From: Yonghong Song <yhs@fb.com>
To: <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Fangrui Song <maskray@google.com>, <kernel-team@fb.com>
Subject: [RFC PATCH bpf-next 03/13] bpf: Support new sign-extension mov insns
Date: Wed, 28 Jun 2023 23:37:33 -0700 [thread overview]
Message-ID: <20230629063733.1650134-1-yhs@fb.com> (raw)
In-Reply-To: <20230629063715.1646832-1-yhs@fb.com>
Add interpreter/jit support for new sign-extension mov insns.
The verifier support is basic and the better register range
calculation will be done in the future revision.
NOTE: currently new insns support:
ALU:
dst = (s8)src
dst = (s16)src
ALU64:
dst = (s8)src
dst = (s16)src
dst = (s32)src
while unsigned mov insns support:
ALU:
dst = (u32)src
ALU64:
dst = src
Should we support more unsigned-extension mov insns like below?
ALU:
dst = (u8)src
dst = (u16)src
ALU64:
dst = (u8)src
dst = (u16)src
dst = (u32)src
Signed-off-by: Yonghong Song <yhs@fb.com>
---
arch/x86/net/bpf_jit_comp.c | 43 ++++++++++++++++++++++++++++++++++---
kernel/bpf/core.c | 28 ++++++++++++++++++++++--
kernel/bpf/verifier.c | 14 +++++++++++-
3 files changed, 79 insertions(+), 6 deletions(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index 70d6a2c289ec..7c85d1b01931 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -701,6 +701,38 @@ static void emit_mov_reg(u8 **pprog, bool is64, u32 dst_reg, u32 src_reg)
*pprog = prog;
}
+static void emit_movs_reg(u8 **pprog, int num_bits, bool is64, u32 dst_reg,
+ u32 src_reg)
+{
+ u8 *prog = *pprog;
+
+ if (is64) {
+ /* movs[b,w,l]q dst, src */
+ if (num_bits == 8)
+ EMIT4(add_2mod(0x48, src_reg, dst_reg), 0x0f, 0xbe,
+ add_2reg(0xC0, src_reg, dst_reg));
+ else if (num_bits == 16)
+ EMIT4(add_2mod(0x48, src_reg, dst_reg), 0x0f, 0xbf,
+ add_2reg(0xC0, src_reg, dst_reg));
+ else if (num_bits == 32)
+ EMIT3(add_2mod(0x48, src_reg, dst_reg), 0x63,
+ add_2reg(0xC0, src_reg, dst_reg));
+ } else {
+ /* movs[b,w]l dst, src */
+ if (num_bits == 8) {
+ EMIT4(add_2mod(0x40, src_reg, dst_reg), 0x0f, 0xbe,
+ add_2reg(0xC0, src_reg, dst_reg));
+ } else if (num_bits == 16) {
+ if (is_ereg(dst_reg) || is_ereg(src_reg))
+ EMIT1(add_2mod(0x40, src_reg, dst_reg));
+ EMIT3(add_2mod(0x0f, src_reg, dst_reg), 0xbf,
+ add_2reg(0xC0, src_reg, dst_reg));
+ }
+ }
+
+ *pprog = prog;
+}
+
/* Emit the suffix (ModR/M etc) for addressing *(ptr_reg + off) and val_reg */
static void emit_insn_suffix(u8 **pprog, u32 ptr_reg, u32 val_reg, int off)
{
@@ -1051,9 +1083,14 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image
case BPF_ALU64 | BPF_MOV | BPF_X:
case BPF_ALU | BPF_MOV | BPF_X:
- emit_mov_reg(&prog,
- BPF_CLASS(insn->code) == BPF_ALU64,
- dst_reg, src_reg);
+ if (insn->off == 0)
+ emit_mov_reg(&prog,
+ BPF_CLASS(insn->code) == BPF_ALU64,
+ dst_reg, src_reg);
+ else
+ emit_movs_reg(&prog, insn->off,
+ BPF_CLASS(insn->code) == BPF_ALU64,
+ dst_reg, src_reg);
break;
/* neg dst */
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index acb7abd2eba0..72ee246ac3af 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -61,6 +61,7 @@
#define AX regs[BPF_REG_AX]
#define ARG1 regs[BPF_REG_ARG1]
#define CTX regs[BPF_REG_CTX]
+#define OFF insn->off
#define IMM insn->imm
struct bpf_mem_alloc bpf_global_ma;
@@ -1736,13 +1737,36 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn)
DST = -DST;
