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Commit 280050cc authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

x86 bpf_jit: support MOD operation 



commit b6069a95 (filter: add MOD operation) added generic
support for modulus operation in BPF.

This patch brings JIT support for x86_64

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: George Bakos <gbakos@alpinista.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 26964bb7

arch/x86/net/bpf_jit_comp.c

+25 −0
Original line number Diff line number Diff line
@@ -280,6 +280,31 @@ void bpf_jit_compile(struct sk_filter *fp) 
				}

				EMIT4(0x31, 0xd2, 0xf7, 0xf3); /* xor %edx,%edx; div %ebx */

				break;

			case BPF_S_ALU_MOD_X: /* A %= X; */

				seen |= SEEN_XREG;

				EMIT2(0x85, 0xdb);	/* test %ebx,%ebx */

				if (pc_ret0 > 0) {

					/* addrs[pc_ret0 - 1] is start address of target

					 * (addrs[i] - 6) is the address following this jmp

					 * ("xor %edx,%edx; div %ebx;mov %edx,%eax" being 6 bytes long)

					 */

					EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -

								(addrs[i] - 6));

				} else {

					EMIT_COND_JMP(X86_JNE, 2 + 5);

					CLEAR_A();

					EMIT1_off32(0xe9, cleanup_addr - (addrs[i] - 6)); /* jmp .+off32 */

				}

				EMIT2(0x31, 0xd2);	/* xor %edx,%edx */

				EMIT2(0xf7, 0xf3);	/* div %ebx */

				EMIT2(0x89, 0xd0);	/* mov %edx,%eax */

				break;

			case BPF_S_ALU_MOD_K: /* A %= K; */

				EMIT2(0x31, 0xd2);	/* xor %edx,%edx */

				EMIT1(0xb9);EMIT(K, 4);	/* mov imm32,%ecx */

				EMIT2(0xf7, 0xf1);	/* div %ecx */

				EMIT2(0x89, 0xd0);	/* mov %edx,%eax */

				break;

			case BPF_S_ALU_DIV_K: /* A = reciprocal_divide(A, K); */

				EMIT3(0x48, 0x69, 0xc0); /* imul imm32,%rax,%rax */

				EMIT(K, 4);