From ce71b9df8893ec954e56c5979df6da274f20f65e Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Sun, 22 Nov 2009 05:26:55 +0100 Subject: tracing: Use the perf recursion protection from trace event When we commit a trace to perf, we first check if we are recursing in the same buffer so that we don't mess-up the buffer with a recursing trace. But later on, we do the same check from perf to avoid commit recursion. The recursion check is desired early before we touch the buffer but we want to do this check only once. Then export the recursion protection from perf and use it from the trace events before submitting a trace. v2: Put appropriate Reported-by tag Reported-by: Peter Zijlstra Signed-off-by: Frederic Weisbecker Cc: Arnaldo Carvalho de Melo Cc: Paul Mackerras Cc: Steven Rostedt Cc: Masami Hiramatsu Cc: Jason Baron LKML-Reference: <1258864015-10579-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar --- kernel/trace/trace_syscalls.c | 47 ++++++++++++++++--------------------------- 1 file changed, 17 insertions(+), 30 deletions(-) (limited to 'kernel/trace/trace_syscalls.c') diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 51213b0aa81b..0bb934875263 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -477,10 +477,11 @@ static int sys_prof_refcount_exit; static void prof_syscall_enter(struct pt_regs *regs, long id) { struct syscall_metadata *sys_data; - struct perf_trace_buf *trace_buf; struct syscall_trace_enter *rec; unsigned long flags; + char *trace_buf; char *raw_data; + int *recursion; int syscall_nr; int size; int cpu; @@ -505,6 +506,9 @@ static void prof_syscall_enter(struct pt_regs *regs, long id) /* Protect the per cpu buffer, begin the rcu read side */ local_irq_save(flags); + if (perf_swevent_get_recursion_context(&recursion)) + goto end_recursion; + cpu = smp_processor_id(); if (in_nmi()) @@ -515,18 +519,7 @@ static void prof_syscall_enter(struct pt_regs *regs, long id) if (!trace_buf) goto end; - trace_buf = per_cpu_ptr(trace_buf, cpu); - - if (trace_buf->recursion++) - goto end_recursion; - - /* - * Make recursion update visible before entering perf_tp_event - * so that we protect from perf recursions. - */ - barrier(); - - raw_data = trace_buf->buf; + raw_data = per_cpu_ptr(trace_buf, cpu); /* zero the dead bytes from align to not leak stack to user */ *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL; @@ -539,9 +532,9 @@ static void prof_syscall_enter(struct pt_regs *regs, long id) (unsigned long *)&rec->args); perf_tp_event(sys_data->enter_id, 0, 1, rec, size); -end_recursion: - trace_buf->recursion--; end: + perf_swevent_put_recursion_context(recursion); +end_recursion: local_irq_restore(flags); } @@ -588,10 +581,11 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret) { struct syscall_metadata *sys_data; struct syscall_trace_exit *rec; - struct perf_trace_buf *trace_buf; unsigned long flags; int syscall_nr; + char *trace_buf; char *raw_data; + int *recursion; int size; int cpu; @@ -617,6 +611,10 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret) /* Protect the per cpu buffer, begin the rcu read side */ local_irq_save(flags); + + if (perf_swevent_get_recursion_context(&recursion)) + goto end_recursion; + cpu = smp_processor_id(); if (in_nmi()) @@ -627,18 +625,7 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret) if (!trace_buf) goto end; - trace_buf = per_cpu_ptr(trace_buf, cpu); - - if (trace_buf->recursion++) - goto end_recursion; - - /* - * Make recursion update visible before entering perf_tp_event - * so that we protect from perf recursions. - */ - barrier(); - - raw_data = trace_buf->buf; + raw_data = per_cpu_ptr(trace_buf, cpu); /* zero the dead bytes from align to not leak stack to user */ *(u64 *)(&raw_data[size - sizeof(u64)]) = 0ULL; @@ -652,9 +639,9 @@ static void prof_syscall_exit(struct pt_regs *regs, long ret) perf_tp_event(sys_data->exit_id, 0, 1, rec, size); -end_recursion: - trace_buf->recursion--; end: + perf_swevent_put_recursion_context(recursion); +end_recursion: local_irq_restore(flags); } -- cgit v1.2.3