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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>
This commit is contained in:
Alexei Starovoitov
David S. Miller
parent
9509b1c150
commit
f3c2af7ba1
@ -178,41 +178,26 @@ static struct bpf_binary_header *bpf_alloc_binary(unsigned int proglen,
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return header;
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}
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void bpf_jit_compile(struct sk_filter *fp)
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struct jit_context {
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unsigned int cleanup_addr; /* epilogue code offset */
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int pc_ret0; /* bpf index of first RET #0 instruction (if any) */
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u8 seen;
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};
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static int do_jit(struct sk_filter *bpf_prog, int *addrs, u8 *image,
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int oldproglen, struct jit_context *ctx)
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{
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const struct sock_filter *filter = bpf_prog->insns;
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int flen = bpf_prog->len;
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u8 temp[64];
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u8 *prog;
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unsigned int proglen, oldproglen = 0;
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int ilen, i;
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int ilen, i, proglen;
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int t_offset, f_offset;
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u8 t_op, f_op, seen = 0, pass;
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u8 *image = NULL;
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struct bpf_binary_header *header = NULL;
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u8 t_op, f_op, seen = 0;
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u8 *func;
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int pc_ret0 = -1; /* bpf index of first RET #0 instruction (if any) */
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unsigned int cleanup_addr; /* epilogue code offset */
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unsigned int *addrs;
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const struct sock_filter *filter = fp->insns;
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int flen = fp->len;
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unsigned int cleanup_addr = ctx->cleanup_addr;
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u8 seen_or_pass0 = ctx->seen;
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if (!bpf_jit_enable)
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return;
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addrs = kmalloc(flen * sizeof(*addrs), GFP_KERNEL);
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if (addrs == NULL)
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return;
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/* Before first pass, make a rough estimation of addrs[]
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* each bpf instruction is translated to less than 64 bytes
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*/
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for (proglen = 0, i = 0; i < flen; i++) {
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proglen += 64;
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addrs[i] = proglen;
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}
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cleanup_addr = proglen; /* epilogue address */
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for (pass = 0; pass < 10; pass++) {
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u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen;
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/* no prologue/epilogue for trivial filters (RET something) */
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proglen = 0;
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prog = temp;
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@ -325,12 +310,12 @@ void bpf_jit_compile(struct sk_filter *fp)
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case BPF_S_ALU_DIV_X: /* A /= X; */
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seen |= SEEN_XREG;
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EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
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if (pc_ret0 > 0) {
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if (ctx->pc_ret0 > 0) {
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/* addrs[pc_ret0 - 1] is start address of target
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* (addrs[i] - 4) is the address following this jmp
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* ("xor %edx,%edx; div %ebx" being 4 bytes long)
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*/
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EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
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EMIT_COND_JMP(X86_JE, addrs[ctx->pc_ret0 - 1] -
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(addrs[i] - 4));
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} else {
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EMIT_COND_JMP(X86_JNE, 2 + 5);
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@ -342,12 +327,12 @@ void bpf_jit_compile(struct sk_filter *fp)
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case BPF_S_ALU_MOD_X: /* A %= X; */
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seen |= SEEN_XREG;
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EMIT2(0x85, 0xdb); /* test %ebx,%ebx */
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if (pc_ret0 > 0) {
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if (ctx->pc_ret0 > 0) {
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/* addrs[pc_ret0 - 1] is start address of target
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* (addrs[i] - 6) is the address following this jmp
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* ("xor %edx,%edx; div %ebx;mov %edx,%eax" being 6 bytes long)
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*/
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EMIT_COND_JMP(X86_JE, addrs[pc_ret0 - 1] -
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EMIT_COND_JMP(X86_JE, addrs[ctx->pc_ret0 - 1] -
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(addrs[i] - 6));
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} else {
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EMIT_COND_JMP(X86_JNE, 2 + 5);
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@ -441,8 +426,8 @@ void bpf_jit_compile(struct sk_filter *fp)
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break;
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case BPF_S_RET_K:
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if (!K) {
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if (pc_ret0 == -1)
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pc_ret0 = i;
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if (ctx->pc_ret0 == -1)
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ctx->pc_ret0 = i;
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CLEAR_A();
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} else {
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EMIT1_off32(0xb8, K); /* mov $imm32,%eax */
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@ -603,7 +588,7 @@ void bpf_jit_compile(struct sk_filter *fp)
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int off = pkt_type_offset();
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if (off < 0)
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goto out;
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return -EINVAL;
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if (is_imm8(off)) {
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/* movzbl off8(%rdi),%eax */
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EMIT4(0x0f, 0xb6, 0x47, off);
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@ -725,36 +710,79 @@ cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i];
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}
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EMIT_COND_JMP(f_op, f_offset);
