system/linux
system/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux synced 2024-10-16 08:19:01 +00:00
Code Issues Packages Projects Releases Wiki Activity

bpf: Return value in kprobe get_func_ip only for entry address

Browse source 
Changing return value of kprobe's version of bpf_get_func_ip
to return zero if the attach address is not on the function's
entry point.

For kprobes attached in the middle of the function we can't easily
get to the function address especially now with the CONFIG_X86_KERNEL_IBT
support.

If user cares about current IP for kprobes attached within the
function body, they can get it with PT_REGS_IP(ctx).

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20220926153340.1621984-6-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Jiri Olsa 2022-09-26 17:33:39 +02:00 committed by Alexei Starovoitov
parent c09eb2e578
commit 0e253f7e55
4 changed files with 8 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
include/uapi/linux/bpf.h
View file

@ -4951,6 +4951,7 @@ union bpf_attr {
* Get address of the traced function (for tracing and kprobe programs).
* Return
* Address of the traced function.
* 0 for kprobes placed within the function (not at the entry).
*
* u64 bpf_get_attach_cookie(void *ctx)
* Description

5
kernel/trace/bpf_trace.c
View file

@ -1048,7 +1048,10 @@ BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
{
struct kprobe *kp = kprobe_running();
return kp ? (uintptr_t)kp->addr : 0;
if (!kp || !(kp->flags & KPROBE_FLAG_ON_FUNC_ENTRY))
return 0;
return get_entry_ip((uintptr_t)kp->addr);
}
static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {

1
tools/include/uapi/linux/bpf.h
View file

@ -4951,6 +4951,7 @@ union bpf_attr {
* Get address of the traced function (for tracing and kprobe programs).
* Return
* Address of the traced function.
* 0 for kprobes placed within the function (not at the entry).
*
* u64 bpf_get_attach_cookie(void *ctx)
* Description

4
tools/testing/selftests/bpf/progs/get_func_ip_test.c
View file

@ -69,7 +69,7 @@ int test6(struct pt_regs *ctx)
{
__u64 addr = bpf_get_func_ip(ctx);
test6_result = (const void *) addr == &bpf_fentry_test6 + 5;
test6_result = (const void *) addr == 0;
return 0;
}
@ -79,6 +79,6 @@ int test7(struct pt_regs *ctx)
{
__u64 addr = bpf_get_func_ip(ctx);
test7_result = (const void *) addr == &bpf_fentry_test7 + 5;
test7_result = (const void *) addr == 0;
return 0;
}