OrgACRN
/
acrn-kernel
mirror of https://github.com/projectacrn/acrn-kernel.git
1
0
Fork 0
Code Issues Releases Wiki Activity
acrn-kernel/arch/powerpc/net/bpf_jit_comp.c

684 lines
19 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-only
/* bpf_jit_comp.c: BPF JIT compiler
*
* Copyright 2011 Matt Evans <matt@ozlabs.org>, IBM Corporation
*
* Based on the x86 BPF compiler, by Eric Dumazet (eric.dumazet@gmail.com)
* Ported to ppc32 by Denis Kirjanov <kda@linux-powerpc.org>
*/
#include <linux/moduleloader.h>
#include <asm/cacheflush.h>
#include <asm/asm-compat.h>
#include <linux/netdevice.h>
#include <linux/filter.h>
#include <linux/if_vlan.h>
#include "bpf_jit32.h"
static inline void bpf_flush_icache(void *start, void *end)
{
smp_wmb();
flush_icache_range((unsigned long)start, (unsigned long)end);
}
static void bpf_jit_build_prologue(struct bpf_prog *fp, u32 *image,
struct codegen_context *ctx)
{
int i;
const struct sock_filter *filter = fp->insns;
if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) {
/* Make stackframe */
if (ctx->seen & SEEN_DATAREF) {
/* If we call any helpers (for loads), save LR */
EMIT(PPC_INST_MFLR | __PPC_RT(R0));
PPC_BPF_STL(0, 1, PPC_LR_STKOFF);
/* Back up non-volatile regs. */
PPC_BPF_STL(r_D, 1, -(REG_SZ*(32-r_D)));
PPC_BPF_STL(r_HL, 1, -(REG_SZ*(32-r_HL)));
}
if (ctx->seen & SEEN_MEM) {
/*
* Conditionally save regs r15-r31 as some will be used
* for M[] data.
*/
for (i = r_M; i < (r_M+16); i++) {
if (ctx->seen & (1 << (i-r_M)))
PPC_BPF_STL(i, 1, -(REG_SZ*(32-i)));
}
}
PPC_BPF_STLU(1, 1, -BPF_PPC_STACKFRAME);
}
if (ctx->seen & SEEN_DATAREF) {
/*
* If this filter needs to access skb data,
* prepare r_D and r_HL:
* r_HL = skb->len - skb->data_len
* r_D = skb->data
*/
PPC_LWZ_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
data_len));
PPC_LWZ_OFFS(r_HL, r_skb, offsetof(struct sk_buff, len));
EMIT(PPC_RAW_SUB(r_HL, r_HL, r_scratch1));
PPC_LL_OFFS(r_D, r_skb, offsetof(struct sk_buff, data));
}
if (ctx->seen & SEEN_XREG) {
/*
* TODO: Could also detect whether first instr. sets X and
* avoid this (as below, with A).
*/
EMIT(PPC_RAW_LI(r_X, 0));
}
/* make sure we dont leak kernel information to user */
if (bpf_needs_clear_a(&filter[0]))
EMIT(PPC_RAW_LI(r_A, 0));
}
static void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx)
{
int i;
if (ctx->seen & (SEEN_MEM | SEEN_DATAREF)) {
EMIT(PPC_RAW_ADDI(1, 1, BPF_PPC_STACKFRAME));
if (ctx->seen & SEEN_DATAREF) {
PPC_BPF_LL(0, 1, PPC_LR_STKOFF);
EMIT(PPC_RAW_MTLR(0));
PPC_BPF_LL(r_D, 1, -(REG_SZ*(32-r_D)));
PPC_BPF_LL(r_HL, 1, -(REG_SZ*(32-r_HL)));
}
if (ctx->seen & SEEN_MEM) {
/* Restore any saved non-vol registers */
for (i = r_M; i < (r_M+16); i++) {
if (ctx->seen & (1 << (i-r_M)))
PPC_BPF_LL(i, 1, -(REG_SZ*(32-i)));
}
}
}
/* The RETs have left a return value in R3. */
EMIT(PPC_RAW_BLR());
}
#define CHOOSE_LOAD_FUNC(K, func) \
((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
/* Assemble the body code between the prologue & epilogue. */
static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image,
struct codegen_context *ctx,
unsigned int *addrs)
{
const struct sock_filter *filter = fp->insns;
int flen = fp->len;
u8 *func;
unsigned int true_cond;
int i;
/* Start of epilogue code */
unsigned int exit_addr = addrs[flen];
for (i = 0; i < flen; i++) {
unsigned int K = filter[i].k;
u16 code = bpf_anc_helper(&filter[i]);
/*
* addrs[] maps a BPF bytecode address into a real offset from
* the start of the body code.
