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Merge branch 's390-bpf-push-pop'
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Michael Holzheu says:

====================
s390/bpf: recache skb->data/hlen for skb_vlan_push/pop

Here the s390 backend for Alexei's patch 4e10df9 ("bpf: introduce
bpf_skb_vlan_push/pop() helpers") plus two bugfixes and two minor
improvements.

The first patch "s390/bpf: clear correct BPF accumulator register" will
also go upstream via Martin's "fixes" branch.

* v2: Integrated suggestions from Joe Perches
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
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David S. Miller committed Jul 29, 2015
2 parents 35e455f + 9db7f2b commit b88d0a0
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Showing 2 changed files with 53 additions and 45 deletions.
5 changes: 4 additions & 1 deletion arch/s390/net/bpf_jit.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,8 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
* | BPF stack | |
* | | |
* +---------------+ |
* | 8 byte skbp | |
* R15+170 -> +---------------+ |
* | 8 byte hlen | |
* R15+168 -> +---------------+ |
* | 4 byte align | |
Expand All @@ -51,11 +53,12 @@ extern u8 sk_load_word[], sk_load_half[], sk_load_byte[];
* We get 160 bytes stack space from calling function, but only use
* 12 * 8 byte for old backchain, r15..r6, and tail_call_cnt.
*/
#define STK_SPACE (MAX_BPF_STACK + 8 + 4 + 4 + 160)
#define STK_SPACE (MAX_BPF_STACK + 8 + 8 + 4 + 4 + 160)
#define STK_160_UNUSED (160 - 12 * 8)
#define STK_OFF (STK_SPACE - STK_160_UNUSED)
#define STK_OFF_TMP 160 /* Offset of tmp buffer on stack */
#define STK_OFF_HLEN 168 /* Offset of SKB header length on stack */
#define STK_OFF_SKBP 170 /* Offset of SKB pointer on stack */

#define STK_OFF_R6 (160 - 11 * 8) /* Offset of r6 on stack */
#define STK_OFF_TCCNT (160 - 12 * 8) /* Offset of tail_call_cnt on stack */
Expand Down
93 changes: 49 additions & 44 deletions arch/s390/net/bpf_jit_comp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -45,14 +45,15 @@ struct bpf_jit {
int labels[1]; /* Labels for local jumps */
};

#define BPF_SIZE_MAX 4096 /* Max size for program */
#define BPF_SIZE_MAX 0x7ffff /* Max size for program (20 bit signed displ) */

#define SEEN_SKB 1 /* skb access */
#define SEEN_MEM 2 /* use mem[] for temporary storage */
#define SEEN_RET0 4 /* ret0_ip points to a valid return 0 */
#define SEEN_LITERAL 8 /* code uses literals */
#define SEEN_FUNC 16 /* calls C functions */
#define SEEN_TAIL_CALL 32 /* code uses tail calls */
#define SEEN_SKB_CHANGE 64 /* code changes skb data */
#define SEEN_STACK (SEEN_FUNC | SEEN_MEM | SEEN_SKB)

/*
Expand Down Expand Up @@ -203,19 +204,11 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
_EMIT6(op1 | __disp, op2); \
})

#define EMIT6_DISP(op1, op2, b1, b2, b3, disp) \
({ \
_EMIT6_DISP(op1 | reg(b1, b2) << 16 | \
reg_high(b3) << 8, op2, disp); \
REG_SET_SEEN(b1); \
REG_SET_SEEN(b2); \
REG_SET_SEEN(b3); \
})

#define _EMIT6_DISP_LH(op1, op2, disp) \
({ \
unsigned int __disp_h = ((u32)disp) & 0xff000; \
unsigned int __disp_l = ((u32)disp) & 0x00fff; \
u32 _disp = (u32) disp; \
unsigned int __disp_h = _disp & 0xff000; \
unsigned int __disp_l = _disp & 0x00fff; \
_EMIT6(op1 | __disp_l, op2 | __disp_h >> 4); \
})

Expand Down Expand Up @@ -389,13 +382,33 @@ static void save_restore_regs(struct bpf_jit *jit, int op)
} while (re <= 15);
}

/*
* For SKB access %b1 contains the SKB pointer. For "bpf_jit.S"
* we store the SKB header length on the stack and the SKB data
* pointer in REG_SKB_DATA.
*/
static void emit_load_skb_data_hlen(struct bpf_jit *jit)
{
/* Header length: llgf %w1,<len>(%b1) */
EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_1,
offsetof(struct sk_buff, len));
/* s %w1,<data_len>(%b1) */
EMIT4_DISP(0x5b000000, REG_W1, BPF_REG_1,
offsetof(struct sk_buff, data_len));
/* stg %w1,ST_OFF_HLEN(%r0,%r15) */
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15, STK_OFF_HLEN);
/* lg %skb_data,data_off(%b1) */
EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
BPF_REG_1, offsetof(struct sk_buff, data));
}