CONT;
ALU_MOV_X:
- DST = (u32) SRC;
+ switch (OFF) {
+ case 0:
+ DST = (u32) SRC;
+ break;
+ case 8:
+ DST = (s8) SRC;
+ break;
+ case 16:
+ DST = (s16) SRC;
+ break;
+ }
CONT;
ALU_MOV_K:
DST = (u32) IMM;
CONT;
ALU64_MOV_X:
- DST = SRC;
+ switch (OFF) {
+ case 0:
+ DST = SRC;
+ break;
+ case 8:
+ DST = (s8) SRC;
+ break;
+ case 16:
+ DST = (s16) SRC;
+ break;
+ case 32:
+ DST = (s32) SRC;
+ break;
+ }
CONT;
ALU64_MOV_K:
DST = IMM;
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6845504d42a5..5c5b37b6b39a 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -12926,11 +12926,23 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
} else if (opcode == BPF_MOV) {
if (BPF_SRC(insn->code) == BPF_X) {
- if (insn->imm != 0 || insn->off != 0) {
+ if (insn->imm != 0) {
verbose(env, "BPF_MOV uses reserved fields\n");
return -EINVAL;
}
+ if (BPF_CLASS(insn->code) == BPF_ALU) {
+ if (insn->off != 0 && insn->off != 8 && insn->off != 16) {
+ verbose(env, "BPF_MOV uses reserved fields\n");
+ return -EINVAL;
+ }
+ } else {
+ if (insn->off != 0 && insn->off != 8 && insn->off != 16 && insn->off != 32) {
+ verbose(env, "BPF_MOV uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
/* check src operand */
err = check_reg_arg(env, insn->src_reg, SRC_OP);
if (err)
--
2.34.1
next prev parent reply other threads:[~2023-06-29 6:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-29 6:37 [RFC PATCH bpf-next 00/13] bpf: Support new insns from cpu v4 Yonghong Song
2023-06-29 6:37 ` [RFC PATCH bpf-next 01/13] bpf: Support new sign-extension load insns Yonghong Song
2023-07-03 0:53 ` Alexei Starovoitov
2023-07-03 15:29 ` Yonghong Song
2023-06-29 6:37 ` [RFC PATCH bpf-next 02/13] bpf: Add verifier support for " Yonghong Song
2023-07-02 14:28 ` kernel test robot
2023-07-02 18:06 ` Yonghong Song
2023-06-29 6:37 ` Yonghong Song [this message]
2023-06-29 6:37 ` [RFC PATCH bpf-next 04/13] bpf: Support new unconditional bswap instruction Yonghong Song
2023-06-29 6:37 ` [RFC PATCH bpf-next 05/13] bpf: Support new signed div/mod instructions Yonghong Song
2023-06-29 6:37 ` [RFC PATCH bpf-next 06/13] bpf: Support new 32bit offset jmp instruction Yonghong Song
2023-06-29 6:37 ` [RFC PATCH bpf-next 07/13] bpf: Add kernel/bpftool asm support for new instructions Yonghong Song
2023-07-03 2:01 ` kernel test robot
2023-06-29 6:38 ` [RFC PATCH bpf-next 08/13] selftests/bpf: Add unit tests for new sign-extension load insns Yonghong Song
2023-06-29 6:38 ` [RFC PATCH bpf-next 09/13] selftests/bpf: Add unit tests for new sign-extension mov insns Yonghong Song
2023-06-29 6:38 ` [RFC PATCH bpf-next 10/13] selftests/bpf: Add unit tests for new bswap insns Yonghong Song
2023-06-29 6:38 ` [RFC PATCH bpf-next 11/13] selftests/bpf: Add unit tests for new sdiv/smod insns Yonghong Song
2023-06-29 6:38 ` [RFC PATCH bpf-next 12/13] selftests/bpf: Add unit tests for new gotol insn Yonghong Song
2023-06-29 6:38 ` [RFC PATCH bpf-next 13/13] selftests/bpf: Add a cpuv4 test runner for cpu=v4 testing Yonghong Song
[not found] ` <PH7PR21MB38786422B9929D253E279810A325A@PH7PR21MB3878.namprd21.prod.outlook.com>
2023-06-29 14:17 ` [RFC PATCH bpf-next 00/13] bpf: Support new insns from cpu v4 Yonghong Song
2023-07-03 21:11 ` Daniel Xu
2023-07-03 23:36 ` Yonghong Song
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