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1ca8bf6f7b
Certain ARM CPU implementations (e.g. Cortex-A15) may not raise a floating- point exception whenever deprecated short-vector VFP instructions are executed. Instead these instructions are treated as UNALLOCATED. Change the VFP exception handling code to emulate short-vector instructions even if FPEXC exception bits are not set. Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org> Tested-by: Will Deacon <will.deacon@arm.com> Tested-by: Rob Clark <robdclark@gmail.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
324 lines
8.7 KiB
ArmAsm
324 lines
8.7 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 <linux/init.h>
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#include <linux/linkage.h>
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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 <asm/assembler.h>
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#include <asm/asm-offsets.h>
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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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dec_preempt_count_ti r10, r4
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ret 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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tst r5, #FPSCR_LENGTH_MASK
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beq skip
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orr r1, r1, #FPEXC_DEX
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b process_exception
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skip:
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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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dec_preempt_count_ti r10, r4
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ret 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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ret 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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ret \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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ret 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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ret 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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ret 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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ret 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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ret 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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ret 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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ret 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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ret 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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ret 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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