From 4d854f4f31ec4b317dfe316111ddac0fab81f735 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Mon, 26 Sep 2022 17:33:37 +0200 Subject: bpf: Use given function address for trampoline ip arg Using function address given at the generation time as the trampoline ip argument. This way we get directly the function address that we need, so we don't need to: - read the ip from the stack - subtract X86_PATCH_SIZE - subtract ENDBR_INSN_SIZE if CONFIG_X86_KERNEL_IBT is enabled which is not even implemented yet ;-) Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20220926153340.1621984-4-jolsa@kernel.org Signed-off-by: Alexei Starovoitov --- arch/x86/net/bpf_jit_comp.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'arch/x86/net') diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index ae89f4143eb4..d4a6183197e9 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -662,7 +662,7 @@ static void emit_mov_imm64(u8 **pprog, u32 dst_reg, */ emit_mov_imm32(&prog, false, dst_reg, imm32_lo); } else { - /* movabsq %rax, imm64 */ + /* movabsq rax, imm64 */ EMIT2(add_1mod(0x48, dst_reg), add_1reg(0xB8, dst_reg)); EMIT(imm32_lo, 4); EMIT(imm32_hi, 4); @@ -2039,13 +2039,14 @@ static int invoke_bpf_mod_ret(const struct btf_func_model *m, u8 **pprog, int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end, const struct btf_func_model *m, u32 flags, struct bpf_tramp_links *tlinks, - void *orig_call) + void *func_addr) { int ret, i, nr_args = m->nr_args, extra_nregs = 0; int regs_off, ip_off, args_off, stack_size = nr_args * 8, run_ctx_off; struct bpf_tramp_links *fentry = &tlinks[BPF_TRAMP_FENTRY]; struct bpf_tramp_links *fexit = &tlinks[BPF_TRAMP_FEXIT]; struct bpf_tramp_links *fmod_ret = &tlinks[BPF_TRAMP_MODIFY_RETURN]; + void *orig_call = func_addr; u8 **branches = NULL; u8 *prog; bool save_ret; @@ -2126,12 +2127,10 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i if (flags & BPF_TRAMP_F_IP_ARG) { /* Store IP address of the traced function: - * mov rax, QWORD PTR [rbp + 8] - * sub rax, X86_PATCH_SIZE + * movabsq rax, func_addr * mov QWORD PTR [rbp - ip_off], rax */ - emit_ldx(&prog, BPF_DW, BPF_REG_0, BPF_REG_FP, 8); - EMIT4(0x48, 0x83, 0xe8, X86_PATCH_SIZE); + emit_mov_imm64(&prog, BPF_REG_0, (long) func_addr >> 32, (u32) (long) func_addr); emit_stx(&prog, BPF_DW, BPF_REG_FP, BPF_REG_0, -ip_off); } -- cgit v1.2.3