diff options
Diffstat (limited to 'arch/arm64/net/bpf_jit_comp.c')
| -rw-r--r-- | arch/arm64/net/bpf_jit_comp.c | 128 |
1 files changed, 113 insertions, 15 deletions
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index fcc675aa1670..4bf50458b35d 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -191,6 +191,47 @@ static bool is_addsub_imm(u32 imm) return !(imm & ~0xfff) || !(imm & ~0xfff000); } +/* + * There are 3 types of AArch64 LDR/STR (immediate) instruction: + * Post-index, Pre-index, Unsigned offset. + * + * For BPF ldr/str, the "unsigned offset" type is sufficient. + * + * "Unsigned offset" type LDR(immediate) format: + * + * 3 2 1 0 + * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * |x x|1 1 1 0 0 1 0 1| imm12 | Rn | Rt | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * scale + * + * "Unsigned offset" type STR(immediate) format: + * 3 2 1 0 + * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * |x x|1 1 1 0 0 1 0 0| imm12 | Rn | Rt | + * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + * scale + * + * The offset is calculated from imm12 and scale in the following way: + * + * offset = (u64)imm12 << scale + */ +static bool is_lsi_offset(s16 offset, int scale) +{ + if (offset < 0) + return false; + + if (offset > (0xFFF << scale)) + return false; + + if (offset & ((1 << scale) - 1)) + return false; + + return true; +} + /* Tail call offset to jump into */ #if IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) #define PROLOGUE_OFFSET 8 @@ -971,19 +1012,38 @@ emit_cond_jmp: case BPF_LDX | BPF_PROBE_MEM | BPF_W: case BPF_LDX | BPF_PROBE_MEM | BPF_H: case BPF_LDX | BPF_PROBE_MEM | BPF_B: - emit_a64_mov_i(1, tmp, off, ctx); switch (BPF_SIZE(code)) { case BPF_W: - emit(A64_LDR32(dst, src, tmp), ctx); + if (is_lsi_offset(off, 2)) { + emit(A64_LDR32I(dst, src, off), ctx); + } else { + emit_a64_mov_i(1, tmp, off, ctx); + emit(A64_LDR32(dst, src, tmp), ctx); + } break; case BPF_H: - emit(A64_LDRH(dst, src, tmp), ctx); + if (is_lsi_offset(off, 1)) { + emit(A64_LDRHI(dst, src, off), ctx); + } else { + emit_a64_mov_i(1, tmp, off, ctx); + emit(A64_LDRH(dst, src, tmp), ctx); + } break; case BPF_B: - emit(A64_LDRB(dst, src, tmp), ctx); + if (is_lsi_offset(off, 0)) { + emit(A64_LDRBI(dst, src, off), ctx); + } else { + emit_a64_mov_i(1, tmp, off, ctx); + emit(A64_LDRB(dst, src, tmp), ctx); + } break; case BPF_DW: - emit(A64_LDR64(dst, src, tmp), ctx); + if (is_lsi_offset(off, 3)) { + emit(A64_LDR64I(dst, src, off), ctx); + } else { + emit_a64_mov_i(1, tmp, off, ctx); + emit(A64_LDR64(dst, src, tmp), ctx); + } break; } @@ -1011,20 +1071,39 @@ emit_cond_jmp: case BPF_ST | BPF_MEM | BPF_B: case BPF_ST | BPF_MEM | BPF_DW: /* Load imm to a register then store it */ - 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); + if (is_lsi_offset(off, 2)) { + emit(A64_STR32I(tmp, dst, off), ctx); + } else { + emit_a64_mov_i(1, tmp2, off, ctx); + emit(A64_STR32(tmp, dst, tmp2), ctx); + } break; case BPF_H: - emit(A64_STRH(tmp, dst, tmp2), ctx); + if (is_lsi_offset(off, 1)) { + emit(A64_STRHI(tmp, dst, off), ctx); + } else { + emit_a64_mov_i(1, tmp2, off, ctx); + emit(A64_STRH(tmp, dst, tmp2), ctx); + } break; case BPF_B: - emit(A64_STRB(tmp, dst, tmp2), ctx); + if (is_lsi_offset(off, 0)) { + emit(A64_STRBI(tmp, dst, off), ctx); + } else { + emit_a64_mov_i(1, tmp2, off, ctx); + emit(A64_STRB(tmp, dst, tmp2), ctx); + } break; case BPF_DW: - emit(A64_STR64(tmp, dst, tmp2), ctx); + if (is_lsi_offset(off, 3)) { + emit(A64_STR64I(tmp, dst, off), ctx); + } else { + emit_a64_mov_i(1, tmp2, off, ctx); + emit(A64_STR64(tmp, dst, tmp2), ctx); + } break; } break; @@ -1034,19 +1113,38 @@ emit_cond_jmp: case BPF_STX | BPF_MEM | BPF_H: case BPF_STX | BPF_MEM | BPF_B: case BPF_STX | BPF_MEM | BPF_DW: - emit_a64_mov_i(1, tmp, off, ctx); switch (BPF_SIZE(code)) { case BPF_W: - emit(A64_STR32(src, dst, tmp), ctx); + if (is_lsi_offset(off, 2)) { + emit(A64_STR32I(src, dst, off), ctx); + } else { + emit_a64_mov_i(1, tmp, off, ctx); + emit(A64_STR32(src, dst, tmp), ctx); + } break; case BPF_H: - emit(A64_STRH(src, dst, tmp), ctx); + if (is_lsi_offset(off, 1)) { + emit(A64_STRHI(src, dst, off), ctx); + } else { + emit_a64_mov_i(1, tmp, off, ctx); + emit(A64_STRH(src, dst, tmp), ctx); + } break; case BPF_B: - emit(A64_STRB(src, dst, tmp), ctx); + if (is_lsi_offset(off, 0)) { + emit(A64_STRBI(src, dst, off), ctx); + } else { + emit_a64_mov_i(1, tmp, off, ctx); + emit(A64_STRB(src, dst, tmp), ctx); + } break; case BPF_DW: - emit(A64_STR64(src, dst, tmp), ctx); + if (is_lsi_offset(off, 3)) { + emit(A64_STR64I(src, dst, off), ctx); + } else { + emit_a64_mov_i(1, tmp, off, ctx); + emit(A64_STR64(src, dst, tmp), ctx); + } break; } break; |