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powerpc/bpf: Fix BPF_SUB when imm == 0x80000000

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We aren't handling subtraction involving an immediate value of
0x80000000 properly. Fix the same.

Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fold in fix from Naveen to use imm <= 32768]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/fc4b1276eb10761fd7ce0814c8dd089da2815251.1633464148.git.naveen.n.rao@linux.vnet.ibm.com
This commit is contained in:
Naveen N. Rao 2021-10-06 01:55:23 +05:30 committed by Michael Ellerman
parent 8bbc9d8224
commit 5855c4c1f4
1 changed files with 17 additions and 10 deletions
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27
arch/powerpc/net/bpf_jit_comp64.c
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@ -330,18 +330,25 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
EMIT(PPC_RAW_SUB(dst_reg, dst_reg, src_reg));
goto bpf_alu32_trunc;
case BPF_ALU | BPF_ADD | BPF_K: /* (u32) dst += (u32) imm */
case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
case BPF_ALU64 | BPF_ADD | BPF_K: /* dst += imm */
if (!imm) {
goto bpf_alu32_trunc;
} else if (imm >= -32768 && imm < 32768) {
EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));
} else {
PPC_LI32(b2p[TMP_REG_1], imm);
EMIT(PPC_RAW_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]));
}
goto bpf_alu32_trunc;
case BPF_ALU | BPF_SUB | BPF_K: /* (u32) dst -= (u32) imm */
case BPF_ALU64 | BPF_SUB | BPF_K: /* dst -= imm */
if (BPF_OP(code) == BPF_SUB)
imm = -imm;
if (imm) {
if (imm >= -32768 && imm < 32768)
EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));
else {
PPC_LI32(b2p[TMP_REG_1], imm);
EMIT(PPC_RAW_ADD(dst_reg, dst_reg, b2p[TMP_REG_1]));
}
if (!imm) {
goto bpf_alu32_trunc;
} else if (imm > -32768 && imm <= 32768) {
EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(-imm)));
} else {
PPC_LI32(b2p[TMP_REG_1], imm);
EMIT(PPC_RAW_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]));
}
goto bpf_alu32_trunc;
case BPF_ALU | BPF_MUL | BPF_X: /* (u32) dst *= (u32) src */