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 <jolsa@xxxxxxxxxx>
---
arch/x86/net/bpf_jit_comp.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index ae89f4143eb4..1047686cc545 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -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
+ * mov 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);
}
--
2.37.3
