[PATCH v2 2/6] perf/x86: convert perf_callchain_kernel() to use the new unwinder

From: Josh Poimboeuf
Date: Fri Sep 16 2016 - 15:19:58 EST


Convert perf_callchain_kernel() to use the new unwinder. dump_trace()
has been deprecated.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
arch/x86/events/core.c | 33 ++++++++++-----------------------
1 file changed, 10 insertions(+), 23 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index dd3a1dc..d31735f 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -37,6 +37,7 @@
#include <asm/timer.h>
#include <asm/desc.h>
#include <asm/ldt.h>
+#include <asm/unwind.h>

#include "perf_event.h"

@@ -2267,31 +2268,12 @@ void arch_perf_update_userpage(struct perf_event *event,
cyc2ns_read_end(data);
}

-/*
- * callchain support
- */
-
-static int backtrace_stack(void *data, const char *name)
-{
- return 0;
-}
-
-static int backtrace_address(void *data, unsigned long addr, int reliable)
-{
- struct perf_callchain_entry_ctx *entry = data;
-
- return perf_callchain_store(entry, addr);
-}
-
-static const struct stacktrace_ops backtrace_ops = {
- .stack = backtrace_stack,
- .address = backtrace_address,
- .walk_stack = print_context_stack_bp,
-};
-
void
perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs)
{
+ struct unwind_state state;
+ unsigned long addr;
+
if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) {
/* TODO: We don't support guest os callchain now */
return;
@@ -2300,7 +2282,12 @@ perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *re
if (perf_callchain_store(entry, regs->ip))
return;

- dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
+ for (unwind_start(&state, current, regs, NULL); !unwind_done(&state);
+ unwind_next_frame(&state)) {
+ addr = unwind_get_return_address(&state);
+ if (!addr || perf_callchain_store(entry, addr))
+ return;
+ }
}

static inline int
--
2.7.4