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bpf: Support new unconditional bswap instruction

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The existing 'be' and 'le' insns will do conditional bswap
depends on host endianness. This patch implements
unconditional bswap insns.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20230728011213.3712808-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Yonghong Song 2023-07-27 18:12:13 -07:00 • committed by Alexei Starovoitov
parent 1f1e864b65
commit 0845c3db7b
3 changed files with 20 additions and 2 deletions
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1
arch/x86/net/bpf_jit_comp.c
View file

@ -1322,6 +1322,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image
break; break;
case BPF_ALU | BPF_END | BPF_FROM_BE: case BPF_ALU | BPF_END | BPF_FROM_BE:
case BPF_ALU64 | BPF_END | BPF_FROM_LE:
switch (imm32) { switch (imm32) {
case 16: case 16:
/* Emit 'ror %ax, 8' to swap lower 2 bytes */ /* Emit 'ror %ax, 8' to swap lower 2 bytes */

14
kernel/bpf/core.c
View file

@ -1524,6 +1524,7 @@ EXPORT_SYMBOL_GPL(__bpf_call_base);
INSN_3(ALU64, DIV, X), \ INSN_3(ALU64, DIV, X), \
INSN_3(ALU64, MOD, X), \ INSN_3(ALU64, MOD, X), \
INSN_2(ALU64, NEG), \ INSN_2(ALU64, NEG), \
INSN_3(ALU64, END, TO_LE), \
/* Immediate based. */ \ /* Immediate based. */ \
INSN_3(ALU64, ADD, K), \ INSN_3(ALU64, ADD, K), \
INSN_3(ALU64, SUB, K), \ INSN_3(ALU64, SUB, K), \
@ -1848,6 +1849,19 @@ select_insn:
break; break;
} }
CONT; CONT;
ALU64_END_TO_LE:
switch (IMM) {
case 16:
DST = (__force u16) __swab16(DST);
break;
case 32:
DST = (__force u32) __swab32(DST);
break;
case 64:
DST = (__force u64) __swab64(DST);
break;
}
CONT;
/* CALL */ /* CALL */
JMP_CALL: JMP_CALL:

7
kernel/bpf/verifier.c
View file

@ -3012,8 +3012,10 @@ static bool is_reg64(struct bpf_verifier_env *env, struct bpf_insn *insn,
} }
} }
if (class == BPF_ALU64 && op == BPF_END && (insn->imm == 16 || insn->imm == 32))
return false;
if (class == BPF_ALU64 || class == BPF_JMP || if (class == BPF_ALU64 || class == BPF_JMP ||
/* BPF_END always use BPF_ALU class. */
(class == BPF_ALU && op == BPF_END && insn->imm == 64)) (class == BPF_ALU && op == BPF_END && insn->imm == 64))
return true; return true;
@ -13076,7 +13078,8 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
} else { } else {
if (insn->src_reg != BPF_REG_0 || insn->off != 0 || if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
(insn->imm != 16 && insn->imm != 32 && insn->imm != 64) || (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
BPF_CLASS(insn->code) == BPF_ALU64) { (BPF_CLASS(insn->code) == BPF_ALU64 &&
BPF_SRC(insn->code) != BPF_TO_LE)) {
verbose(env, "BPF_END uses reserved fields\n"); verbose(env, "BPF_END uses reserved fields\n");
return -EINVAL; return -EINVAL;
} }