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-rw-r--r--arch/x86/net/bpf_jit.S77
1 files changed, 18 insertions, 59 deletions
diff --git a/arch/x86/net/bpf_jit.S b/arch/x86/net/bpf_jit.S
index 0149575..6440221 100644
--- a/arch/x86/net/bpf_jit.S
+++ b/arch/x86/net/bpf_jit.S
@@ -12,13 +12,16 @@
/*
* Calling convention :
- * rdi : skb pointer
+ * rbx : skb pointer (callee saved)
* esi : offset of byte(s) to fetch in skb (can be scratched)
- * r8 : copy of skb->data
+ * r10 : copy of skb->data
* r9d : hlen = skb->len - skb->data_len
*/
-#define SKBDATA %r8
+#define SKBDATA %r10
#define SKF_MAX_NEG_OFF $(-0x200000) /* SKF_LL_OFF from filter.h */
+#define MAX_BPF_STACK (512 /* from filter.h */ + \
+ 32 /* space for rbx,r13,r14,r15 */ + \
+ 8 /* space for skb_copy_bits */)
sk_load_word:
.globl sk_load_word
@@ -68,53 +71,31 @@ sk_load_byte_positive_offset:
movzbl (SKBDATA,%rsi),%eax
ret
-/**
- * sk_load_byte_msh - BPF_S_LDX_B_MSH helper
- *
- * Implements BPF_S_LDX_B_MSH : ldxb 4*([offset]&0xf)
- * Must preserve A accumulator (%eax)
- * Inputs : %esi is the offset value
- */
-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
-
/* rsi contains offset and can be scratched */
#define bpf_slow_path_common(LEN) \
- push %rdi; /* save skb */ \
+ mov %rbx, %rdi; /* arg1 == skb */ \
push %r9; \
push SKBDATA; \
/* rsi already has offset */ \
mov $LEN,%ecx; /* len */ \
- lea -12(%rbp),%rdx; \
+ lea - MAX_BPF_STACK + 32(%rbp),%rdx; \
call skb_copy_bits; \
test %eax,%eax; \
pop SKBDATA; \
- pop %r9; \
- pop %rdi
+ pop %r9;
bpf_slow_path_word:
bpf_slow_path_common(4)
js bpf_error
- mov -12(%rbp),%eax
+ mov - MAX_BPF_STACK + 32(%rbp),%eax
bswap %eax
ret
bpf_slow_path_half:
bpf_slow_path_common(2)
js bpf_error
- mov -12(%rbp),%ax
+ mov - MAX_BPF_STACK + 32(%rbp),%ax
rol $8,%ax
movzwl %ax,%eax
ret
@@ -122,21 +103,11 @@ bpf_slow_path_half:
bpf_slow_path_byte:
bpf_slow_path_common(1)
js bpf_error
- movzbl -12(%rbp),%eax
- ret
-
-bpf_slow_path_byte_msh:
- xchg %eax,%ebx /* dont lose A , X is about to be scratched */
- bpf_slow_path_common(1)
- js bpf_error
- movzbl -12(%rbp),%eax
- and $15,%al
- shl $2,%al
- xchg %eax,%ebx
+ movzbl - MAX_BPF_STACK + 32(%rbp),%eax
ret
#define sk_negative_common(SIZE) \
- push %rdi; /* save skb */ \
+ mov %rbx, %rdi; /* arg1 == skb */ \
push %r9; \
push SKBDATA; \
/* rsi already has offset */ \
@@ -145,10 +116,8 @@ bpf_slow_path_byte_msh:
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 */
@@ -179,22 +148,12 @@ sk_load_byte_negative_offset:
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
+ xor %eax,%eax
+ mov - MAX_BPF_STACK(%rbp),%rbx
+ mov - MAX_BPF_STACK + 8(%rbp),%r13
+ mov - MAX_BPF_STACK + 16(%rbp),%r14
+ mov - MAX_BPF_STACK + 24(%rbp),%r15
leaveq
ret
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