arch/arm/vfp/vfphw.S - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  *  linux/arch/arm/vfp/vfphw.S
  *
  *  Copyright (C) 2004 ARM Limited.
  *  Written by Deep Blue Solutions Limited.
  *
  * 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

 	.fpu	vfpv2
 	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.
 	local_bh_enable_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"
 	local_bh_enable_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
 	.fpu	vfpv2
 	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
 1:	vmov	r0, s\dr
 	ret	lr
 	.org	1b + 8
 	.endr
 	.irp	dr,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
 1:	vmov	r0, s\dr
 	ret	lr
 	.org	1b + 8
 	.endr
 ENDPROC(vfp_get_float)

 ENTRY(vfp_put_float)
 	tbl_branch r1, r3, #3
 	.fpu	vfpv2
 	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
 1:	vmov	s\dr, r0
 	ret	lr
 	.org	1b + 8
 	.endr
 	.irp	dr,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
 1:	vmov	s\dr, r0
 	ret	lr
 	.org	1b + 8
 	.endr
 ENDPROC(vfp_put_float)

 ENTRY(vfp_get_double)
 	tbl_branch r0, r3, #3
 	.fpu	vfpv2
 	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
 1:	vmov	r0, r1, d\dr
 	ret	lr
 	.org	1b + 8
 	.endr
 #ifdef CONFIG_VFPv3
 	@ d16 - d31 registers
 	.fpu	vfpv3
 	.irp	dr,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
 1:	vmov	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
 	.fpu	vfpv2
 	.irp	dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
 1:	vmov	d\dr, r0, r1
 	ret	lr
 	.org	1b + 8
 	.endr
 #ifdef CONFIG_VFPv3
 	.fpu	vfpv3
 	@ d16 - d31 registers
 	.irp	dr,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
 1:	vmov	d\dr, r0, r1
 	ret	lr
 	.org	1b + 8
 	.endr
 #endif
 ENDPROC(vfp_put_double)
	/* SPDX-License-Identifier: GPL-2.0-only */
	/*
	* linux/arch/arm/vfp/vfphw.S
	*
	* Copyright (C) 2004 ARM Limited.
	* Written by Deep Blue Solutions Limited.
	*
	* 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

	.fpu vfpv2
	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.
	local_bh_enable_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"
	local_bh_enable_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
	.fpu vfpv2
	.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
	1: vmov r0, s\dr
	ret lr
	.org 1b + 8
	.endr
	.irp dr,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
	1: vmov r0, s\dr
	ret lr
	.org 1b + 8
	.endr
	ENDPROC(vfp_get_float)

	ENTRY(vfp_put_float)
	tbl_branch r1, r3, #3
	.fpu vfpv2
	.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
	1: vmov s\dr, r0
	ret lr
	.org 1b + 8
	.endr
	.irp dr,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
	1: vmov s\dr, r0
	ret lr
	.org 1b + 8
	.endr
	ENDPROC(vfp_put_float)

	ENTRY(vfp_get_double)
	tbl_branch r0, r3, #3
	.fpu vfpv2
	.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
	1: vmov r0, r1, d\dr
	ret lr
	.org 1b + 8
	.endr
	#ifdef CONFIG_VFPv3
	@ d16 - d31 registers
	.fpu vfpv3
	.irp dr,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
	1: vmov 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
	.fpu vfpv2
	.irp dr,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15
	1: vmov d\dr, r0, r1
	ret lr
	.org 1b + 8
	.endr
	#ifdef CONFIG_VFPv3
	.fpu vfpv3
	@ d16 - d31 registers
	.irp dr,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
	1: vmov d\dr, r0, r1
	ret lr
	.org 1b + 8
	.endr
	#endif
	ENDPROC(vfp_put_double)