/*
* linux/arch/arm/vfp/vfphw.S
*
* Copyright (C) 2004 ARM Limited.
* Written by Deep Blue Solutions Limited.
*
* 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.
*
* This code is called from the kernel's undefined instruction trap.
* r9 holds the return address for successful handling.
* lr holds the return address for unrecognised instructions.
* r10 points at the start of the private FP workspace in the thread structure
* sp points to a struct pt_regs (as defined in include/asm/proc/ptrace.h)
*/
#include <linux/init.h>
#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/vfpmacros.h>
#include <linux/kern_levels.h>
#include <asm/assembler.h>
#include <asm/asm-offsets.h>
.macro DBGSTR, str
#ifdef DEBUG
stmfd sp!, {r0-r3, ip, lr}
ldr r0, =1f
bl printk
ldmfd sp!, {r0-r3, ip, lr}
.pushsection .rodata, "a"
1: .ascii KERN_DEBUG "VFP: \str\n"
.byte 0
.previous
#endif
.endm
.macro DBGSTR1, str, arg
#ifdef DEBUG
stmfd sp!, {r0-r3, ip, lr}
mov r1, \arg
ldr r0, =1f
bl printk
ldmfd sp!, {r0-r3, ip, lr}
.pushsection .rodata, "a"
1: .ascii KERN_DEBUG "VFP: \str\n"
.byte 0
.previous
#endif
.endm
.macro DBGSTR3, str, arg1, arg2, arg3
#ifdef DEBUG
stmfd sp!, {r0-r3, ip, lr}
mov r3, \arg3
mov r2, \arg2
mov r1, \arg1
ldr r0, =1f
bl printk
ldmfd sp!, {r0-r3, ip, lr}
.pushsection .rodata, "a"
1: .ascii KERN_DEBUG "VFP: \str\n"
.byte 0
.previous
#endif
.endm
@ VFP hardware support entry point.
@
@ r0 = instruction opcode (32-bit ARM or two 16-bit Thumb)
@ r2 = PC value to resume execution after successful emulation
@ r9 = normal "successful" return address
@ r10 = vfp_state union
@ r11 = CPU number
@ lr = unrecognised instruction return address
@ IRQs enabled.
ENTRY(vfp_support_entry)
DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10
ldr r3, [sp, #S_PSR] @ Neither lazy restore nor FP exceptions
and r3, r3, #MODE_MASK @ are supported in kernel mode
teq r3, #USR_MODE
bne vfp_kmode_exception @ Returns through lr
VFPFMRX r1, FPEXC @ Is the VFP enabled?
DBGSTR1 "fpexc %08x", r1
tst r1, #FPEXC_EN
bne look_for_VFP_exceptions @ VFP is already enabled
DBGSTR1 "enable %x", r10
ldr r3, vfp_current_hw_state_address
orr r1, r1, #FPEXC_EN @ user FPEXC has the enable bit set
ldr r4, [r3, r11, lsl #2] @ vfp_current_hw_state pointer
bic r5, r1, #FPEXC_EX @ make sure exceptions are disabled
cmp r4, r10 @ this thread owns the hw context?
#ifndef CONFIG_SMP
@ For UP, checking that this thread owns the hw context is
@ sufficient to determine that the hardware state is valid.
beq vfp_hw_state_valid
@ On UP, we lazily save the VFP context. As a different
@ thread wants ownership of the VFP hardware, save the old
@ state if there was a previous (valid) owner.
VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
@ exceptions, so we can get at the
@ rest of it
DBGSTR1 "save old state %p", r4
cmp r4, #0 @ if the vfp_current_hw_state is NULL
beq vfp_reload_hw @ then the hw state needs reloading
VFPFSTMIA r4, r5 @ save the working registers
VFPFMRX r5, FPSCR @ current status
#ifndef CONFIG_CPU_FEROCEON
tst r1, #FPEXC_EX @ is there additional state to save?
beq 1f
VFPFMRX r6, FPINST @ FPINST (only if FPEXC.EX is set)
tst r1, #FPEXC_FP2V @ is there an FPINST2 to read?
beq 1f
VFPFMRX r8, FPINST2 @ FPINST2 if needed (and present)
1:
#endif
stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
vfp_reload_hw:
#else
@ For SMP, if this thread does not own the hw context, then we
@ need to reload it. No need to save the old state as on SMP,
@ we always save the state when we switch away from a thread.
bne vfp_reload_hw
@ This thread has ownership of the current hardware context.
@ However, it may have been migrated to another CPU, in which
@ case the saved state is newer than the hardware context.
