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linux/arch/s390/net/bpf_jit_comp.c
Heiko Carstens 3af57f78c3 s390/bpf,jit: fix 32 bit divisions, use unsigned divide instructions 
The s390 bpf jit compiler emits the signed divide instructions "dr" and "d"
for unsigned divisions.
This can cause problems: the dividend will be zero extended to a 64 bit value
and the divisor is the 32 bit signed value as specified A or X accumulator,
even though A and X are supposed to be treated as unsigned values.

The divide instrunctions will generate an exception if the result cannot be
expressed with a 32 bit signed value.
This is the case if e.g. the dividend is 0xffffffff and the divisor either 1
or also 0xffffffff (signed: -1).

To avoid all these issues simply use unsigned divide instructions.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-01-17 18:54:49 -08:00

897 lines
24 KiB
C
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/*
* BPF Jit compiler for s390.
*
* Copyright IBM Corp. 2012
*
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
*/
#include <linux/moduleloader.h>
#include <linux/netdevice.h>
#include <linux/if_vlan.h>
#include <linux/filter.h>
#include <linux/random.h>
#include <linux/init.h>
#include <asm/cacheflush.h>
#include <asm/facility.h>
#include <asm/dis.h>
/*
* Conventions:
* %r2 = skb pointer
* %r3 = offset parameter
* %r4 = scratch register / length parameter
* %r5 = BPF A accumulator
* %r8 = return address
* %r9 = save register for skb pointer
* %r10 = skb->data
* %r11 = skb->len - skb->data_len (headlen)
* %r12 = BPF X accumulator
* %r13 = literal pool pointer
* 0(%r15) - 63(%r15) scratch memory array with BPF_MEMWORDS
*/
int bpf_jit_enable __read_mostly;
/*
* assembly code in arch/x86/net/bpf_jit.S
*/
extern u8 sk_load_word[], sk_load_half[], sk_load_byte[], sk_load_byte_msh[];
extern u8 sk_load_word_ind[], sk_load_half_ind[], sk_load_byte_ind[];
struct bpf_jit {
unsigned int seen;
u8 *start;
u8 *prg;
u8 *mid;
u8 *lit;
u8 *end;
u8 *base_ip;
u8 *ret0_ip;
u8 *exit_ip;
unsigned int off_load_word;
unsigned int off_load_half;
unsigned int off_load_byte;
unsigned int off_load_bmsh;
unsigned int off_load_iword;
unsigned int off_load_ihalf;
unsigned int off_load_ibyte;
};
#define BPF_SIZE_MAX 4096 /* Max size for program */
#define SEEN_DATAREF 1 /* might call external helpers */
#define SEEN_XREG 2 /* ebx is used */
#define SEEN_MEM 4 /* use mem[] for temporary storage */
#define SEEN_RET0 8 /* pc_ret0 points to a valid return 0 */
#define SEEN_LITERAL 16 /* code uses literals */
#define SEEN_LOAD_WORD 32 /* code uses sk_load_word */
#define SEEN_LOAD_HALF 64 /* code uses sk_load_half */
#define SEEN_LOAD_BYTE 128 /* code uses sk_load_byte */
#define SEEN_LOAD_BMSH 256 /* code uses sk_load_byte_msh */
#define SEEN_LOAD_IWORD 512 /* code uses sk_load_word_ind */
#define SEEN_LOAD_IHALF 1024 /* code uses sk_load_half_ind */
#define SEEN_LOAD_IBYTE 2048 /* code uses sk_load_byte_ind */
#define EMIT2(op) \
({ \
if (jit->prg + 2 <= jit->mid) \
*(u16 *) jit->prg = op; \
jit->prg += 2; \
})
#define EMIT4(op) \
({ \
if (jit->prg + 4 <= jit->mid) \
*(u32 *) jit->prg = op; \
jit->prg += 4; \
})
#define EMIT4_DISP(op, disp) \
({ \
unsigned int __disp = (disp) & 0xfff; \
EMIT4(op | __disp); \
})
#define EMIT4_IMM(op, imm) \
({ \
unsigned int __imm = (imm) & 0xffff; \
