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217 lines
5.3 KiB
217 lines
5.3 KiB
/* |
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* arch/xtensa/lib/strncpy_user.S |
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* |
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* This file is subject to the terms and conditions of the GNU General |
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* Public License. See the file "COPYING" in the main directory of |
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* this archive for more details. |
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* |
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* Returns: -EFAULT if exception before terminator, N if the entire |
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* buffer filled, else strlen. |
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* |
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* Copyright (C) 2002 Tensilica Inc. |
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*/ |
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#include <linux/errno.h> |
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#include <linux/linkage.h> |
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#include <asm/asmmacro.h> |
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#include <asm/core.h> |
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/* |
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* char *__strncpy_user(char *dst, const char *src, size_t len) |
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*/ |
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#ifdef __XTENSA_EB__ |
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# define MASK0 0xff000000 |
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# define MASK1 0x00ff0000 |
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# define MASK2 0x0000ff00 |
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# define MASK3 0x000000ff |
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#else |
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# define MASK0 0x000000ff |
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# define MASK1 0x0000ff00 |
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# define MASK2 0x00ff0000 |
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# define MASK3 0xff000000 |
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#endif |
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# Register use |
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# a0/ return address |
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# a1/ stack pointer |
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# a2/ return value |
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# a3/ src |
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# a4/ len |
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# a5/ mask0 |
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# a6/ mask1 |
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# a7/ mask2 |
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# a8/ mask3 |
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# a9/ tmp |
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# a10/ tmp |
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# a11/ dst |
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# a12/ tmp |
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.text |
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ENTRY(__strncpy_user) |
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abi_entry_default |
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# a2/ dst, a3/ src, a4/ len |
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mov a11, a2 # leave dst in return value register |
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beqz a4, .Lret # if len is zero |
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movi a5, MASK0 # mask for byte 0 |
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movi a6, MASK1 # mask for byte 1 |
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movi a7, MASK2 # mask for byte 2 |
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movi a8, MASK3 # mask for byte 3 |
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bbsi.l a3, 0, .Lsrc1mod2 # if only 8-bit aligned |
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bbsi.l a3, 1, .Lsrc2mod4 # if only 16-bit aligned |
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.Lsrcaligned: # return here when src is word-aligned |
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srli a12, a4, 2 # number of loop iterations with 4B per loop |
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movi a9, 3 |
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bnone a11, a9, .Laligned |
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j .Ldstunaligned |
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.Lsrc1mod2: # src address is odd |
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EX(11f) l8ui a9, a3, 0 # get byte 0 |
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addi a3, a3, 1 # advance src pointer |
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EX(10f) s8i a9, a11, 0 # store byte 0 |
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beqz a9, .Lret # if byte 0 is zero |
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addi a11, a11, 1 # advance dst pointer |
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addi a4, a4, -1 # decrement len |
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beqz a4, .Lret # if len is zero |
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bbci.l a3, 1, .Lsrcaligned # if src is now word-aligned |
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.Lsrc2mod4: # src address is 2 mod 4 |
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EX(11f) l8ui a9, a3, 0 # get byte 0 |
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/* 1-cycle interlock */ |
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EX(10f) s8i a9, a11, 0 # store byte 0 |
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beqz a9, .Lret # if byte 0 is zero |
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addi a11, a11, 1 # advance dst pointer |
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addi a4, a4, -1 # decrement len |
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beqz a4, .Lret # if len is zero |
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EX(11f) l8ui a9, a3, 1 # get byte 0 |
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addi a3, a3, 2 # advance src pointer |
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EX(10f) s8i a9, a11, 0 # store byte 0 |
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beqz a9, .Lret # if byte 0 is zero |
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addi a11, a11, 1 # advance dst pointer |
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addi a4, a4, -1 # decrement len |
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bnez a4, .Lsrcaligned # if len is nonzero |
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.Lret: |
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sub a2, a11, a2 # compute strlen |
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abi_ret_default |
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/* |
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* dst is word-aligned, src is word-aligned |
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*/ |
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.align 4 # 1 mod 4 alignment for LOOPNEZ |
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.byte 0 # (0 mod 4 alignment for LBEG) |
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.Laligned: |
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#if XCHAL_HAVE_LOOPS |
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loopnez a12, .Loop1done |
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#else |
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beqz a12, .Loop1done |
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slli a12, a12, 2 |
