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-rw-r--r--arch/x86/net/bpf_jit.S122
1 files changed, 91 insertions, 31 deletions
diff --git a/arch/x86/net/bpf_jit.S b/arch/x86/net/bpf_jit.S
index 66870223f8c5..877b9a1b2152 100644
--- a/arch/x86/net/bpf_jit.S
+++ b/arch/x86/net/bpf_jit.S
@@ -18,17 +18,17 @@
* r9d : hlen = skb->len - skb->data_len
*/
#define SKBDATA %r8
-
-sk_load_word_ind:
- .globl sk_load_word_ind
-
- add %ebx,%esi /* offset += X */
-# test %esi,%esi /* if (offset < 0) goto bpf_error; */
- js bpf_error
+#define SKF_MAX_NEG_OFF $(-0x200000) /* SKF_LL_OFF from filter.h */
sk_load_word:
.globl sk_load_word
+ test %esi,%esi
+ js bpf_slow_path_word_neg
+
+sk_load_word_positive_offset:
+ .globl sk_load_word_positive_offset
+
mov %r9d,%eax # hlen
sub %esi,%eax # hlen - offset
cmp $3,%eax
@@ -37,16 +37,15 @@ sk_load_word:
bswap %eax /* ntohl() */
ret
-
-sk_load_half_ind:
- .globl sk_load_half_ind
-
- add %ebx,%esi /* offset += X */
- js bpf_error
-
sk_load_half:
.globl sk_load_half
+ test %esi,%esi
+ js bpf_slow_path_half_neg
+
+sk_load_half_positive_offset:
+ .globl sk_load_half_positive_offset
+
mov %r9d,%eax
sub %esi,%eax # hlen - offset
cmp $1,%eax
@@ -55,14 +54,15 @@ sk_load_half:
rol $8,%ax # ntohs()
ret
-sk_load_byte_ind:
- .globl sk_load_byte_ind
- add %ebx,%esi /* offset += X */
- js bpf_error
-
sk_load_byte:
.globl sk_load_byte
+ test %esi,%esi
+ js bpf_slow_path_byte_neg
+
+sk_load_byte_positive_offset:
+ .globl sk_load_byte_positive_offset
+
cmp %esi,%r9d /* if (offset >= hlen) goto bpf_slow_path_byte */
jle bpf_slow_path_byte
movzbl (SKBDATA,%rsi),%eax
@@ -73,25 +73,21 @@ sk_load_byte:
*
* Implements BPF_S_LDX_B_MSH : ldxb 4*([offset]&0xf)
* Must preserve A accumulator (%eax)
- * Inputs : %esi is the offset value, already known positive
+ * Inputs : %esi is the offset value
*/
-ENTRY(sk_load_byte_msh)
- CFI_STARTPROC
+sk_load_byte_msh:
+ .globl sk_load_byte_msh
+ test %esi,%esi
+ js bpf_slow_path_byte_msh_neg
+
+sk_load_byte_msh_positive_offset:
+ .globl sk_load_byte_msh_positive_offset
cmp %esi,%r9d /* if (offset >= hlen) goto bpf_slow_path_byte_msh */
jle bpf_slow_path_byte_msh
movzbl (SKBDATA,%rsi),%ebx
and $15,%bl
shl $2,%bl
ret
- CFI_ENDPROC
-ENDPROC(sk_load_byte_msh)
-
-bpf_error:
-# force a return 0 from jit handler
- xor %eax,%eax
- mov -8(%rbp),%rbx
- leaveq
- ret
/* rsi contains offset and can be scratched */
#define bpf_slow_path_common(LEN) \
@@ -138,3 +134,67 @@ bpf_slow_path_byte_msh:
shl $2,%al
xchg %eax,%ebx
ret
+
+#define sk_negative_common(SIZE) \
+ push %rdi; /* save skb */ \
+ push %r9; \
+ push SKBDATA; \
+/* rsi already has offset */ \
+ mov $SIZE,%ecx; /* size */ \
+ call bpf_internal_load_pointer_neg_helper; \
+ test %rax,%rax; \
+ pop SKBDATA; \
+ pop %r9; \
+ pop %rdi; \
+ jz bpf_error
+
+
+bpf_slow_path_word_neg:
+ cmp SKF_MAX_NEG_OFF, %esi /* test range */
+ jl bpf_error /* offset lower -> error */
+sk_load_word_negative_offset:
+ .globl sk_load_word_negative_offset
+ sk_negative_common(4)
+ mov (%rax), %eax
+ bswap %eax
+ ret
+
+bpf_slow_path_half_neg:
+ cmp SKF_MAX_NEG_OFF, %esi
+ jl bpf_error
+sk_load_half_negative_offset:
+ .globl sk_load_half_negative_offset
+ sk_negative_common(2)
+ mov (%rax),%ax
+ rol $8,%ax
+ movzwl %ax,%eax
+ ret
+
+bpf_slow_path_byte_neg:
+ cmp SKF_MAX_NEG_OFF, %esi
+ jl bpf_error
+sk_load_byte_negative_offset:
+ .globl sk_load_byte_negative_offset
+ sk_negative_common(1)
+ movzbl (%rax), %eax
+ ret
+
+bpf_slow_path_byte_msh_neg:
+ cmp SKF_MAX_NEG_OFF, %esi
+ jl bpf_error
+sk_load_byte_msh_negative_offset:
+ .globl sk_load_byte_msh_negative_offset
+ xchg %eax,%ebx /* dont lose A , X is about to be scratched */
+ sk_negative_common(1)
+ movzbl (%rax),%eax
+ and $15,%al
+ shl $2,%al
+ xchg %eax,%ebx
+ ret
+
+bpf_error:
+# force a return 0 from jit handler
+ xor %eax,%eax
+ mov -8(%rbp),%rbx
+ leaveq
+ ret