EMIT4(op | __imm); \
})
#define EMIT4_PCREL(op, pcrel) \
({ \
long __pcrel = ((pcrel) >> 1) & 0xffff; \
EMIT4(op | __pcrel); \
})
#define EMIT6(op1, op2) \
({ \
if (jit->prg + 6 <= jit->mid) { \
*(u32 *) jit->prg = op1; \
*(u16 *) (jit->prg + 4) = op2; \
} \
jit->prg += 6; \
})
#define EMIT6_DISP(op1, op2, disp) \
({ \
unsigned int __disp = (disp) & 0xfff; \
EMIT6(op1 | __disp, op2); \
})
#define EMIT6_IMM(op, imm) \
({ \
unsigned int __imm = (imm); \
EMIT6(op | (__imm >> 16), __imm & 0xffff); \
})
#define EMIT_CONST(val) \
({ \
unsigned int ret; \
ret = (unsigned int) (jit->lit - jit->base_ip); \
jit->seen |= SEEN_LITERAL; \
if (jit->lit + 4 <= jit->end) \
*(u32 *) jit->lit = val; \
jit->lit += 4; \
ret; \
})
#define EMIT_FN_CONST(bit, fn) \
({ \
unsigned int ret; \
ret = (unsigned int) (jit->lit - jit->base_ip); \
if (jit->seen & bit) { \
jit->seen |= SEEN_LITERAL; \
if (jit->lit + 8 <= jit->end) \
*(void **) jit->lit = fn; \
jit->lit += 8; \
} \
ret; \
})
static void bpf_jit_prologue(struct bpf_jit *jit)
{
/* Save registers and create stack frame if necessary */
if (jit->seen & SEEN_DATAREF) {
/* stmg %r8,%r15,88(%r15) */
EMIT6(0xeb8ff058, 0x0024);
/* lgr %r14,%r15 */
EMIT4(0xb90400ef);
/* aghi %r15,<offset> */
EMIT4_IMM(0xa7fb0000, (jit->seen & SEEN_MEM) ? -112 : -80);
/* stg %r14,152(%r15) */
EMIT6(0xe3e0f098, 0x0024);
} else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))
/* stmg %r12,%r13,120(%r15) */
EMIT6(0xebcdf078, 0x0024);
else if (jit->seen & SEEN_XREG)
/* stg %r12,120(%r15) */
EMIT6(0xe3c0f078, 0x0024);
else if (jit->seen & SEEN_LITERAL)
/* stg %r13,128(%r15) */
EMIT6(0xe3d0f080, 0x0024);
/* Setup literal pool */
if (jit->seen & SEEN_LITERAL) {
/* basr %r13,0 */
EMIT2(0x0dd0);
jit->base_ip = jit->prg;
}
jit->off_load_word = EMIT_FN_CONST(SEEN_LOAD_WORD, sk_load_word);
jit->off_load_half = EMIT_FN_CONST(SEEN_LOAD_HALF, sk_load_half);
jit->off_load_byte = EMIT_FN_CONST(SEEN_LOAD_BYTE, sk_load_byte);
jit->off_load_bmsh = EMIT_FN_CONST(SEEN_LOAD_BMSH, sk_load_byte_msh);
jit->off_load_iword = EMIT_FN_CONST(SEEN_LOAD_IWORD, sk_load_word_ind);
jit->off_load_ihalf = EMIT_FN_CONST(SEEN_LOAD_IHALF, sk_load_half_ind);
jit->off_load_ibyte = EMIT_FN_CONST(SEEN_LOAD_IBYTE, sk_load_byte_ind);
/* Filter needs to access skb data */
if (jit->seen & SEEN_DATAREF) {
/* l %r11,<len>(%r2) */
EMIT4_DISP(0x58b02000, offsetof(struct sk_buff, len));
/* s %r11,<data_len>(%r2) */
EMIT4_DISP(0x5bb02000, offsetof(struct sk_buff, data_len));
/* lg %r10,<data>(%r2) */
EMIT6_DISP(0xe3a02000, 0x0004,
offsetof(struct sk_buff, data));
}
}
static void bpf_jit_epilogue(struct bpf_jit *jit)
{
/* Return 0 */
if (jit->seen & SEEN_RET0) {
jit->ret0_ip = jit->prg;
/* lghi %r2,0 */
EMIT4(0xa7290000);
}
jit->exit_ip = jit->prg;
/* Restore registers */
if (jit->seen & SEEN_DATAREF)
/* lmg %r8,%r15,<offset>(%r15) */
EMIT6_DISP(0xeb8ff000, 0x0004,
(jit->seen & SEEN_MEM) ? 200 : 168);
else if ((jit->seen & SEEN_XREG) && (jit->seen & SEEN_LITERAL))
/* lmg %r12,%r13,120(%r15) */
EMIT6(0xebcdf078, 0x0004);
else if (jit->seen & SEEN_XREG)
/* lg %r12,120(%r15) */
EMIT6(0xe3c0f078, 0x0004);
else if (jit->seen & SEEN_LITERAL)
/* lg %r13,128(%r15) */
EMIT6(0xe3d0f080, 0x0004);
/* br %r14 */
EMIT2(0x07fe);
}
/* Helper to find the offset of pkt_type in sk_buff
* Make sure its still a 3bit field starting at the MSBs within a byte.
