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perf: Expose get/put_callchain_entry() 

Sanitize and expose get/put_callchain_entry(). This would be used by bpf
stack map.

Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200630062846.664389-2-songliubraving@fb.com
This commit is contained in:
Song Liu 2020-06-29 23:28:43 -07:00 committed by Alexei Starovoitov
parent bba1dc0b55
commit d141b8bc57
2 changed files with 8 additions and 7 deletions
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2
include/linux/perf_event.h
View File

@ -1244,6 +1244,8 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
extern struct perf_callchain_entry *perf_callchain(struct perf_event *event, struct pt_regs *regs);
extern int get_callchain_buffers(int max_stack);
extern void put_callchain_buffers(void);
extern struct perf_callchain_entry *get_callchain_entry(int *rctx);
extern void put_callchain_entry(int rctx);
extern int sysctl_perf_event_max_stack;
extern int sysctl_perf_event_max_contexts_per_stack;

13
kernel/events/callchain.c
View File

@ -149,7 +149,7 @@ void put_callchain_buffers(void)
}
}
static struct perf_callchain_entry *get_callchain_entry(int *rctx)
struct perf_callchain_entry *get_callchain_entry(int *rctx)
{
int cpu;
struct callchain_cpus_entries *entries;
@ -159,8 +159,10 @@ static struct perf_callchain_entry *get_callchain_entry(int *rctx)
return NULL;
entries = rcu_dereference(callchain_cpus_entries);
if (!entries)
if (!entries) {
put_recursion_context(this_cpu_ptr(callchain_recursion), *rctx);
return NULL;
}
cpu = smp_processor_id();
@ -168,7 +170,7 @@ static struct perf_callchain_entry *get_callchain_entry(int *rctx)
(*rctx * perf_callchain_entry__sizeof()));
}
static void
void
put_callchain_entry(int rctx)
{
put_recursion_context(this_cpu_ptr(callchain_recursion), rctx);
@ -183,11 +185,8 @@ get_perf_callchain(struct pt_regs *regs, u32 init_nr, bool kernel, bool user,
int rctx;
entry = get_callchain_entry(&rctx);
if (rctx == -1)
return NULL;
if (!entry)
goto exit_put;
return NULL;
ctx.entry = entry;
ctx.max_stack = max_stack;