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bpf: Add bpf_get_func_ip helper for tracing programs

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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: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-4-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2021-07-14 11:43:55 +02:00 committed by Andrii Nakryiko
parent bef77595ca
commit 97e2a9c9a1
1 changed files with 7 additions and 0 deletions
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7
include/uapi/linux/bpf.h
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@ -4841,6 +4841,12 @@ union bpf_attr {
* **-EINVAL** if *timer* was not initialized with bpf_timer_init() earlier.
* **-EDEADLK** if callback_fn tried to call bpf_timer_cancel() on its
* 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) \
FN(unspec), \
@ -5016,6 +5022,7 @@ union bpf_attr {
FN(timer_set_callback), \
FN(timer_start), \
FN(timer_cancel), \
FN(get_func_ip), \
/* */
/* integer value in 'imm' field of BPF_CALL instruction selects which helper