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authorAlexei Starovoitov <ast@fb.com>2016-02-17 19:58:57 -0800
committerDavid S. Miller <davem@davemloft.net>2016-02-20 00:21:44 -0500
commit568b329a02f75ed3aaae5eb2cca384cb9e09cb29 (patch)
treeae50fa4f98c1c7ad07ad834677be3304a282499e /kernel/events/callchain.c
parent6b83d28a55a891a9d70fc61ccb1c138e47dcbe74 (diff)
perf: generalize perf_callchain
. avoid walking the stack when there is no room left in the buffer . generalize get_perf_callchain() to be called from bpf helper Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/events/callchain.c')
-rw-r--r--kernel/events/callchain.c32
1 files changed, 20 insertions, 12 deletions
diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c
index 9c418002b8c1..343c22f5e867 100644
--- a/kernel/events/callchain.c
+++ b/kernel/events/callchain.c
@@ -159,15 +159,24 @@ put_callchain_entry(int rctx)
struct perf_callchain_entry *
perf_callchain(struct perf_event *event, struct pt_regs *regs)
{
- int rctx;
- struct perf_callchain_entry *entry;
-
- int kernel = !event->attr.exclude_callchain_kernel;
- int user = !event->attr.exclude_callchain_user;
+ 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;
if (!kernel && !user)
return NULL;
+ return get_perf_callchain(regs, 0, kernel, user, crosstask, true);
+}
+
+struct perf_callchain_entry *
+get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
+ bool crosstask, bool add_mark)
+{
+ struct perf_callchain_entry *entry;
+ int rctx;
+
entry = get_callchain_entry(&rctx);
if (rctx == -1)
return NULL;
@@ -175,10 +184,11 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
if (!entry)
goto exit_put;
- entry->nr = 0;
+ entry->nr = init_nr;
if (kernel && !user_mode(regs)) {
- perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
+ if (add_mark)
+ perf_callchain_store(entry, PERF_CONTEXT_KERNEL);
perf_callchain_kernel(entry, regs);
}
@@ -191,13 +201,11 @@ perf_callchain(struct perf_event *event, struct pt_regs *regs)
}
if (regs) {
- /*
- * Disallow cross-task user callchains.
- */
- if (event->ctx->task && event->ctx->task != current)
+ if (crosstask)
goto exit_put;
- perf_callchain_store(entry, PERF_CONTEXT_USER);
+ if (add_mark)
+ perf_callchain_store(entry, PERF_CONTEXT_USER);
perf_callchain_user(entry, regs);
}
}