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bpf: Add support to inline bpf_get_func_ip helper on x86 

Adding support to inline it on x86, because it's single
load instruction.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220316122419.933957-6-jolsa@kernel.org
This commit is contained in:
Jiri Olsa 2022-03-16 13:24:11 +01:00 committed by Alexei Starovoitov
parent 42a5712094
commit 97ee4d20ee
2 changed files with 21 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
kernel/bpf/verifier.c
View File

@ -13678,7 +13678,7 @@ patch_map_ops_generic:
continue;
}
/* Implement bpf_get_func_ip inline. */
/* Implement tracing bpf_get_func_ip inline. */
if (prog_type == BPF_PROG_TYPE_TRACING &&
insn->imm == BPF_FUNC_get_func_ip) {
/* Load IP address from ctx - 16 */
@ -13693,6 +13693,25 @@ patch_map_ops_generic:
continue;
}
#ifdef CONFIG_X86
/* Implement kprobe_multi bpf_get_func_ip inline. */
if (prog_type == BPF_PROG_TYPE_KPROBE &&
eatype == BPF_TRACE_KPROBE_MULTI &&
insn->imm == BPF_FUNC_get_func_ip) {
/* Load IP address from ctx (struct pt_regs) ip */
insn_buf[0] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_1,
offsetof(struct pt_regs, ip));
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;
}
#endif
patch_call_imm:
fn = env->ops->get_func_proto(insn->imm, env->prog);
/* all functions that have prototype and verifier allowed

1
kernel/trace/bpf_trace.c
View File

@ -1039,6 +1039,7 @@ static const struct bpf_func_proto bpf_get_func_ip_proto_kprobe = {
BPF_CALL_1(bpf_get_func_ip_kprobe_multi, struct pt_regs *, regs)
{
/* This helper call is inlined by verifier on x86. */
return instruction_pointer(regs);
}