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bpf: Use stack id functions instead of __bpf_get_stackid

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Replacing __bpf_get_stackid calls with sequence of following functions:

  stackid_fastpath
  stackid_new_bucket
  stackid_install

This makes code more structured and allows us to easily disable
preemption only in bpf_get_stackid in following changes.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20260803210149.296496-5-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2026-08-03 23:01:41 +02:00 committed by Andrii Nakryiko
parent bb4e6f4e1b
commit 09b3fd6caa
1 changed files with 27 additions and 16 deletions
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43
kernel/bpf/stackmap.c
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@ -584,22 +584,13 @@ stackid_new_bucket(struct stackid *stackid, struct bpf_map *map)
return bucket;
}
static long __bpf_get_stackid(struct stackid *stackid, struct bpf_map *map,
struct perf_callchain_entry *trace, u64 flags)
static long stackid_install(struct stackid *stackid, struct bpf_map *map,
struct stack_map_bucket *new_bucket, u64 flags)
{
struct bpf_stack_map *smap = container_of(map, struct bpf_stack_map, map);
struct stack_map_bucket *new_bucket, *old_bucket;
bool user = flags & BPF_F_USER_STACK;
struct stack_map_bucket *old_bucket;
u32 trace_len;
int err;
err = stackid_fastpath(stackid, map, trace, flags);
if (err != -ENOENT)
return err;
new_bucket = stackid_new_bucket(stackid, map);
if (!new_bucket)
return -ENOMEM;
if (stack_map_use_build_id(map)) {
struct bpf_stack_build_id *id_offs;
@ -629,10 +620,12 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
{
u32 elem_size = stack_map_data_size(map);
bool user = flags & BPF_F_USER_STACK;
struct stack_map_bucket *new_bucket;
struct perf_callchain_entry *trace;
struct stackid stackid;
bool kernel = !user;
u32 max_depth;
int err;
if (unlikely(flags & ~(BPF_F_SKIP_FIELD_MASK | BPF_F_USER_STACK |
BPF_F_FAST_STACK_CMP | BPF_F_REUSE_STACKID)))
@ -646,7 +639,15 @@ BPF_CALL_3(bpf_get_stackid, struct pt_regs *, regs, struct bpf_map *, map,
/* couldn't fetch the stack trace */
return -EFAULT;
return __bpf_get_stackid(&stackid, map, trace, flags);
err = stackid_fastpath(&stackid, map, trace, flags);
if (err != -ENOENT)
return err;
new_bucket = stackid_new_bucket(&stackid, map);
if (!new_bucket)
return -ENOMEM;
return stackid_install(&stackid, map, new_bucket, flags);
}
const struct bpf_func_proto bpf_get_stackid_proto = {
@ -674,6 +675,7 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
struct bpf_map *, map, u64, flags)
{
struct perf_event *event = ctx->event;
struct stack_map_bucket *new_bucket;
struct perf_callchain_entry *trace;
struct stackid stackid;
bool kernel, user;
@ -701,7 +703,6 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
if (kernel) {
trace->nr = nr_kernel;
ret = __bpf_get_stackid(&stackid, map, trace, flags);
} else { /* user */
u64 skip = flags & BPF_F_SKIP_FIELD_MASK;
@ -710,12 +711,22 @@ BPF_CALL_3(bpf_get_stackid_pe, struct bpf_perf_event_data_kern *, ctx,
return -EFAULT;
flags = (flags & ~BPF_F_SKIP_FIELD_MASK) | skip;
ret = __bpf_get_stackid(&stackid, map, trace, flags);
}
ret = stackid_fastpath(&stackid, map, trace, flags);
if (ret != -ENOENT)
goto out;
new_bucket = stackid_new_bucket(&stackid, map);
if (new_bucket) {
trace->nr = nr;
return stackid_install(&stackid, map, new_bucket, flags);
}
ret = -ENOMEM;
out:
/* restore nr */
trace->nr = nr;
return ret;
}