*/
addrs[i] = ctx->idx * 4;
switch (code) {
/*** ALU ops ***/
case BPF_ALU | BPF_ADD | BPF_X: /* A += X; */
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_ADD(r_A, r_A, r_X));
break;
case BPF_ALU | BPF_ADD | BPF_K: /* A += K; */
if (!K)
break;
EMIT(PPC_RAW_ADDI(r_A, r_A, IMM_L(K)));
if (K >= 32768)
EMIT(PPC_RAW_ADDIS(r_A, r_A, IMM_HA(K)));
break;
case BPF_ALU | BPF_SUB | BPF_X: /* A -= X; */
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_SUB(r_A, r_A, r_X));
break;
case BPF_ALU | BPF_SUB | BPF_K: /* A -= K */
if (!K)
break;
EMIT(PPC_RAW_ADDI(r_A, r_A, IMM_L(-K)));
if (K >= 32768)
EMIT(PPC_RAW_ADDIS(r_A, r_A, IMM_HA(-K)));
break;
case BPF_ALU | BPF_MUL | BPF_X: /* A *= X; */
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_MULW(r_A, r_A, r_X));
break;
case BPF_ALU | BPF_MUL | BPF_K: /* A *= K */
if (K < 32768)
EMIT(PPC_RAW_MULI(r_A, r_A, K));
else {
PPC_LI32(r_scratch1, K);
EMIT(PPC_RAW_MULW(r_A, r_A, r_scratch1));
}
break;
case BPF_ALU | BPF_MOD | BPF_X: /* A %= X; */
case BPF_ALU | BPF_DIV | BPF_X: /* A /= X; */
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_CMPWI(r_X, 0));
if (ctx->pc_ret0 != -1) {
PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
} else {
PPC_BCC_SHORT(COND_NE, (ctx->idx*4)+12);
EMIT(PPC_RAW_LI(r_ret, 0));
PPC_JMP(exit_addr);
}
if (code == (BPF_ALU | BPF_MOD | BPF_X)) {
EMIT(PPC_RAW_DIVWU(r_scratch1, r_A, r_X));
EMIT(PPC_RAW_MULW(r_scratch1, r_X, r_scratch1));
EMIT(PPC_RAW_SUB(r_A, r_A, r_scratch1));
} else {
EMIT(PPC_RAW_DIVWU(r_A, r_A, r_X));
}
break;
case BPF_ALU | BPF_MOD | BPF_K: /* A %= K; */
PPC_LI32(r_scratch2, K);
EMIT(PPC_RAW_DIVWU(r_scratch1, r_A, r_scratch2));
EMIT(PPC_RAW_MULW(r_scratch1, r_scratch2, r_scratch1));
EMIT(PPC_RAW_SUB(r_A, r_A, r_scratch1));
break;
case BPF_ALU | BPF_DIV | BPF_K: /* A /= K */
if (K == 1)
break;
PPC_LI32(r_scratch1, K);
EMIT(PPC_RAW_DIVWU(r_A, r_A, r_scratch1));
break;
case BPF_ALU | BPF_AND | BPF_X:
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_AND(r_A, r_A, r_X));
break;
case BPF_ALU | BPF_AND | BPF_K:
if (!IMM_H(K))
EMIT(PPC_RAW_ANDI(r_A, r_A, K));
else {
PPC_LI32(r_scratch1, K);
EMIT(PPC_RAW_AND(r_A, r_A, r_scratch1));
}
break;
case BPF_ALU | BPF_OR | BPF_X:
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_OR(r_A, r_A, r_X));
break;
case BPF_ALU | BPF_OR | BPF_K:
if (IMM_L(K))
EMIT(PPC_RAW_ORI(r_A, r_A, IMM_L(K)));
if (K >= 65536)
EMIT(PPC_RAW_ORIS(r_A, r_A, IMM_H(K)));
break;
case BPF_ANC | SKF_AD_ALU_XOR_X:
case BPF_ALU | BPF_XOR | BPF_X: /* A ^= X */
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_XOR(r_A, r_A, r_X));
break;
case BPF_ALU | BPF_XOR | BPF_K: /* A ^= K */
if (IMM_L(K))
EMIT(PPC_RAW_XORI(r_A, r_A, IMM_L(K)));
if (K >= 65536)
EMIT(PPC_RAW_XORIS(r_A, r_A, IMM_H(K)));
break;
case BPF_ALU | BPF_LSH | BPF_X: /* A <<= X; */
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_SLW(r_A, r_A, r_X));
break;
case BPF_ALU | BPF_LSH | BPF_K:
if (K == 0)
break;
else
EMIT(PPC_RAW_SLWI(r_A, r_A, K));
break;
case BPF_ALU | BPF_RSH | BPF_X: /* A >>= X; */
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_SRW(r_A, r_A, r_X));
break;
case BPF_ALU | BPF_RSH | BPF_K: /* A >>= K; */
if (K == 0)
break;
else
EMIT(PPC_RAW_SRWI(r_A, r_A, K));
break;
case BPF_ALU | BPF_NEG:
EMIT(PPC_RAW_NEG(r_A, r_A));
break;
case BPF_RET | BPF_K:
PPC_LI32(r_ret, K);
if (!K) {
if (ctx->pc_ret0 == -1)
ctx->pc_ret0 = i;
}
/*
* If this isn't the very last instruction, branch to
* the epilogue if we've stuff to clean up. Otherwise,
* if there's nothing to tidy, just return. If we /are/
* the last instruction, we're about to fall through to
* the epilogue to return.
