690 lines
19 KiB
C
Executable file
690 lines
19 KiB
C
Executable file
/* bpf_jit_comp.c: BPF JIT compiler
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*
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* Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation
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*
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* Based on the x86 BPF compiler, by Eric Dumazet (eric.dumazet@gmail.com)
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* Ported to ppc32 by Denis Kirjanov <kda@linux-powerpc.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*/
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#include <linux/moduleloader.h>
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#include <asm/cacheflush.h>
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#include <asm/asm-compat.h>
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#include <linux/netdevice.h>
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#include <linux/filter.h>
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#include <linux/if_vlan.h>
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#include "bpf_jit32.h"
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static inline void bpf_flush_icache(void *start, void *end)
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{
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smp_wmb();
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flush_icache_range((unsigned long)start, (unsigned long)end);
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}
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static void bpf_jit_build_prologue(struct bpf_prog *fp, u32 *image,
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struct codegen_context *ctx)
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{
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int i;
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const struct sock_filter *filter = fp->insns;
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if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) {
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/* Make stackframe */
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if (ctx->seen & SEEN_DATAREF) {
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/* If we call any helpers (for loads), save LR */
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EMIT(PPC_INST_MFLR | __PPC_RT(R0));
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PPC_BPF_STL(0, 1, PPC_LR_STKOFF);
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/* Back up non-volatile regs. */
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PPC_BPF_STL(r_D, 1, -(REG_SZ*(32-r_D)));
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PPC_BPF_STL(r_HL, 1, -(REG_SZ*(32-r_HL)));
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}
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if (ctx->seen & SEEN_MEM) {
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/*
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* Conditionally save regs r15-r31 as some will be used
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* for M[] data.
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*/
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for (i = r_M; i < (r_M+16); i++) {
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if (ctx->seen & (1 << (i-r_M)))
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PPC_BPF_STL(i, 1, -(REG_SZ*(32-i)));
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}
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}
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PPC_BPF_STLU(1, 1, -BPF_PPC_STACKFRAME);
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}
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if (ctx->seen & SEEN_DATAREF) {
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/*
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* If this filter needs to access skb data,
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* prepare r_D and r_HL:
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* r_HL = skb->len - skb->data_len
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* r_D = skb->data
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*/
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PPC_LWZ_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
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data_len));
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PPC_LWZ_OFFS(r_HL, r_skb, offsetof(struct sk_buff, len));
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PPC_SUB(r_HL, r_HL, r_scratch1);
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PPC_LL_OFFS(r_D, r_skb, offsetof(struct sk_buff, data));
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}
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if (ctx->seen & SEEN_XREG) {
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/*
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* TODO: Could also detect whether first instr. sets X and
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* avoid this (as below, with A).
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*/
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PPC_LI(r_X, 0);
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}
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/* make sure we dont leak kernel information to user */
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if (bpf_needs_clear_a(&filter[0]))
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PPC_LI(r_A, 0);
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}
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static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx)
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{
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int i;
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if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) {
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PPC_ADDI(1, 1, BPF_PPC_STACKFRAME);
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if (ctx->seen & SEEN_DATAREF) {
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PPC_BPF_LL(0, 1, PPC_LR_STKOFF);
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PPC_MTLR(0);
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PPC_BPF_LL(r_D, 1, -(REG_SZ*(32-r_D)));
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PPC_BPF_LL(r_HL, 1, -(REG_SZ*(32-r_HL)));
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}
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if (ctx->seen & SEEN_MEM) {
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/* Restore any saved non-vol registers */
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for (i = r_M; i < (r_M+16); i++) {
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if (ctx->seen & (1 << (i-r_M)))
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PPC_BPF_LL(i, 1, -(REG_SZ*(32-i)));
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}
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}
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}
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/* The RETs have left a return value in R3. */
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PPC_BLR();
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}
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#define CHOOSE_LOAD_FUNC(K, func) \
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((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
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/* Assemble the body code between the prologue & epilogue. */
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static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
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struct codegen_context *ctx,
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unsigned int *addrs)
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{
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const struct sock_filter *filter = fp->insns;
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int flen = fp->len;
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u8 *func;
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unsigned int true_cond;
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int i;
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/* Start of epilogue code */
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unsigned int exit_addr = addrs[flen];
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for (i = 0; i < flen; i++) {
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unsigned int K = filter[i].k;
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u16 code = bpf_anc_helper(&filter[i]);
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/*
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* addrs[] maps a BPF bytecode address into a real offset from
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* the start of the body code.
