From f3c2af7ba17a83809806880062c9ad541744fb95 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 13 May 2014 19:50:45 -0700 Subject: [PATCH] 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 Signed-off-by: David S. Miller --- arch/x86/net/bpf_jit_comp.c | 157 +++++++++++++++++++++--------------- 1 file changed, 92 insertions(+), 65 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index dc017735bb91..c5fa7c9cb665 100644 --- 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) -- 2.20.1