/*
* Emit function prologue
*
* Save registers and create stack frame if necessary.
* See stack frame layout desription in "bpf_jit.h"!
*/
static void bpf_jit_prologue(struct bpf_jit *jit)
static void bpf_jit_prologue(struct bpf_jit *jit, bool is_classic)
{
if (jit->seen & SEEN_TAIL_CALL) {
/* xc STK_OFF_TCCNT(4,%r15),STK_OFF_TCCNT(%r15) */
Expand Down Expand Up @@ -429,32 +442,21 @@ static void bpf_jit_prologue(struct bpf_jit *jit)
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0,
REG_15, 152);
}
/*
* For SKB access %b1 contains the SKB pointer. For "bpf_jit.S"
* we store the SKB header length on the stack and the SKB data
* pointer in REG_SKB_DATA.
*/
if (jit->seen & SEEN_SKB) {
/* Header length: llgf %w1,<len>(%b1) */
EMIT6_DISP_LH(0xe3000000, 0x0016, REG_W1, REG_0, BPF_REG_1,
offsetof(struct sk_buff, len));
/* s %w1,<data_len>(%b1) */
EMIT4_DISP(0x5b000000, REG_W1, BPF_REG_1,
offsetof(struct sk_buff, data_len));
/* stg %w1,ST_OFF_HLEN(%r0,%r15) */
if (jit->seen & SEEN_SKB)
emit_load_skb_data_hlen(jit);
if (jit->seen & SEEN_SKB_CHANGE)
/* stg %b1,ST_OFF_SKBP(%r0,%r15) */
EMIT6_DISP_LH(0xe3000000, 0x0024, REG_W1, REG_0, REG_15,
STK_OFF_HLEN);
/* lg %skb_data,data_off(%b1) */
EMIT6_DISP_LH(0xe3000000, 0x0004, REG_SKB_DATA, REG_0,
BPF_REG_1, offsetof(struct sk_buff, data));
STK_OFF_SKBP);
/* Clear A (%b0) and X (%b7) registers for converted BPF programs */
if (is_classic) {
if (REG_SEEN(BPF_REG_A))
/* lghi %ba,0 */
EMIT4_IMM(0xa7090000, BPF_REG_A, 0);
if (REG_SEEN(BPF_REG_X))
/* lghi %bx,0 */
EMIT4_IMM(0xa7090000, BPF_REG_X, 0);
}
/* BPF compatibility: clear A (%b7) and X (%b8) registers */
if (REG_SEEN(BPF_REG_7))
/* lghi %b7,0 */
EMIT4_IMM(0xa7090000, BPF_REG_7, 0);
if (REG_SEEN(BPF_REG_8))
/* lghi %b8,0 */
EMIT4_IMM(0xa7090000, BPF_REG_8, 0);
}

/*
Expand Down Expand Up @@ -973,19 +975,22 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i
*/
const u64 func = (u64)__bpf_call_base + imm;

if (bpf_helper_changes_skb_data((void *)func))
/* TODO reload skb->data, hlen */
return -1;

REG_SET_SEEN(BPF_REG_5);
jit->seen |= SEEN_FUNC;
/* lg %w1,<d(imm)>(%l) */
EMIT6_DISP(0xe3000000, 0x0004, REG_W1, REG_0, REG_L,
EMIT_CONST_U64(func));
EMIT6_DISP_LH(0xe3000000, 0x0004, REG_W1, REG_0, REG_L,
EMIT_CONST_U64(func));
/* basr %r14,%w1 */
EMIT2(0x0d00, REG_14, REG_W1);
/* lgr %b0,%r2: load return value into %b0 */
EMIT4(0xb9040000, BPF_REG_0, REG_2);
if (bpf_helper_changes_skb_data((void *)func)) {
jit->seen |= SEEN_SKB_CHANGE;
/* lg %b1,ST_OFF_SKBP(%r15) */
EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_1, REG_0,
REG_15, STK_OFF_SKBP);
emit_load_skb_data_hlen(jit);
}
break;
}
case BPF_JMP | BPF_CALL | BPF_X:
Expand Down Expand Up @@ -1240,7 +1245,7 @@ static int bpf_jit_prog(struct bpf_jit *jit, struct bpf_prog *fp)
jit->lit = jit->lit_start;
jit->prg = 0;

bpf_jit_prologue(jit);
bpf_jit_prologue(jit, fp->type == BPF_PROG_TYPE_UNSPEC);
for (i = 0; i < fp->len; i += insn_count) {
insn_count = bpf_jit_insn(jit, fp, i);
if (insn_count < 0)
Expand Down

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