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perf: generalize perf_callchain

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. 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>
This commit is contained in:
Alexei Starovoitov
2016-02-17 19:58:57 -08:00
committed by David S. Miller
parent 6b83d28a55
commit 568b329a02
8 changed files with 51 additions and 29 deletions
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32
kernel/events/callchain.c
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@@ -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);
}
}

2
kernel/events/internal.h
View File

@@ -182,8 +182,6 @@ DEFINE_OUTPUT_COPY(__output_copy_user, arch_perf_out_copy_user)
/* Callchain handling */
extern struct perf_callchain_entry *
perf_callchain(struct perf_event *event, struct pt_regs *regs);
extern int get_callchain_buffers(void);
extern void put_callchain_buffers(void);
static inline int get_recursion_context(int *recursion)
{