ab3da15643
The support code in vfp_support_entry does not care whether the exception that caused it to be invoked occurred in kernel mode or in user mode. However, neither condition that could trigger this exception (lazy restore and VFP bounce to support code) is currently allowable in kernel mode. In either case, print a message describing the condition before letting the undefined instruction handler run its course and trigger an oops. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Acked-by: Nicolas Pitre <nico@linaro.org>
325 lines
8.9 KiB
ArmAsm
325 lines
8.9 KiB
ArmAsm
/*
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* linux/arch/arm/vfp/vfphw.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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* This code is called from the kernel's undefined instruction trap.
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* r9 holds the return address for successful handling.
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* lr holds the return address for unrecognised instructions.
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* r10 points at the start of the private FP workspace in the thread structure
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* sp points to a struct pt_regs (as defined in include/asm/proc/ptrace.h)
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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 <linux/kern_levels.h>
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#include "../kernel/entry-header.S"
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.macro DBGSTR, str
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#ifdef DEBUG
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stmfd sp!, {r0-r3, ip, lr}
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ldr r0, =1f
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bl printk
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ldmfd sp!, {r0-r3, ip, lr}
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.pushsection .rodata, "a"
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1: .ascii KERN_DEBUG "VFP: \str\n"
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.byte 0
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.previous
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#endif
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.endm
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.macro DBGSTR1, str, arg
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#ifdef DEBUG
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stmfd sp!, {r0-r3, ip, lr}
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mov r1, \arg
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ldr r0, =1f
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bl printk
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ldmfd sp!, {r0-r3, ip, lr}
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.pushsection .rodata, "a"
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1: .ascii KERN_DEBUG "VFP: \str\n"
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.byte 0
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.previous
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#endif
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.endm
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.macro DBGSTR3, str, arg1, arg2, arg3
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#ifdef DEBUG
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stmfd sp!, {r0-r3, ip, lr}
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mov r3, \arg3
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mov r2, \arg2
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mov r1, \arg1
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ldr r0, =1f
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bl printk
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ldmfd sp!, {r0-r3, ip, lr}
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.pushsection .rodata, "a"
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1: .ascii KERN_DEBUG "VFP: \str\n"
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.byte 0
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.previous
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#endif
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.endm
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@ VFP hardware support 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 = vfp_state union
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@ r11 = CPU number
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@ lr = unrecognised instruction return address
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@ IRQs enabled.
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ENTRY(vfp_support_entry)
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DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10
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ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exceptions
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and r3, r3, #MODE_MASK @ are supported in kernel mode
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teq r3, #USR_MODE
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bne vfp_kmode_exception @ Returns through lr
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VFPFMRX r1, FPEXC @ Is the VFP enabled?
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DBGSTR1 "fpexc %08x", r1
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tst r1, #FPEXC_EN
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bne look_for_VFP_exceptions @ VFP is already enabled
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DBGSTR1 "enable %x", r10
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ldr r3, vfp_current_hw_state_address
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orr r1, r1, #FPEXC_EN @ user FPEXC has the enable bit set
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ldr r4, [r3, r11, lsl #2] @ vfp_current_hw_state pointer
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bic r5, r1, #FPEXC_EX @ make sure exceptions are disabled
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cmp r4, r10 @ this thread owns the hw context?
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#ifndef CONFIG_SMP
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@ For UP, checking that this thread owns the hw context is
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@ sufficient to determine that the hardware state is valid.
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beq vfp_hw_state_valid
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@ On UP, we lazily save the VFP context. As a different
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@ thread wants ownership of the VFP hardware, save the old
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@ state if there was a previous (valid) owner.
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VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
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@ exceptions, so we can get at the
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@ rest of it
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DBGSTR1 "save old state %p", r4
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cmp r4, #0 @ if the vfp_current_hw_state is NULL
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beq vfp_reload_hw @ then the hw state needs reloading
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VFPFSTMIA r4, r5 @ save the working registers
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VFPFMRX r5, FPSCR @ current status
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#ifndef CONFIG_CPU_FEROCEON
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tst r1, #FPEXC_EX @ is there additional state to save?
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beq 1f
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VFPFMRX r6, FPINST @ FPINST (only if FPEXC.EX is set)
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tst r1, #FPEXC_FP2V @ is there an FPINST2 to read?
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beq 1f
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VFPFMRX r8, FPINST2 @ FPINST2 if needed (and present)
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1:
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#endif
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stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
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vfp_reload_hw:
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#else
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@ For SMP, if this thread does not own the hw context, then we
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@ need to reload it. No need to save the old state as on SMP,
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@ we always save the state when we switch away from a thread.
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bne vfp_reload_hw
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@ This thread has ownership of the current hardware context.
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@ However, it may have been migrated to another CPU, in which
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@ case the saved state is newer than the hardware context.
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@ Check this by looking at the CPU number which the state was
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@ last loaded onto.
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ldr ip, [r10, #VFP_CPU]
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teq ip, r11
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beq vfp_hw_state_valid
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vfp_reload_hw:
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@ We're loading this threads state into the VFP hardware. Update
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@ the CPU number which contains the most up to date VFP context.
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str r11, [r10, #VFP_CPU]
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VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
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@ exceptions, so we can get at the
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@ rest of it
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#endif
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DBGSTR1 "load state %p", r10
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str r10, [r3, r11, lsl #2] @ update the vfp_current_hw_state pointer
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@ Load the saved state back into the VFP
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VFPFLDMIA r10, r5 @ reload the working registers while
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@ FPEXC is in a safe state
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ldmia r10, {r1, r5, r6, r8} @ load FPEXC, FPSCR, FPINST, FPINST2
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#ifndef CONFIG_CPU_FEROCEON
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tst r1, #FPEXC_EX @ is there additional state to restore?
