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-rw-r--r--net/core/filter.c36
1 files changed, 30 insertions, 6 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index c3936d0724b8..e471c9b09670 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -9756,22 +9756,46 @@ static u32 sock_ops_convert_ctx_access(enum bpf_access_type type,
static struct bpf_insn *bpf_convert_data_end_access(const struct bpf_insn *si,
struct bpf_insn *insn)
{
- /* si->dst_reg = skb->data */
+ int reg;
+ int temp_reg_off = offsetof(struct sk_buff, cb) +
+ offsetof(struct sk_skb_cb, temp_reg);
+
+ if (si->src_reg == si->dst_reg) {
+ /* We need an extra register, choose and save a register. */
+ reg = BPF_REG_9;
+ if (si->src_reg == reg || si->dst_reg == reg)
+ reg--;
+ if (si->src_reg == reg || si->dst_reg == reg)
+ reg--;
+ *insn++ = BPF_STX_MEM(BPF_DW, si->src_reg, reg, temp_reg_off);
+ } else {
+ reg = si->dst_reg;
+ }
+
+ /* reg = skb->data */
*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, data),
- si->dst_reg, si->src_reg,
+ reg, si->src_reg,
offsetof(struct sk_buff, data));
/* AX = skb->len */
*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, len),
BPF_REG_AX, si->src_reg,
offsetof(struct sk_buff, len));
- /* si->dst_reg = skb->data + skb->len */
- *insn++ = BPF_ALU64_REG(BPF_ADD, si->dst_reg, BPF_REG_AX);
+ /* reg = skb->data + skb->len */
+ *insn++ = BPF_ALU64_REG(BPF_ADD, reg, BPF_REG_AX);
/* AX = skb->data_len */
*insn++ = BPF_LDX_MEM(BPF_FIELD_SIZEOF(struct sk_buff, data_len),
BPF_REG_AX, si->src_reg,
offsetof(struct sk_buff, data_len));
- /* si->dst_reg = skb->data + skb->len - skb->data_len */
- *insn++ = BPF_ALU64_REG(BPF_SUB, si->dst_reg, BPF_REG_AX);
+
+ /* reg = skb->data + skb->len - skb->data_len */
+ *insn++ = BPF_ALU64_REG(BPF_SUB, reg, BPF_REG_AX);
+
+ if (si->src_reg == si->dst_reg) {
+ /* Restore the saved register */
+ *insn++ = BPF_MOV64_REG(BPF_REG_AX, si->src_reg);
+ *insn++ = BPF_MOV64_REG(si->dst_reg, reg);
+ *insn++ = BPF_LDX_MEM(BPF_DW, reg, BPF_REG_AX, temp_reg_off);
+ }
return insn;
}