| /* |
| * 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 |