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*/
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addrs[i] = ctx->idx * 4;
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switch (code) {
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/*** ALU ops ***/
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case BPF_ALU | BPF_ADD | BPF_X: /* A += X; */
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ctx->seen |= SEEN_XREG;
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PPC_ADD(r_A, r_A, r_X);
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break;
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case BPF_ALU | BPF_ADD | BPF_K: /* A += K; */
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if (!K)
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break;
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PPC_ADDI(r_A, r_A, IMM_L(K));
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if (K >= 32768)
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PPC_ADDIS(r_A, r_A, IMM_HA(K));
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break;
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case BPF_ALU | BPF_SUB | BPF_X: /* A -= X; */
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ctx->seen |= SEEN_XREG;
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PPC_SUB(r_A, r_A, r_X);
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break;
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case BPF_ALU | BPF_SUB | BPF_K: /* A -= K */
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if (!K)
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break;
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PPC_ADDI(r_A, r_A, IMM_L(-K));
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if (K >= 32768)
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PPC_ADDIS(r_A, r_A, IMM_HA(-K));
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break;
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case BPF_ALU | BPF_MUL | BPF_X: /* A *= X; */
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ctx->seen |= SEEN_XREG;
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PPC_MULW(r_A, r_A, r_X);
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break;
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case BPF_ALU | BPF_MUL | BPF_K: /* A *= K */
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if (K < 32768)
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PPC_MULI(r_A, r_A, K);
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else {
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PPC_LI32(r_scratch1, K);
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PPC_MULW(r_A, r_A, r_scratch1);
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}
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break;
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case BPF_ALU | BPF_MOD | BPF_X: /* A %= X; */
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case BPF_ALU | BPF_DIV | BPF_X: /* A /= X; */
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ctx->seen |= SEEN_XREG;
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PPC_CMPWI(r_X, 0);
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if (ctx->pc_ret0 != -1) {
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PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
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} else {
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PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
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PPC_LI(r_ret, 0);
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PPC_JMP(exit_addr);
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}
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if (code == (BPF_ALU | BPF_MOD | BPF_X)) {
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PPC_DIVWU(r_scratch1, r_A, r_X);
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PPC_MULW(r_scratch1, r_X, r_scratch1);
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PPC_SUB(r_A, r_A, r_scratch1);
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} else {
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PPC_DIVWU(r_A, r_A, r_X);
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}
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break;
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case BPF_ALU | BPF_MOD | BPF_K: /* A %= K; */
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PPC_LI32(r_scratch2, K);
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PPC_DIVWU(r_scratch1, r_A, r_scratch2);
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PPC_MULW(r_scratch1, r_scratch2, r_scratch1);
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PPC_SUB(r_A, r_A, r_scratch1);
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break;
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case BPF_ALU | BPF_DIV | BPF_K: /* A /= K */
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if (K == 1)
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break;
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PPC_LI32(r_scratch1, K);
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PPC_DIVWU(r_A, r_A, r_scratch1);
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break;
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case BPF_ALU | BPF_AND | BPF_X:
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ctx->seen |= SEEN_XREG;
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PPC_AND(r_A, r_A, r_X);
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break;
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case BPF_ALU | BPF_AND | BPF_K:
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if (!IMM_H(K))
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PPC_ANDI(r_A, r_A, K);
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else {
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PPC_LI32(r_scratch1, K);
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PPC_AND(r_A, r_A, r_scratch1);
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}
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break;
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case BPF_ALU | BPF_OR | BPF_X:
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ctx->seen |= SEEN_XREG;
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PPC_OR(r_A, r_A, r_X);
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break;
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case BPF_ALU | BPF_OR | BPF_K:
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if (IMM_L(K))
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PPC_ORI(r_A, r_A, IMM_L(K));
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if (K >= 65536)
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PPC_ORIS(r_A, r_A, IMM_H(K));
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break;
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case BPF_ANC | SKF_AD_ALU_XOR_X:
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case BPF_ALU | BPF_XOR | BPF_X: /* A ^= X */
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ctx->seen |= SEEN_XREG;
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PPC_XOR(r_A, r_A, r_X);
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break;
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case BPF_ALU | BPF_XOR | BPF_K: /* A ^= K */
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if (IMM_L(K))
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PPC_XORI(r_A, r_A, IMM_L(K));
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if (K >= 65536)
