linux-kernel - [PATCH v2 11/11] perf/x86: Enable SFrame unwinding for deferred user callchains

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Message-ID: <79e489ab275f6df5bf200747a0e9b878469301d4.1726268190.git.jpoimboe@kernel.org>
Date: Sat, 14 Sep 2024 01:02:13 +0200
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: x86@...nel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	linux-kernel@...r.kernel.org,
	Indu Bhagat <indu.bhagat@...cle.com>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	linux-perf-users@...r.kernel.org,
	Mark Brown <broonie@...nel.org>,
	linux-toolchains@...r.kernel.org,
	Jordan Rome <jordalgo@...a.com>,
	Sam James <sam@...too.org>
Subject: [PATCH v2 11/11] perf/x86: Enable SFrame unwinding for deferred user callchains

Use SFrame for deferred user callchains, if available.

Non-deferred user callchains still need to use frame pointers, as SFrame
is likely to fault when it pages in the .sframe section.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 arch/x86/events/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index d6ea265d9aa8..d618c50865d3 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2861,6 +2861,7 @@ static int __perf_callchain_user32(struct pt_regs *regs,
 static void __perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 				  struct pt_regs *regs, bool atomic)
 {
+	bool unwind_type = USER_UNWIND_TYPE_AUTO;
 	struct user_unwind_state state;
 
 	if (perf_guest_state()) {
@@ -2879,13 +2880,14 @@ static void __perf_callchain_user(struct perf_callchain_entry_ctx *entry,
 	if (atomic) {
 		if (!nmi_uaccess_okay())
 			return;
+		unwind_type = USER_UNWIND_TYPE_FP;
 		pagefault_disable();
 	}
 
 	if (__perf_callchain_user32(regs, entry))
 		goto done;
 
-	for_each_user_frame(&state, USER_UNWIND_TYPE_FP) {
+	for_each_user_frame(&state, unwind_type) {
 		if (perf_callchain_store(entry, state.ip))
 			goto done;
 	}
-- 
2.46.0