*/
if (i != flen - 1) {
/*
* Note: 'seen' is properly valid only on pass
* #2. Both parts of this conditional are the
* same instruction size though, meaning the
* first pass will still correctly determine the
* code size/addresses.
*/
if (ctx->seen)
PPC_JMP(exit_addr);
else
EMIT(PPC_RAW_BLR());
}
break;
case BPF_RET | BPF_A:
EMIT(PPC_RAW_MR(r_ret, r_A));
if (i != flen - 1) {
if (ctx->seen)
PPC_JMP(exit_addr);
else
EMIT(PPC_RAW_BLR());
}
break;
case BPF_MISC | BPF_TAX: /* X = A */
EMIT(PPC_RAW_MR(r_X, r_A));
break;
case BPF_MISC | BPF_TXA: /* A = X */
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_MR(r_A, r_X));
break;
/*** Constant loads/M[] access ***/
case BPF_LD | BPF_IMM: /* A = K */
PPC_LI32(r_A, K);
break;
case BPF_LDX | BPF_IMM: /* X = K */
PPC_LI32(r_X, K);
break;
case BPF_LD | BPF_MEM: /* A = mem[K] */
EMIT(PPC_RAW_MR(r_A, r_M + (K & 0xf)));
ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
break;
case BPF_LDX | BPF_MEM: /* X = mem[K] */
EMIT(PPC_RAW_MR(r_X, r_M + (K & 0xf)));
ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
break;
case BPF_ST: /* mem[K] = A */
EMIT(PPC_RAW_MR(r_M + (K & 0xf), r_A));
ctx->seen |= SEEN_MEM | (1<<(K & 0xf));
break;
case BPF_STX: /* mem[K] = X */
EMIT(PPC_RAW_MR(r_M + (K & 0xf), r_X));
ctx->seen |= SEEN_XREG | SEEN_MEM | (1<<(K & 0xf));
break;
case BPF_LD | BPF_W | BPF_LEN: /* A = skb->len; */
BUILD_BUG_ON(sizeof_field(struct sk_buff, len) != 4);
PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff, len));
break;
case BPF_LDX | BPF_W | BPF_ABS: /* A = *((u32 *)(seccomp_data + K)); */
PPC_LWZ_OFFS(r_A, r_skb, K);
break;
case BPF_LDX | BPF_W | BPF_LEN: /* X = skb->len; */
PPC_LWZ_OFFS(r_X, r_skb, offsetof(struct sk_buff, len));
break;
/*** Ancillary info loads ***/
case BPF_ANC | SKF_AD_PROTOCOL: /* A = ntohs(skb->protocol); */
BUILD_BUG_ON(sizeof_field(struct sk_buff,
protocol) != 2);
PPC_NTOHS_OFFS(r_A, r_skb, offsetof(struct sk_buff,
protocol));
break;
case BPF_ANC | SKF_AD_IFINDEX:
case BPF_ANC | SKF_AD_HATYPE:
BUILD_BUG_ON(sizeof_field(struct net_device,
ifindex) != 4);
BUILD_BUG_ON(sizeof_field(struct net_device,
type) != 2);
PPC_LL_OFFS(r_scratch1, r_skb, offsetof(struct sk_buff,
dev));
EMIT(PPC_RAW_CMPDI(r_scratch1, 0));
if (ctx->pc_ret0 != -1) {
PPC_BCC(COND_EQ, addrs[ctx->pc_ret0]);
} else {
/* Exit, returning 0; first pass hits here. */
PPC_BCC_SHORT(COND_NE, ctx->idx * 4 + 12);
EMIT(PPC_RAW_LI(r_ret, 0));
PPC_JMP(exit_addr);
}
if (code == (BPF_ANC | SKF_AD_IFINDEX)) {
PPC_LWZ_OFFS(r_A, r_scratch1,
offsetof(struct net_device, ifindex));
} else {
PPC_LHZ_OFFS(r_A, r_scratch1,
