1/*
  2 * BPF Jit compiler for s390, help functions.
  3 *
  4 * Copyright IBM Corp. 2012
  5 *
  6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
  7 */
  8#include <linux/linkage.h>
  9
 10/*
 11 * Calling convention:
 12 * registers %r2, %r6-%r8, %r10-%r11, %r13, %r15 are call saved
 13 *   %r2: skb pointer
 14 *   %r3: offset parameter
 15 *   %r5: BPF A accumulator
 16 *   %r8: return address
 17 *   %r9: save register for skb pointer
 18 *   %r10: skb->data
 19 *   %r11: skb->len - skb->data_len (headlen)
 20 *   %r12: BPF X accumulator
 21 *
 22 * skb_copy_bits takes 4 parameters:
 23 *   %r2 = skb pointer
 24 *   %r3 = offset into skb data
 25 *   %r4 = length to copy
 26 *   %r5 = pointer to temp buffer
 27 */
 28#define SKBDATA	%r8
 29
 30	/* A = *(u32 *) (skb->data+K+X) */
 31ENTRY(sk_load_word_ind)
 32	ar	%r3,%r12		# offset += X
 33	bmr	%r8			# < 0 -> return with cc
 34
 35	/* A = *(u32 *) (skb->data+K) */
 36ENTRY(sk_load_word)
 37	llgfr	%r1,%r3			# extend offset
 38	ahi	%r3,4			# offset + 4
 39	clr	%r11,%r3		# hlen <= offset + 4 ?
 40	jl	sk_load_word_slow
 41	l	%r5,0(%r1,%r10)		# get word from skb
 42	xr	%r1,%r1			# set cc to zero
 43	br	%r8
 44
 45sk_load_word_slow:
 46	lgr	%r9,%r2			# save %r2
 47	lhi	%r4,4			# 4 bytes
 48	la	%r5,160(%r15)		# pointer to temp buffer
 49	brasl	%r14,skb_copy_bits	# get data from skb
 50	l	%r5,160(%r15)		# load result from temp buffer
 51	ltgr	%r2,%r2			# set cc to (%r2 != 0)
 52	lgr	%r2,%r9			# restore %r2
 53	br	%r8
 54
 55	/* A = *(u16 *) (skb->data+K+X) */
 56ENTRY(sk_load_half_ind)
 57	ar	%r3,%r12		# offset += X
 58	bmr	%r8			# < 0 -> return with cc
 59
 60	/* A = *(u16 *) (skb->data+K) */
 61ENTRY(sk_load_half)
 62	llgfr	%r1,%r3			# extend offset
 63	ahi	%r3,2			# offset + 2
 64	clr	%r11,%r3		# hlen <= offset + 2 ?
 65	jl	sk_load_half_slow
 66	llgh	%r5,0(%r1,%r10)		# get half from skb
 67	xr	%r1,%r1			# set cc to zero
 68	br	%r8
 69
 70sk_load_half_slow:
 71	lgr	%r9,%r2			# save %r2
 72	lhi	%r4,2			# 2 bytes
 73	la	%r5,162(%r15)		# pointer to temp buffer
 74	brasl	%r14,skb_copy_bits	# get data from skb
 75	xc	160(2,%r15),160(%r15)
 76	l	%r5,160(%r15)		# load result from temp buffer
 77	ltgr	%r2,%r2			# set cc to (%r2 != 0)
 78	lgr	%r2,%r9			# restore %r2
 79	br	%r8
 80
 81	/* A = *(u8 *) (skb->data+K+X) */
 82ENTRY(sk_load_byte_ind)
 83	ar	%r3,%r12		# offset += X
 84	bmr	%r8			# < 0 -> return with cc
 85
 86	/* A = *(u8 *) (skb->data+K) */
 87ENTRY(sk_load_byte)
 88	llgfr	%r1,%r3			# extend offset
 89	clr	%r11,%r3		# hlen < offset ?
 90	jle	sk_load_byte_slow
 91	lhi	%r5,0
 92	ic	%r5,0(%r1,%r10)		# get byte from skb
 93	xr	%r1,%r1			# set cc to zero
 94	br	%r8
 95
 96sk_load_byte_slow:
 97	lgr	%r9,%r2			# save %r2
 98	lhi	%r4,1			# 1 bytes
 99	la	%r5,163(%r15)		# pointer to temp buffer
100	brasl	%r14,skb_copy_bits	# get data from skb
101	xc	160(3,%r15),160(%r15)
102	l	%r5,160(%r15)		# load result from temp buffer
103	ltgr	%r2,%r2			# set cc to (%r2 != 0)
104	lgr	%r2,%r9			# restore %r2
105	br	%r8
106
107	/* A = (*(u8 *)(skb->data+K) & 0xf) << 2 */
108ENTRY(sk_load_byte_msh)
109	llgfr	%r1,%r3			# extend offset
110	clr	%r11,%r3		# hlen < offset ?
111	jle	sk_load_byte_slow
112	lhi	%r12,0
113	ic	%r12,0(%r1,%r10)	# get byte from skb
114	nill	%r12,0x0f
115	sll	%r12,2
116	xr	%r1,%r1			# set cc to zero
117	br	%r8
118
119sk_load_byte_msh_slow:
120	lgr	%r9,%r2			# save %r2
121	lhi	%r4,2			# 2 bytes
122	la	%r5,162(%r15)		# pointer to temp buffer
123	brasl	%r14,skb_copy_bits	# get data from skb
124	xc	160(3,%r15),160(%r15)
125	l	%r12,160(%r15)		# load result from temp buffer
126	nill	%r12,0x0f
127	sll	%r12,2
128	ltgr	%r2,%r2			# set cc to (%r2 != 0)
129	lgr	%r2,%r9			# restore %r2
130	br	%r8