1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 */
 14
 15#include <linux/linkage.h>
 16#include <asm/errno.h>
 17#include <asm/cache.h>
 18#include <arch/chip.h>
 19
 20/* Access user memory, but use MMU to avoid propagating kernel exceptions. */
 21
 22/*
 23 * strnlen_user_asm takes the pointer in r0, and the length bound in r1.
 24 * It returns the length, including the terminating NUL, or zero on exception.
 25 * If length is greater than the bound, returns one plus the bound.
 26 */
 27STD_ENTRY(strnlen_user_asm)
 28	{ bz r1, 2f; addi r3, r0, -1 }  /* bias down to include NUL */
 291:      { lb_u r4, r0; addi r1, r1, -1 }
 30	bz r4, 2f
 31	{ bnzt r1, 1b; addi r0, r0, 1 }
 322:      { sub r0, r0, r3; jrp lr }
 33	STD_ENDPROC(strnlen_user_asm)
 34	.pushsection .fixup,"ax"
 35strnlen_user_fault:
 36	{ move r0, zero; jrp lr }
 37	ENDPROC(strnlen_user_fault)
 38	.section __ex_table,"a"
 39	.word 1b, strnlen_user_fault
 40	.popsection
 41
 42/*
 43 * strncpy_from_user_asm takes the kernel target pointer in r0,
 44 * the userspace source pointer in r1, and the length bound (including
 45 * the trailing NUL) in r2.  On success, it returns the string length
 46 * (not including the trailing NUL), or -EFAULT on failure.
 47 */
 48STD_ENTRY(strncpy_from_user_asm)
 49	{ bz r2, 2f; move r3, r0 }
 501:      { lb_u r4, r1; addi r1, r1, 1; addi r2, r2, -1 }
 51	{ sb r0, r4; addi r0, r0, 1 }
 52	bz r2, 2f
 53	bnzt r4, 1b
 54	addi r0, r0, -1   /* don't count the trailing NUL */
 552:      { sub r0, r0, r3; jrp lr }
 56	STD_ENDPROC(strncpy_from_user_asm)
 57	.pushsection .fixup,"ax"
 58strncpy_from_user_fault:
 59	{ movei r0, -EFAULT; jrp lr }
 60	ENDPROC(strncpy_from_user_fault)
 61	.section __ex_table,"a"
 62	.word 1b, strncpy_from_user_fault
 63	.popsection
 64
 65/*
 66 * clear_user_asm takes the user target address in r0 and the
 67 * number of bytes to zero in r1.
 68 * It returns the number of uncopiable bytes (hopefully zero) in r0.
 69 * Note that we don't use a separate .fixup section here since we fall
 70 * through into the "fixup" code as the last straight-line bundle anyway.
 71 */
 72STD_ENTRY(clear_user_asm)
 73	{ bz r1, 2f; or r2, r0, r1 }
 74	andi r2, r2, 3
 75	bzt r2, .Lclear_aligned_user_asm
 761:      { sb r0, zero; addi r0, r0, 1; addi r1, r1, -1 }
 77	bnzt r1, 1b
 782:      { move r0, r1; jrp lr }
 79	.pushsection __ex_table,"a"
 80	.word 1b, 2b
 81	.popsection
 82
 83.Lclear_aligned_user_asm:
 841:      { sw r0, zero; addi r0, r0, 4; addi r1, r1, -4 }
 85	bnzt r1, 1b
 862:      { move r0, r1; jrp lr }
 87	STD_ENDPROC(clear_user_asm)
 88	.pushsection __ex_table,"a"
 89	.word 1b, 2b
 90	.popsection
 91
 92/*
 93 * flush_user_asm takes the user target address in r0 and the
 94 * number of bytes to flush in r1.
 95 * It returns the number of unflushable bytes (hopefully zero) in r0.
 96 */
 97STD_ENTRY(flush_user_asm)
 98	bz r1, 2f
 99	{ movei r2, L2_CACHE_BYTES; add r1, r0, r1 }
100	{ sub r2, zero, r2; addi r1, r1, L2_CACHE_BYTES-1 }
101	{ and r0, r0, r2; and r1, r1, r2 }
102	{ sub r1, r1, r0 }
1031:      { flush r0; addi r1, r1, -CHIP_FLUSH_STRIDE() }
104	{ addi r0, r0, CHIP_FLUSH_STRIDE(); bnzt r1, 1b }
1052:      { move r0, r1; jrp lr }
106	STD_ENDPROC(flush_user_asm)
107	.pushsection __ex_table,"a"
108	.word 1b, 2b
109	.popsection
110
111/*
112 * inv_user_asm takes the user target address in r0 and the
113 * number of bytes to invalidate in r1.
114 * It returns the number of not inv'able bytes (hopefully zero) in r0.
115 */
116STD_ENTRY(inv_user_asm)
117	bz r1, 2f
118	{ movei r2, L2_CACHE_BYTES; add r1, r0, r1 }
119	{ sub r2, zero, r2; addi r1, r1, L2_CACHE_BYTES-1 }
120	{ and r0, r0, r2; and r1, r1, r2 }
121	{ sub r1, r1, r0 }
1221:      { inv r0; addi r1, r1, -CHIP_INV_STRIDE() }
123	{ addi r0, r0, CHIP_INV_STRIDE(); bnzt r1, 1b }
1242:      { move r0, r1; jrp lr }
125	STD_ENDPROC(inv_user_asm)
126	.pushsection __ex_table,"a"
127	.word 1b, 2b
128	.popsection
129
130/*
131 * finv_user_asm takes the user target address in r0 and the
132 * number of bytes to flush-invalidate in r1.
133 * It returns the number of not finv'able bytes (hopefully zero) in r0.
134 */
135STD_ENTRY(finv_user_asm)
136	bz r1, 2f
137	{ movei r2, L2_CACHE_BYTES; add r1, r0, r1 }
138	{ sub r2, zero, r2; addi r1, r1, L2_CACHE_BYTES-1 }
139	{ and r0, r0, r2; and r1, r1, r2 }
140	{ sub r1, r1, r0 }
1411:      { finv r0; addi r1, r1, -CHIP_FINV_STRIDE() }
142	{ addi r0, r0, CHIP_FINV_STRIDE(); bnzt r1, 1b }
1432:      { move r0, r1; jrp lr }
144	STD_ENDPROC(finv_user_asm)
145	.pushsection __ex_table,"a"
146	.word 1b, 2b
147	.popsection