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PPC_XORIS(r_A, r_A, IMM_H(K));
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break;
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case BPF_ALU | BPF_LSH | BPF_X: /* A <<= X; */
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ctx->seen |= SEEN_XREG;
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PPC_SLW(r_A, r_A, r_X);
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break;
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case BPF_ALU | BPF_LSH | BPF_K:
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if (K == 0)
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break;
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else
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PPC_SLWI(r_A, r_A, K);
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break;
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case BPF_ALU | BPF_RSH | BPF_X: /* A >>= X; */
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ctx->seen |= SEEN_XREG;
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PPC_SRW(r_A, r_A, r_X);
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break;
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case BPF_ALU | BPF_RSH | BPF_K: /* A >>= K; */
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if (K == 0)
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break;
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else
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PPC_SRWI(r_A, r_A, K);
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break;
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case BPF_ALU | BPF_NEG:
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PPC_NEG(r_A, r_A);
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break;
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case BPF_RET | BPF_K:
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PPC_LI32(r_ret, K);
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if (!K) {
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if (ctx->pc_ret0 == -1)
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ctx->pc_ret0 = i;
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}
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/*
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* If this isn't the very last instruction, branch to
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* the epilogue if we've stuff to clean up. Otherwise,
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* if there's nothing to tidy, just return. If we /are/
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* the last instruction, we're about to fall through to
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* the epilogue to return.
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*/
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if (i != flen - 1) {
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/*
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* Note: 'seen' is properly valid only on pass
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* #2. Both parts of this conditional are the
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* same instruction size though, meaning the
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* first pass will still correctly determine the
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* code size/addresses.
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*/
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if (ctx->seen)
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PPC_JMP(exit_addr);
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else
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PPC_BLR();
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}
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break;
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case BPF_RET | BPF_A:
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PPC_MR(r_ret, r_A);
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if (i != flen - 1) {
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if (ctx->seen)
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PPC_JMP(exit_addr);
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else
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PPC_BLR();
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}
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break;
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case BPF_MISC | BPF_TAX: /* X = A */
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PPC_MR(r_X, r_A);
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break;
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case BPF_MISC | BPF_TXA: /* A = X */
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ctx->seen |= SEEN_XREG;
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PPC_MR(r_A, r_X);
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break;
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/*** Constant loads/M[] access ***/
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case BPF_LD | BPF_IMM: /* A = K */
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PPC_LI32(r_A, K);
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break;
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case BPF_LDX | BPF_IMM: /* X = K */
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PPC_LI32(r_X, K);
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break;
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case BPF_LD | BPF_MEM: /* A = mem[K] */
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PPC_MR(r_A, r_M + (K & 0xf));
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ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
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break;
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case BPF_LDX | BPF_MEM: /* X = mem[K] */
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PPC_MR(r_X, r_M + (K & 0xf));
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ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
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break;
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case BPF_ST: /* mem[K] = A */
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PPC_MR(r_M + (K & 0xf), r_A);
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ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
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break;
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case BPF_STX: /* mem[K] = X */
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PPC_MR(r_M + (K & 0xf), r_X);
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ctx->seen |= SEEN_XREG | SEEN_MEM | (1<<(K & 0xf));
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break;
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case BPF_LD | BPF_W | BPF_LEN: /* A = skb->len; */
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
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PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, len));
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break;
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case BPF_LDX | BPF_W | BPF_ABS: /* A = *((u32 *)(seccomp_data + K)); */
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PPC_LWZ_OFFS(r_A, r_skb, K);
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break;
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case BPF_LDX | BPF_W | BPF_LEN: /* X = skb->len; */
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PPC_LWZ_OFFS(r_X, r_skb, offsetof(struct sk_buff, len));