@ Check this by looking at the CPU number which the state was
@ last loaded onto.
ldr ip, [r10, #VFP_CPU]
teq ip, r11
beq vfp_hw_state_valid
vfp_reload_hw:
@ We're loading this threads state into the VFP hardware. Update
@ the CPU number which contains the most up to date VFP context.
str r11, [r10, #VFP_CPU]
VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
@ exceptions, so we can get at the
@ rest of it
#endif
DBGSTR1 "load state %p", r10
str r10, [r3, r11, lsl #2] @ update the vfp_current_hw_state pointer
@ Load the saved state back into the VFP
VFPFLDMIA r10, r5 @ reload the working registers while
@ FPEXC is in a safe state
ldmia r10, {r1, r5, r6, r8} @ load FPEXC, FPSCR, FPINST, FPINST2
#ifndef CONFIG_CPU_FEROCEON
tst r1, #FPEXC_EX @ is there additional state to restore?
beq 1f
VFPFMXR FPINST, r6 @ restore FPINST (only if FPEXC.EX is set)
tst r1, #FPEXC_FP2V @ is there an FPINST2 to write?
beq 1f
VFPFMXR FPINST2, r8 @ FPINST2 if needed (and present)
1:
#endif
VFPFMXR FPSCR, r5 @ restore status
@ The context stored in the VFP hardware is up to date with this thread
vfp_hw_state_valid:
tst r1, #FPEXC_EX
bne process_exception @ might as well handle the pending
@ exception before retrying branch
@ out before setting an FPEXC that
@ stops us reading stuff
VFPFMXR FPEXC, r1 @ Restore FPEXC last
sub r2, r2, #4 @ Retry current instruction - if Thumb
str r2, [sp, #S_PC] @ mode it's two 16-bit instructions,
@ else it's one 32-bit instruction, so
@ always subtract 4 from the following
@ instruction address.
dec_preempt_count_ti r10, r4
ret r9 @ we think we have handled things
look_for_VFP_exceptions:
@ Check for synchronous or asynchronous exception
tst r1, #FPEXC_EX | FPEXC_DEX
bne process_exception
@ On some implementations of the VFP subarch 1, setting FPSCR.IXE
@ causes all the CDP instructions to be bounced synchronously without
@ setting the FPEXC.EX bit
VFPFMRX r5, FPSCR
tst r5, #FPSCR_IXE
bne process_exception
tst r5, #FPSCR_LENGTH_MASK
beq skip
orr r1, r1, #FPEXC_DEX
b process_exception
skip:
@ Fall into hand on to next handler - appropriate coproc instr
@ not recognised by VFP
DBGSTR "not VFP"
dec_preempt_count_ti r10, r4
ret lr
process_exception:
DBGSTR "bounce"
mov r2, sp @ nothing stacked - regdump is at TOS
mov lr, r9 @ setup for a return to the user code.
@ Now call the C code to package up the bounce to the support code
@ r0 holds the trigger instruction
@ r1 holds the FPEXC value
@ r2 pointer to register dump
b VFP_bounce @ we have handled this - the support
@ code will raise an exception if
@ required. If not, the user code will
@ retry the faulted instruction
ENDPROC(vfp_support_entry)
ENTRY(vfp_save_state)
@ Save the current VFP state
@ r0 - save location
@ r1 - FPEXC
DBGSTR1 "save VFP state %p", r0
VFPFSTMIA r0, r2 @ save the working registers
VFPFMRX r2, FPSCR @ current status
tst r1, #FPEXC_EX @ is there additional state to save?
beq 1f
VFPFMRX r3, FPINST @ FPINST (only if FPEXC.EX is set)
tst r1, #FPEXC_FP2V @ is there an FPINST2 to read?
beq 1f
VFPFMRX r12, FPINST2 @ FPINST2 if needed (and present)
1:
stmia r0, {r1, r2, r3, r12} @ save FPEXC, FPSCR, FPINST, FPINST2
ret lr
ENDPROC(vfp_save_state)
.align
vfp_current_hw_state_address:
.word vfp_current_hw_state
.macro tbl_branch, base, tmp, shift
#ifdef CONFIG_THUMB2_KERNEL
adr \tmp, 1f
add \tmp, \tmp, \base, lsl \shift
ret \tmp
#else
add pc, pc, \base, lsl \shift
mov r0, r0
#endif
1:
.endm
ENTRY(vfp_get_float)
tbl_branch r0, r3, #3
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
1: mrc p10, 0, r0, c\dr, c0, 0 @ fmrs r0, s0
ret lr
.org 1b + 8
1: mrc p10, 0, r0, c\dr, c0, 4 @ fmrs r0, s1
ret lr
.org 1b + 8
.endr
ENDPROC(vfp_get_float)
ENTRY(vfp_put_float)
tbl_branch r1, r3, #3
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
1: mcr p10, 0, r0, c\dr, c0, 0 @ fmsr r0, s0
ret lr
.org 1b + 8
1: mcr p10, 0, r0, c\dr, c0, 4 @ fmsr r0, s1
ret lr
.org 1b + 8
.endr
ENDPROC(vfp_put_float)
ENTRY(vfp_get_double)
tbl_branch r0, r3, #3
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
1: fmrrd r0, r1, d\dr
ret lr
.org 1b + 8
.endr
#ifdef CONFIG_VFPv3
@ d16 - d31 registers
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
1: mrrc p11, 3, r0, r1, c\dr @ fmrrd r0, r1, d\dr
ret lr
.org 1b + 8
.endr
#endif
@ virtual register 16 (or 32 if VFPv3) for compare with zero
mov r0, #0
mov r1, #0
ret lr
ENDPROC(vfp_get_double)
ENTRY(vfp_put_double)
tbl_branch r2, r3, #3
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
1: fmdrr d\dr, r0, r1
ret lr
.org 1b + 8
.endr
#ifdef CONFIG_VFPv3
@ d16 - d31 registers
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
1: mcrr p11, 3, r0, r1, c\dr @ fmdrr r0, r1, d\dr
ret lr
.org 1b + 8
.endr
#endif
ENDPROC(vfp_put_double)
