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79a4fa341b
Unsigned branch instructions could be used for r2 to fix the wrong behavior when a negative length is passed to memcpy and memmove. This commit fixes the generic arm implementation of memcpy amd memmove.
333 lines
7.6 KiB
ArmAsm
333 lines
7.6 KiB
ArmAsm
/* Copyright (C) 2006-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by MontaVista Software, Inc. (written by Nicolas Pitre)
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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/* Thumb requires excessive IT insns here. */
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#define NO_THUMB
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#include <sysdep.h>
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#include <arm-features.h>
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/*
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* Data preload for architectures that support it (ARM V5TE and above)
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*/
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#if (!defined (__ARM_ARCH_2__) && !defined (__ARM_ARCH_3__) \
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&& !defined (__ARM_ARCH_3M__) && !defined (__ARM_ARCH_4__) \
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&& !defined (__ARM_ARCH_4T__) && !defined (__ARM_ARCH_5__) \
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&& !defined (__ARM_ARCH_5T__))
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#define PLD(code...) code
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#else
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#define PLD(code...)
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#endif
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/*
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* This can be used to enable code to cacheline align the source pointer.
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* Experiments on tested architectures (StrongARM and XScale) didn't show
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* this a worthwhile thing to do. That might be different in the future.
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*/
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//#define CALGN(code...) code
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#define CALGN(code...)
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/*
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* Endian independent macros for shifting bytes within registers.
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*/
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#ifndef __ARMEB__
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#define PULL lsr
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#define PUSH lsl
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#else
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#define PULL lsl
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#define PUSH lsr
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#endif
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.text
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.syntax unified
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/*
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* Prototype: void *memmove(void *dest, const void *src, size_t n);
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*
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* Note:
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*
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* If the memory regions don't overlap, we simply branch to memcpy which is
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* normally a bit faster. Otherwise the copy is done going downwards.
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*/
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ENTRY(memmove)
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subs ip, r0, r1
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cmphi r2, ip
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#if !IS_IN (libc)
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bls memcpy
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#else
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bls HIDDEN_JUMPTARGET(memcpy)
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#endif
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push {r0, r4, lr}
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cfi_adjust_cfa_offset (12)
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cfi_rel_offset (r4, 4)
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cfi_rel_offset (lr, 8)
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cfi_remember_state
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add r1, r1, r2
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add r0, r0, r2
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subs r2, r2, #4
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blo 8f
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ands ip, r0, #3
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PLD( pld [r1, #-4] )
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bne 9f
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ands ip, r1, #3
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bne 10f
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1: subs r2, r2, #(28)
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push {r5 - r8}
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cfi_adjust_cfa_offset (16)
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cfi_rel_offset (r5, 0)
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cfi_rel_offset (r6, 4)
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cfi_rel_offset (r7, 8)
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cfi_rel_offset (r8, 12)
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blo 5f
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CALGN( ands ip, r1, #31 )
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CALGN( sbcsne r4, ip, r2 ) @ C is always set here
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CALGN( bcs 2f )
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CALGN( adr r4, 6f )
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CALGN( subs r2, r2, ip ) @ C is set here
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#ifndef ARM_ALWAYS_BX
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CALGN( add pc, r4, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2))
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#else
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CALGN( add r4, r4, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2))
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CALGN( bx r4 )
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#endif
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PLD( pld [r1, #-4] )
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2: PLD( cmp r2, #96 )
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PLD( pld [r1, #-32] )
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PLD( blo 4f )
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PLD( pld [r1, #-64] )
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PLD( pld [r1, #-96] )
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3: PLD( pld [r1, #-128] )
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4: ldmdb r1!, {r3, r4, r5, r6, r7, r8, ip, lr}
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subs r2, r2, #32
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stmdb r0!, {r3, r4, r5, r6, r7, r8, ip, lr}
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bhs 3b
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5: ands ip, r2, #28
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rsb ip, ip, #32
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#ifndef ARM_ALWAYS_BX
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/* C is always clear here. */
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addne pc, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
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b 7f
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#else
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beq 7f
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push {r10}
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cfi_adjust_cfa_offset (4)
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cfi_rel_offset (r10, 0)
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0: add r10, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
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/* If alignment is not perfect, then there will be some
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padding (nop) instructions between this BX and label 6.
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The computation above assumed that two instructions
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later is exactly the right spot. */
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add r10, #(6f - (0b + PC_OFS))
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bx r10
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#endif
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.p2align ARM_BX_ALIGN_LOG2
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6: nop
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.p2align ARM_BX_ALIGN_LOG2
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ldr r3, [r1, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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ldr r4, [r1, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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ldr r5, [r1, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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ldr r6, [r1, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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ldr r7, [r1, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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ldr r8, [r1, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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ldr lr, [r1, #-4]!
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#ifndef ARM_ALWAYS_BX
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add pc, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
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nop
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#else
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0: add r10, pc, ip, lsl #(ARM_BX_ALIGN_LOG2 - 2)
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/* If alignment is not perfect, then there will be some
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padding (nop) instructions between this BX and label 66.