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break;
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/*** Ancillary info loads ***/
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case BPF_ANC | SKF_AD_PROTOCOL: /* A = ntohs(skb->protocol); */
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
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protocol) != 2);
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PPC_NTOHS_OFFS(r_A, r_skb, offsetof(struct sk_buff,
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protocol));
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break;
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case BPF_ANC | SKF_AD_IFINDEX:
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case BPF_ANC | SKF_AD_HATYPE:
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BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
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ifindex) != 4);
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BUILD_BUG_ON(FIELD_SIZEOF(struct net_device,
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type) != 2);
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PPC_LL_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
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dev));
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PPC_CMPDI(r_scratch1, 0);
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if (ctx->pc_ret0 != -1) {
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PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
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} else {
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/* Exit, returning 0; first pass hits here. */
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PPC_BCC_SHORT(COND_NE, ctx->idx * 4 + 12);
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PPC_LI(r_ret, 0);
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PPC_JMP(exit_addr);
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}
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if (code == (BPF_ANC | SKF_AD_IFINDEX)) {
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PPC_LWZ_OFFS(r_A, r_scratch1,
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offsetof(struct net_device, ifindex));
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} else {
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PPC_LHZ_OFFS(r_A, r_scratch1,
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offsetof(struct net_device, type));
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}
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break;
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case BPF_ANC | SKF_AD_MARK:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
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PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
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mark));
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break;
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case BPF_ANC | SKF_AD_RXHASH:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
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PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
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hash));
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break;
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case BPF_ANC | SKF_AD_VLAN_TAG:
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case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
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BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
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PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
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vlan_tci));
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if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) {
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PPC_ANDI(r_A, r_A, ~VLAN_TAG_PRESENT);
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} else {
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PPC_ANDI(r_A, r_A, VLAN_TAG_PRESENT);
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PPC_SRWI(r_A, r_A, 12);
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}
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break;
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case BPF_ANC | SKF_AD_QUEUE:
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BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,
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queue_mapping) != 2);
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PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
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queue_mapping));
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break;
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case BPF_ANC | SKF_AD_PKTTYPE:
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PPC_LBZ_OFFS(r_A, r_skb, PKT_TYPE_OFFSET());
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PPC_ANDI(r_A, r_A, PKT_TYPE_MAX);
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PPC_SRWI(r_A, r_A, 5);
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break;
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case BPF_ANC | SKF_AD_CPU:
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PPC_BPF_LOAD_CPU(r_A);
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break;
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/*** Absolute loads from packet header/data ***/
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case BPF_LD | BPF_W | BPF_ABS:
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func = CHOOSE_LOAD_FUNC(K, sk_load_word);
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goto common_load;
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case BPF_LD | BPF_H | BPF_ABS:
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func = CHOOSE_LOAD_FUNC(K, sk_load_half);
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goto common_load;
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case BPF_LD | BPF_B | BPF_ABS:
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func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
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common_load:
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/* Load from [K]. */
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ctx->seen |= SEEN_DATAREF;
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PPC_FUNC_ADDR(r_scratch1, func);
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PPC_MTLR(r_scratch1);
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PPC_LI32(r_addr, K);
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PPC_BLRL();
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/*
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* Helper returns 'lt' condition on error, and an
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* appropriate return value in r3
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*/
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PPC_BCC(COND_LT, exit_addr);
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break;
|
|
|
|
/*** Indirect loads from packet header/data ***/
|
|
case BPF_LD | BPF_W | BPF_IND:
|
|
func = sk_load_word;
|
|
goto common_load_ind;
|
|
case BPF_LD | BPF_H | BPF_IND:
|
|
func = sk_load_half;
|
|
goto common_load_ind;
|
|
case BPF_LD | BPF_B | BPF_IND:
|
|
func = sk_load_byte;
|
|
common_load_ind:
|
|
/*
|
|
* Load from [X + K]. Negative offsets are tested for
|
|
* in the helper functions.
