/*
* BPF JIT compiler for ARM64
*
- * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@gmail.com>
+ * Copyright (C) 2014-2015 Zi Shen Lim <zlim.lnx@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
[BPF_REG_8] = A64_R(21),
[BPF_REG_9] = A64_R(22),
/* read-only frame pointer to access stack */
- [BPF_REG_FP] = A64_FP,
+ [BPF_REG_FP] = A64_R(25),
/* temporary register for internal BPF JIT */
[TMP_REG_1] = A64_R(23),
[TMP_REG_2] = A64_R(24),
/* Stack must be multiples of 16B */
#define STACK_ALIGN(sz) (((sz) + 15) & ~15)
+#define _STACK_SIZE \
+ (MAX_BPF_STACK \
+ + 4 /* extra for skb_copy_bits buffer */)
+
+#define STACK_SIZE STACK_ALIGN(_STACK_SIZE)
+
static void build_prologue(struct jit_ctx *ctx)
{
const u8 r6 = bpf2a64[BPF_REG_6];
const u8 rx = bpf2a64[BPF_REG_X];
const u8 tmp1 = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
- int stack_size = MAX_BPF_STACK;
- stack_size += 4; /* extra for skb_copy_bits buffer */
- stack_size = STACK_ALIGN(stack_size);
+ /*
+ * BPF prog stack layout
+ *
+ * high
+ * original A64_SP => 0:+-----+ BPF prologue
+ * |FP/LR|
+ * current A64_FP => -16:+-----+
+ * | ... | callee saved registers
+ * +-----+
+ * | | x25/x26
+ * BPF fp register => -80:+-----+ <= (BPF_FP)
+ * | |
+ * | ... | BPF prog stack
+ * | |
+ * +-----+ <= (BPF_FP - MAX_BPF_STACK)
+ * |RSVD | JIT scratchpad
+ * current A64_SP => +-----+ <= (BPF_FP - STACK_SIZE)
+ * | |
+ * | ... | Function call stack
+ * | |
+ * +-----+
+ * low
+ *
+ */
+
+ /* Save FP and LR registers to stay align with ARM64 AAPCS */
+ emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
+ emit(A64_MOV(1, A64_FP, A64_SP), ctx);
/* Save callee-saved register */
emit(A64_PUSH(r6, r7, A64_SP), ctx);
if (ctx->tmp_used)
emit(A64_PUSH(tmp1, tmp2, A64_SP), ctx);
- /* Set up BPF stack */
- emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
+ /* Save fp (x25) and x26. SP requires 16 bytes alignment */
+ emit(A64_PUSH(fp, A64_R(26), A64_SP), ctx);
- /* Set up frame pointer */
+ /* Set up BPF prog stack base register (x25) */
emit(A64_MOV(1, fp, A64_SP), ctx);
+ /* Set up function call stack */
+ emit(A64_SUB_I(1, A64_SP, A64_SP, STACK_SIZE), ctx);
+
/* Clear registers A and X */
emit_a64_mov_i64(ra, 0, ctx);
emit_a64_mov_i64(rx, 0, ctx);
const u8 fp = bpf2a64[BPF_REG_FP];
const u8 tmp1 = bpf2a64[TMP_REG_1];
const u8 tmp2 = bpf2a64[TMP_REG_2];
- int stack_size = MAX_BPF_STACK;
-
- stack_size += 4; /* extra for skb_copy_bits buffer */
- stack_size = STACK_ALIGN(stack_size);
/* We're done with BPF stack */
- emit(A64_ADD_I(1, A64_SP, A64_SP, stack_size), ctx);
+ emit(A64_ADD_I(1, A64_SP, A64_SP, STACK_SIZE), ctx);
+
+ /* Restore fs (x25) and x26 */
+ emit(A64_POP(fp, A64_R(26), A64_SP), ctx);
/* Restore callee-saved register */
if (ctx->tmp_used)
emit(A64_POP(r8, r9, A64_SP), ctx);
emit(A64_POP(r6, r7, A64_SP), ctx);
- /* Restore frame pointer */
- emit(A64_MOV(1, fp, A64_SP), ctx);
+ /* Restore FP/LR registers */
+ emit(A64_POP(A64_FP, A64_LR, A64_SP), ctx);
/* Set return value */
emit(A64_MOV(1, A64_R(0), r0), ctx);
u8 jmp_cond;
s32 jmp_offset;
+#define check_imm(bits, imm) do { \