*/
#define PKT_TYPE_MAX 0xe0
static int pkt_type_offset;
static int __init bpf_pkt_type_offset_init(void)
{
struct sk_buff skb_probe = {
.pkt_type = ~0,
};
char *ct = (char *)&skb_probe;
int off;
pkt_type_offset = -1;
for (off = 0; off < sizeof(struct sk_buff); off++) {
if (!ct[off])
continue;
if (ct[off] == PKT_TYPE_MAX)
pkt_type_offset = off;
else {
/* Found non matching bit pattern, fix needed. */
WARN_ON_ONCE(1);
pkt_type_offset = -1;
return -1;
}
}
return 0;
}
device_initcall(bpf_pkt_type_offset_init);
/*
* make sure we dont leak kernel information to user
*/
static void bpf_jit_noleaks(struct bpf_jit *jit, struct sock_filter *filter)
{
/* Clear temporary memory if (seen & SEEN_MEM) */
if (jit->seen & SEEN_MEM)
/* xc 0(64,%r15),0(%r15) */
EMIT6(0xd73ff000, 0xf000);
/* Clear X if (seen & SEEN_XREG) */
if (jit->seen & SEEN_XREG)
/* lhi %r12,0 */
EMIT4(0xa7c80000);
/* Clear A if the first register does not set it. */
switch (filter[0].code) {
case BPF_S_LD_W_ABS:
case BPF_S_LD_H_ABS:
case BPF_S_LD_B_ABS:
case BPF_S_LD_W_LEN:
case BPF_S_LD_W_IND:
case BPF_S_LD_H_IND:
case BPF_S_LD_B_IND:
case BPF_S_LDX_B_MSH:
case BPF_S_LD_IMM:
case BPF_S_LD_MEM:
case BPF_S_MISC_TXA:
case BPF_S_ANC_PROTOCOL:
case BPF_S_ANC_PKTTYPE:
case BPF_S_ANC_IFINDEX:
case BPF_S_ANC_MARK:
case BPF_S_ANC_QUEUE:
case BPF_S_ANC_HATYPE:
case BPF_S_ANC_RXHASH:
case BPF_S_ANC_CPU:
case BPF_S_ANC_VLAN_TAG:
case BPF_S_ANC_VLAN_TAG_PRESENT:
case BPF_S_RET_K:
/* first instruction sets A register */
break;
default: /* A = 0 */
/* lhi %r5,0 */
EMIT4(0xa7580000);
}
}
static int bpf_jit_insn(struct bpf_jit *jit, struct sock_filter *filter,
unsigned int *addrs, int i, int last)
{
unsigned int K;
int offset;
unsigned int mask;
K = filter->k;
switch (filter->code) {
case BPF_S_ALU_ADD_X: /* A += X */
jit->seen |= SEEN_XREG;
/* ar %r5,%r12 */
EMIT2(0x1a5c);
break;
case BPF_S_ALU_ADD_K: /* A += K */
if (!K)
break;
if (K <= 16383)
/* ahi %r5,<K> */
EMIT4_IMM(0xa75a0000, K);
else if (test_facility(21))
/* alfi %r5,<K> */
EMIT6_IMM(0xc25b0000, K);
else
/* a %r5,<d(K)>(%r13) */
EMIT4_DISP(0x5a50d000, EMIT_CONST(K));
break;
case BPF_S_ALU_SUB_X: /* A -= X */
jit->seen |= SEEN_XREG;
/* sr %r5,%r12 */
EMIT2(0x1b5c);
break;
case BPF_S_ALU_SUB_K: /* A -= K */
if (!K)
break;
if (K <= 16384)
/* ahi %r5,-K */
EMIT4_IMM(0xa75a0000, -K);
else if (test_facility(21))
/* alfi %r5,-K */
EMIT6_IMM(0xc25b0000, -K);
else
/* s %r5,<d(K)>(%r13) */
EMIT4_DISP(0x5b50d000, EMIT_CONST(K));
break;
case BPF_S_ALU_MUL_X: /* A *= X */
jit->seen |= SEEN_XREG;
/* msr %r5,%r12 */
EMIT4(0xb252005c);
break;
case BPF_S_ALU_MUL_K: /* A *= K */
if (K <= 16383)
/* mhi %r5,K */
EMIT4_IMM(0xa75c0000, K);
else if (test_facility(34))
/* msfi %r5,<K> */
EMIT6_IMM(0xc2510000, K);
else
/* ms %r5,<d(K)>(%r13) */
EMIT4_DISP(0x7150d000, EMIT_CONST(K));
