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Diffstat (limited to 'arch/xtensa/lib/usercopy.S')
| -rw-r--r-- | arch/xtensa/lib/usercopy.S | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/arch/xtensa/lib/usercopy.S b/arch/xtensa/lib/usercopy.S new file mode 100644 index 000000000000..265db2693cbd --- /dev/null +++ b/arch/xtensa/lib/usercopy.S @@ -0,0 +1,321 @@ +/* + * 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 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 loose 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 <xtensa/coreasm.h> + +#ifdef __XTENSA_EB__ +#define ALIGN(R, W0, W1) src R, W0, W1 +#define SSA8(R) ssa8b R +#else +#define ALIGN(R, W0, W1) src R, W1, W0 +#define SSA8(R) ssa8l R +#endif + +/* 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 + + + .text + .align 4 + .global __xtensa_copy_user + .type __xtensa_copy_user,@function +__xtensa_copy_user: + entry sp, 16 # minimal stack frame + # 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 + retw + +/* + * Destination is unaligned + */ + +.Ldst1mod2: # dst is only byte aligned + bltui a4, 7, .Lbytecopy # do short copies byte by byte + + # copy 1 byte + EX(l8ui, a6, a3, 0, l_fixup) + addi a3, a3, 1 + EX(s8i, a6, a5, 0, s_fixup) + 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(l8ui, a6, a3, 0, l_fixup) + EX(l8ui, a7, a3, 1, l_fixup) + addi a3, a3, 2 + EX(s8i, a6, a5, 0, s_fixup) + EX(s8i, a7, a5, 1, s_fixup) + 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(l8ui, a6, a3, 0, l_fixup) + addi a3, a3, 1 + EX(s8i, a6, a5, 0, s_fixup) + 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 + retw + +/* + * 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(l32i, a6, a3, 0, l_fixup) + EX(l32i, a7, a3, 4, l_fixup) + EX(s32i, a6, a5, 0, s_fixup) + EX(l32i, a6, a3, 8, l_fixup) + EX(s32i, a7, a5, 4, s_fixup) + EX(l32i, a7, a3, 12, l_fixup) + EX(s32i, a6, a5, 8, s_fixup) + addi a3, a3, 16 + EX(s32i, a7, a5, 12, s_fixup) + 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(l32i, a6, a3, 0, l_fixup) + EX(l32i, a7, a3, 4, l_fixup) + addi a3, a3, 8 + EX(s32i, a6, a5, 0, s_fixup) + EX(s32i, a7, a5, 4, s_fixup) + addi a5, a5, 8 +.L2: + bbci.l a4, 2, .L3 + # copy 4 bytes + EX(l32i, a6, a3, 0, l_fixup) + addi a3, a3, 4 + EX(s32i, a6, a5, 0, s_fixup) + addi a5, a5, 4 +.L3: + bbci.l a4, 1, .L4 + # copy 2 bytes + EX(l16ui, a6, a3, 0, l_fixup) + addi a3, a3, 2 + EX(s16i, a6, a5, 0, s_fixup) + addi a5, a5, 2 +.L4: + bbci.l a4, 0, .L5 + # copy 1 byte + EX(l8ui, a6, a3, 0, l_fixup) + EX(s8i, a6, a5, 0, s_fixup) +.L5: + movi a2, 0 # return success for len bytes copied + retw + +/* + * 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(l32i, a6, a3, 0, l_fixup) # load first word +#if XCHAL_HAVE_LOOPS + loopnez a7, .Loop2done +#else /* !XCHAL_HAVE_LOOPS */ + beqz a7, .Loop2done + slli a10, a7, 4 + add a10, a10, a3 # a10 = end of last 16B source chunk +#endif /* !XCHAL_HAVE_LOOPS */ +.Loop2: + EX(l32i, a7, a3, 4, l_fixup) + EX(l32i, a8, a3, 8, l_fixup) + ALIGN( a6, a6, a7) + EX(s32i, a6, a5, 0, s_fixup) + EX(l32i, a9, a3, 12, l_fixup) + ALIGN( a7, a7, a8) + EX(s32i, a7, a5, 4, s_fixup) + EX(l32i, a6, a3, 16, l_fixup) + ALIGN( a8, a8, a9) + EX(s32i, a8, a5, 8, s_fixup) + addi a3, a3, 16 + ALIGN( a9, a9, a6) + EX(s32i, a9, a5, 12, s_fixup) + addi a5, a5, 16 +#if !XCHAL_HAVE_LOOPS + blt a3, a10, .Loop2 +#endif /* !XCHAL_HAVE_LOOPS */ +.Loop2done: + bbci.l a4, 3, .L12 + # copy 8 bytes + EX(l32i, a7, a3, 4, l_fixup) + EX(l32i, a8, a3, 8, l_fixup) + ALIGN( a6, a6, a7) + EX(s32i, a6, a5, 0, s_fixup) + addi a3, a3, 8 + ALIGN( a7, a7, a8) + EX(s32i, a7, a5, 4, s_fixup) + addi a5, a5, 8 + mov a6, a8 +.L12: + bbci.l a4, 2, .L13 + # copy 4 bytes + EX(l32i, a7, a3, 4, l_fixup) + addi a3, a3, 4 + ALIGN( a6, a6, a7) + EX(s32i, a6, a5, 0, s_fixup) + 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(l8ui, a6, a3, 0, l_fixup) + EX(l8ui, a7, a3, 1, l_fixup) + addi a3, a3, 2 + EX(s8i, a6, a5, 0, s_fixup) + EX(s8i, a7, a5, 1, s_fixup) + addi a5, a5, 2 +.L14: + bbci.l a4, 0, .L15 + # copy 1 byte + EX(l8ui, a6, a3, 0, l_fixup) + EX(s8i, a6, a5, 0, s_fixup) +.L15: + movi a2, 0 # return success for len bytes copied + retw + + + .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) + * + * Clearing the remaining pieces of kernel memory plugs security + * holes. This functionality is the equivalent of the *_zeroing + * functions that some architectures provide. + */ + +.Lmemset: + .word memset + +s_fixup: + sub a2, a5, a2 /* a2 <-- bytes copied */ + sub a2, a11, a2 /* a2 <-- bytes not copied */ + retw + +l_fixup: + sub a2, a5, a2 /* a2 <-- bytes copied */ + sub a2, a11, a2 /* a2 <-- bytes not copied == return value */ + + /* void *memset(void *s, int c, size_t n); */ + mov a6, a5 /* s */ + movi a7, 0 /* c */ + mov a8, a2 /* n */ + l32r a4, .Lmemset + callx4 a4 + /* Ignore memset return value in a6. */ + /* a2 still contains bytes not copied. */ + retw + |