Commit 97ee4d20 authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

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: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220316122419.933957-6-jolsa@kernel.org
parent 42a57120

kernel/bpf/verifier.c

+20 −1
Original line number Diff line number Diff line
@@ -13678,7 +13678,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env) 
			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 @@ static int do_misc_fixups(struct bpf_verifier_env *env) 
			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

kernel/trace/bpf_trace.c

+1 −0
Original line number Diff line number Diff line
@@ -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);

}