From: Jiri Olsa <jolsa@kernel.org>
To: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, Martin KaFai Lau <kafai@fb.com>,
Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
John Fastabend <john.fastabend@gmail.com>,
KP Singh <kpsingh@chromium.org>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>,
"Masami Hiramatsu (Google)" <mhiramat@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Martynas Pumputis <m@lambda.lt>
Subject: [PATCHv4 bpf-next 3/6] bpf: Use given function address for trampoline ip arg
Date: Thu, 22 Sep 2022 23:03:17 +0200 [thread overview]
Message-ID: <20220922210320.1076658-4-jolsa@kernel.org> (raw)
In-Reply-To: <20220922210320.1076658-1-jolsa@kernel.org>
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@kernel.org>
---
arch/x86/net/bpf_jit_comp.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
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);
}
--
2.37.3
next prev parent reply other threads:[~2022-09-22 21:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-22 21:03 [PATCHv4 bpf-next 0/6] bpf: Fixes for CONFIG_X86_KERNEL_IBT Jiri Olsa
2022-09-22 21:03 ` [PATCHv4 bpf-next 1/6] kprobes: Add new KPROBE_FLAG_ON_FUNC_ENTRY kprobe flag Jiri Olsa
2022-09-22 21:03 ` [PATCHv4 bpf-next 2/6] ftrace: Keep the resolved addr in kallsyms_callback Jiri Olsa
2022-09-22 21:03 ` Jiri Olsa [this message]
2022-09-22 21:03 ` [PATCHv4 bpf-next 4/6] bpf: Adjust kprobe_multi entry_ip for CONFIG_X86_KERNEL_IBT Jiri Olsa
2022-09-23 21:40 ` Andrii Nakryiko
2022-09-22 21:03 ` [PATCHv4 bpf-next 5/6] bpf: Return value in kprobe get_func_ip only for entry address Jiri Olsa
2022-09-23 21:42 ` Andrii Nakryiko
2022-09-26 13:58 ` Jiri Olsa
2022-09-25 5:42 ` Martynas Pumputis
2022-09-26 13:58 ` Jiri Olsa
2022-09-22 21:03 ` [PATCHv4 bpf-next 6/6] selftests/bpf: Fix get_func_ip offset test for CONFIG_X86_KERNEL_IBT Jiri Olsa
2022-09-23 21:43 ` Andrii Nakryiko
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