From 7e6f3cd89f04a0a577002d5696288b482109d25c Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 14 Jul 2021 11:43:53 +0200 Subject: bpf, x86: Store caller's ip in trampoline stack Storing caller's ip in trampoline's stack. Trampoline programs can reach the IP in (ctx - 8) address, so there's no change in program's arguments interface. The IP address is takes from [fp + 8], which is return address from the initial 'call fentry' call to trampoline. This IP address will be returned via bpf_get_func_ip helper helper, which is added in following patches. Signed-off-by: Jiri Olsa Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210714094400.396467-2-jolsa@kernel.org --- include/linux/bpf.h | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'include/linux') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a9a4a480a6d0..94d77dc7ce35 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -579,6 +579,11 @@ struct btf_func_model { */ #define BPF_TRAMP_F_SKIP_FRAME BIT(2) +/* Store IP address of the caller on the trampoline stack, + * so it's available for trampoline's programs. + */ +#define BPF_TRAMP_F_IP_ARG BIT(3) + /* Each call __bpf_prog_enter + call bpf_func + call __bpf_prog_exit is ~50 * bytes on x86. Pick a number to fit into BPF_IMAGE_SIZE / 2 */ -- cgit v1.2.3