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| /*
| * arch/xtensa/lib/usercopy.S
| *
| * Copy to/from user space (derived from arch/xtensa/lib/hal/memcopy.S)
| *
| * DO NOT COMBINE this function with <arch/xtensa/lib/hal/memcopy.S>.
| * It needs to remain separate and distinct. The hal files are part
| * of the Xtensa link-time HAL, and those files may differ per
| * processor configuration. Patching the kernel for another
| * processor configuration includes replacing the hal files, and we
| * could lose the special functionality for accessing user-space
| * memory during such a patch. We sacrifice a little code space here
| * in favor to simplify code maintenance.
| *
| * This file is subject to the terms and conditions of the GNU General
| * Public License. See the file "COPYING" in the main directory of
| * this archive for more details.
| *
| * Copyright (C) 2002 Tensilica Inc.
| */
|
|
| /*
| * size_t __xtensa_copy_user (void *dst, const void *src, size_t len);
| *
| * The returned value is the number of bytes not copied. Implies zero
| * is success.
| *
| * The general case algorithm is as follows:
| * If the destination and source are both aligned,
| * do 16B chunks with a loop, and then finish up with
| * 8B, 4B, 2B, and 1B copies conditional on the length.
| * If destination is aligned and source unaligned,
| * do the same, but use SRC to align the source data.
| * If destination is unaligned, align it by conditionally
| * copying 1B and 2B and then retest.
| * This code tries to use fall-through braches for the common
| * case of aligned destinations (except for the branches to
| * the alignment label).
| *
| * Register use:
| * a0/ return address
| * a1/ stack pointer
| * a2/ return value
| * a3/ src
| * a4/ length
| * a5/ dst
| * a6/ tmp
| * a7/ tmp
| * a8/ tmp
| * a9/ tmp
| * a10/ tmp
| * a11/ original length
| */
|
| #include <linux/linkage.h>
| #include <asm/asmmacro.h>
| #include <asm/core.h>
|
| .text
| ENTRY(__xtensa_copy_user)
|
| abi_entry_default
| # a2/ dst, a3/ src, a4/ len
| mov a5, a2 # copy dst so that a2 is return value
| mov a11, a4 # preserve original len for error case
| .Lcommon:
| bbsi.l a2, 0, .Ldst1mod2 # if dst is 1 mod 2
| bbsi.l a2, 1, .Ldst2mod4 # if dst is 2 mod 4
| .Ldstaligned: # return here from .Ldstunaligned when dst is aligned
| srli a7, a4, 4 # number of loop iterations with 16B
| # per iteration
| movi a8, 3 # if source is also aligned,
| bnone a3, a8, .Laligned # then use word copy
| __ssa8 a3 # set shift amount from byte offset
| bnez a4, .Lsrcunaligned
| movi a2, 0 # return success for len==0
| abi_ret_default
|
| /*
| * Destination is unaligned
| */
|
| .Ldst1mod2: # dst is only byte aligned
| bltui a4, 7, .Lbytecopy # do short copies byte by byte
|
| # copy 1 byte
| EX(10f) l8ui a6, a3, 0
| addi a3, a3, 1
| EX(10f) s8i a6, a5, 0
| addi a5, a5, 1
| addi a4, a4, -1
| bbci.l a5, 1, .Ldstaligned # if dst is now aligned, then
| # return to main algorithm
| .Ldst2mod4: # dst 16-bit aligned
| # copy 2 bytes
| bltui a4, 6, .Lbytecopy # do short copies byte by byte
| EX(10f) l8ui a6, a3, 0
| EX(10f) l8ui a7, a3, 1
| addi a3, a3, 2
| EX(10f) s8i a6, a5, 0
| EX(10f) s8i a7, a5, 1
| addi a5, a5, 2
| addi a4, a4, -2
| j .Ldstaligned # dst is now aligned, return to main algorithm
|
| /*
| * Byte by byte copy
| */
| .align 4
| .byte 0 # 1 mod 4 alignment for LOOPNEZ
| # (0 mod 4 alignment for LBEG)
| .Lbytecopy:
| #if XCHAL_HAVE_LOOPS
| loopnez a4, .Lbytecopydone
| #else /* !XCHAL_HAVE_LOOPS */
| beqz a4, .Lbytecopydone
| add a7, a3, a4 # a7 = end address for source
| #endif /* !XCHAL_HAVE_LOOPS */
| .Lnextbyte:
| EX(10f) l8ui a6, a3, 0
| addi a3, a3, 1
| EX(10f) s8i a6, a5, 0
| addi a5, a5, 1
| #if !XCHAL_HAVE_LOOPS
| blt a3, a7, .Lnextbyte
| #endif /* !XCHAL_HAVE_LOOPS */
| .Lbytecopydone:
| movi a2, 0 # return success for len bytes copied
| abi_ret_default
|
| /*
| * Destination and source are word-aligned.