break;
case BPF_S_ALU_DIV_X: /* A /= X */
jit->seen |= SEEN_XREG | SEEN_RET0;
/* ltr %r12,%r12 */
EMIT2(0x12cc);
/* jz <ret0> */
EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg));
/* lhi %r4,0 */
EMIT4(0xa7480000);
/* dlr %r4,%r12 */
EMIT4(0xb997004c);
break;
case BPF_S_ALU_DIV_K: /* A /= K */
if (K == 1)
break;
/* lhi %r4,0 */
EMIT4(0xa7480000);
/* dl %r4,<d(K)>(%r13) */
EMIT6_DISP(0xe340d000, 0x0097, EMIT_CONST(K));
break;
case BPF_S_ALU_MOD_X: /* A %= X */
jit->seen |= SEEN_XREG | SEEN_RET0;
/* ltr %r12,%r12 */
EMIT2(0x12cc);
/* jz <ret0> */
EMIT4_PCREL(0xa7840000, (jit->ret0_ip - jit->prg));
/* lhi %r4,0 */
EMIT4(0xa7480000);
/* dlr %r4,%r12 */
EMIT4(0xb997004c);
/* lr %r5,%r4 */
EMIT2(0x1854);
break;
case BPF_S_ALU_MOD_K: /* A %= K */
if (K == 1) {
/* lhi %r5,0 */
EMIT4(0xa7580000);
break;
}
/* lhi %r4,0 */
EMIT4(0xa7480000);
/* dl %r4,<d(K)>(%r13) */
EMIT6_DISP(0xe340d000, 0x0097, EMIT_CONST(K));
/* lr %r5,%r4 */
EMIT2(0x1854);
break;
case BPF_S_ALU_AND_X: /* A &= X */
jit->seen |= SEEN_XREG;
/* nr %r5,%r12 */
EMIT2(0x145c);
break;
case BPF_S_ALU_AND_K: /* A &= K */
if (test_facility(21))
/* nilf %r5,<K> */
EMIT6_IMM(0xc05b0000, K);
else
/* n %r5,<d(K)>(%r13) */
EMIT4_DISP(0x5450d000, EMIT_CONST(K));
break;
case BPF_S_ALU_OR_X: /* A |= X */
jit->seen |= SEEN_XREG;
/* or %r5,%r12 */
EMIT2(0x165c);
break;
case BPF_S_ALU_OR_K: /* A |= K */
if (test_facility(21))
/* oilf %r5,<K> */
EMIT6_IMM(0xc05d0000, K);
else
/* o %r5,<d(K)>(%r13) */
EMIT4_DISP(0x5650d000, EMIT_CONST(K));
break;
case BPF_S_ANC_ALU_XOR_X: /* A ^= X; */
case BPF_S_ALU_XOR_X:
jit->seen |= SEEN_XREG;
/* xr %r5,%r12 */
EMIT2(0x175c);
break;
case BPF_S_ALU_XOR_K: /* A ^= K */
if (!K)
break;
/* x %r5,<d(K)>(%r13) */
EMIT4_DISP(0x5750d000, EMIT_CONST(K));
break;
case BPF_S_ALU_LSH_X: /* A <<= X; */
jit->seen |= SEEN_XREG;
/* sll %r5,0(%r12) */
EMIT4(0x8950c000);
break;
case BPF_S_ALU_LSH_K: /* A <<= K */
if (K == 0)
break;
/* sll %r5,K */
EMIT4_DISP(0x89500000, K);
break;
case BPF_S_ALU_RSH_X: /* A >>= X; */
jit->seen |= SEEN_XREG;
/* srl %r5,0(%r12) */
EMIT4(0x8850c000);
break;
case BPF_S_ALU_RSH_K: /* A >>= K; */
if (K == 0)
break;
/* srl %r5,K */
EMIT4_DISP(0x88500000, K);
break;
case BPF_S_ALU_NEG: /* A = -A */
/* lnr %r5,%r5 */
EMIT2(0x1155);
break;
case BPF_S_JMP_JA: /* ip += K */
offset = addrs[i + K] + jit->start - jit->prg;
EMIT4_PCREL(0xa7f40000, offset);
break;
case BPF_S_JMP_JGT_K: /* ip += (A > K) ? jt : jf */
mask = 0x200000; /* jh */
goto kbranch;
case BPF_S_JMP_JGE_K: /* ip += (A >= K) ? jt : jf */
mask = 0xa00000; /* jhe */
goto kbranch;
case BPF_S_JMP_JEQ_K: /* ip += (A == K) ? jt : jf */
mask = 0x800000; /* je */
kbranch: /* Emit compare if the branch targets are different */
if (filter->jt != filter->jf) {
if (K <= 16383)
/* chi %r5,<K> */
EMIT4_IMM(0xa75e0000, K);
