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+/*
+ * 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)
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