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bpf: Make find_linfo widely available

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Move find_linfo() as bpf_find_linfo() into core.c to allow for its use
in the verifier in subsequent patches.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Link: https://lore.kernel.org/r/20260408021359.3786905-4-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Kumar Kartikeya Dwivedi 2026-04-08 04:13:54 +02:00 committed by Alexei Starovoitov
parent fbb98834a9
commit 4f64d5b664
3 changed files with 39 additions and 42 deletions
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1
include/linux/bpf.h
View File

@ -3945,6 +3945,7 @@ static inline bool bpf_is_subprog(const struct bpf_prog *prog)
return prog->aux->func_idx != 0;
}
const struct bpf_line_info *bpf_find_linfo(const struct bpf_prog *prog, u32 insn_off);
void bpf_get_linfo_file_line(struct btf *btf, const struct bpf_line_info *linfo,
const char **filep, const char **linep, int *nump);
int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char **filep,

37
kernel/bpf/core.c
View File

@ -3335,6 +3335,43 @@ void bpf_get_linfo_file_line(struct btf *btf, const struct bpf_line_info *linfo,
*nump = BPF_LINE_INFO_LINE_NUM(linfo->line_col);
}
const struct bpf_line_info *bpf_find_linfo(const struct bpf_prog *prog, u32 insn_off)
{
const struct bpf_line_info *linfo;
u32 nr_linfo;
int l, r, m;
nr_linfo = prog->aux->nr_linfo;
if (!nr_linfo || insn_off >= prog->len)
return NULL;
linfo = prog->aux->linfo;
/* Loop invariant: linfo[l].insn_off <= insns_off.
* linfo[0].insn_off == 0 which always satisfies above condition.
* Binary search is searching for rightmost linfo entry that satisfies
* the above invariant, giving us the desired record that covers given
* instruction offset.
*/
l = 0;
r = nr_linfo - 1;
while (l < r) {
/* (r - l + 1) / 2 means we break a tie to the right, so if:
* l=1, r=2, linfo[l].insn_off <= insn_off, linfo[r].insn_off > insn_off,
* then m=2, we see that linfo[m].insn_off > insn_off, and so
* r becomes 1 and we exit the loop with correct l==1.
* If the tie was broken to the left, m=1 would end us up in
* an endless loop where l and m stay at 1 and r stays at 2.
*/
m = l + (r - l + 1) / 2;
if (linfo[m].insn_off <= insn_off)
l = m;
else
r = m - 1;
}
return &linfo[l];
}
int bpf_prog_get_file_line(struct bpf_prog *prog, unsigned long ip, const char **filep,
const char **linep, int *nump)
{

43
kernel/bpf/log.c
View File

@ -329,47 +329,6 @@ __printf(2, 3) void bpf_log(struct bpf_verifier_log *log,
}
EXPORT_SYMBOL_GPL(bpf_log);
static const struct bpf_line_info *
find_linfo(const struct bpf_verifier_env *env, u32 insn_off)
{
const struct bpf_line_info *linfo;
const struct bpf_prog *prog;
u32 nr_linfo;
int l, r, m;
prog = env->prog;
nr_linfo = prog->aux->nr_linfo;
if (!nr_linfo || insn_off >= prog->len)
return NULL;
linfo = prog->aux->linfo;
/* Loop invariant: linfo[l].insn_off <= insns_off.
* linfo[0].insn_off == 0 which always satisfies above condition.
* Binary search is searching for rightmost linfo entry that satisfies
* the above invariant, giving us the desired record that covers given
* instruction offset.
*/
l = 0;
r = nr_linfo - 1;
while (l < r) {
/* (r - l + 1) / 2 means we break a tie to the right, so if:
* l=1, r=2, linfo[l].insn_off <= insn_off, linfo[r].insn_off > insn_off,
* then m=2, we see that linfo[m].insn_off > insn_off, and so
* r becomes 1 and we exit the loop with correct l==1.
* If the tie was broken to the left, m=1 would end us up in
* an endless loop where l and m stay at 1 and r stays at 2.
*/
m = l + (r - l + 1) / 2;
if (linfo[m].insn_off <= insn_off)
l = m;
else
r = m - 1;
}
return &linfo[l];
}
static const char *ltrim(const char *s)
{
while (isspace(*s))
@ -390,7 +349,7 @@ __printf(3, 4) void verbose_linfo(struct bpf_verifier_env *env,
return;
prev_linfo = env->prev_linfo;
linfo = find_linfo(env, insn_off);
linfo = bpf_find_linfo(env->prog, insn_off);
if (!linfo || linfo == prev_linfo)
return;