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The computation above assumed that two instructions
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later is exactly the right spot. */
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add r10, #(66f - (0b + PC_OFS))
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bx r10
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#endif
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.p2align ARM_BX_ALIGN_LOG2
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66: nop
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.p2align ARM_BX_ALIGN_LOG2
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str r3, [r0, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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str r4, [r0, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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str r5, [r0, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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str r6, [r0, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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str r7, [r0, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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str r8, [r0, #-4]!
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.p2align ARM_BX_ALIGN_LOG2
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str lr, [r0, #-4]!
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#ifdef ARM_ALWAYS_BX
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pop {r10}
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cfi_adjust_cfa_offset (-4)
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cfi_restore (r10)
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#endif
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CALGN( bcs 2b )
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7: pop {r5 - r8}
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cfi_adjust_cfa_offset (-16)
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cfi_restore (r5)
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cfi_restore (r6)
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cfi_restore (r7)
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cfi_restore (r8)
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8: movs r2, r2, lsl #31
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ldrbne r3, [r1, #-1]!
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ldrbcs r4, [r1, #-1]!
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ldrbcs ip, [r1, #-1]
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strbne r3, [r0, #-1]!
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strbcs r4, [r0, #-1]!
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strbcs ip, [r0, #-1]
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#if ((defined (__ARM_ARCH_4T__) && defined (__THUMB_INTERWORK__)) \
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|| defined (ARM_ALWAYS_BX))
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pop {r0, r4, lr}
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cfi_adjust_cfa_offset (-12)
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cfi_restore (r4)
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cfi_restore (lr)
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bx lr
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#else
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pop {r0, r4, pc}
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#endif
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cfi_restore_state
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9: cmp ip, #2
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ldrbgt r3, [r1, #-1]!
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ldrbge r4, [r1, #-1]!
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ldrb lr, [r1, #-1]!
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strbgt r3, [r0, #-1]!
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strbge r4, [r0, #-1]!
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subs r2, r2, ip
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strb lr, [r0, #-1]!
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blo 8b
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ands ip, r1, #3
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beq 1b
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10: bic r1, r1, #3
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cmp ip, #2
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ldr r3, [r1, #0]
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beq 17f
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blt 18f
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.macro backward_copy_shift push pull
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subs r2, r2, #28
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blo 14f
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CALGN( ands ip, r1, #31 )
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CALGN( rsb ip, ip, #32 )
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CALGN( sbcsne r4, ip, r2 ) @ C is always set here
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CALGN( subcc r2, r2, ip )
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CALGN( bcc 15f )
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11: push {r5 - r8, r10}
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cfi_adjust_cfa_offset (20)
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cfi_rel_offset (r5, 0)
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cfi_rel_offset (r6, 4)
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cfi_rel_offset (r7, 8)
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cfi_rel_offset (r8, 12)
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cfi_rel_offset (r10, 16)
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PLD( pld [r1, #-4] )
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PLD( cmp r2, #96 )
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PLD( pld [r1, #-32] )
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PLD( blo 13f )
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PLD( pld [r1, #-64] )
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PLD( pld [r1, #-96] )
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12: PLD( pld [r1, #-128] )
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13: ldmdb r1!, {r7, r8, r10, ip}
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mov lr, r3, PUSH #\push
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subs r2, r2, #32
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ldmdb r1!, {r3, r4, r5, r6}
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orr lr, lr, ip, PULL #\pull
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mov ip, ip, PUSH #\push
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orr ip, ip, r10, PULL #\pull
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mov r10, r10, PUSH #\push
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orr r10, r10, r8, PULL #\pull
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mov r8, r8, PUSH #\push
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orr r8, r8, r7, PULL #\pull
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mov r7, r7, PUSH #\push
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orr r7, r7, r6, PULL #\pull
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mov r6, r6, PUSH #\push
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orr r6, r6, r5, PULL #\pull
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mov r5, r5, PUSH #\push
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orr r5, r5, r4, PULL #\pull
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mov r4, r4, PUSH #\push
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orr r4, r4, r3, PULL #\pull
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stmdb r0!, {r4 - r8, r10, ip, lr}
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bhs 12b
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pop {r5 - r8, r10}
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cfi_adjust_cfa_offset (-20)
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cfi_restore (r5)
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cfi_restore (r6)
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cfi_restore (r7)
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cfi_restore (r8)
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cfi_restore (r10)
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14: ands ip, r2, #28
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beq 16f
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15: mov lr, r3, PUSH #\push
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ldr r3, [r1, #-4]!
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subs ip, ip, #4
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orr lr, lr, r3, PULL #\pull
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str lr, [r0, #-4]!
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bgt 15b
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CALGN( cmp r2, #0 )
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CALGN( bge 11b )
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16: add r1, r1, #(\pull / 8)
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b 8b
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.endm
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backward_copy_shift push=8 pull=24
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17: backward_copy_shift push=16 pull=16
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18: backward_copy_shift push=24 pull=8
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END(memmove)
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libc_hidden_builtin_def (memmove)
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