else if (test_facility(21))
/* clfi %r5,<K> */
EMIT6_IMM(0xc25f0000, K);
else
/* c %r5,<d(K)>(%r13) */
EMIT4_DISP(0x5950d000, EMIT_CONST(K));
}
branch: if (filter->jt == filter->jf) {
if (filter->jt == 0)
break;
/* j <jt> */
offset = addrs[i + filter->jt] + jit->start - jit->prg;
EMIT4_PCREL(0xa7f40000, offset);
break;
}
if (filter->jt != 0) {
/* brc <mask>,<jt> */
offset = addrs[i + filter->jt] + jit->start - jit->prg;
EMIT4_PCREL(0xa7040000 | mask, offset);
}
if (filter->jf != 0) {
/* brc <mask^15>,<jf> */
offset = addrs[i + filter->jf] + jit->start - jit->prg;
EMIT4_PCREL(0xa7040000 | (mask ^ 0xf00000), offset);
}
break;
case BPF_S_JMP_JSET_K: /* ip += (A & K) ? jt : jf */
mask = 0x700000; /* jnz */
/* Emit test if the branch targets are different */
if (filter->jt != filter->jf) {
if (K > 65535) {
/* lr %r4,%r5 */
EMIT2(0x1845);
/* n %r4,<d(K)>(%r13) */
EMIT4_DISP(0x5440d000, EMIT_CONST(K));
} else
/* tmll %r5,K */
EMIT4_IMM(0xa7510000, K);
}
goto branch;
case BPF_S_JMP_JGT_X: /* ip += (A > X) ? jt : jf */
mask = 0x200000; /* jh */
goto xbranch;
case BPF_S_JMP_JGE_X: /* ip += (A >= X) ? jt : jf */
mask = 0xa00000; /* jhe */
goto xbranch;
case BPF_S_JMP_JEQ_X: /* ip += (A == X) ? jt : jf */
mask = 0x800000; /* je */
xbranch: /* Emit compare if the branch targets are different */
if (filter->jt != filter->jf) {
jit->seen |= SEEN_XREG;
/* cr %r5,%r12 */
EMIT2(0x195c);
}
goto branch;
case BPF_S_JMP_JSET_X: /* ip += (A & X) ? jt : jf */
mask = 0x700000; /* jnz */
/* Emit test if the branch targets are different */
if (filter->jt != filter->jf) {
jit->seen |= SEEN_XREG;
/* lr %r4,%r5 */
EMIT2(0x1845);
/* nr %r4,%r12 */
EMIT2(0x144c);
}
goto branch;
case BPF_S_LD_W_ABS: /* A = *(u32 *) (skb->data+K) */
jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_WORD;
offset = jit->off_load_word;
goto load_abs;
case BPF_S_LD_H_ABS: /* A = *(u16 *) (skb->data+K) */
jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_HALF;
offset = jit->off_load_half;
goto load_abs;
case BPF_S_LD_B_ABS: /* A = *(u8 *) (skb->data+K) */
jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_BYTE;
offset = jit->off_load_byte;
load_abs: if ((int) K < 0)
goto out;
call_fn: /* lg %r1,<d(function)>(%r13) */
EMIT6_DISP(0xe310d000, 0x0004, offset);
/* l %r3,<d(K)>(%r13) */
EMIT4_DISP(0x5830d000, EMIT_CONST(K));
/* basr %r8,%r1 */
EMIT2(0x0d81);
/* jnz <ret0> */
EMIT4_PCREL(0xa7740000, (jit->ret0_ip - jit->prg));
break;
case BPF_S_LD_W_IND: /* A = *(u32 *) (skb->data+K+X) */
jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IWORD;
offset = jit->off_load_iword;
goto call_fn;
case BPF_S_LD_H_IND: /* A = *(u16 *) (skb->data+K+X) */
jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IHALF;
offset = jit->off_load_ihalf;
goto call_fn;
case BPF_S_LD_B_IND: /* A = *(u8 *) (skb->data+K+X) */
