Commit 9b99edca authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov

bpf: Add bpf_get_func_ip helper for tracing programs

Adding bpf_get_func_ip helper for BPF_PROG_TYPE_TRACING programs,
specifically for all trampoline attach types.

The trampoline's caller IP address is stored in (ctx - 8) address.
so there's no reason to actually call the helper, but rather fixup
the call instruction and return [ctx - 8] value directly.
Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-4-jolsa@kernel.org
parent 1e37392c
...@@ -4841,6 +4841,12 @@ union bpf_attr { ...@@ -4841,6 +4841,12 @@ union bpf_attr {
* **-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier. * **-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier.
* **-EDEADLK** if callback_fn tried to call bpf_timer_cancel() on its * **-EDEADLK** if callback_fn tried to call bpf_timer_cancel() on its
* own timer which would have led to a deadlock otherwise. * own timer which would have led to a deadlock otherwise.
*
* u64 bpf_get_func_ip(void *ctx)
* Description
* Get address of the traced function (for tracing programs).
* Return
* Address of the traced function.
*/ */
#define __BPF_FUNC_MAPPER(FN) \ #define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \ FN(unspec), \
...@@ -5016,6 +5022,7 @@ union bpf_attr { ...@@ -5016,6 +5022,7 @@ union bpf_attr {
FN(timer_set_callback), \ FN(timer_set_callback), \
FN(timer_start), \ FN(timer_start), \
FN(timer_cancel), \ FN(timer_cancel), \
FN(get_func_ip), \
/* */ /* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper /* integer value in 'imm' field of BPF_CALL instruction selects which helper
......
...@@ -6161,6 +6161,27 @@ static int check_bpf_snprintf_call(struct bpf_verifier_env *env, ...@@ -6161,6 +6161,27 @@ static int check_bpf_snprintf_call(struct bpf_verifier_env *env,
return err; return err;
} }
static int check_get_func_ip(struct bpf_verifier_env *env)
{
enum bpf_attach_type eatype = env->prog->expected_attach_type;
enum bpf_prog_type type = resolve_prog_type(env->prog);
int func_id = BPF_FUNC_get_func_ip;
if (type == BPF_PROG_TYPE_TRACING) {
if (eatype != BPF_TRACE_FENTRY && eatype != BPF_TRACE_FEXIT &&
eatype != BPF_MODIFY_RETURN) {
verbose(env, "func %s#%d supported only for fentry/fexit/fmod_ret programs\n",
func_id_name(func_id), func_id);
return -ENOTSUPP;
}
return 0;
}
verbose(env, "func %s#%d not supported for program type %d\n",
func_id_name(func_id), func_id, type);
return -ENOTSUPP;
}
static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn, static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
int *insn_idx_p) int *insn_idx_p)
{ {
...@@ -6439,6 +6460,12 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn ...@@ -6439,6 +6460,12 @@ static int check_helper_call(struct bpf_verifier_env *env, struct bpf_insn *insn
if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack) if (func_id == BPF_FUNC_get_stackid || func_id == BPF_FUNC_get_stack)
env->prog->call_get_stack = true; env->prog->call_get_stack = true;
if (func_id == BPF_FUNC_get_func_ip) {
if (check_get_func_ip(env))
return -ENOTSUPP;
env->prog->call_get_func_ip = true;
}
if (changes_data) if (changes_data)
clear_all_pkt_pointers(env); clear_all_pkt_pointers(env);
return 0; return 0;
...@@ -12632,6 +12659,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env) ...@@ -12632,6 +12659,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
{ {
struct bpf_prog *prog = env->prog; struct bpf_prog *prog = env->prog;
bool expect_blinding = bpf_jit_blinding_enabled(prog); bool expect_blinding = bpf_jit_blinding_enabled(prog);
enum bpf_prog_type prog_type = resolve_prog_type(prog);
struct bpf_insn *insn = prog->insnsi; struct bpf_insn *insn = prog->insnsi;
const struct bpf_func_proto *fn; const struct bpf_func_proto *fn;
const int insn_cnt = prog->len; const int insn_cnt = prog->len;
...@@ -12998,6 +13026,21 @@ static int do_misc_fixups(struct bpf_verifier_env *env) ...@@ -12998,6 +13026,21 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
continue; continue;
} }
/* Implement bpf_get_func_ip inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_ip) {
/* Load IP address from ctx - 8 */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1, -8);
new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, 1);
if (!new_prog)
return -ENOMEM;
env->prog = prog = new_prog;
insn = new_prog->insnsi + i + delta;
continue;
}
patch_call_imm: patch_call_imm:
fn = env->ops->get_func_proto(insn->imm, env->prog); fn = env->ops->get_func_proto(insn->imm, env->prog);
/* all functions that have prototype and verifier allowed /* all functions that have prototype and verifier allowed
......
...@@ -948,6 +948,19 @@ const struct bpf_func_proto bpf_snprintf_btf_proto = { ...@@ -948,6 +948,19 @@ const struct bpf_func_proto bpf_snprintf_btf_proto = {
.arg5_type = ARG_ANYTHING, .arg5_type = ARG_ANYTHING,
}; };
BPF_CALL_1(bpf_get_func_ip_tracing, void *, ctx)
{
/* This helper call is inlined by verifier. */
return ((u64 *)ctx)[-1];
}
static const struct bpf_func_proto bpf_get_func_ip_proto_tracing = {
.func = bpf_get_func_ip_tracing,
.gpl_only = true,
.ret_type = RET_INTEGER,
.arg1_type = ARG_PTR_TO_CTX,
};
const struct bpf_func_proto * const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{ {
...@@ -1058,6 +1071,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) ...@@ -1058,6 +1071,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_for_each_map_elem_proto; return &bpf_for_each_map_elem_proto;
case BPF_FUNC_snprintf: case BPF_FUNC_snprintf:
return &bpf_snprintf_proto; return &bpf_snprintf_proto;
case BPF_FUNC_get_func_ip:
return &bpf_get_func_ip_proto_tracing;
default: default:
return bpf_base_func_proto(func_id); return bpf_base_func_proto(func_id);
} }
......
...@@ -4841,6 +4841,12 @@ union bpf_attr { ...@@ -4841,6 +4841,12 @@ union bpf_attr {
* **-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier. * **-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier.
* **-EDEADLK** if callback_fn tried to call bpf_timer_cancel() on its * **-EDEADLK** if callback_fn tried to call bpf_timer_cancel() on its
* own timer which would have led to a deadlock otherwise. * own timer which would have led to a deadlock otherwise.
*
* u64 bpf_get_func_ip(void *ctx)
* Description
* Get address of the traced function (for tracing programs).
* Return
* Address of the traced function.
*/ */
#define __BPF_FUNC_MAPPER(FN) \ #define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \ FN(unspec), \
...@@ -5016,6 +5022,7 @@ union bpf_attr { ...@@ -5016,6 +5022,7 @@ union bpf_attr {
FN(timer_set_callback), \ FN(timer_set_callback), \
FN(timer_start), \ FN(timer_start), \
FN(timer_cancel), \ FN(timer_cancel), \
FN(get_func_ip), \
/* */ /* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper /* integer value in 'imm' field of BPF_CALL instruction selects which helper
......
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