forked from Minki/linux
f27d6e1723
Commit d3f79584a8 ("ARM: cleanup undefined instruction entry code")
improved the register scheduling when handling undefined instructions.
A side effect of this is that r5 is now used as a temporary, whilst the
VFP probing code relies on r5 containing a non-zero value when VFP is
not supported.
This patch fixes the VFP detection code so that we don't rely on the
contents of r5. Without this patch, Linux dies loudly on CPUs without
VFP support.
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
72 lines
1.8 KiB
ArmAsm
72 lines
1.8 KiB
ArmAsm
/*
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* linux/arch/arm/vfp/entry.S
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*
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* Copyright (C) 2004 ARM Limited.
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* Written by Deep Blue Solutions Limited.
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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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#include <asm/thread_info.h>
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#include <asm/vfpmacros.h>
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#include "../kernel/entry-header.S"
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@ VFP entry point.
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@
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@ r0 = instruction opcode (32-bit ARM or two 16-bit Thumb)
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@ r2 = PC value to resume execution after successful emulation
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@ r9 = normal "successful" return address
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@ r10 = this threads thread_info structure
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@ lr = unrecognised instruction return address
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@ IRQs disabled.
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@
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ENTRY(do_vfp)
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#ifdef CONFIG_PREEMPT_COUNT
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ldr r4, [r10, #TI_PREEMPT] @ get preempt count
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add r11, r4, #1 @ increment it
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str r11, [r10, #TI_PREEMPT]
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#endif
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enable_irq
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ldr r4, .LCvfp
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ldr r11, [r10, #TI_CPU] @ CPU number
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add r10, r10, #TI_VFPSTATE @ r10 = workspace
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ldr pc, [r4] @ call VFP entry point
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ENDPROC(do_vfp)
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ENTRY(vfp_null_entry)
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#ifdef CONFIG_PREEMPT_COUNT
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get_thread_info r10
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ldr r4, [r10, #TI_PREEMPT] @ get preempt count
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sub r11, r4, #1 @ decrement it
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str r11, [r10, #TI_PREEMPT]
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#endif
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mov pc, lr
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ENDPROC(vfp_null_entry)
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.align 2
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.LCvfp:
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.word vfp_vector
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@ This code is called if the VFP does not exist. It needs to flag the
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@ failure to the VFP initialisation code.
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__INIT
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ENTRY(vfp_testing_entry)
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#ifdef CONFIG_PREEMPT_COUNT
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get_thread_info r10
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ldr r4, [r10, #TI_PREEMPT] @ get preempt count
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sub r11, r4, #1 @ decrement it
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str r11, [r10, #TI_PREEMPT]
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#endif
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ldr r0, VFP_arch_address
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str r0, [r0] @ set to non-zero value
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mov pc, r9 @ we have handled the fault
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ENDPROC(vfp_testing_entry)
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.align 2
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VFP_arch_address:
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.word VFP_arch
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__FINIT
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