs)
{
+ struct user_stackframe frame = { .sp = regs->regs[29],
+ .pc = regs->cp0_epc,
+ .ra = regs->regs[31] };
+ const unsigned long low_addr = ALIGN(frame.sp, THREAD_SIZE);
+ const unsigned int max_instr_check = PAGE_SIZE / 4;
+ const unsigned long high_addr = low_addr + THREAD_SIZE;
+
+
+ while (entry->nr < PERF_MAX_STACK_DEPTH &&
+ !unwind_user_frame(&frame, max_instr_check)) {
+ perf_callchain_store(entry, frame.ra);
+ if (frame.sp < low_addr || frame.sp > high_addr)
+ break;
+ }
}
static void save_raw_perf_callchain(struct perf_callchain_entry *entry,
--
1.7.4.1
