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perf/ftrace: Add recursion protection to the ftrace callback

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If a ftrace callback does not supply its own recursion protection and
does not set the RECURSION_SAFE flag in its ftrace_ops, then ftrace will
make a helper trampoline to do so before calling the callback instead of
just calling the callback directly.

The default for ftrace_ops is going to change. It will expect that handlers
provide their own recursion protection, unless its ftrace_ops states
otherwise.

Link: https://lkml.kernel.org/r/20201028115613.444477858@goodmis.org
Link: https://lkml.kernel.org/r/20201106023547.466892083@goodmis.org

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Josh  Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2020-11-05 21:32:43 -05:00
parent 4b750b573c
commit 5d15a624c3
1 changed files with 8 additions and 1 deletions
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9
kernel/trace/trace_event_perf.c
View File

@ -439,10 +439,15 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
struct hlist_head head;
struct pt_regs regs;
int rctx;
int bit;
if ((unsigned long)ops->private != smp_processor_id())
return;
bit = ftrace_test_recursion_trylock();
if (bit < 0)
return;
event = container_of(ops, struct perf_event, ftrace_ops);
/*
@ -463,13 +468,15 @@ perf_ftrace_function_call(unsigned long ip, unsigned long parent_ip,
entry = perf_trace_buf_alloc(ENTRY_SIZE, NULL, &rctx);
if (!entry)
return;
goto out;
entry->ip = ip;
entry->parent_ip = parent_ip;
perf_trace_buf_submit(entry, ENTRY_SIZE, rctx, TRACE_FN,
1, &regs, &head, NULL);
out:
ftrace_test_recursion_unlock(bit);
#undef ENTRY_SIZE
}