|
|
*/
|
|
ctx->seen |= SEEN_DATAREF | SEEN_XREG;
|
|
PPC_FUNC_ADDR(r_scratch1, func);
|
|
PPC_MTLR(r_scratch1);
|
|
PPC_ADDI(r_addr, r_X, IMM_L(K));
|
|
if (K >= 32768)
|
|
PPC_ADDIS(r_addr, r_addr, IMM_HA(K));
|
|
PPC_BLRL();
|
|
/* If error, cr0.LT set */
|
|
PPC_BCC(COND_LT, exit_addr);
|
|
break;
|
|
|
|
case BPF_LDX | BPF_B | BPF_MSH:
|
|
func = CHOOSE_LOAD_FUNC(K, sk_load_byte_msh);
|
|
goto common_load;
|
|
break;
|
|
|
|
/*** Jump and branches ***/
|
|
case BPF_JMP | BPF_JA:
|
|
if (K != 0)
|
|
PPC_JMP(addrs[i + 1 + K]);
|
|
break;
|
|
|
|
case BPF_JMP | BPF_JGT | BPF_K:
|
|
case BPF_JMP | BPF_JGT | BPF_X:
|
|
true_cond = COND_GT;
|
|
goto cond_branch;
|
|
case BPF_JMP | BPF_JGE | BPF_K:
|
|
case BPF_JMP | BPF_JGE | BPF_X:
|
|
true_cond = COND_GE;
|
|
goto cond_branch;
|
|
case BPF_JMP | BPF_JEQ | BPF_K:
|
|
case BPF_JMP | BPF_JEQ | BPF_X:
|
|
true_cond = COND_EQ;
|
|
goto cond_branch;
|
|
case BPF_JMP | BPF_JSET | BPF_K:
|
|
case BPF_JMP | BPF_JSET | BPF_X:
|
|
true_cond = COND_NE;
|
|
/* Fall through */
|
|
cond_branch:
|
|
/* same targets, can avoid doing the test :) */
|
|
if (filter[i].jt == filter[i].jf) {
|
|
if (filter[i].jt > 0)
|
|
PPC_JMP(addrs[i + 1 + filter[i].jt]);
|
|
break;
|
|
}
|
|
|
|
switch (code) {
|
|
case BPF_JMP | BPF_JGT | BPF_X:
|
|
case BPF_JMP | BPF_JGE | BPF_X:
|
|
case BPF_JMP | BPF_JEQ | BPF_X:
|
|
ctx->seen |= SEEN_XREG;
|
|
PPC_CMPLW(r_A, r_X);
|
|
break;
|
|
case BPF_JMP | BPF_JSET | BPF_X:
|
|
ctx->seen |= SEEN_XREG;
|
|
PPC_AND_DOT(r_scratch1, r_A, r_X);
|
|
break;
|
|
case BPF_JMP | BPF_JEQ | BPF_K:
|
|
case BPF_JMP | BPF_JGT | BPF_K:
|
|
case BPF_JMP | BPF_JGE | BPF_K:
|
|
if (K < 32768)
|
|
PPC_CMPLWI(r_A, K);
|
|
else {
|
|
PPC_LI32(r_scratch1, K);
|
|
PPC_CMPLW(r_A, r_scratch1);
|
|
}
|
|
break;
|
|
case BPF_JMP | BPF_JSET | BPF_K:
|
|
if (K < 32768)
|
|
/* PPC_ANDI is /only/ dot-form */
|
|
PPC_ANDI(r_scratch1, r_A, K);
|
|
else {
|
|
PPC_LI32(r_scratch1, K);
|
|
PPC_AND_DOT(r_scratch1, r_A,
|
|
r_scratch1);
|
|
}
|
|
break;
|
|
}
|
|
/* Sometimes branches are constructed "backward", with
|
|
* the false path being the branch and true path being
|
|
* a fallthrough to the next instruction.
