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authorRussell King <rmk+kernel@armlinux.org.uk>2018-01-13 21:06:16 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-01-31 14:03:43 +0100
commit5911dd3f92aefd86b4a86286c94398681c453802 (patch)
tree4caced539b0937c85c80fa1d42f5bf97bccd049b /arch/arm
parent0da4a4d0c7f941638e2e7e515c2d758de8976418 (diff)
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ARM: net: bpf: fix LDX instructions
commit ec19e02b343db991d2d1610c409efefebf4e2ca9 upstream. When the source and destination register are identical, our JIT does not generate correct code, which leads to kernel oopses. Fix this by (a) generating more efficient code, and (b) making use of the temporary earlier if we will overwrite the address register. Fixes: 39c13c204bb1 ("arm: eBPF JIT compiler") Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/net/bpf_jit_32.c61
1 files changed, 33 insertions, 28 deletions
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index 95bb3f896c8f..715e7250de86 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -913,33 +913,53 @@ static inline void emit_str_r(const u8 dst, const u8 src, bool dstk,
}
/* dst = *(size*)(src + off) */
-static inline void emit_ldx_r(const u8 dst, const u8 src, bool dstk,
- const s32 off, struct jit_ctx *ctx, const u8 sz){
+static inline void emit_ldx_r(const u8 dst[], const u8 src, bool dstk,
+ s32 off, struct jit_ctx *ctx, const u8 sz){
const u8 *tmp = bpf2a32[TMP_REG_1];
- u8 rd = dstk ? tmp[1] : dst;
+ const u8 *rd = dstk ? tmp : dst;
u8 rm = src;
+ s32 off_max;
- if (off) {
+ if (sz == BPF_H)
+ off_max = 0xff;
+ else
+ off_max = 0xfff;
+
+ if (off < 0 || off > off_max) {
emit_a32_mov_i(tmp[0], off, false, ctx);
emit(ARM_ADD_R(tmp[0], tmp[0], src), ctx);
rm = tmp[0];
+ off = 0;
+ } else if (rd[1] == rm) {
+ emit(ARM_MOV_R(tmp[0], rm), ctx);
+ rm = tmp[0];
}
switch (sz) {
- case BPF_W:
- /* Load a Word */
- emit(ARM_LDR_I(rd, rm, 0), ctx);
+ case BPF_B:
+ /* Load a Byte */
+ emit(ARM_LDRB_I(rd[1], rm, off), ctx);
+ emit_a32_mov_i(dst[0], 0, dstk, ctx);
break;
case BPF_H:
/* Load a HalfWord */
- emit(ARM_LDRH_I(rd, rm, 0), ctx);
+ emit(ARM_LDRH_I(rd[1], rm, off), ctx);
+ emit_a32_mov_i(dst[0], 0, dstk, ctx);
break;
- case BPF_B:
- /* Load a Byte */
- emit(ARM_LDRB_I(rd, rm, 0), ctx);
+ case BPF_W:
+ /* Load a Word */
+ emit(ARM_LDR_I(rd[1], rm, off), ctx);
+ emit_a32_mov_i(dst[0], 0, dstk, ctx);
+ break;
+ case BPF_DW:
+ /* Load a Double Word */
+ emit(ARM_LDR_I(rd[1], rm, off), ctx);
+ emit(ARM_LDR_I(rd[0], rm, off + 4), ctx);
break;
}
if (dstk)
- emit(ARM_STR_I(rd, ARM_SP, STACK_VAR(dst)), ctx);
+ emit(ARM_STR_I(rd[1], ARM_SP, STACK_VAR(dst[1])), ctx);
+ if (dstk && sz == BPF_DW)
+ emit(ARM_STR_I(rd[0], ARM_SP, STACK_VAR(dst[0])), ctx);
}
/* Arithmatic Operation */
@@ -1440,22 +1460,7 @@ exit:
rn = sstk ? tmp2[1] : src_lo;
if (sstk)
emit(ARM_LDR_I(rn, ARM_SP, STACK_VAR(src_lo)), ctx);
- switch (BPF_SIZE(code)) {
- case BPF_W:
- /* Load a Word */
- case BPF_H:
- /* Load a Half-Word */
- case BPF_B:
- /* Load a Byte */
- emit_ldx_r(dst_lo, rn, dstk, off, ctx, BPF_SIZE(code));
- emit_a32_mov_i(dst_hi, 0, dstk, ctx);
- break;
- case BPF_DW:
- /* Load a double word */
- emit_ldx_r(dst_lo, rn, dstk, off, ctx, BPF_W);
- emit_ldx_r(dst_hi, rn, dstk, off+4, ctx, BPF_W);
- break;
- }
+ emit_ldx_r(dst, rn, dstk, off, ctx, BPF_SIZE(code));
break;
/* R0 = ntohx(*(size *)(((struct sk_buff *)R6)->data + imm)) */
case BPF_LD | BPF_ABS | BPF_W: