arch/arm/vfp/vfphw.S - kernel/skids - Git at Google

 /*
  *  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
 @  r11 = CPU number
 @  lr  = failure return

 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_EN
 	bne	look_for_VFP_exceptions	@ VFP is already enabled

 	DBGSTR1 "enable %x", r10
 	ldr	r3, last_VFP_context_address
 	orr	r1, r1, #FPEXC_EN	@ user FPEXC has the enable bit set
 	ldr	r4, [r3, r11, lsl #2]	@ last_VFP_context pointer
 	bic	r5, r1, #FPEXC_EX	@ 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

 #ifndef CONFIG_SMP
 	@ Save out the current registers to the old thread state
 	@ No need for SMP since this is not done lazily

 	DBGSTR1	"save old state %p", r4
 	cmp	r4, #0
 	beq	no_old_VFP_process
 	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
 					@ and point r4 at the word at the
 					@ start of the register dump
 #endif

 no_old_VFP_process:
 	DBGSTR1	"load state %p", r10
 	str	r10, [r3, r11, lsl #2]	@ update the last_VFP_context 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

 check_for_exception:
 	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
 	str	r2, [sp, #S_PC]		@ retry the instruction
 #ifdef CONFIG_PREEMPT
 	get_thread_info	r10
 	ldr	r4, [r10, #TI_PREEMPT]	@ get preempt count
 	sub	r11, r4, #1		@ decrement it
 	str	r11, [r10, #TI_PREEMPT]
 #endif
 	mov	pc, 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

 	@ Fall into hand on to next handler - appropriate coproc instr
 	@ not recognised by VFP

 	DBGSTR	"not VFP"
 #ifdef CONFIG_PREEMPT
 	get_thread_info	r10
 	ldr	r4, [r10, #TI_PREEMPT]	@ get preempt count
 	sub	r11, r4, #1		@ decrement it
 	str	r11, [r10, #TI_PREEMPT]
 #endif
 	mov	pc, 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
 	mov	pc, lr
 ENDPROC(vfp_save_state)

 last_VFP_context_address:
 	.word	last_VFP_context

 	.macro	tbl_branch, base, tmp, shift
 #ifdef CONFIG_THUMB2_KERNEL
 	adr	\tmp, 1f
 	add	\tmp, \tmp, \base, lsl \shift
 	mov	pc, \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
 	mov	pc, lr
 	.org	1b + 8
 1:	mrc	p10, 0, r0, c\dr, c0, 4	@ fmrs	r0, s1
 	mov	pc, 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
 	mov	pc, lr
 	.org	1b + 8
 1:	mcr	p10, 0, r0, c\dr, c0, 4	@ fmsr	r0, s1
 	mov	pc, 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
 	mov	pc, 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
 	mov	pc, lr
 	.org	1b + 8
 	.endr
 #endif

 	@ virtual register 16 (or 32 if VFPv3) for compare with zero
 	mov	r0, #0
 	mov	r1, #0
 	mov	pc, 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
 	mov	pc, 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
 	mov	pc, lr
 	.org	1b + 8
 	.endr
 #endif
 ENDPROC(vfp_put_double)
	/*
	* 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
	@ r11 = CPU number
	@ lr = failure return

	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_EN
	bne look_for_VFP_exceptions @ VFP is already enabled

	DBGSTR1 "enable %x", r10
	ldr r3, last_VFP_context_address
	orr r1, r1, #FPEXC_EN @ user FPEXC has the enable bit set
	ldr r4, [r3, r11, lsl #2] @ last_VFP_context pointer
	bic r5, r1, #FPEXC_EX @ 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

	#ifndef CONFIG_SMP
	@ Save out the current registers to the old thread state
	@ No need for SMP since this is not done lazily

	DBGSTR1 "save old state %p", r4
	cmp r4, #0
	beq no_old_VFP_process
	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
	@ and point r4 at the word at the
	@ start of the register dump
	#endif

	no_old_VFP_process:
	DBGSTR1 "load state %p", r10
	str r10, [r3, r11, lsl #2] @ update the last_VFP_context 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

	check_for_exception:
	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
	str r2, [sp, #S_PC] @ retry the instruction
	#ifdef CONFIG_PREEMPT
	get_thread_info r10
	ldr r4, [r10, #TI_PREEMPT] @ get preempt count
	sub r11, r4, #1 @ decrement it
	str r11, [r10, #TI_PREEMPT]
	#endif
	mov pc, 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

	@ Fall into hand on to next handler - appropriate coproc instr
	@ not recognised by VFP

	DBGSTR "not VFP"
	#ifdef CONFIG_PREEMPT
	get_thread_info r10
	ldr r4, [r10, #TI_PREEMPT] @ get preempt count
	sub r11, r4, #1 @ decrement it
	str r11, [r10, #TI_PREEMPT]
	#endif
	mov pc, 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
	mov pc, lr
	ENDPROC(vfp_save_state)

	last_VFP_context_address:
	.word last_VFP_context

	.macro tbl_branch, base, tmp, shift
	#ifdef CONFIG_THUMB2_KERNEL
	adr \tmp, 1f
	add \tmp, \tmp, \base, lsl \shift
	mov pc, \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
	mov pc, lr
	.org 1b + 8
	1: mrc p10, 0, r0, c\dr, c0, 4 @ fmrs r0, s1
	mov pc, 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
	mov pc, lr
	.org 1b + 8
	1: mcr p10, 0, r0, c\dr, c0, 4 @ fmsr r0, s1
	mov pc, 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
	mov pc, 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
	mov pc, lr
	.org 1b + 8
	.endr
	#endif

	@ virtual register 16 (or 32 if VFPv3) for compare with zero
	mov r0, #0
	mov r1, #0
	mov pc, 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
	mov pc, 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
	mov pc, lr
	.org 1b + 8
	.endr
	#endif
	ENDPROC(vfp_put_double)