|
|
*/
|
|
if (filter[i].jt == 0)
|
|
/* Swap the sense of the branch */
|
|
PPC_BCC(true_cond ^ COND_CMP_TRUE,
|
|
addrs[i + 1 + filter[i].jf]);
|
|
else {
|
|
PPC_BCC(true_cond, addrs[i + 1 + filter[i].jt]);
|
|
if (filter[i].jf != 0)
|
|
PPC_JMP(addrs[i + 1 + filter[i].jf]);
|
|
}
|
|
break;
|
|
default:
|
|
/* The filter contains something cruel & unusual.
|
|
* We don't handle it, but also there shouldn't be
|
|
* anything missing from our list.
|
|
*/
|
|
if (printk_ratelimit())
|
|
pr_err("BPF filter opcode %04x (@%d) unsupported\n",
|
|
filter[i].code, i);
|
|
return -ENOTSUPP;
|
|
}
|
|
|
|
}
|
|
/* Set end-of-body-code address for exit. */
|
|
addrs[i] = ctx->idx * 4;
|
|
|
|
return 0;
|
|
}
|
|
|
|
void bpf_jit_compile(struct bpf_prog *fp)
|
|
{
|
|
unsigned int proglen;
|
|
unsigned int alloclen;
|
|
u32 *image = NULL;
|
|
u32 *code_base;
|
|
unsigned int *addrs;
|
|
struct codegen_context cgctx;
|
|
int pass;
|
|
int flen = fp->len;
|
|
|
|
if (!bpf_jit_enable)
|
|
return;
|
|
|
|
addrs = kcalloc(flen + 1, sizeof(*addrs), GFP_KERNEL);
|
|
if (addrs == NULL)
|
|
return;
|
|
|
|
/*
|
|
* There are multiple assembly passes as the generated code will change
|
|
* size as it settles down, figuring out the max branch offsets/exit
|
|
* paths required.
|
|
*
|
|
* The range of standard conditional branches is +/- 32Kbytes. Since
|
|
* BPF_MAXINSNS = 4096, we can only jump from (worst case) start to
|
|
* finish with 8 bytes/instruction. Not feasible, so long jumps are
|
|
* used, distinct from short branches.
|
|
*
|
|
* Current:
|
|
*
|
|
* For now, both branch types assemble to 2 words (short branches padded
|
|
* with a NOP); this is less efficient, but assembly will always complete
|
|
* after exactly 3 passes:
|
|
*
|
|
* First pass: No code buffer; Program is "faux-generated" -- no code
|
|
* emitted but maximum size of output determined (and addrs[] filled
|
|
* in). Also, we note whether we use M[], whether we use skb data, etc.
|
|
* All generation choices assumed to be 'worst-case', e.g. branches all
|
|
* far (2 instructions), return path code reduction not available, etc.
|
|
*
|
|
* Second pass: Code buffer allocated with size determined previously.
|
|
* Prologue generated to support features we have seen used. Exit paths
|
|
* determined and addrs[] is filled in again, as code may be slightly
|
|
* smaller as a result.
