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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/arm/lib/copy_template.S
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+/*
+ * linux/arch/arm/lib/copy_template.s
+ *
+ * Code template for optimized memory copy functions
+ *
+ * Author: Nicolas Pitre
+ * Created: Sep 28, 2005
+ * Copyright: MontaVista Software, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * Theory of operation
+ * -------------------
+ *
+ * This file provides the core code for a forward memory copy used in
+ * the implementation of memcopy(), copy_to_user() and copy_from_user().
+ *
+ * The including file must define the following accessor macros
+ * according to the need of the given function:
+ *
+ * ldr1w ptr reg abort
+ *
+ * This loads one word from 'ptr', stores it in 'reg' and increments
+ * 'ptr' to the next word. The 'abort' argument is used for fixup tables.
+ *
+ * ldr4w ptr reg1 reg2 reg3 reg4 abort
+ * ldr8w ptr, reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
+ *
+ * This loads four or eight words starting from 'ptr', stores them
+ * in provided registers and increments 'ptr' past those words.
+ * The'abort' argument is used for fixup tables.
+ *
+ * ldr1b ptr reg cond abort
+ *
+ * Similar to ldr1w, but it loads a byte and increments 'ptr' one byte.
+ * It also must apply the condition code if provided, otherwise the
+ * "al" condition is assumed by default.
+ *
+ * str1w ptr reg abort
+ * str8w ptr reg1 reg2 reg3 reg4 reg5 reg6 reg7 reg8 abort
+ * str1b ptr reg cond abort
+ *
+ * Same as their ldr* counterparts, but data is stored to 'ptr' location
+ * rather than being loaded.
+ *
+ * enter reg1 reg2
+ *
+ * Preserve the provided registers on the stack plus any additional
+ * data as needed by the implementation including this code. Called
+ * upon code entry.
+ *
+ * usave reg1 reg2
+ *
+ * Unwind annotation macro is corresponding for 'enter' macro.
+ * It tell unwinder that preserved some provided registers on the stack
+ * and additional data by a prior 'enter' macro.
+ *
+ * exit reg1 reg2
+ *
+ * Restore registers with the values previously saved with the
+ * 'preserv' macro. Called upon code termination.
+ *
+ * LDR1W_SHIFT
+ * STR1W_SHIFT
+ *
+ * Correction to be applied to the "ip" register when branching into
+ * the ldr1w or str1w instructions (some of these macros may expand to
+ * than one 32bit instruction in Thumb-2)
+ */
+
+
+ UNWIND( .fnstart )
+ enter r4, lr
+ UNWIND( .fnend )
+
+ UNWIND( .fnstart )
+ usave r4, lr @ in first stmdb block
+
+ subs r2, r2, #4
+ blt 8f
+ ands ip, r0, #3
+ PLD( pld [r1, #0] )
+ bne 9f
+ ands ip, r1, #3
+ bne 10f
+
+1: subs r2, r2, #(28)
+ stmfd sp!, {r5 - r8}
+ UNWIND( .fnend )
+
+ UNWIND( .fnstart )
+ usave r4, lr
+ UNWIND( .save {r5 - r8} ) @ in second stmfd block
+ blt 5f
+
+ CALGN( ands ip, r0, #31 )
+ CALGN( rsb r3, ip, #32 )
+ CALGN( sbcnes r4, r3, r2 ) @ C is always set here
+ CALGN( bcs 2f )
+ CALGN( adr r4, 6f )
+ CALGN( subs r2, r2, r3 ) @ C gets set
+ CALGN( add pc, r4, ip )
+
+ PLD( pld [r1, #0] )
+2: PLD( subs r2, r2, #96 )
+ PLD( pld [r1, #28] )
+ PLD( blt 4f )
+ PLD( pld [r1, #60] )
+ PLD( pld [r1, #92] )
+
+3: PLD( pld [r1, #124] )
+4: ldr8w r1, r3, r4, r5, r6, r7, r8, ip, lr, abort=20f
+ subs r2, r2, #32
+ str8w r0, r3, r4, r5, r6, r7, r8, ip, lr, abort=20f
+ bge 3b
+ PLD( cmn r2, #96 )
+ PLD( bge 4b )
+
+5: ands ip, r2, #28
+ rsb ip, ip, #32
+#if LDR1W_SHIFT > 0
+ lsl ip, ip, #LDR1W_SHIFT
+#endif
+ addne pc, pc, ip @ C is always clear here
+ b 7f
+6:
+ .rept (1 << LDR1W_SHIFT)
