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bpf: Refactor trampoline update code

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As we need to introduce a third type of attachment for trampolines, the
flattened signature of arch_prepare_bpf_trampoline gets even more
complicated.

Refactor the prog and count argument to arch_prepare_bpf_trampoline to
use bpf_tramp_progs to simplify the addition and accounting for new
attachment types.

Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200304191853.1529-2-kpsingh@chromium.org
This commit is contained in:
KP Singh 2020-03-04 20:18:47 +01:00 • committed by Alexei Starovoitov
parent cc6fa77102
commit 88fd9e5352
4 changed files with 71 additions and 45 deletions
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13
include/linux/bpf.h
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@ -433,6 +433,16 @@ struct btf_func_model {
*/
#define BPF_TRAMP_F_SKIP_FRAME BIT(2)
/* 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
*/
#define BPF_MAX_TRAMP_PROGS 40
struct bpf_tramp_progs {
struct bpf_prog *progs[BPF_MAX_TRAMP_PROGS];
int nr_progs;
};
/* Different use cases for BPF trampoline:
* 1. replace nop at the function entry (kprobe equivalent)
* flags = BPF_TRAMP_F_RESTORE_REGS
@ -455,8 +465,7 @@ struct btf_func_model {
*/
int arch_prepare_bpf_trampoline(void *image, void *image_end,
const struct btf_func_model *m, u32 flags,
struct bpf_prog **fentry_progs, int fentry_cnt,
struct bpf_prog **fexit_progs, int fexit_cnt,
struct bpf_tramp_progs *tprogs,
void *orig_call);
/* these two functions are called from generated trampoline */
u64 notrace __bpf_prog_enter(void);