Merge branch 'bpf-ppc-div-fix'

Naveen N. Rao says: ==================== The first patch updates DIV64 overflow tests to properly detect error conditions. The second patch fixes powerpc64 JIT to generate the proper unsigned division instruction for BPF_ALU64. ==================== Acked-by: Sandipan Das <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]>
modi0012 · Jun 13, 2019 · 09f6ac2 · 09f6ac2
2 parents 0e26574 + 758f204
commit 09f6ac2
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Showing 4 changed files with 16 additions and 9 deletions.
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
@@ -338,6 +338,7 @@
 #define PPC_INST_MADDLD			0x10000033
 #define PPC_INST_DIVWU			0x7c000396
 #define PPC_INST_DIVD			0x7c0003d2
+#define PPC_INST_DIVDU			0x7c000392
 #define PPC_INST_RLWINM			0x54000000
 #define PPC_INST_RLWINM_DOT		0x54000001
 #define PPC_INST_RLWIMI			0x50000000

diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h
@@ -116,7 +116,7 @@
 				     ___PPC_RA(a) | IMM_L(i))
 #define PPC_DIVWU(d, a, b)	EMIT(PPC_INST_DIVWU | ___PPC_RT(d) |	      \
 				     ___PPC_RA(a) | ___PPC_RB(b))
-#define PPC_DIVD(d, a, b)	EMIT(PPC_INST_DIVD | ___PPC_RT(d) |	      \
+#define PPC_DIVDU(d, a, b)	EMIT(PPC_INST_DIVDU | ___PPC_RT(d) |	      \
 				     ___PPC_RA(a) | ___PPC_RB(b))
 #define PPC_AND(d, a, b)	EMIT(PPC_INST_AND | ___PPC_RA(d) |	      \
 				     ___PPC_RS(a) | ___PPC_RB(b))

diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
@@ -399,12 +399,12 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
 		case BPF_ALU64 | BPF_DIV | BPF_X: /* dst /= src */
 		case BPF_ALU64 | BPF_MOD | BPF_X: /* dst %= src */
 			if (BPF_OP(code) == BPF_MOD) {
-				PPC_DIVD(b2p[TMP_REG_1], dst_reg, src_reg);
+				PPC_DIVDU(b2p[TMP_REG_1], dst_reg, src_reg);
 				PPC_MULD(b2p[TMP_REG_1], src_reg,
 						b2p[TMP_REG_1]);
 				PPC_SUB(dst_reg, dst_reg, b2p[TMP_REG_1]);
 			} else
-				PPC_DIVD(dst_reg, dst_reg, src_reg);
+				PPC_DIVDU(dst_reg, dst_reg, src_reg);
 			break;
 		case BPF_ALU | BPF_MOD | BPF_K: /* (u32) dst %= (u32) imm */
 		case BPF_ALU | BPF_DIV | BPF_K: /* (u32) dst /= (u32) imm */
@@ -432,15 +432,15 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
 				break;
 			case BPF_ALU64:
 				if (BPF_OP(code) == BPF_MOD) {
-					PPC_DIVD(b2p[TMP_REG_2], dst_reg,
+					PPC_DIVDU(b2p[TMP_REG_2], dst_reg,
 							b2p[TMP_REG_1]);
 					PPC_MULD(b2p[TMP_REG_1],
 							b2p[TMP_REG_1],
 							b2p[TMP_REG_2]);
 					PPC_SUB(dst_reg, dst_reg,
 							b2p[TMP_REG_1]);
 				} else
-					PPC_DIVD(dst_reg, dst_reg,
+					PPC_DIVDU(dst_reg, dst_reg,
 							b2p[TMP_REG_1]);
 				break;
 			}

diff --git a/tools/testing/selftests/bpf/verifier/div_overflow.c b/tools/testing/selftests/bpf/verifier/div_overflow.c
@@ -29,8 +29,11 @@
 	"DIV64 overflow, check 1",
 	.insns = {
 	BPF_MOV64_IMM(BPF_REG_1, -1),
-	BPF_LD_IMM64(BPF_REG_0, LLONG_MIN),
-	BPF_ALU64_REG(BPF_DIV, BPF_REG_0, BPF_REG_1),
+	BPF_LD_IMM64(BPF_REG_2, LLONG_MIN),
+	BPF_ALU64_REG(BPF_DIV, BPF_REG_2, BPF_REG_1),
+	BPF_MOV32_IMM(BPF_REG_0, 0),
+	BPF_JMP_REG(BPF_JEQ, BPF_REG_0, BPF_REG_2, 1),
+	BPF_MOV32_IMM(BPF_REG_0, 1),
 	BPF_EXIT_INSN(),
 	},
 	.prog_type = BPF_PROG_TYPE_SCHED_CLS,
@@ -40,8 +43,11 @@
 {
 	"DIV64 overflow, check 2",
 	.insns = {
-	BPF_LD_IMM64(BPF_REG_0, LLONG_MIN),
-	BPF_ALU64_IMM(BPF_DIV, BPF_REG_0, -1),
+	BPF_LD_IMM64(BPF_REG_1, LLONG_MIN),
+	BPF_ALU64_IMM(BPF_DIV, BPF_REG_1, -1),
+	BPF_MOV32_IMM(BPF_REG_0, 0),
+	BPF_JMP_REG(BPF_JEQ, BPF_REG_0, BPF_REG_1, 1),
+	BPF_MOV32_IMM(BPF_REG_0, 1),
 	BPF_EXIT_INSN(),
 	},
 	.prog_type = BPF_PROG_TYPE_SCHED_CLS,