offsetof(struct net_device, type));
}
break;
case BPF_ANC | SKF_AD_MARK:
BUILD_BUG_ON(sizeof_field(struct sk_buff, mark) != 4);
PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
mark));
break;
case BPF_ANC | SKF_AD_RXHASH:
BUILD_BUG_ON(sizeof_field(struct sk_buff, hash) != 4);
PPC_LWZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
hash));
break;
case BPF_ANC | SKF_AD_VLAN_TAG:
BUILD_BUG_ON(sizeof_field(struct sk_buff, vlan_tci) != 2);
PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
vlan_tci));
break;
case BPF_ANC | SKF_AD_VLAN_TAG_PRESENT:
PPC_LBZ_OFFS(r_A, r_skb, PKT_VLAN_PRESENT_OFFSET());
if (PKT_VLAN_PRESENT_BIT)
EMIT(PPC_RAW_SRWI(r_A, r_A, PKT_VLAN_PRESENT_BIT));
if (PKT_VLAN_PRESENT_BIT < 7)
EMIT(PPC_RAW_ANDI(r_A, r_A, 1));
break;
case BPF_ANC | SKF_AD_QUEUE:
BUILD_BUG_ON(sizeof_field(struct sk_buff,
queue_mapping) != 2);
PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
queue_mapping));
break;
case BPF_ANC | SKF_AD_PKTTYPE:
PPC_LBZ_OFFS(r_A, r_skb, PKT_TYPE_OFFSET());
EMIT(PPC_RAW_ANDI(r_A, r_A, PKT_TYPE_MAX));
EMIT(PPC_RAW_SRWI(r_A, r_A, 5));
break;
case BPF_ANC | SKF_AD_CPU:
PPC_BPF_LOAD_CPU(r_A);
break;
/*** Absolute loads from packet header/data ***/
case BPF_LD | BPF_W | BPF_ABS:
func = CHOOSE_LOAD_FUNC(K, sk_load_word);
goto common_load;
case BPF_LD | BPF_H | BPF_ABS:
func = CHOOSE_LOAD_FUNC(K, sk_load_half);
goto common_load;
case BPF_LD | BPF_B | BPF_ABS:
func = CHOOSE_LOAD_FUNC(K, sk_load_byte);
common_load:
/* Load from [K]. */
ctx->seen |= SEEN_DATAREF;
PPC_FUNC_ADDR(r_scratch1, func);
EMIT(PPC_RAW_MTLR(r_scratch1));
PPC_LI32(r_addr, K);
EMIT(PPC_RAW_BLRL());
/*
* Helper returns 'lt' condition on error, and an
* appropriate return value in r3
*/
PPC_BCC(COND_LT, exit_addr);
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);
EMIT(PPC_RAW_MTLR(r_scratch1));
EMIT(PPC_RAW_ADDI(r_addr, r_X, IMM_L(K)));
if (K >= 32768)
EMIT(PPC_RAW_ADDIS(r_addr, r_addr, IMM_HA(K)));
EMIT(PPC_RAW_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;
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;
EMIT(PPC_RAW_CMPLW(r_A, r_X));
break;
case BPF_JMP | BPF_JSET | BPF_X:
ctx->seen |= SEEN_XREG;
EMIT(PPC_RAW_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)
EMIT(PPC_RAW_CMPLWI(r_A, K));
else {
PPC_LI32(r_scratch1, K);
EMIT(PPC_RAW_CMPLW(r_A, r_scratch1));
}
break;
case BPF_JMP | BPF_JSET | BPF_K:
if (K < 32768)
/* PPC_ANDI is /only/ dot-form */
EMIT(PPC_RAW_ANDI(r_scratch1, r_A, K));
else {
PPC_LI32(r_scratch1, K);
EMIT(PPC_RAW_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);
}
Reference in New Issue View Git Blame Copy Permalink