|
|
*
|
|
* Third pass: Code generated 'for real', and branch destinations
|
|
* determined from now-accurate addrs[] map.
|
|
*
|
|
* Ideal:
|
|
*
|
|
* If we optimise this, near branches will be shorter. On the
|
|
* first assembly pass, we should err on the side of caution and
|
|
* generate the biggest code. On subsequent passes, branches will be
|
|
* generated short or long and code size will reduce. With smaller
|
|
* code, more branches may fall into the short category, and code will
|
|
* reduce more.
|
|
*
|
|
* Finally, if we see one pass generate code the same size as the
|
|
* previous pass we have converged and should now generate code for
|
|
* real. Allocating at the end will also save the memory that would
|
|
* otherwise be wasted by the (small) current code shrinkage.
|
|
* Preferably, we should do a small number of passes (e.g. 5) and if we
|
|
* haven't converged by then, get impatient and force code to generate
|
|
* as-is, even if the odd branch would be left long. The chances of a
|
|
* long jump are tiny with all but the most enormous of BPF filter
|
|
* inputs, so we should usually converge on the third pass.
|
|
*/
|
|
|
|
cgctx.idx = 0;
|
|
cgctx.seen = 0;
|
|
cgctx.pc_ret0 = -1;
|
|
/* Scouting faux-generate pass 0 */
|
|
if (bpf_jit_build_body(fp, 0, &cgctx, addrs))
|
|
/* We hit something illegal or unsupported. */
|
|
goto out;
|
|
|
|
/*
|
|
* Pretend to build prologue, given the features we've seen. This will
|
|
* update ctgtx.idx as it pretends to output instructions, then we can
|
|
* calculate total size from idx.
|
|
*/
|
|
bpf_jit_build_prologue(fp, 0, &cgctx);
|
|
bpf_jit_build_epilogue(0, &cgctx);
|
|
|
|
proglen = cgctx.idx * 4;
|
|
alloclen = proglen + FUNCTION_DESCR_SIZE;
|
|
image = module_alloc(alloclen);
|
|
if (!image)
|
|
goto out;
|
|
|
|
code_base = image + (FUNCTION_DESCR_SIZE/4);
|
|
|
|
/* Code generation passes 1-2 */
|
|
for (pass = 1; pass < 3; pass++) {
|
|
/* Now build the prologue, body code & epilogue for real. */
|
|
cgctx.idx = 0;
|
|
bpf_jit_build_prologue(fp, code_base, &cgctx);
|
|
bpf_jit_build_body(fp, code_base, &cgctx, addrs);
|
|
bpf_jit_build_epilogue(code_base, &cgctx);
|
|
|
|
if (bpf_jit_enable > 1)
|
|
pr_info("Pass %d: shrink = %d, seen = 0x%x\n", pass,
|
|
proglen - (cgctx.idx * 4), cgctx.seen);
|
|
}
|
|
|
|
if (bpf_jit_enable > 1)
|
|
/* Note that we output the base address of the code_base
|
|
* rather than image, since opcodes are in code_base.
|
|
*/
|
|
bpf_jit_dump(flen, proglen, pass, code_base);
|
|
|
|
bpf_flush_icache(code_base, code_base + (proglen/4));
|
|
|
|
#ifdef CONFIG_PPC64
|
|
/* Function descriptor nastiness: Address + TOC */
|
|
((u64 *)image)[0] = (u64)code_base;
|
|
((u64 *)image)[1] = local_paca->kernel_toc;
|
|
#endif
|
|
|
|
fp->bpf_func = (void *)image;
|
|
fp->jited = 1;
|
|
|
|
out:
|
|
kfree(addrs);
|
|
return;
|
|
}
|
|
|
|
void bpf_jit_free(struct bpf_prog *fp)
|
|
{
|
|
if (fp->jited)
|
|
module_memfree(fp->bpf_func);
|
|
|
|
bpf_prog_unlock_free(fp);
|
|
}
|