jit->seen |= SEEN_DATAREF | SEEN_RET0 | SEEN_LOAD_IBYTE;
offset = jit->off_load_ibyte;
goto call_fn;
case BPF_S_LDX_B_MSH:
/* X = (*(u8 *)(skb->data+K) & 0xf) << 2 */
jit->seen |= SEEN_RET0;
if ((int) K < 0) {
/* j <ret0> */
EMIT4_PCREL(0xa7f40000, (jit->ret0_ip - jit->prg));
break;
}
jit->seen |= SEEN_DATAREF | SEEN_LOAD_BMSH;
offset = jit->off_load_bmsh;
goto call_fn;
case BPF_S_LD_W_LEN: /* A = skb->len; */
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4);
/* l %r5,<d(len)>(%r2) */
EMIT4_DISP(0x58502000, offsetof(struct sk_buff, len));
break;
case BPF_S_LDX_W_LEN: /* X = skb->len; */
jit->seen |= SEEN_XREG;
/* l %r12,<d(len)>(%r2) */
EMIT4_DISP(0x58c02000, offsetof(struct sk_buff, len));
break;
case BPF_S_LD_IMM: /* A = K */
if (K <= 16383)
/* lhi %r5,K */
EMIT4_IMM(0xa7580000, K);
else if (test_facility(21))
/* llilf %r5,<K> */
EMIT6_IMM(0xc05f0000, K);
else
/* l %r5,<d(K)>(%r13) */
EMIT4_DISP(0x5850d000, EMIT_CONST(K));
break;
case BPF_S_LDX_IMM: /* X = K */
jit->seen |= SEEN_XREG;
if (K <= 16383)
/* lhi %r12,<K> */
EMIT4_IMM(0xa7c80000, K);
else if (test_facility(21))
/* llilf %r12,<K> */
EMIT6_IMM(0xc0cf0000, K);
else
/* l %r12,<d(K)>(%r13) */
EMIT4_DISP(0x58c0d000, EMIT_CONST(K));
break;
case BPF_S_LD_MEM: /* A = mem[K] */
jit->seen |= SEEN_MEM;
/* l %r5,<K>(%r15) */
EMIT4_DISP(0x5850f000,
(jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
break;
case BPF_S_LDX_MEM: /* X = mem[K] */
jit->seen |= SEEN_XREG | SEEN_MEM;
/* l %r12,<K>(%r15) */
EMIT4_DISP(0x58c0f000,
(jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
break;
case BPF_S_MISC_TAX: /* X = A */
jit->seen |= SEEN_XREG;
/* lr %r12,%r5 */
EMIT2(0x18c5);
break;
case BPF_S_MISC_TXA: /* A = X */
jit->seen |= SEEN_XREG;
/* lr %r5,%r12 */
EMIT2(0x185c);
break;
case BPF_S_RET_K:
if (K == 0) {
jit->seen |= SEEN_RET0;
if (last)
break;
/* j <ret0> */
EMIT4_PCREL(0xa7f40000, jit->ret0_ip - jit->prg);
} else {
if (K <= 16383)
/* lghi %r2,K */
EMIT4_IMM(0xa7290000, K);
else
/* llgf %r2,<K>(%r13) */
EMIT6_DISP(0xe320d000, 0x0016, EMIT_CONST(K));
/* j <exit> */
if (last && !(jit->seen & SEEN_RET0))
break;
EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
}
break;
case BPF_S_RET_A:
/* llgfr %r2,%r5 */
EMIT4(0xb9160025);
/* j <exit> */
EMIT4_PCREL(0xa7f40000, jit->exit_ip - jit->prg);
break;
case BPF_S_ST: /* mem[K] = A */
jit->seen |= SEEN_MEM;
/* st %r5,<K>(%r15) */
EMIT4_DISP(0x5050f000,
(jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
break;
case BPF_S_STX: /* mem[K] = X : mov %ebx,off8(%rbp) */
jit->seen |= SEEN_XREG | SEEN_MEM;
/* st %r12,<K>(%r15) */
EMIT4_DISP(0x50c0f000,
(jit->seen & SEEN_DATAREF) ? 160 + K*4 : K*4);
break;
case BPF_S_ANC_PROTOCOL: /* A = ntohs(skb->protocol); */
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
/* lhi %r5,0 */
EMIT4(0xa7580000);
