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bpf: Remove trace_in argument from __bpf_get_stack

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Now with the new callchain_* helper functions we can process trace_in
case directly in bpf_get_stack_pe function and remove it from
__bpf_get_stack which makes things easier for preemption fix in
following change.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260803210149.296496-9-jolsa@kernel.org
This commit is contained in:
Jiri Olsa
2026-08-03 23:01:45 +02:00
committed by Andrii Nakryiko
parent 014fbe5902
commit 58cfc2201d
1 changed files with 35 additions and 14 deletions
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49
kernel/bpf/stackmap.c
View File

@@ -780,7 +780,6 @@ static long callchain_finalize(void *buf, u32 size, u32 trace_nr, u32 elem_size,
}
static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
struct perf_callchain_entry *trace_in,
void *buf, u32 size, u64 flags, bool may_fault)
{
bool user_build_id = flags & BPF_F_USER_BUILD_ID;
@@ -819,10 +818,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
if (may_fault)
rcu_read_lock(); /* need RCU for perf's callchain below */
if (trace_in) {
trace = trace_in;
trace->nr = min_t(u32, trace->nr, max_depth);
} else if (kernel && task) {
if (kernel && task) {
trace = get_callchain_entry_for_task(task, max_depth);
} else {
trace = get_perf_callchain(regs, kernel, user, max_depth,
@@ -853,7 +849,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task,
BPF_CALL_4(bpf_get_stack, struct pt_regs *, regs, void *, buf, u32, size,
u64, flags)
{
return __bpf_get_stack(regs, NULL, NULL, buf, size, flags, false /* !may_fault */);
return __bpf_get_stack(regs, NULL, buf, size, flags, false /* !may_fault */);
}
const struct bpf_func_proto bpf_get_stack_proto = {
@@ -869,7 +865,7 @@ const struct bpf_func_proto bpf_get_stack_proto = {
BPF_CALL_4(bpf_get_stack_sleepable, struct pt_regs *, regs, void *, buf, u32, size,
u64, flags)
{
return __bpf_get_stack(regs, NULL, NULL, buf, size, flags, true /* may_fault */);
return __bpf_get_stack(regs, NULL, buf, size, flags, true /* may_fault */);
}
const struct bpf_func_proto bpf_get_stack_sleepable_proto = {
@@ -893,7 +889,7 @@ static long __bpf_get_task_stack(struct task_struct *task, void *buf, u32 size,
regs = task_pt_regs(task);
if (regs)
res = __bpf_get_stack(regs, task, NULL, buf, size, flags, may_fault);
res = __bpf_get_stack(regs, task, buf, size, flags, may_fault);
put_task_stack(task);
return res;
@@ -933,6 +929,32 @@ const struct bpf_func_proto bpf_get_task_stack_sleepable_proto = {
.arg4_type = ARG_ANYTHING,
};
static int __bpf_get_stack_pe(struct perf_callchain_entry *trace, void *buf, u32 size,
u64 flags)
{
bool user_build_id = flags & BPF_F_USER_BUILD_ID;
u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
bool user = flags & BPF_F_USER_STACK;
u32 elem_size, max_depth, nr_trace;
bool kernel = !user;
if (kernel && user_build_id)
return -EINVAL;
elem_size = user_build_id ? sizeof(struct bpf_stack_build_id) : sizeof(u64);
if (unlikely(size % elem_size))
return -EINVAL;
max_depth = stack_map_calculate_max_depth(size, elem_size, flags);
trace->nr = min_t(u32, trace->nr, max_depth);
if (trace->nr < skip)
return -EFAULT;
nr_trace = callchain_store(trace, buf, elem_size, flags);
return callchain_finalize(buf, size, nr_trace, elem_size, flags, false /* !may_fault */);
}
BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
void *, buf, u32, size, u64, flags)
{
@@ -944,7 +966,7 @@ BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
__u64 nr_kernel;
if (!(event->attr.sample_type & PERF_SAMPLE_CALLCHAIN))
return __bpf_get_stack(regs, NULL, NULL, buf, size, flags, false /* !may_fault */);
return __bpf_get_stack(regs, NULL, buf, size, flags, false /* !may_fault */);
if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
BPF_F_USER_BUILD_ID)))
@@ -964,7 +986,7 @@ BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
__u64 nr = trace->nr;
trace->nr = nr_kernel;
err = __bpf_get_stack(regs, NULL, trace, buf, size, flags, false /* !may_fault */);
err = __bpf_get_stack_pe(trace, buf, size, flags);
/* restore nr */
trace->nr = nr;
@@ -974,14 +996,13 @@ BPF_CALL_4(bpf_get_stack_pe, struct bpf_perf_event_data_kern *, ctx,
skip += nr_kernel;
if (skip > BPF_F_SKIP_FIELD_MASK)
goto clear;
flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
err = __bpf_get_stack(regs, NULL, trace, buf, size, flags, false /* !may_fault */);
err = __bpf_get_stack_pe(trace, buf, size, flags);
}
return err;
clear:
memset(buf, 0, size);
if (err < 0)
memset(buf, 0, size);
return err;
}