Commit 5855c4c1 authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Michael Ellerman
Browse files

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



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

Fixes: 156d0e29 ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fold in fix from Naveen to use imm <= 32768]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/fc4b1276eb10761fd7ce0814c8dd089da2815251.1633464148.git.naveen.n.rao@linux.vnet.ibm.com
parent 8bbc9d82

arch/powerpc/net/bpf_jit_comp64.c

+17 −10
Original line number Diff line number Diff line
@@ -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 */

		case BPF_ALU64 | BPF_SUB | BPF_K: /* dst -= imm */

			if (BPF_OP(code) == BPF_SUB)

				imm = -imm;

			if (imm) {

				if (imm >= -32768 && imm < 32768)

			if (!imm) {

				goto bpf_alu32_trunc;

			} else if (imm >= -32768 && imm < 32768) {

				EMIT(PPC_RAW_ADDI(dst_reg, dst_reg, IMM_L(imm)));

				else {

			} 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 (!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 */