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Diffstat (limited to 'arch/xtensa/lib/strncpy_user.S')
| -rw-r--r-- | arch/xtensa/lib/strncpy_user.S | 225 |
1 files changed, 225 insertions, 0 deletions
diff --git a/arch/xtensa/lib/strncpy_user.S b/arch/xtensa/lib/strncpy_user.S new file mode 100644 index 000000000..1ad0ecf45 --- /dev/null +++ b/arch/xtensa/lib/strncpy_user.S @@ -0,0 +1,225 @@ +/* + * arch/xtensa/lib/strncpy_user.S + * + * 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. + * + * Returns: -EFAULT if exception before terminator, N if the entire + * buffer filled, else strlen. + * + * Copyright (C) 2002 Tensilica Inc. + */ + +#include <variant/core.h> +#include <linux/errno.h> + +/* Load or store instructions that may cause exceptions use the EX macro. */ + +#define EX(insn,reg1,reg2,offset,handler) \ +9: insn reg1, reg2, offset; \ + .section __ex_table, "a"; \ + .word 9b, handler; \ + .previous + +/* + * char *__strncpy_user(char *dst, const char *src, size_t len) + */ + +#ifdef __XTENSA_EB__ +# define MASK0 0xff000000 +# define MASK1 0x00ff0000 +# define MASK2 0x0000ff00 +# define MASK3 0x000000ff +#else +# define MASK0 0x000000ff +# define MASK1 0x0000ff00 +# define MASK2 0x00ff0000 +# define MASK3 0xff000000 +#endif + +# Register use +# a0/ return address +# a1/ stack pointer +# a2/ return value +# a3/ src +# a4/ len +# a5/ mask0 +# a6/ mask1 +# a7/ mask2 +# a8/ mask3 +# a9/ tmp +# a10/ tmp +# a11/ dst +# a12/ tmp + +.text +.align 4 +.global __strncpy_user +.type __strncpy_user,@function +__strncpy_user: + entry sp, 16 # minimal stack frame + # a2/ dst, a3/ src, a4/ len + mov a11, a2 # leave dst in return value register + beqz a4, .Lret # if len is zero + movi a5, MASK0 # mask for byte 0 + movi a6, MASK1 # mask for byte 1 + movi a7, MASK2 # mask for byte 2 + movi a8, MASK3 # mask for byte 3 + bbsi.l a3, 0, .Lsrc1mod2 # if only 8-bit aligned + bbsi.l a3, 1, .Lsrc2mod4 # if only 16-bit aligned +.Lsrcaligned: # return here when src is word-aligned + srli a12, a4, 2 # number of loop iterations with 4B per loop + movi a9, 3 + bnone a11, a9, .Laligned + j .Ldstunaligned + +.Lsrc1mod2: # src address is odd + EX(l8ui, a9, a3, 0, fixup_l) # get byte 0 + addi a3, a3, 1 # advance src pointer + EX(s8i, a9, a11, 0, fixup_s) # store byte 0 + beqz a9, .Lret # if byte 0 is zero + addi a11, a11, 1 # advance dst pointer + addi a4, a4, -1 # decrement len + beqz a4, .Lret # if len is zero + bbci.l a3, 1, .Lsrcaligned # if src is now word-aligned + +.Lsrc2mod4: # src address is 2 mod 4 + EX(l8ui, a9, a3, 0, fixup_l) # get byte 0 + /* 1-cycle interlock */ + EX(s8i, a9, a11, 0, fixup_s) # store byte 0 + beqz a9, .Lret # if byte 0 is zero + addi a11, a11, 1 # advance dst pointer + addi a4, a4, -1 # decrement len + beqz a4, .Lret # if len is zero + EX(l8ui, a9, a3, 1, fixup_l) # get byte 0 + addi a3, a3, 2 # advance src pointer + EX(s8i, a9, a11, 0, fixup_s) # store byte 0 + beqz a9, .Lret # if byte 0 is zero + addi a11, a11, 1 # advance dst pointer + addi a4, a4, -1 # decrement len + bnez a4, .Lsrcaligned # if len is nonzero +.Lret: + sub a2, a11, a2 # compute strlen + retw + +/* + * dst is word-aligned, src is word-aligned + */ + .align 4 # 1 mod 4 alignment for LOOPNEZ + .byte 0 # (0 mod 4 alignment for LBEG) +.Laligned: +#if XCHAL_HAVE_LOOPS + loopnez a12, .Loop1done +#else + beqz a12, .Loop1done + slli a12, a12, 2 + add a12, a12, a11 # a12 = end of last 4B chunck +#endif +.Loop1: + EX(l32i, a9, a3, 0, fixup_l) # get word from src + addi a3, a3, 4 # advance src pointer + bnone a9, a5, .Lz0 # if byte 0 is zero + bnone a9, a6, .Lz1 # if byte 1 is zero + bnone a9, a7, .Lz2 # if byte 2 is zero + EX(s32i, a9, a11, 0, fixup_s) # store word to dst + bnone a9, a8, .Lz3 # if byte 3 is zero + addi a11, a11, 4 # advance dst pointer +#if !XCHAL_HAVE_LOOPS + blt a11, a12, .Loop1 +#endif + +.Loop1done: + bbci.l a4, 1, .L100 + # copy 2 bytes + EX(l16ui, a9, a3, 0, fixup_l) + addi a3, a3, 2 # advance src pointer +#ifdef __XTENSA_EB__ + bnone a9, a7, .Lz0 # if byte 2 is zero + bnone a9, a8, .Lz1 # if byte 3 is zero +#else + bnone a9, a5, .Lz0 # if byte 0 is zero + bnone a9, a6, .Lz1 # if byte 1 is zero +#endif + EX(s16i, a9, a11, 0, fixup_s) + addi a11, a11, 2 # advance dst pointer +.L100: + bbci.l a4, 0, .Lret + EX(l8ui, a9, a3, 0, fixup_l) + /* slot */ + EX(s8i, a9, a11, 0, fixup_s) + beqz a9, .Lret # if byte is zero + addi a11, a11, 1-3 # advance dst ptr 1, but also cancel + # the effect of adding 3 in .Lz3 code + /* fall thru to .Lz3 and "retw" */ + +.Lz3: # byte 3 is zero + addi a11, a11, 3 # advance dst pointer + sub a2, a11, a2 # compute strlen + retw +.Lz0: # byte 0 is zero +#ifdef __XTENSA_EB__ + movi a9, 0 +#endif /* __XTENSA_EB__ */ + EX(s8i, a9, a11, 0, fixup_s) + sub a2, a11, a2 # compute strlen + retw +.Lz1: # byte 1 is zero +#ifdef __XTENSA_EB__ + extui a9, a9, 16, 16 +#endif /* __XTENSA_EB__ */ + EX(s16i, a9, a11, 0, fixup_s) + addi a11, a11, 1 # advance dst pointer + sub a2, a11, a2 # compute strlen + retw +.Lz2: # byte 2 is zero +#ifdef __XTENSA_EB__ + extui a9, a9, 16, 16 +#endif /* __XTENSA_EB__ */ + EX(s16i, a9, a11, 0, fixup_s) + movi a9, 0 + EX(s8i, a9, a11, 2, fixup_s) + addi a11, a11, 2 # advance dst pointer + sub a2, a11, a2 # compute strlen + retw + + .align 4 # 1 mod 4 alignment for LOOPNEZ + .byte 0 # (0 mod 4 alignment for LBEG) +.Ldstunaligned: +/* + * for now just use byte copy loop + */ +#if XCHAL_HAVE_LOOPS + loopnez a4, .Lunalignedend +#else + beqz a4, .Lunalignedend + add a12, a11, a4 # a12 = ending address +#endif /* XCHAL_HAVE_LOOPS */ +.Lnextbyte: + EX(l8ui, a9, a3, 0, fixup_l) + addi a3, a3, 1 + EX(s8i, a9, a11, 0, fixup_s) + beqz a9, .Lunalignedend + addi a11, a11, 1 +#if !XCHAL_HAVE_LOOPS + blt a11, a12, .Lnextbyte +#endif + +.Lunalignedend: + sub a2, a11, a2 # compute strlen + retw + + + .section .fixup, "ax" + .align 4 + + /* For now, just return -EFAULT. Future implementations might + * like to clear remaining kernel space, like the fixup + * implementation in memset(). Thus, we differentiate between + * load/store fixups. */ + +fixup_s: +fixup_l: + movi a2, -EFAULT + retw + |