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add a12, a12, a11 # a12 = end of last 4B chunck |
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#endif |
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.Loop1: |
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EX(11f) l32i a9, a3, 0 # get word from src |
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addi a3, a3, 4 # advance src pointer |
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bnone a9, a5, .Lz0 # if byte 0 is zero |
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bnone a9, a6, .Lz1 # if byte 1 is zero |
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bnone a9, a7, .Lz2 # if byte 2 is zero |
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EX(10f) s32i a9, a11, 0 # store word to dst |
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bnone a9, a8, .Lz3 # if byte 3 is zero |
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addi a11, a11, 4 # advance dst pointer |
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#if !XCHAL_HAVE_LOOPS |
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blt a11, a12, .Loop1 |
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#endif |
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.Loop1done: |
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bbci.l a4, 1, .L100 |
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# copy 2 bytes |
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EX(11f) l16ui a9, a3, 0 |
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addi a3, a3, 2 # advance src pointer |
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#ifdef __XTENSA_EB__ |
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bnone a9, a7, .Lz0 # if byte 2 is zero |
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bnone a9, a8, .Lz1 # if byte 3 is zero |
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#else |
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bnone a9, a5, .Lz0 # if byte 0 is zero |
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bnone a9, a6, .Lz1 # if byte 1 is zero |
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#endif |
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EX(10f) s16i a9, a11, 0 |
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addi a11, a11, 2 # advance dst pointer |
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.L100: |
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bbci.l a4, 0, .Lret |
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EX(11f) l8ui a9, a3, 0 |
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/* slot */ |
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EX(10f) s8i a9, a11, 0 |
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beqz a9, .Lret # if byte is zero |
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addi a11, a11, 1-3 # advance dst ptr 1, but also cancel |
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# the effect of adding 3 in .Lz3 code |
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/* fall thru to .Lz3 and "retw" */ |
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.Lz3: # byte 3 is zero |
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addi a11, a11, 3 # advance dst pointer |
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sub a2, a11, a2 # compute strlen |
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abi_ret_default |
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.Lz0: # byte 0 is zero |
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#ifdef __XTENSA_EB__ |
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movi a9, 0 |
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#endif /* __XTENSA_EB__ */ |
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EX(10f) s8i a9, a11, 0 |
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sub a2, a11, a2 # compute strlen |
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abi_ret_default |
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.Lz1: # byte 1 is zero |
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#ifdef __XTENSA_EB__ |
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extui a9, a9, 16, 16 |
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#endif /* __XTENSA_EB__ */ |
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EX(10f) s16i a9, a11, 0 |
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addi a11, a11, 1 # advance dst pointer |
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sub a2, a11, a2 # compute strlen |
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abi_ret_default |
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.Lz2: # byte 2 is zero |
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#ifdef __XTENSA_EB__ |
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extui a9, a9, 16, 16 |
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#endif /* __XTENSA_EB__ */ |
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EX(10f) s16i a9, a11, 0 |
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movi a9, 0 |
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EX(10f) s8i a9, a11, 2 |
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addi a11, a11, 2 # advance dst pointer |
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sub a2, a11, a2 # compute strlen |
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abi_ret_default |
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.align 4 # 1 mod 4 alignment for LOOPNEZ |
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.byte 0 # (0 mod 4 alignment for LBEG) |
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.Ldstunaligned: |
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/* |
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* for now just use byte copy loop |
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*/ |
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#if XCHAL_HAVE_LOOPS |
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loopnez a4, .Lunalignedend |
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#else |
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beqz a4, .Lunalignedend |
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add a12, a11, a4 # a12 = ending address |
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#endif /* XCHAL_HAVE_LOOPS */ |
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.Lnextbyte: |
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EX(11f) l8ui a9, a3, 0 |
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addi a3, a3, 1 |
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EX(10f) s8i a9, a11, 0 |
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beqz a9, .Lunalignedend |
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addi a11, a11, 1 |
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#if !XCHAL_HAVE_LOOPS |
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blt a11, a12, .Lnextbyte |
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#endif |
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.Lunalignedend: |
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sub a2, a11, a2 # compute strlen |
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abi_ret_default |
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ENDPROC(__strncpy_user) |
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.section .fixup, "ax" |
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.align 4 |
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/* For now, just return -EFAULT. Future implementations might |
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* like to clear remaining kernel space, like the fixup |
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* implementation in memset(). Thus, we differentiate between |
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* load/store fixups. */ |
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10: |
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11: |
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movi a2, -EFAULT |
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abi_ret_default
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