net: filter: x86: split bpf_jit_compile()

Split bpf_jit_compile() into two functions to improve readability
of for(pass++) loop. The change follows similar style of JIT compilers
for arm, powerpc, s390

The body of new do_jit() was not reformatted to reduce noise
in this patch, since the following patch replaces most of it.

Tested with BPF testsuite.

Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index dc01773..c5fa7c9 100644 (file)
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -178,41 +178,26 @@ static struct bpf_binary_header *bpf_alloc_binary(unsigned int proglen,
        return header;
 }
 
-void bpf_jit_compile(struct sk_filter *fp)
+struct jit_context {
+       unsigned int cleanup_addr; /* epilogue code offset */
+       int pc_ret0; /* bpf index of first RET #0 instruction (if any) */
+       u8 seen;
+};
+
+static int do_jit(struct sk_filter *bpf_prog, int *addrs, u8 *image,
+                 int oldproglen, struct jit_context *ctx)
 {
+       const struct sock_filter *filter = bpf_prog->insns;
+       int flen = bpf_prog->len;
        u8 temp[64];
        u8 *prog;
-       unsigned int proglen, oldproglen = 0;
-       int ilen, i;
+       int ilen, i, proglen;
        int t_offset, f_offset;
-       u8 t_op, f_op, seen = 0, pass;
-       u8 *image = NULL;
-       struct bpf_binary_header *header = NULL;
+       u8 t_op, f_op, seen = 0;
        u8 *func;
-       int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
-       unsigned int cleanup_addr; /* epilogue code offset */
-       unsigned int *addrs;
-       const struct sock_filter *filter = fp->insns;
-       int flen = fp->len;
-
-       if (!bpf_jit_enable)
-               return;
-
-       addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
-       if (addrs == NULL)
-               return;
-
-       /* Before first pass, make a rough estimation of addrs[]
-        * each bpf instruction is translated to less than 64 bytes
-        */
-       for (proglen = 0, i = 0; i < flen; i++) {
-               proglen += 64;
-               addrs[i] = proglen;
-       }
-       cleanup_addr = proglen; /* epilogue address */
+       unsigned int cleanup_addr = ctx->cleanup_addr;
+       u8 seen_or_pass0 = ctx->seen;
 
-       for (pass = 0; pass < 10; pass++) {
-               u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
                /* no prologue/epilogue for trivial filters (RET something) */
                proglen = 0;
                prog = temp;
@@ -325,12 +310,12 @@ void bpf_jit_compile(struct sk_filter *fp)
                        case BPF_S_ALU_DIV_X: /* A /= X; */
                                seen |= SEEN_XREG;
                                EMIT2(0x85, 0xdb);      /* test %ebx,%ebx */
-                               if (pc_ret0 > 0) {
+                               if (ctx->pc_ret0 > 0) {
                                        /* addrs[pc_ret0 - 1] is start address of target
                                         * (addrs[i] - 4) is the address following this jmp
                                         * ("xor %edx,%edx; div %ebx" being 4 bytes long)
                                         */
-                                       EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
+                                       EMIT_COND_JMP(X86_JE, addrs[ctx->pc_ret0 - 1] -
                                                                (addrs[i] - 4));
                                } else {
                                        EMIT_COND_JMP(X86_JNE, 2 + 5);
@@ -342,12 +327,12 @@ void bpf_jit_compile(struct sk_filter *fp)
                        case BPF_S_ALU_MOD_X: /* A %= X; */
                                seen |= SEEN_XREG;
                                EMIT2(0x85, 0xdb);      /* test %ebx,%ebx */
-                               if (pc_ret0 > 0) {
+                               if (ctx->pc_ret0 > 0) {
                                        /* addrs[pc_ret0 - 1] is start address of target
                                         * (addrs[i] - 6) is the address following this jmp
                                         * ("xor %edx,%edx; div %ebx;mov %edx,%eax" being 6 bytes long)
                                         */
-                                       EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
+                                       EMIT_COND_JMP(X86_JE, addrs[ctx->pc_ret0 - 1] -
                                                                (addrs[i] - 6));
                                } else {
                                        EMIT_COND_JMP(X86_JNE, 2 + 5);
@@ -441,8 +426,8 @@ void bpf_jit_compile(struct sk_filter *fp)
                                break;
                        case BPF_S_RET_K:
                                if (!K) {
-                                       if (pc_ret0 == -1)
-                                               pc_ret0 = i;
+                                       if (ctx->pc_ret0 == -1)
+                                               ctx->pc_ret0 = i;
                                        CLEAR_A();
                                } else {
                                        EMIT1_off32(0xb8, K);   /* mov $imm32,%eax */
@@ -603,7 +588,7 @@ void bpf_jit_compile(struct sk_filter *fp)
                                int off = pkt_type_offset();
 