/* icm %r5,3,<d(protocol)>(%r2) */
EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, protocol));
break;
case BPF_S_ANC_IFINDEX: /* if (!skb->dev) return 0;
* A = skb->dev->ifindex */
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
jit->seen |= SEEN_RET0;
/* lg %r1,<d(dev)>(%r2) */
EMIT6_DISP(0xe3102000, 0x0004, offsetof(struct sk_buff, dev));
/* ltgr %r1,%r1 */
EMIT4(0xb9020011);
/* jz <ret0> */
EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
/* l %r5,<d(ifindex)>(%r1) */
EMIT4_DISP(0x58501000, offsetof(struct net_device, ifindex));
break;
case BPF_S_ANC_MARK: /* A = skb->mark */
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
/* l %r5,<d(mark)>(%r2) */
EMIT4_DISP(0x58502000, offsetof(struct sk_buff, mark));
break;
case BPF_S_ANC_QUEUE: /* A = skb->queue_mapping */
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
/* lhi %r5,0 */
EMIT4(0xa7580000);
/* icm %r5,3,<d(queue_mapping)>(%r2) */
EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, queue_mapping));
break;
case BPF_S_ANC_HATYPE: /* if (!skb->dev) return 0;
* A = skb->dev->type */
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
jit->seen |= SEEN_RET0;
/* lg %r1,<d(dev)>(%r2) */
EMIT6_DISP(0xe3102000, 0x0004, offsetof(struct sk_buff, dev));
/* ltgr %r1,%r1 */
EMIT4(0xb9020011);
/* jz <ret0> */
EMIT4_PCREL(0xa7840000, jit->ret0_ip - jit->prg);
/* lhi %r5,0 */
EMIT4(0xa7580000);
/* icm %r5,3,<d(type)>(%r1) */
EMIT4_DISP(0xbf531000, offsetof(struct net_device, type));
break;
case BPF_S_ANC_RXHASH: /* A = skb->rxhash */
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, rxhash) != 4);
/* l %r5,<d(rxhash)>(%r2) */
EMIT4_DISP(0x58502000, offsetof(struct sk_buff, rxhash));
break;
case BPF_S_ANC_VLAN_TAG:
case BPF_S_ANC_VLAN_TAG_PRESENT:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
/* lhi %r5,0 */
EMIT4(0xa7580000);
/* icm %r5,3,<d(vlan_tci)>(%r2) */
EMIT4_DISP(0xbf532000, offsetof(struct sk_buff, vlan_tci));
if (filter->code == BPF_S_ANC_VLAN_TAG) {
/* nill %r5,0xefff */
EMIT4_IMM(0xa5570000, ~VLAN_TAG_PRESENT);
} else {
/* nill %r5,0x1000 */
EMIT4_IMM(0xa5570000, VLAN_TAG_PRESENT);
/* srl %r5,12 */
EMIT4_DISP(0x88500000, 12);
}
break;
case BPF_S_ANC_PKTTYPE:
if (pkt_type_offset < 0)
goto out;
/* lhi %r5,0 */
EMIT4(0xa7580000);
/* ic %r5,<d(pkt_type_offset)>(%r2) */
EMIT4_DISP(0x43502000, pkt_type_offset);
/* srl %r5,5 */
EMIT4_DISP(0x88500000, 5);
break;
case BPF_S_ANC_CPU: /* A = smp_processor_id() */
#ifdef CONFIG_SMP
/* l %r5,<d(cpu_nr)> */
EMIT4_DISP(0x58500000, offsetof(struct _lowcore, cpu_nr));
#else
/* lhi %r5,0 */
EMIT4(0xa7580000);
#endif
break;
default: /* too complex, give up */
goto out;
}
addrs[i] = jit->prg - jit->start;
return 0;
out:
return -1;
}
/*
* Note: for security reasons, bpf code will follow a randomly
* sized amount of illegal instructions.
