/*
* 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 <asm/thread_info.h>
#include <asm/vfpmacros.h>
#include "../kernel/entry-header.S"
.macro DBGSTR, str
#ifdef DEBUG
stmfd sp!, {r0-r3, ip, lr}
add r0, pc, #4
bl printk
b 1f
.asciz "<7>VFP: \str\n"
.balign 4
1: ldmfd sp!, {r0-r3, ip, lr}
#endif
.endm
.macro DBGSTR1, str, arg
#ifdef DEBUG
stmfd sp!, {r0-r3, ip, lr}
mov r1, \arg
add r0, pc, #4
bl printk
b 1f
.asciz "<7>VFP: \str\n"
.balign 4
1: ldmfd sp!, {r0-r3, ip, lr}
#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
add r0, pc, #4
bl printk
b 1f
.asciz "<7>VFP: \str\n"
.balign 4
1: ldmfd sp!, {r0-r3, ip, lr}
#endif
.endm
@ VFP hardware support entry point.
@
@ r0 = faulted instruction
@ r2 = faulted PC+4
@ r9 = successful return
@ r10 = vfp_state union
@ lr = failure return
.globl vfp_support_entry
vfp_support_entry:
DBGSTR3 "instr %08x pc %08x state %p", r0, r2, r10
VFPFMRX r1, FPEXC @ Is the VFP enabled?
DBGSTR1 "fpexc %08x", r1
tst r1, #FPEXC_ENABLE
bne look_for_VFP_exceptions @ VFP is already enabled
DBGSTR1 "enable %x", r10
ldr r3, last_VFP_context_address
orr r1, r1, #FPEXC_ENABLE @ user FPEXC has the enable bit set
ldr r4, [r3] @ last_VFP_context pointer
bic r5, r1, #FPEXC_EXCEPTION @ make sure exceptions are disabled
cmp r4, r10
beq check_for_exception @ we are returning to the same
@ process, so the registers are
@ still there. In this case, we do
@ not want to drop a pending exception.
VFPFMXR FPEXC, r5 @ enable VFP, disable any pending
@ exceptions, so we can get at the
@ rest of it
@ Save out the current registers to the old thread state
DBGSTR1 "save old state %p", r4
cmp r4, #0
beq no_old_VFP_process
VFPFMRX r5, FPSCR @ current status
VFPFMRX r6, FPINST @ FPINST (always there, rev0 onwards)
tst r1, #FPEXC_FPV2 @ is there an FPINST2 to read?
VFPFMRX r8, FPINST2, NE @ FPINST2 if needed - avoids reading
@ nonexistant reg on rev0
VFPFSTMIA r4 @ save the working registers
add r4, r4, #8*16+4
stmia r4, {r1, r5, r6, r8} @ save FPEXC, FPSCR, FPINST, FPINST2
@ and point r4 at the word at the
@ start of the register dump
no_old_VFP_process:
DBGSTR1 "load state %p", r10
str r10, [r3] @ update the last_VFP_context pointer
@ Load the saved state back into the VFP
add r4, r10, #8*16+4
ldmia r4, {r1, r5, r6, r8} @ load FPEXC, FPSCR, FPINST, FPINST2
VFPFLDMIA r10 @ reload the working registers while
@ FPEXC is in a safe state
tst r1, #FPEXC_FPV2 @ is there an FPINST2 to write?
VFPFMXR FPINST2, r8, NE @ FPINST2 if needed - avoids writing
@ nonexistant reg on rev0
VFPFMXR FPINST, r6
VFPFMXR FPSCR, r5 @ restore status
check_for_exception:
tst r1, #FPEXC_EXCEPTION
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
str r2, [sp, #S_PC] @ retry the instruction
mov pc, r9 @ we think we have handled things
look_for_VFP_exceptions:
tst r1, #FPEXC_EXCEPTION
bne process_exception
VFPFMRX r5, FPSCR
tst r5, #FPSCR_IXE @ IXE doesn't set FPEXC_EXCEPTION !
bne process_exception
@ Fall into hand on to next handler - appropriate coproc instr
@ not recognised by VFP
DBGSTR "not VFP"
mov pc, lr
process_exception:
DBGSTR "bounce"
sub r2, r2, #4
str r2, [sp, #S_PC] @ retry the instruction on exit from
@ the imprecise exception handling in
@ the support code
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 VFP9_bounce @ we have handled this - the support
@ code will raise an exception if
@ required. If not, the user code will
@ retry the faulted instruction
last_VFP_context_address:
.word last_VFP_context
.globl vfp_get_float
vfp_get_float:
add pc, pc, r0, lsl #3
mov r0, r0
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
mrc p10, 0, r0, c\dr, c0, 0 @ fmrs r0, s0
mov pc, lr
mrc p10, 0, r0, c\dr, c0, 4 @ fmrs r0, s1
mov pc, lr
.endr
.globl vfp_put_float
vfp_put_float:
add pc, pc, r0, lsl #3
mov r0, r0
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
mcr p10, 0, r1, c\dr, c0, 0 @ fmsr r0, s0
mov pc, lr
mcr p10, 0, r1, c\dr, c0, 4 @ fmsr r0, s1
mov pc, lr
.endr
.globl vfp_get_double
vfp_get_double:
mov r0, r0, lsr #1
add pc, pc, r0, lsl #3
mov r0, r0
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
mrrc p10, 1, r0, r1, c\dr @ fmrrd r0, r1, d\dr
mov pc, lr
.endr
@ virtual register 16 for compare with zero
mov r0, #0
mov r1, #0
mov pc, lr
.globl vfp_put_double
vfp_put_double:
mov r0, r0, lsr #1
add pc, pc, r0, lsl #3
mov r0, r0
.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
mcrr p10, 1, r1, r2, c\dr @ fmrrd r1, r2, d\dr
mov pc, lr
.endr
