korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-26 21:54:11 +08:00
Code Issues Packages Projects Releases Wiki Activity

bpf, mips64: remove unneeded zero check from div/mod with k

Browse Source 
The verifier in both cBPF and eBPF reject div/mod by 0 imm,
so this can never load. Remove emitting such test and reject
it from being JITed instead (the latter is actually also not
needed, but given practice in sparc64, ppc64 today, so
doesn't hurt to add it here either).

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Daney <david.daney@cavium.com>
Reviewed-by: David Daney <david.daney@cavium.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2018-01-26 23:33:46 +01:00 committed by Alexei Starovoitov
parent 1fb5c9c622
commit e472d5d8af
1 changed files with 4 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
arch/mips/net/ebpf_jit.c
View File

@ -741,16 +741,11 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
break; break;
case BPF_ALU | BPF_DIV | BPF_K: /* ALU_IMM */ case BPF_ALU | BPF_DIV | BPF_K: /* ALU_IMM */
case BPF_ALU | BPF_MOD | BPF_K: /* ALU_IMM */ case BPF_ALU | BPF_MOD | BPF_K: /* ALU_IMM */
if (insn->imm == 0)
return -EINVAL;
dst = ebpf_to_mips_reg(ctx, insn, dst_reg); dst = ebpf_to_mips_reg(ctx, insn, dst_reg);
if (dst < 0) if (dst < 0)
return dst; return dst;
if (insn->imm == 0) { /* Div by zero */
b_off = b_imm(exit_idx, ctx);
if (is_bad_offset(b_off))
return -E2BIG;
emit_instr(ctx, beq, MIPS_R_ZERO, MIPS_R_ZERO, b_off);
emit_instr(ctx, addu, MIPS_R_V0, MIPS_R_ZERO, MIPS_R_ZERO);
}
td = get_reg_val_type(ctx, this_idx, insn->dst_reg); td = get_reg_val_type(ctx, this_idx, insn->dst_reg);
if (td == REG_64BIT || td == REG_32BIT_ZERO_EX) if (td == REG_64BIT || td == REG_32BIT_ZERO_EX)
/* sign extend */ /* sign extend */
@ -770,19 +765,13 @@ static int build_one_insn(const struct bpf_insn *insn, struct jit_ctx *ctx,
break; break;
case BPF_ALU64 | BPF_DIV | BPF_K: /* ALU_IMM */ case BPF_ALU64 | BPF_DIV | BPF_K: /* ALU_IMM */
case BPF_ALU64 | BPF_MOD | BPF_K: /* ALU_IMM */ case BPF_ALU64 | BPF_MOD | BPF_K: /* ALU_IMM */
if (insn->imm == 0)
return -EINVAL;
dst = ebpf_to_mips_reg(ctx, insn, dst_reg); dst = ebpf_to_mips_reg(ctx, insn, dst_reg);
if (dst < 0) if (dst < 0)
return dst; return dst;
if (insn->imm == 0) { /* Div by zero */
b_off = b_imm(exit_idx, ctx);
if (is_bad_offset(b_off))
return -E2BIG;
emit_instr(ctx, beq, MIPS_R_ZERO, MIPS_R_ZERO, b_off);
emit_instr(ctx, addu, MIPS_R_V0, MIPS_R_ZERO, MIPS_R_ZERO);
}
if (get_reg_val_type(ctx, this_idx, insn->dst_reg) == REG_32BIT) if (get_reg_val_type(ctx, this_idx, insn->dst_reg) == REG_32BIT)
emit_instr(ctx, dinsu, dst, MIPS_R_ZERO, 32, 32); emit_instr(ctx, dinsu, dst, MIPS_R_ZERO, 32, 32);
if (insn->imm == 1) { if (insn->imm == 1) {
/* div by 1 is a nop, mod by 1 is zero */ /* div by 1 is a nop, mod by 1 is zero */
if (bpf_op == BPF_MOD) if (bpf_op == BPF_MOD)