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break;
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default:
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/* hmm, too complex filter, give up with jit compiler */
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goto out;
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}
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ilen = prog - temp;
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if (image) {
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if (unlikely(proglen + ilen > oldproglen)) {
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pr_err("bpb_jit_compile fatal error\n");
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kfree(addrs);
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module_free(NULL, header);
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return;
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}
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memcpy(image + proglen, temp, ilen);
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}
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proglen += ilen;
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addrs[i] = proglen;
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prog = temp;
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default:
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/* hmm, too complex filter, give up with jit compiler */
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return -EINVAL;
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}
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/* last bpf instruction is always a RET :
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* use it to give the cleanup instruction(s) addr
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*/
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cleanup_addr = proglen - 1; /* ret */
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if (seen_or_pass0)
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cleanup_addr -= 1; /* leaveq */
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if (seen_or_pass0 & SEEN_XREG)
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cleanup_addr -= 4; /* mov -8(%rbp),%rbx */
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ilen = prog - temp;
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if (image) {
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if (unlikely(proglen + ilen > oldproglen)) {
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pr_err("bpb_jit_compile fatal error\n");
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return -EFAULT;
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}
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memcpy(image + proglen, temp, ilen);
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}
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proglen += ilen;
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addrs[i] = proglen;
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prog = temp;
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}
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/* last bpf instruction is always a RET :
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* use it to give the cleanup instruction(s) addr
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*/
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ctx->cleanup_addr = proglen - 1; /* ret */
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if (seen_or_pass0)
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ctx->cleanup_addr -= 1; /* leaveq */
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if (seen_or_pass0 & SEEN_XREG)
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ctx->cleanup_addr -= 4; /* mov -8(%rbp),%rbx */
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ctx->seen = seen;
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return proglen;
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}
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void bpf_jit_compile(struct sk_filter *prog)
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{
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struct bpf_binary_header *header = NULL;
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int proglen, oldproglen = 0;
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struct jit_context ctx = {};
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u8 *image = NULL;
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int *addrs;
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int pass;
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int i;
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if (!bpf_jit_enable)
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return;
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if (!prog || !prog->len)
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return;
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addrs = kmalloc(prog->len * sizeof(*addrs), GFP_KERNEL);
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if (!addrs)
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return;
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/* Before first pass, make a rough estimation of addrs[]
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* each bpf instruction is translated to less than 64 bytes
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*/
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for (proglen = 0, i = 0; i < prog->len; i++) {
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proglen += 64;
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addrs[i] = proglen;
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}
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ctx.cleanup_addr = proglen;
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ctx.seen = SEEN_XREG | SEEN_DATAREF | SEEN_MEM;
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ctx.pc_ret0 = -1;
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for (pass = 0; pass < 10; pass++) {
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proglen = do_jit(prog, addrs, image, oldproglen, &ctx);
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if (proglen <= 0) {
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image = NULL;
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if (header)
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module_free(NULL, header);
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goto out;
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}
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if (image) {
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if (proglen != oldproglen)
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pr_err("bpb_jit_compile proglen=%u != oldproglen=%u\n", proglen, oldproglen);
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pr_err("bpf_jit: proglen=%d != oldproglen=%d\n",
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proglen, oldproglen);
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break;
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}
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if (proglen == oldproglen) {
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@ -766,17 +794,16 @@ cond_branch: f_offset = addrs[i + filter[i].jf] - addrs[i];
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}
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if (bpf_jit_enable > 1)
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bpf_jit_dump(flen, proglen, pass, image);
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bpf_jit_dump(prog->len, proglen, 0, image);
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if (image) {
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bpf_flush_icache(header, image + proglen);
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set_memory_ro((unsigned long)header, header->pages);
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fp->bpf_func = (void *)image;
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fp->jited = 1;
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prog->bpf_func = (void *)image;
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prog->jited = 1;
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}
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out:
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kfree(addrs);
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return;
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}
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static void bpf_jit_free_deferred(struct work_struct *work)
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