| */
| # copy 16 bytes per iteration for word-aligned dst and word-aligned src
| .align 4 # 1 mod 4 alignment for LOOPNEZ
| .byte 0 # (0 mod 4 alignment for LBEG)
| .Laligned:
| #if XCHAL_HAVE_LOOPS
| loopnez a7, .Loop1done
| #else /* !XCHAL_HAVE_LOOPS */
| beqz a7, .Loop1done
| slli a8, a7, 4
| add a8, a8, a3 # a8 = end of last 16B source chunk
| #endif /* !XCHAL_HAVE_LOOPS */
| .Loop1:
| EX(10f) l32i a6, a3, 0
| EX(10f) l32i a7, a3, 4
| EX(10f) s32i a6, a5, 0
| EX(10f) l32i a6, a3, 8
| EX(10f) s32i a7, a5, 4
| EX(10f) l32i a7, a3, 12
| EX(10f) s32i a6, a5, 8
| addi a3, a3, 16
| EX(10f) s32i a7, a5, 12
| addi a5, a5, 16
| #if !XCHAL_HAVE_LOOPS
| blt a3, a8, .Loop1
| #endif /* !XCHAL_HAVE_LOOPS */
| .Loop1done:
| bbci.l a4, 3, .L2
| # copy 8 bytes
| EX(10f) l32i a6, a3, 0
| EX(10f) l32i a7, a3, 4
| addi a3, a3, 8
| EX(10f) s32i a6, a5, 0
| EX(10f) s32i a7, a5, 4
| addi a5, a5, 8
| .L2:
| bbci.l a4, 2, .L3
| # copy 4 bytes
| EX(10f) l32i a6, a3, 0
| addi a3, a3, 4
| EX(10f) s32i a6, a5, 0
| addi a5, a5, 4
| .L3:
| bbci.l a4, 1, .L4
| # copy 2 bytes
| EX(10f) l16ui a6, a3, 0
| addi a3, a3, 2
| EX(10f) s16i a6, a5, 0
| addi a5, a5, 2
| .L4:
| bbci.l a4, 0, .L5
| # copy 1 byte
| EX(10f) l8ui a6, a3, 0
| EX(10f) s8i a6, a5, 0
| .L5:
| movi a2, 0 # return success for len bytes copied
| abi_ret_default
|
| /*
| * Destination is aligned, Source is unaligned
| */
|
| .align 4
| .byte 0 # 1 mod 4 alignement for LOOPNEZ
| # (0 mod 4 alignment for LBEG)
| .Lsrcunaligned:
| # copy 16 bytes per iteration for word-aligned dst and unaligned src
| and a10, a3, a8 # save unalignment offset for below
| sub a3, a3, a10 # align a3 (to avoid sim warnings only; not needed for hardware)
| EX(10f) l32i a6, a3, 0 # load first word
| #if XCHAL_HAVE_LOOPS
| loopnez a7, .Loop2done
| #else /* !XCHAL_HAVE_LOOPS */
| beqz a7, .Loop2done
| slli a12, a7, 4
| add a12, a12, a3 # a12 = end of last 16B source chunk
| #endif /* !XCHAL_HAVE_LOOPS */
| .Loop2:
| EX(10f) l32i a7, a3, 4
| EX(10f) l32i a8, a3, 8
| __src_b a6, a6, a7
| EX(10f) s32i a6, a5, 0
| EX(10f) l32i a9, a3, 12
| __src_b a7, a7, a8
| EX(10f) s32i a7, a5, 4
| EX(10f) l32i a6, a3, 16
| __src_b a8, a8, a9
| EX(10f) s32i a8, a5, 8
| addi a3, a3, 16
| __src_b a9, a9, a6
| EX(10f) s32i a9, a5, 12
| addi a5, a5, 16
| #if !XCHAL_HAVE_LOOPS
| blt a3, a12, .Loop2
| #endif /* !XCHAL_HAVE_LOOPS */
| .Loop2done:
| bbci.l a4, 3, .L12
| # copy 8 bytes
| EX(10f) l32i a7, a3, 4
| EX(10f) l32i a8, a3, 8
| __src_b a6, a6, a7
| EX(10f) s32i a6, a5, 0
| addi a3, a3, 8
| __src_b a7, a7, a8
| EX(10f) s32i a7, a5, 4
| addi a5, a5, 8
| mov a6, a8
| .L12:
| bbci.l a4, 2, .L13
| # copy 4 bytes
| EX(10f) l32i a7, a3, 4
| addi a3, a3, 4
| __src_b a6, a6, a7
| EX(10f) s32i a6, a5, 0
| addi a5, a5, 4
| mov a6, a7
| .L13:
| add a3, a3, a10 # readjust a3 with correct misalignment
| bbci.l a4, 1, .L14
| # copy 2 bytes
| EX(10f) l8ui a6, a3, 0
| EX(10f) l8ui a7, a3, 1
| addi a3, a3, 2
| EX(10f) s8i a6, a5, 0
| EX(10f) s8i a7, a5, 1
| addi a5, a5, 2
| .L14:
| bbci.l a4, 0, .L15
| # copy 1 byte
| EX(10f) l8ui a6, a3, 0
| EX(10f) s8i a6, a5, 0
| .L15:
| movi a2, 0 # return success for len bytes copied
| abi_ret_default
|
| ENDPROC(__xtensa_copy_user)
|
| .section .fixup, "ax"
| .align 4
|
| /* a2 = original dst; a5 = current dst; a11= original len
| * bytes_copied = a5 - a2
| * retval = bytes_not_copied = original len - bytes_copied
| * retval = a11 - (a5 - a2)
| */
|
|
| 10:
| sub a2, a5, a2 /* a2 <-- bytes copied */
| sub a2, a11, a2 /* a2 <-- bytes not copied */
| abi_ret_default
|
|
