From: Yonghong Song <yhs@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>, <bpf@ietf.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Fangrui Song <maskray@google.com>, <kernel-team@fb.com>
Subject: [PATCH bpf-next v3 07/17] bpf: Support new 32bit offset jmp instruction
Date: Wed, 19 Jul 2023 17:01:40 -0700 [thread overview]
Message-ID: <20230720000140.105530-1-yhs@fb.com> (raw)
In-Reply-To: <20230720000103.99949-1-yhs@fb.com>
Add interpreter/jit/verifier support for 32bit offset jmp instruction.
If a conditional jmp instruction needs more than 16bit offset,
it can be simulated with a conditional jmp + a 32bit jmp insn.
Signed-off-by: Yonghong Song <yhs@fb.com>
---
arch/x86/net/bpf_jit_comp.c | 28 ++++++++++++++++++----------
kernel/bpf/core.c | 19 ++++++++++++++++---
kernel/bpf/verifier.c | 32 ++++++++++++++++++++++----------
3 files changed, 56 insertions(+), 23 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index a89b62eb2b40..a5930042139d 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1815,16 +1815,24 @@ st: if (is_imm8(insn->off))
break;
case BPF_JMP | BPF_JA:
- if (insn->off == -1)
- /* -1 jmp instructions will always jump
- * backwards two bytes. Explicitly handling
- * this case avoids wasting too many passes
- * when there are long sequences of replaced
- * dead code.
- */
- jmp_offset = -2;
- else
- jmp_offset = addrs[i + insn->off] - addrs[i];
+ case BPF_JMP32 | BPF_JA:
+ if (BPF_CLASS(insn->code) == BPF_JMP) {
+ if (insn->off == -1)
+ /* -1 jmp instructions will always jump
+ * backwards two bytes. Explicitly handling
+ * this case avoids wasting too many passes
+ * when there are long sequences of replaced
+ * dead code.
+ */
+ jmp_offset = -2;
+ else
+ jmp_offset = addrs[i + insn->off] - addrs[i];
+ } else {
+ if (insn->imm == -1)
+ jmp_offset = -2;
+ else
+ jmp_offset = addrs[i + insn->imm] - addrs[i];
+ }
if (!jmp_offset) {
/*
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 646d2fe537be..db0b631908c2 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -373,7 +373,12 @@ static int bpf_adj_delta_to_off(struct bpf_insn *insn, u32 pos, s32 end_old,
{
const s32 off_min = S16_MIN, off_max = S16_MAX;
s32 delta = end_new - end_old;
- s32 off = insn->off;
+ s32 off;
+
+ if (insn->code == (BPF_JMP32 | BPF_JA))
+ off = insn->imm;
+ else
+ off = insn->off;
if (curr < pos && curr + off + 1 >= end_old)
off += delta;
@@ -381,8 +386,12 @@ static int bpf_adj_delta_to_off(struct bpf_insn *insn, u32 pos, s32 end_old,
off -= delta;
if (off < off_min || off > off_max)
return -ERANGE;
- if (!probe_pass)
- insn->off = off;
+ if (!probe_pass) {
+ if (insn->code == (BPF_JMP32 | BPF_JA))
+ insn->imm = off;
+ else
+ insn->off = off;
+ }
return 0;
}
@@ -1593,6 +1602,7 @@ EXPORT_SYMBOL_GPL(__bpf_call_base);
INSN_3(JMP, JSLE, K), \
INSN_3(JMP, JSET, K), \
INSN_2(JMP, JA), \
+ INSN_2(JMP32, JA), \
/* Store instructions. */ \
/* Register based. */ \
INSN_3(STX, MEM, B), \
@@ -1989,6 +1999,9 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn)
JMP_JA:
insn += insn->off;
CONT;
+ JMP32_JA:
+ insn += insn->imm;
+ CONT;
JMP_EXIT:
return BPF_R0;
/* JMP */
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9436fa795f39..daf23c5da2ee 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2855,7 +2855,10 @@ static int check_subprogs(struct bpf_verifier_env *env)
goto next;
if (BPF_OP(code) == BPF_EXIT || BPF_OP(code) == BPF_CALL)
goto next;
- off = i + insn[i].off + 1;
+ if (code == (BPF_JMP32 | BPF_JA))
+ off = i + insn[i].imm + 1;
+ else
+ off = i + insn[i].off + 1;
if (off < subprog_start || off >= subprog_end) {
verbose(env, "jump out of range from insn %d to %d\n", i, off);
return -EINVAL;
@@ -2867,6 +2870,7 @@ static int check_subprogs(struct bpf_verifier_env *env)
* or unconditional jump back
*/
if (code != (BPF_JMP | BPF_EXIT) &&
+ code != (BPF_JMP32 | BPF_JA) &&
code != (BPF_JMP | BPF_JA)) {
verbose(env, "last insn is not an exit or jmp\n");
return -EINVAL;
@@ -14792,7 +14796,7 @@ static int visit_func_call_insn(int t, struct bpf_insn *insns,
static int visit_insn(int t, struct bpf_verifier_env *env)
{
struct bpf_insn *insns = env->prog->insnsi, *insn = &insns[t];
- int ret;
+ int ret, off;
if (bpf_pseudo_func(insn))
return visit_func_call_insn(t, insns, env, true);