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beq 1f
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VFPFMXR FPINST, r6 @ restore FPINST (only if FPEXC.EX is set)
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tst r1, #FPEXC_FP2V @ is there an FPINST2 to write?
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beq 1f
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VFPFMXR FPINST2, r8 @ FPINST2 if needed (and present)
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1:
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#endif
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VFPFMXR FPSCR, r5 @ restore status
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@ The context stored in the VFP hardware is up to date with this thread
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vfp_hw_state_valid:
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tst r1, #FPEXC_EX
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bne process_exception @ might as well handle the pending
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@ exception before retrying branch
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@ out before setting an FPEXC that
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@ stops us reading stuff
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VFPFMXR FPEXC, r1 @ Restore FPEXC last
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sub r2, r2, #4 @ Retry current instruction - if Thumb
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str r2, [sp, #S_PC] @ mode it's two 16-bit instructions,
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@ else it's one 32-bit instruction, so
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@ always subtract 4 from the following
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@ instruction address.
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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, r9 @ we think we have handled things
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look_for_VFP_exceptions:
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@ Check for synchronous or asynchronous exception
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tst r1, #FPEXC_EX | FPEXC_DEX
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bne process_exception
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@ On some implementations of the VFP subarch 1, setting FPSCR.IXE
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@ causes all the CDP instructions to be bounced synchronously without
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@ setting the FPEXC.EX bit
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VFPFMRX r5, FPSCR
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tst r5, #FPSCR_IXE
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bne process_exception
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@ Fall into hand on to next handler - appropriate coproc instr
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@ not recognised by VFP
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DBGSTR "not VFP"
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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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process_exception:
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DBGSTR "bounce"
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mov r2, sp @ nothing stacked - regdump is at TOS
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mov lr, r9 @ setup for a return to the user code.
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@ Now call the C code to package up the bounce to the support code
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@ r0 holds the trigger instruction
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@ r1 holds the FPEXC value
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@ r2 pointer to register dump
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b VFP_bounce @ we have handled this - the support
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@ code will raise an exception if
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@ required. If not, the user code will
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@ retry the faulted instruction
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ENDPROC(vfp_support_entry)
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ENTRY(vfp_save_state)
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@ Save the current VFP state
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@ r0 - save location
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@ r1 - FPEXC
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DBGSTR1 "save VFP state %p", r0
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VFPFSTMIA r0, r2 @ save the working registers
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VFPFMRX r2, FPSCR @ current status
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tst r1, #FPEXC_EX @ is there additional state to save?
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beq 1f
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VFPFMRX r3, FPINST @ FPINST (only if FPEXC.EX is set)
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tst r1, #FPEXC_FP2V @ is there an FPINST2 to read?
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beq 1f
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VFPFMRX r12, FPINST2 @ FPINST2 if needed (and present)
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1:
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stmia r0, {r1, r2, r3, r12} @ save FPEXC, FPSCR, FPINST, FPINST2
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mov pc, lr
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ENDPROC(vfp_save_state)
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.align
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vfp_current_hw_state_address:
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.word vfp_current_hw_state
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.macro tbl_branch, base, tmp, shift
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#ifdef CONFIG_THUMB2_KERNEL
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adr \tmp, 1f
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add \tmp, \tmp, \base, lsl \shift
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mov pc, \tmp
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#else
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add pc, pc, \base, lsl \shift
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mov r0, r0
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#endif
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1:
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.endm
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ENTRY(vfp_get_float)
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tbl_branch r0, r3, #3
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: mrc p10, 0, r0, c\dr, c0, 0 @ fmrs r0, s0
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mov pc, lr
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.org 1b + 8
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1: mrc p10, 0, r0, c\dr, c0, 4 @ fmrs r0, s1
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mov pc, lr
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.org 1b + 8
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.endr
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ENDPROC(vfp_get_float)
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ENTRY(vfp_put_float)
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tbl_branch r1, r3, #3
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: mcr p10, 0, r0, c\dr, c0, 0 @ fmsr r0, s0
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mov pc, lr
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.org 1b + 8
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1: mcr p10, 0, r0, c\dr, c0, 4 @ fmsr r0, s1
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mov pc, lr
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.org 1b + 8
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.endr
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ENDPROC(vfp_put_float)
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ENTRY(vfp_get_double)
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tbl_branch r0, r3, #3
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: fmrrd r0, r1, d\dr
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mov pc, lr
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.org 1b + 8
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.endr
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#ifdef CONFIG_VFPv3
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@ d16 - d31 registers
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: mrrc p11, 3, r0, r1, c\dr @ fmrrd r0, r1, d\dr
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mov pc, lr
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.org 1b + 8
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.endr
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#endif
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@ virtual register 16 (or 32 if VFPv3) for compare with zero
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mov r0, #0
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mov r1, #0
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mov pc, lr
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ENDPROC(vfp_get_double)
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ENTRY(vfp_put_double)
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tbl_branch r2, r3, #3
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: fmdrr d\dr, r0, r1
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mov pc, lr
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.org 1b + 8
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.endr
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#ifdef CONFIG_VFPv3
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@ d16 - d31 registers
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.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
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1: mcrr p11, 3, r0, r1, c\dr @ fmdrr r0, r1, d\dr
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mov pc, lr
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.org 1b + 8
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.endr
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#endif
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ENDPROC(vfp_put_double)
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