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-rw-r--r--arch/x86/net/bpf_jit.S140
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diff --git a/arch/x86/net/bpf_jit.S b/arch/x86/net/bpf_jit.S
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+/* bpf_jit.S : BPF JIT helper functions
+ *
+ * Copyright (C) 2011 Eric Dumazet (eric.dumazet@gmail.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+#include <linux/linkage.h>
+#include <asm/dwarf2.h>
+
+/*
+ * Calling convention :
+ * rdi : skb pointer
+ * esi : offset of byte(s) to fetch in skb (can be scratched)
+ * r8 : copy of skb->data
+ * 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
+
+sk_load_word:
+ .globl sk_load_word
+
+ mov %r9d,%eax # hlen
+ sub %esi,%eax # hlen - offset
+ cmp $3,%eax
+ jle bpf_slow_path_word
+ mov (SKBDATA,%rsi),%eax
+ 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
+
+ mov %r9d,%eax
+ sub %esi,%eax # hlen - offset
+ cmp $1,%eax
+ jle bpf_slow_path_half
+ movzwl (SKBDATA,%rsi),%eax
+ 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
+
+ cmp %esi,%r9d /* if (offset >= hlen) goto bpf_slow_path_byte */
+ jle bpf_slow_path_byte
+ 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, already known positive
+ */
+ENTRY(sk_load_byte_msh)
+ CFI_STARTPROC
+ 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) \
+ push %rdi; /* save skb */ \
+ push %r9; \
+ push SKBDATA; \
+/* rsi already has offset */ \
+ mov $LEN,%ecx; /* len */ \
+ lea -12(%rbp),%rdx; \
+ call skb_copy_bits; \
+ test %eax,%eax; \
+ pop SKBDATA; \
+ pop %r9; \
+ pop %rdi
+
+
+bpf_slow_path_word:
+ bpf_slow_path_common(4)
+ js bpf_error
+ mov -12(%rbp),%eax
+ bswap %eax
+ ret
+
+bpf_slow_path_half:
+ bpf_slow_path_common(2)
+ js bpf_error
+ mov -12(%rbp),%ax
+ rol $8,%ax
+ movzwl %ax,%eax
+ ret
+
+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
+ ret
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