@@ -14840,14 +14844,19 @@ static int visit_insn(int t, struct bpf_verifier_env *env)
if (BPF_SRC(insn->code) != BPF_K)
return -EINVAL;
+ if (BPF_CLASS(insn->code) == BPF_JMP)
+ off = insn->off;
+ else
+ off = insn->imm;
+
/* unconditional jump with single edge */
- ret = push_insn(t, t + insn->off + 1, FALLTHROUGH, env,
+ ret = push_insn(t, t + off + 1, FALLTHROUGH, env,
true);
if (ret)
return ret;
- mark_prune_point(env, t + insn->off + 1);
- mark_jmp_point(env, t + insn->off + 1);
+ mark_prune_point(env, t + off + 1);
+ mark_jmp_point(env, t + off + 1);
return ret;
@@ -16643,15 +16652,18 @@ static int do_check(struct bpf_verifier_env *env)
mark_reg_scratched(env, BPF_REG_0);
} else if (opcode == BPF_JA) {
if (BPF_SRC(insn->code) != BPF_K ||
- insn->imm != 0 ||
insn->src_reg != BPF_REG_0 ||
insn->dst_reg != BPF_REG_0 ||
- class == BPF_JMP32) {
+ (class == BPF_JMP && insn->imm != 0) ||
+ (class == BPF_JMP32 && insn->off != 0)) {
verbose(env, "BPF_JA uses reserved fields\n");
return -EINVAL;
}
- env->insn_idx += insn->off + 1;
+ if (class == BPF_JMP)
+ env->insn_idx += insn->off + 1;
+ else
+ env->insn_idx += insn->imm + 1;
continue;
} else if (opcode == BPF_EXIT) {
@@ -17498,13 +17510,13 @@ static bool insn_is_cond_jump(u8 code)
{
u8 op;
+ op = BPF_OP(code);
if (BPF_CLASS(code) == BPF_JMP32)
- return true;
+ return op != BPF_JA;
if (BPF_CLASS(code) != BPF_JMP)
return false;
- op = BPF_OP(code);
return op != BPF_JA && op != BPF_EXIT && op != BPF_CALL;
}
--
2.34.1
next prev parent reply other threads:[~2023-07-20 0:02 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-20 0:01 [PATCH bpf-next v3 00/17] bpf: Support new insns from cpu v4 Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 01/17] bpf: Support new sign-extension load insns Yonghong Song
2023-07-20 20:33 ` Eduard Zingerman
2023-07-24 4:03 ` [Bpf] " Yonghong Song
2023-07-24 4:03 ` Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 02/17] bpf: Support new sign-extension mov insns Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 03/17] bpf: Handle sign-extenstin ctx member accesses Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 04/17] bpf: Support new unconditional bswap instruction Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 05/17] bpf: Support new signed div/mod instructions Yonghong Song
2023-07-20 0:01 ` [Bpf] " Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 06/17] bpf: Fix jit blinding with new sdiv/smov insns Yonghong Song
2023-07-20 0:01 ` Yonghong Song [this message]
2023-07-20 0:01 ` [PATCH bpf-next v3 08/17] bpf: Add kernel/bpftool asm support for new instructions Yonghong Song
2023-07-21 14:36 ` Quentin Monnet
2023-07-21 14:36 ` [Bpf] " Quentin Monnet
2023-07-20 0:01 ` [PATCH bpf-next v3 09/17] selftests/bpf: Fix a test_verifier failure Yonghong Song
2023-07-20 0:01 ` [PATCH bpf-next v3 10/17] selftests/bpf: Add a cpuv4 test runner for cpu=v4 testing Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 11/17] selftests/bpf: Add unit tests for new sign-extension load insns Yonghong Song
2023-07-20 6:31 ` [Bpf] " Yonghong Song
2023-07-20 6:31 ` Yonghong Song
2023-07-20 6:36 ` [Bpf] " Yonghong Song
2023-07-20 6:36 ` Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 12/17] selftests/bpf: Add unit tests for new sign-extension mov insns Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 13/17] selftests/bpf: Add unit tests for new bswap insns Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 14/17] selftests/bpf: Add unit tests for new sdiv/smod insns Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 15/17] selftests/bpf: Add unit tests for new gotol insn Yonghong Song
2023-07-20 0:02 ` [Bpf] " Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 16/17] selftests/bpf: Test ldsx with more complex cases Yonghong Song
2023-07-20 0:02 ` [PATCH bpf-next v3 17/17] docs/bpf: Add documentation for new instructions Yonghong Song
2023-07-20 20:35 ` [PATCH bpf-next v3 00/17] bpf: Support new insns from cpu v4 Eduard Zingerman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230720000140.105530-1-yhs@fb.com \
--to=yhs@fb.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@ietf.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kernel-team@fb.com \
--cc=maskray@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.