Commit e5f02cac authored by Brendan Jackman's avatar Brendan Jackman Committed by Alexei Starovoitov
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bpf: x86: Factor out a lookup table for some ALU opcodes 



A later commit will need to lookup a subset of these opcodes. To
avoid duplicating code, pull out a table.

The shift opcodes won't be needed by that later commit, but they're
already duplicated, so fold them into the table anyway.

Signed-off-by: default avatarBrendan Jackman <jackmanb@google.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarJohn Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210114181751.768687-4-jackmanb@google.com
parent 74007cfc

arch/x86/net/bpf_jit_comp.c

+15 −18
Original line number Diff line number Diff line
@@ -205,6 +205,18 @@ static u8 add_2reg(u8 byte, u32 dst_reg, u32 src_reg) 
	return byte + reg2hex[dst_reg] + (reg2hex[src_reg] << 3);

}



/* Some 1-byte opcodes for binary ALU operations */

static u8 simple_alu_opcodes[] = {

	[BPF_ADD] = 0x01,

	[BPF_SUB] = 0x29,

	[BPF_AND] = 0x21,

	[BPF_OR] = 0x09,

	[BPF_XOR] = 0x31,

	[BPF_LSH] = 0xE0,

	[BPF_RSH] = 0xE8,

	[BPF_ARSH] = 0xF8,

};



static void jit_fill_hole(void *area, unsigned int size)

{

	/* Fill whole space with INT3 instructions */
@@ -862,15 +874,9 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, 
		case BPF_ALU64 | BPF_AND | BPF_X:

		case BPF_ALU64 | BPF_OR | BPF_X:

		case BPF_ALU64 | BPF_XOR | BPF_X:

			switch (BPF_OP(insn->code)) {

			case BPF_ADD: b2 = 0x01; break;

			case BPF_SUB: b2 = 0x29; break;

			case BPF_AND: b2 = 0x21; break;

			case BPF_OR: b2 = 0x09; break;

			case BPF_XOR: b2 = 0x31; break;

			}

			maybe_emit_mod(&prog, dst_reg, src_reg,

				       BPF_CLASS(insn->code) == BPF_ALU64);

			b2 = simple_alu_opcodes[BPF_OP(insn->code)];

			EMIT2(b2, add_2reg(0xC0, dst_reg, src_reg));

			break;
@@ -1050,12 +1056,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, 
			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;

			}



			b3 = simple_alu_opcodes[BPF_OP(insn->code)];

			if (imm32 == 1)

				EMIT2(0xD1, add_1reg(b3, dst_reg));

			else
@@ -1089,11 +1090,7 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, 
			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;

			}

			b3 = simple_alu_opcodes[BPF_OP(insn->code)];

			EMIT2(0xD3, add_1reg(b3, dst_reg));



			if (src_reg != BPF_REG_4)