*/
struct bpf_binary_header {
unsigned int pages;
u8 image[];
};
static struct bpf_binary_header *bpf_alloc_binary(unsigned int bpfsize,
u8 **image_ptr)
{
struct bpf_binary_header *header;
unsigned int sz, hole;
/* Most BPF filters are really small, but if some of them fill a page,
* allow at least 128 extra bytes for illegal instructions.
*/
sz = round_up(bpfsize + sizeof(*header) + 128, PAGE_SIZE);
header = module_alloc(sz);
if (!header)
return NULL;
memset(header, 0, sz);
header->pages = sz / PAGE_SIZE;
hole = sz - (bpfsize + sizeof(*header));
/* Insert random number of illegal instructions before BPF code
* and make sure the first instruction starts at an even address.
*/
*image_ptr = &header->image[(prandom_u32() % hole) & -2];
return header;
}
void bpf_jit_compile(struct sk_filter *fp)
{
struct bpf_binary_header *header = NULL;
unsigned long size, prg_len, lit_len;
struct bpf_jit jit, cjit;
unsigned int *addrs;
int pass, i;
if (!bpf_jit_enable)
return;
addrs = kcalloc(fp->len, sizeof(*addrs), GFP_KERNEL);
if (addrs == NULL)
return;
memset(&jit, 0, sizeof(cjit));
memset(&cjit, 0, sizeof(cjit));
for (pass = 0; pass < 10; pass++) {
jit.prg = jit.start;
jit.lit = jit.mid;
bpf_jit_prologue(&jit);
bpf_jit_noleaks(&jit, fp->insns);
for (i = 0; i < fp->len; i++) {
if (bpf_jit_insn(&jit, fp->insns + i, addrs, i,
i == fp->len - 1))
goto out;
}
bpf_jit_epilogue(&jit);
if (jit.start) {
WARN_ON(jit.prg > cjit.prg || jit.lit > cjit.lit);
if (memcmp(&jit, &cjit, sizeof(jit)) == 0)
break;
} else if (jit.prg == cjit.prg && jit.lit == cjit.lit) {
prg_len = jit.prg - jit.start;
lit_len = jit.lit - jit.mid;
size = prg_len + lit_len;
if (size >= BPF_SIZE_MAX)
goto out;
header = bpf_alloc_binary(size, &jit.start);
if (!header)
goto out;
jit.prg = jit.mid = jit.start + prg_len;
jit.lit = jit.end = jit.start + prg_len + lit_len;
jit.base_ip += (unsigned long) jit.start;
jit.exit_ip += (unsigned long) jit.start;
jit.ret0_ip += (unsigned long) jit.start;
}
cjit = jit;
}
if (bpf_jit_enable > 1) {
bpf_jit_dump(fp->len, jit.end - jit.start, pass, jit.start);
if (jit.start)
print_fn_code(jit.start, jit.mid - jit.start);
}
if (jit.start) {
set_memory_ro((unsigned long)header, header->pages);
fp->bpf_func = (void *) jit.start;
}
out:
kfree(addrs);
}
void bpf_jit_free(struct sk_filter *fp)
{
unsigned long addr = (unsigned long)fp->bpf_func & PAGE_MASK;
struct bpf_binary_header *header = (void *)addr;
if (fp->bpf_func == sk_run_filter)
goto free_filter;
set_memory_rw(addr, header->pages);
module_free(NULL, header);
free_filter:
kfree(fp);
}
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