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bpf: x86: add missing 'shift by register' instructions to x64 eBPF JIT

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'shift by register' operations are supported by eBPF interpreter, but were
accidently left out of x64 JIT compiler. Fix it and add a testcase.

Reported-by: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Fixes: 622582786c ("net: filter: x86: internal BPF JIT")
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2014-08-25 12:27:02 -07:00 committed by David S. Miller
parent 9785820e6d
commit 72b603ee8c
2 changed files with 80 additions and 0 deletions
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42
arch/x86/net/bpf_jit_comp.c
View file

@ -515,6 +515,48 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image,
EMIT3(0xC1, add_1reg(b3, dst_reg), imm32); EMIT3(0xC1, add_1reg(b3, dst_reg), imm32);
break; break;
case BPF_ALU | BPF_LSH | BPF_X:
case BPF_ALU | BPF_RSH | BPF_X:
case BPF_ALU | BPF_ARSH | BPF_X:
case BPF_ALU64 | BPF_LSH | BPF_X:
case BPF_ALU64 | BPF_RSH | BPF_X:
case BPF_ALU64 | BPF_ARSH | BPF_X:
/* check for bad case when dst_reg == rcx */
if (dst_reg == BPF_REG_4) {
/* mov r11, dst_reg */
EMIT_mov(AUX_REG, dst_reg);
dst_reg = AUX_REG;
}
if (src_reg != BPF_REG_4) { /* common case */
EMIT1(0x51); /* push rcx */
/* mov rcx, src_reg */
EMIT_mov(BPF_REG_4, src_reg);
}
/* shl %rax, %cl | shr %rax, %cl | sar %rax, %cl */
if (BPF_CLASS(insn->code) == BPF_ALU64)
EMIT1(add_1mod(0x48, dst_reg));
else if (is_ereg(dst_reg))
EMIT1(add_1mod(0x40, dst_reg));
switch (BPF_OP(insn->code)) {
case BPF_LSH: b3 = 0xE0; break;
case BPF_RSH: b3 = 0xE8; break;
case BPF_ARSH: b3 = 0xF8; break;
}
EMIT2(0xD3, add_1reg(b3, dst_reg));
if (src_reg != BPF_REG_4)
EMIT1(0x59); /* pop rcx */
if (insn->dst_reg == BPF_REG_4)
/* mov dst_reg, r11 */
EMIT_mov(insn->dst_reg, AUX_REG);
break;
case BPF_ALU | BPF_END | BPF_FROM_BE: case BPF_ALU | BPF_END | BPF_FROM_BE:
switch (imm32) { switch (imm32) {
case 16: case 16:

38
lib/test_bpf.c
View file

@ -1341,6 +1341,44 @@ static struct bpf_test tests[] = {
{ }, { },
{ { 0, -1 } } { { 0, -1 } }
}, },
{
"INT: shifts by register",
.u.insns_int = {
BPF_MOV64_IMM(R0, -1234),
BPF_MOV64_IMM(R1, 1),
BPF_ALU32_REG(BPF_RSH, R0, R1),
BPF_JMP_IMM(BPF_JEQ, R0, 0x7ffffd97, 1),
BPF_EXIT_INSN(),
BPF_MOV64_IMM(R2, 1),
BPF_ALU64_REG(BPF_LSH, R0, R2),
BPF_MOV32_IMM(R4, -1234),
BPF_JMP_REG(BPF_JEQ, R0, R4, 1),
BPF_EXIT_INSN(),
BPF_ALU64_IMM(BPF_AND, R4, 63),
BPF_ALU64_REG(BPF_LSH, R0, R4), /* R0 <= 46 */
BPF_MOV64_IMM(R3, 47),
BPF_ALU64_REG(BPF_ARSH, R0, R3),
BPF_JMP_IMM(BPF_JEQ, R0, -617, 1),
BPF_EXIT_INSN(),
BPF_MOV64_IMM(R2, 1),
BPF_ALU64_REG(BPF_LSH, R4, R2), /* R4 = 46 << 1 */
BPF_JMP_IMM(BPF_JEQ, R4, 92, 1),
BPF_EXIT_INSN(),
BPF_MOV64_IMM(R4, 4),
BPF_ALU64_REG(BPF_LSH, R4, R4), /* R4 = 4 << 4 */
BPF_JMP_IMM(BPF_JEQ, R4, 64, 1),
BPF_EXIT_INSN(),
BPF_MOV64_IMM(R4, 5),
BPF_ALU32_REG(BPF_LSH, R4, R4), /* R4 = 5 << 5 */
BPF_JMP_IMM(BPF_JEQ, R4, 160, 1),
BPF_EXIT_INSN(),
BPF_MOV64_IMM(R0, -1),
BPF_EXIT_INSN(),
},
INTERNAL,
{ },
{ { 0, -1 } }
},
{ {
"INT: DIV + ABS", "INT: DIV + ABS",
.u.insns_int = { .u.insns_int = {