+ W(nop)
+ .endr
+ ldr1w r1, r3, abort=20f
+ ldr1w r1, r4, abort=20f
+ ldr1w r1, r5, abort=20f
+ ldr1w r1, r6, abort=20f
+ ldr1w r1, r7, abort=20f
+ ldr1w r1, r8, abort=20f
+ ldr1w r1, lr, abort=20f
+
+#if LDR1W_SHIFT < STR1W_SHIFT
+ lsl ip, ip, #STR1W_SHIFT - LDR1W_SHIFT
+#elif LDR1W_SHIFT > STR1W_SHIFT
+ lsr ip, ip, #LDR1W_SHIFT - STR1W_SHIFT
+#endif
+ add pc, pc, ip
+ nop
+ .rept (1 << STR1W_SHIFT)
+ W(nop)
+ .endr
+ str1w r0, r3, abort=20f
+ str1w r0, r4, abort=20f
+ str1w r0, r5, abort=20f
+ str1w r0, r6, abort=20f
+ str1w r0, r7, abort=20f
+ str1w r0, r8, abort=20f
+ str1w r0, lr, abort=20f
+
+ CALGN( bcs 2b )
+
+7: ldmfd sp!, {r5 - r8}
+ UNWIND( .fnend ) @ end of second stmfd block
+
+ UNWIND( .fnstart )
+ usave r4, lr @ still in first stmdb block
+8: movs r2, r2, lsl #31
+ ldr1b r1, r3, ne, abort=21f
+ ldr1b r1, r4, cs, abort=21f
+ ldr1b r1, ip, cs, abort=21f
+ str1b r0, r3, ne, abort=21f
+ str1b r0, r4, cs, abort=21f
+ str1b r0, ip, cs, abort=21f
+
+ exit r4, pc
+
+9: rsb ip, ip, #4
+ cmp ip, #2
+ ldr1b r1, r3, gt, abort=21f
+ ldr1b r1, r4, ge, abort=21f
+ ldr1b r1, lr, abort=21f
+ str1b r0, r3, gt, abort=21f
+ str1b r0, r4, ge, abort=21f
+ subs r2, r2, ip
+ str1b r0, lr, abort=21f
+ blt 8b
+ ands ip, r1, #3
+ beq 1b
+
+10: bic r1, r1, #3
+ cmp ip, #2
+ ldr1w r1, lr, abort=21f
+ beq 17f
+ bgt 18f
+ UNWIND( .fnend )
+
+
+ .macro forward_copy_shift pull push
+
+ UNWIND( .fnstart )
+ usave r4, lr @ still in first stmdb block
+ subs r2, r2, #28
+ blt 14f
+
+ CALGN( ands ip, r0, #31 )
+ CALGN( rsb ip, ip, #32 )
+ CALGN( sbcnes r4, ip, r2 ) @ C is always set here
+ CALGN( subcc r2, r2, ip )
+ CALGN( bcc 15f )
+
+11: stmfd sp!, {r5 - r9}
+ UNWIND( .fnend )
+
+ UNWIND( .fnstart )
+ usave r4, lr
+ UNWIND( .save {r5 - r9} ) @ in new second stmfd block
+ PLD( pld [r1, #0] )
+ PLD( subs r2, r2, #96 )
+ PLD( pld [r1, #28] )
+ PLD( blt 13f )
+ PLD( pld [r1, #60] )
+ PLD( pld [r1, #92] )
+
+12: PLD( pld [r1, #124] )
+13: ldr4w r1, r4, r5, r6, r7, abort=19f
+ mov r3, lr, lspull #\pull
+ subs r2, r2, #32
+ ldr4w r1, r8, r9, ip, lr, abort=19f
+ orr r3, r3, r4, lspush #\push
+ mov r4, r4, lspull #\pull
+ orr r4, r4, r5, lspush #\push
+ mov r5, r5, lspull #\pull
+ orr r5, r5, r6, lspush #\push
+ mov r6, r6, lspull #\pull
+ orr r6, r6, r7, lspush #\push
+ mov r7, r7, lspull #\pull
+ orr r7, r7, r8, lspush #\push
+ mov r8, r8, lspull #\pull
+ orr r8, r8, r9, lspush #\push
+ mov r9, r9, lspull #\pull
+ orr r9, r9, ip, lspush #\push
+ mov ip, ip, lspull #\pull
+ orr ip, ip, lr, lspush #\push
+ str8w r0, r3, r4, r5, r6, r7, r8, r9, ip, , abort=19f
+ bge 12b
+ PLD( cmn r2, #96 )
+ PLD( bge 13b )
+
+ ldmfd sp!, {r5 - r9}
+ UNWIND( .fnend ) @ end of the second stmfd block
+
+ UNWIND( .fnstart )
+ usave r4, lr @ still in first stmdb block
+14: ands ip, r2, #28
+ beq 16f
+
+15: mov r3, lr, lspull #\pull
+ ldr1w r1, lr, abort=21f
+ subs ip, ip, #4
+ orr r3, r3, lr, lspush #\push
+ str1w r0, r3, abort=21f
+ bgt 15b
+ CALGN( cmp r2, #0 )
+ CALGN( bge 11b )
+
+16: sub r1, r1, #(\push / 8)
+ b 8b
+ UNWIND( .fnend )
+
+ .endm
+
+
+ forward_copy_shift pull=8 push=24
+
+17: forward_copy_shift pull=16 push=16
+
+18: forward_copy_shift pull=24 push=8
+
+
+/*
+ * Abort preamble and completion macros.
+ * If a fixup handler is required then those macros must surround it.
+ * It is assumed that the fixup code will handle the private part of
+ * the exit macro.
+ */
+
+ .macro copy_abort_preamble
+19: ldmfd sp!, {r5 - r9}
+ b 21f
+20: ldmfd sp!, {r5 - r8}
+21:
+ .endm
+
+ .macro copy_abort_end
+ ldmfd sp!, {r4, pc}
+ .endm
+