                                if (off < 0)
-                                       goto out;
+                                       return -EINVAL;
                                if (is_imm8(off)) {
                                        /* movzbl off8(%rdi),%eax */
                                        EMIT4(0x0f, 0xb6, 0x47, off);
@@ -725,36 +710,79 @@ cond_branch:                      f_offset = addrs[i + filter[i].jf] - addrs[i];
                                }
                                EMIT_COND_JMP(f_op, f_offset);
                                break;
-                       default:
-                               /* hmm, too complex filter, give up with jit compiler */
-                               goto out;
-                       }
-                       ilen = prog - temp;
-                       if (image) {
-                               if (unlikely(proglen + ilen > oldproglen)) {
-                                       pr_err("bpb_jit_compile fatal error\n");
-                                       kfree(addrs);
-                                       module_free(NULL, header);
-                                       return;
-                               }
-                               memcpy(image + proglen, temp, ilen);
+               default:
+                       /* hmm, too complex filter, give up with jit compiler */
+                       return -EINVAL;
+               }
+               ilen = prog - temp;
+               if (image) {
+                       if (unlikely(proglen + ilen > oldproglen)) {
+                               pr_err("bpb_jit_compile fatal error\n");
+                               return -EFAULT;
                        }
-                       proglen += ilen;
-                       addrs[i] = proglen;
-                       prog = temp;
+                       memcpy(image + proglen, temp, ilen);
                }
-               /* last bpf instruction is always a RET :
-                * use it to give the cleanup instruction(s) addr
-                */
-               cleanup_addr = proglen - 1; /* ret */
-               if (seen_or_pass0)
-                       cleanup_addr -= 1; /* leaveq */
-               if (seen_or_pass0 & SEEN_XREG)
-                       cleanup_addr -= 4; /* mov  -8(%rbp),%rbx */
+               proglen += ilen;
+               addrs[i] = proglen;
+               prog = temp;
+       }
+       /* last bpf instruction is always a RET :
+        * use it to give the cleanup instruction(s) addr
+        */
+       ctx->cleanup_addr = proglen - 1; /* ret */
+       if (seen_or_pass0)
+               ctx->cleanup_addr -= 1; /* leaveq */
+       if (seen_or_pass0 & SEEN_XREG)
+               ctx->cleanup_addr -= 4; /* mov  -8(%rbp),%rbx */
+
+       ctx->seen = seen;
+
+       return proglen;
+}
+
+void bpf_jit_compile(struct sk_filter *prog)
+{
+       struct bpf_binary_header *header = NULL;
+       int proglen, oldproglen = 0;
+       struct jit_context ctx = {};
+       u8 *image = NULL;
+       int *addrs;
+       int pass;
+       int i;
+
+       if (!bpf_jit_enable)
+               return;
 
+       if (!prog || !prog->len)
+               return;
+
+       addrs = kmalloc(prog->len * sizeof(*addrs), GFP_KERNEL);
+       if (!addrs)
+               return;
+
+       /* Before first pass, make a rough estimation of addrs[]
+        * each bpf instruction is translated to less than 64 bytes
+        */
+       for (proglen = 0, i = 0; i < prog->len; i++) {
+               proglen += 64;
+               addrs[i] = proglen;
+       }
+       ctx.cleanup_addr = proglen;
+       ctx.seen = SEEN_XREG | SEEN_DATAREF | SEEN_MEM;
+       ctx.pc_ret0 = -1;
+
+       for (pass = 0; pass < 10; pass++) {
+               proglen = do_jit(prog, addrs, image, oldproglen, &ctx);
+               if (proglen <= 0) {
+                       image = NULL;
+                       if (header)
+                               module_free(NULL, header);
+                       goto out;
+               }
                if (image) {
                        if (proglen != oldproglen)
-                               pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
+                               pr_err("bpf_jit: proglen=%d != oldproglen=%d\n",
+                                      proglen, oldproglen);
                        break;
                }
                if (proglen == oldproglen) {
@@ -766,17 +794,16 @@ cond_branch:                      f_offset = addrs[i + filter[i].jf] - addrs[i];
        }
 
        if (bpf_jit_enable > 1)
-               bpf_jit_dump(flen, proglen, pass, image);
+               bpf_jit_dump(prog->len, proglen, 0, image);
 
        if (image) {
                bpf_flush_icache(header, image + proglen);
                set_memory_ro((unsigned long)header, header->pages);
-               fp->bpf_func = (void *)image;
-               fp->jited = 1;
+               prog->bpf_func = (void *)image;
+               prog->jited = 1;
        }
 out:
        kfree(addrs);
-       return;
 }
 
 static void bpf_jit_free_deferred(struct work_struct *work)