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Message-ID: <fdb7095ed58246bcf5c7731d83cd73f0f53fe6b0.1730150953.git.jpoimboe@kernel.org>
Date: Mon, 28 Oct 2024 14:48:00 -0700
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>,
linux-trace-kernel@...r.kerne.org,
Andrii Nakryiko <andrii.nakryiko@...il.com>,
Jens Remus <jremus@...ux.ibm.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Florian Weimer <fweimer@...hat.com>,
Andy Lutomirski <luto@...nel.org>
Subject: [PATCH v3 13/19] perf: Remove get_perf_callchain() 'crosstask' argument
get_perf_callchain() doesn't support cross-task unwinding, so it doesn't
make much sense to have 'crosstask' as an argument.
Acked-by: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
include/linux/perf_event.h | 2 +-
kernel/bpf/stackmap.c | 12 ++++--------
kernel/events/callchain.c | 6 +-----
kernel/events/core.c | 9 +++++----
4 files changed, 11 insertions(+), 18 deletions(-)
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 1e956ff9acd3..788f6971d32d 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -1569,7 +1569,7 @@ extern void perf_callchain_user(struct perf_callchain_entry_ctx *entry, struct p
extern void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry, struct pt_regs *regs);
extern struct perf_callchain_entry *
get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
- u32 max_stack, bool crosstask, bool add_mark);
+ u32 max_stack, bool add_mark);
extern int get_callchain_buffers(int max_stack);
extern void put_callchain_buffers(void);
extern struct perf_callchain_entry *get_callchain_entry(int *rctx);
diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c
index ec3a57a5fba1..ee9701337912 100644
--- a/kernel/bpf/stackmap.c
+++ b/kernel/bpf/stackmap.c
@@ -314,8 +314,7 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
if (max_depth > sysctl_perf_event_max_stack)
max_depth = sysctl_perf_event_max_stack;
- trace = get_perf_callchain(regs, kernel, user, max_depth,
- false, false);
+ trace = get_perf_callchain(regs, kernel, user, max_depth, false);
if (unlikely(!trace))
/* couldn't fetch the stack trace */
@@ -430,10 +429,8 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
if (task && user && !user_mode(regs))
goto err_fault;
- /* get_perf_callchain does not support crosstask user stack walking
- * but returns an empty stack instead of NULL.
- */
- if (crosstask && user) {
+ /* get_perf_callchain() does not support crosstask stack walking */
+ if (crosstask) {
err = -EOPNOTSUPP;
goto clear;
}
@@ -451,8 +448,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
else if (kernel && task)
trace = get_callchain_entry_for_task(task, max_depth);
else
- trace = get_perf_callchain(regs, kernel, user, max_depth,
- crosstask, false);
+ trace = get_perf_callchain(regs, kernel, user, max_depth,false);
if (unlikely(!trace) || trace->nr < skip) {
if (may_fault)
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 83834203e144..655fb25a725b 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -217,7 +217,7 @@ static void fixup_uretprobe_trampoline_entries(struct perf_callchain_entry *entr
struct perf_callchain_entry *
get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
- u32 max_stack, bool crosstask, bool add_mark)
+ u32 max_stack, bool add_mark)
{
struct perf_callchain_entry *entry;
struct perf_callchain_entry_ctx ctx;
@@ -248,9 +248,6 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
}
if (regs) {
- if (crosstask)
- goto exit_put;
-
if (add_mark)
perf_callchain_store_context(&ctx, PERF_CONTEXT_USER);
@@ -260,7 +257,6 @@ get_perf_callchain(struct pt_regs *regs, bool kernel, bool user,
}
}
-exit_put:
put_callchain_entry(rctx);
return entry;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1654d6e7c148..ebf143aa427b 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7792,16 +7792,17 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
{
bool kernel = !event->attr.exclude_callchain_kernel;
bool user = !event->attr.exclude_callchain_user;
- /* Disallow cross-task user callchains. */
- bool crosstask = event->ctx->task && event->ctx->task != current;
const u32 max_stack = event->attr.sample_max_stack;
struct perf_callchain_entry *callchain;
if (!kernel && !user)
return &__empty_callchain;
- callchain = get_perf_callchain(regs, kernel, user,
- max_stack, crosstask, true);
+ /* Disallow cross-task callchains. */
+ if (event->ctx->task && event->ctx->task != current)
+ return &__empty_callchain;
+
+ callchain = get_perf_callchain(regs, kernel, user, max_stack, true);
return callchain ?: &__empty_callchain;
}
--
2.47.0
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