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6ebbf2ce43
ARMv6 and greater introduced a new instruction ("bx") which can be used
to return from function calls. Recent CPUs perform better when the
"bx lr" instruction is used rather than the "mov pc, lr" instruction,
and this sequence is strongly recommended to be used by the ARM
architecture manual (section A.4.1.1).
We provide a new macro "ret" with all its variants for the condition
code which will resolve to the appropriate instruction.
Rather than doing this piecemeal, and miss some instances, change all
the "mov pc" instances to use the new macro, with the exception of
the "movs" instruction and the kprobes code. This allows us to detect
the "mov pc, lr" case and fix it up - and also gives us the possibility
of deploying this for other registers depending on the CPU selection.
Reported-by: Will Deacon <will.deacon@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S
Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385
Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci
Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M
Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
139 lines
2.3 KiB
ArmAsm
139 lines
2.3 KiB
ArmAsm
/*
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* linux/arch/arm/kernel/debug.S
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*
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* Copyright (C) 1994-1999 Russell King
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* 32-bit debugging code
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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.text
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/*
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* Some debugging routines (useful if you've got MM problems and
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* printk isn't working). For DEBUGGING ONLY!!! Do not leave
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* references to these in a production kernel!
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*/
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#if !defined(CONFIG_DEBUG_SEMIHOSTING)
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#include CONFIG_DEBUG_LL_INCLUDE
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#endif
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#ifdef CONFIG_MMU
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.macro addruart_current, rx, tmp1, tmp2
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addruart \tmp1, \tmp2, \rx
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mrc p15, 0, \rx, c1, c0
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tst \rx, #1
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moveq \rx, \tmp1
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movne \rx, \tmp2
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.endm
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#else /* !CONFIG_MMU */
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.macro addruart_current, rx, tmp1, tmp2
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addruart \rx, \tmp1
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.endm
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#endif /* CONFIG_MMU */
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/*
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* Useful debugging routines
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*/
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ENTRY(printhex8)
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mov r1, #8
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b printhex
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ENDPROC(printhex8)
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ENTRY(printhex4)
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mov r1, #4
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b printhex
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ENDPROC(printhex4)
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ENTRY(printhex2)
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mov r1, #2
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printhex: adr r2, hexbuf
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add r3, r2, r1
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mov r1, #0
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strb r1, [r3]
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1: and r1, r0, #15
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mov r0, r0, lsr #4
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cmp r1, #10
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addlt r1, r1, #'0'
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addge r1, r1, #'a' - 10
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strb r1, [r3, #-1]!
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teq r3, r2
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bne 1b
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mov r0, r2
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b printascii
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ENDPROC(printhex2)
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hexbuf: .space 16
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.ltorg
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#ifndef CONFIG_DEBUG_SEMIHOSTING
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ENTRY(printascii)
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addruart_current r3, r1, r2
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b 2f
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1: waituart r2, r3
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senduart r1, r3
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busyuart r2, r3
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teq r1, #'\n'
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moveq r1, #'\r'
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beq 1b
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2: teq r0, #0
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ldrneb r1, [r0], #1
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teqne r1, #0
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bne 1b
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ret lr
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ENDPROC(printascii)
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ENTRY(printch)
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addruart_current r3, r1, r2
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mov r1, r0
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mov r0, #0
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b 1b
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ENDPROC(printch)
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#ifdef CONFIG_MMU
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ENTRY(debug_ll_addr)
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addruart r2, r3, ip
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str r2, [r0]
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str r3, [r1]
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ret lr
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ENDPROC(debug_ll_addr)
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#endif
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#else
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ENTRY(printascii)
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mov r1, r0
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mov r0, #0x04 @ SYS_WRITE0
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ARM( svc #0x123456 )
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THUMB( svc #0xab )
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ret lr
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ENDPROC(printascii)
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ENTRY(printch)
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adr r1, hexbuf
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strb r0, [r1]
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mov r0, #0x03 @ SYS_WRITEC
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ARM( svc #0x123456 )
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THUMB( svc #0xab )
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ret lr
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ENDPROC(printch)
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ENTRY(debug_ll_addr)
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mov r2, #0
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str r2, [r0]
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str r2, [r1]
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ret lr
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ENDPROC(debug_ll_addr)
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#endif
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