+ if ((((imm) > 0) && ((imm) >> (bits))) || \
+ (((imm) < 0) && (~(imm) >> (bits)))) { \
+ pr_info("[%2d] imm=%d(0x%x) out of range\n", \
+ i, imm, imm); \
+ return -EINVAL; \
+ } \
+} while (0)
+#define check_imm19(imm) check_imm(19, imm)
+#define check_imm26(imm) check_imm(26, imm)
+
switch (code) {
/* dst = src */
case BPF_ALU | BPF_MOV | BPF_X:
break;
case BPF_ALU | BPF_DIV | BPF_X:
case BPF_ALU64 | BPF_DIV | BPF_X:
- emit(A64_UDIV(is64, dst, dst, src), ctx);
- break;
case BPF_ALU | BPF_MOD | BPF_X:
case BPF_ALU64 | BPF_MOD | BPF_X:
- ctx->tmp_used = 1;
- emit(A64_UDIV(is64, tmp, dst, src), ctx);
- emit(A64_MUL(is64, tmp, tmp, src), ctx);
- emit(A64_SUB(is64, dst, dst, tmp), ctx);
+ {
+ const u8 r0 = bpf2a64[BPF_REG_0];
+
+ /* if (src == 0) return 0 */
+ jmp_offset = 3; /* skip ahead to else path */
+ check_imm19(jmp_offset);
+ emit(A64_CBNZ(is64, src, jmp_offset), ctx);
+ emit(A64_MOVZ(1, r0, 0, 0), ctx);
+ jmp_offset = epilogue_offset(ctx);
+ check_imm26(jmp_offset);
+ emit(A64_B(jmp_offset), ctx);
+ /* else */
+ switch (BPF_OP(code)) {
+ case BPF_DIV:
+ emit(A64_UDIV(is64, dst, dst, src), ctx);
+ break;
+ case BPF_MOD:
+ ctx->tmp_used = 1;
+ emit(A64_UDIV(is64, tmp, dst, src), ctx);
+ emit(A64_MUL(is64, tmp, tmp, src), ctx);
+ emit(A64_SUB(is64, dst, dst, tmp), ctx);
+ break;
+ }
break;
+ }
case BPF_ALU | BPF_LSH | BPF_X:
case BPF_ALU64 | BPF_LSH | BPF_X:
emit(A64_LSLV(is64, dst, dst, src), ctx);
emit(A64_ASR(is64, dst, dst, imm), ctx);
break;
-#define check_imm(bits, imm) do { \
- if ((((imm) > 0) && ((imm) >> (bits))) || \
- (((imm) < 0) && (~(imm) >> (bits)))) { \
- pr_info("[%2d] imm=%d(0x%x) out of range\n", \
- i, imm, imm); \
- return -EINVAL; \
- } \
-} while (0)
-#define check_imm19(imm) check_imm(19, imm)
-#define check_imm26(imm) check_imm(26, imm)
-
/* JUMP off */
case BPF_JMP | BPF_JA:
jmp_offset = bpf2a64_offset(i + off, i, ctx);
case BPF_ST | BPF_MEM | BPF_H:
case BPF_ST | BPF_MEM | BPF_B:
case BPF_ST | BPF_MEM | BPF_DW:
- goto notyet;
+ /* Load imm to a register then store it */
+ ctx->tmp_used = 1;
+ emit_a64_mov_i(1, tmp2, off, ctx);
+ emit_a64_mov_i(1, tmp, imm, ctx);
+ switch (BPF_SIZE(code)) {
+ case BPF_W:
+ emit(A64_STR32(tmp, dst, tmp2), ctx);
+ break;
+ case BPF_H:
+ emit(A64_STRH(tmp, dst, tmp2), ctx);
+ break;
+ case BPF_B:
+ emit(A64_STRB(tmp, dst, tmp2), ctx);
+ break;
+ case BPF_DW:
+ emit(A64_STR64(tmp, dst, tmp2), ctx);
+ break;
+ }
+ break;
/* STX: *(size *)(dst + off) = src */
case BPF_STX | BPF_MEM | BPF_W:
return -EINVAL;
}
emit_a64_mov_i64(r3, size, ctx);
- emit(A64_ADD_I(1, r4, fp, MAX_BPF_STACK), ctx);
+ emit(A64_SUB_I(1, r4, fp, STACK_SIZE), ctx);
emit_a64_mov_i64(r5, (unsigned long)bpf_load_pointer, ctx);
emit(A64_PUSH(A64_FP, A64_LR, A64_SP), ctx);
emit(A64_MOV(1, A64_FP, A64_SP), ctx);
if (bpf_jit_enable > 1)
bpf_jit_dump(prog->len, image_size, 2, ctx.image);
- bpf_flush_icache(ctx.image, ctx.image + ctx.idx);
+ bpf_flush_icache(header, ctx.image + ctx.idx);
set_memory_ro((unsigned long)header, header->pages);
prog->bpf_func = (void *)ctx.image;
- prog->jited = true;
+ prog->jited = 1;
out:
kfree(ctx.offset);
}
Code Review / kvmfornfv.git / blobdiff