2 * linux/arch/arm/vfp/vfpmodule.c
4 * Copyright (C) 2004 ARM Limited.
5 * Written by Deep Blue Solutions Limited.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 #include <linux/types.h>
12 #include <linux/cpu.h>
13 #include <linux/cpu_pm.h>
14 #include <linux/hardirq.h>
15 #include <linux/kernel.h>
16 #include <linux/notifier.h>
17 #include <linux/signal.h>
18 #include <linux/sched.h>
19 #include <linux/smp.h>
20 #include <linux/init.h>
21 #include <linux/uaccess.h>
22 #include <linux/user.h>
23 #include <linux/export.h>
26 #include <asm/cputype.h>
27 #include <asm/system_info.h>
28 #include <asm/thread_notify.h>
35 * Our undef handlers (in entry.S)
37 void vfp_testing_entry(void);
38 void vfp_support_entry(void);
39 void vfp_null_entry(void);
41 void (*vfp_vector
)(void) = vfp_null_entry
;
45 * Used in startup: set to non-zero if VFP checks fail
46 * After startup, holds VFP architecture
48 unsigned int VFP_arch
;
51 * The pointer to the vfpstate structure of the thread which currently
52 * owns the context held in the VFP hardware, or NULL if the hardware
55 * For UP, this is sufficient to tell which thread owns the VFP context.
56 * However, for SMP, we also need to check the CPU number stored in the
57 * saved state too to catch migrations.
59 union vfp_state
*vfp_current_hw_state
[NR_CPUS
];
62 * Is 'thread's most up to date state stored in this CPUs hardware?
63 * Must be called from non-preemptible context.
65 static bool vfp_state_in_hw(unsigned int cpu
, struct thread_info
*thread
)
68 if (thread
->vfpstate
.hard
.cpu
!= cpu
)
71 return vfp_current_hw_state
[cpu
] == &thread
->vfpstate
;
75 * Force a reload of the VFP context from the thread structure. We do
76 * this by ensuring that access to the VFP hardware is disabled, and
77 * clear vfp_current_hw_state. Must be called from non-preemptible context.
79 static void vfp_force_reload(unsigned int cpu
, struct thread_info
*thread
)
81 if (vfp_state_in_hw(cpu
, thread
)) {
82 fmxr(FPEXC
, fmrx(FPEXC
) & ~FPEXC_EN
);
83 vfp_current_hw_state
[cpu
] = NULL
;
86 thread
->vfpstate
.hard
.cpu
= NR_CPUS
;
91 * Per-thread VFP initialization.
93 static void vfp_thread_flush(struct thread_info
*thread
)
95 union vfp_state
*vfp
= &thread
->vfpstate
;
99 * Disable VFP to ensure we initialize it first. We must ensure
100 * that the modification of vfp_current_hw_state[] and hardware
101 * disable are done for the same CPU and without preemption.
103 * Do this first to ensure that preemption won't overwrite our
104 * state saving should access to the VFP be enabled at this point.
107 if (vfp_current_hw_state
[cpu
] == vfp
)
108 vfp_current_hw_state
[cpu
] = NULL
;
109 fmxr(FPEXC
, fmrx(FPEXC
) & ~FPEXC_EN
);
112 memset(vfp
, 0, sizeof(union vfp_state
));
114 vfp
->hard
.fpexc
= FPEXC_EN
;
115 vfp
->hard
.fpscr
= FPSCR_ROUND_NEAREST
;
117 vfp
->hard
.cpu
= NR_CPUS
;
121 static void vfp_thread_exit(struct thread_info
*thread
)
123 /* release case: Per-thread VFP cleanup. */
124 union vfp_state
*vfp
= &thread
->vfpstate
;
125 unsigned int cpu
= get_cpu();
127 if (vfp_current_hw_state
[cpu
] == vfp
)
128 vfp_current_hw_state
[cpu
] = NULL
;
132 static void vfp_thread_copy(struct thread_info
*thread
)
134 struct thread_info
*parent
= current_thread_info();
136 vfp_sync_hwstate(parent
);
137 thread
->vfpstate
= parent
->vfpstate
;
139 thread
->vfpstate
.hard
.cpu
= NR_CPUS
;
144 * When this function is called with the following 'cmd's, the following
145 * is true while this function is being run:
146 * THREAD_NOFTIFY_SWTICH:
147 * - the previously running thread will not be scheduled onto another CPU.
148 * - the next thread to be run (v) will not be running on another CPU.
149 * - thread->cpu is the local CPU number
150 * - not preemptible as we're called in the middle of a thread switch
151 * THREAD_NOTIFY_FLUSH:
152 * - the thread (v) will be running on the local CPU, so
153 * v === current_thread_info()
154 * - thread->cpu is the local CPU number at the time it is accessed,
155 * but may change at any time.
156 * - we could be preempted if tree preempt rcu is enabled, so
157 * it is unsafe to use thread->cpu.
159 * - the thread (v) will be running on the local CPU, so
160 * v === current_thread_info()
161 * - thread->cpu is the local CPU number at the time it is accessed,
162 * but may change at any time.
163 * - we could be preempted if tree preempt rcu is enabled, so
164 * it is unsafe to use thread->cpu.
166 static int vfp_notifier(struct notifier_block
*self
, unsigned long cmd
, void *v
)
168 struct thread_info
*thread
= v
;
175 case THREAD_NOTIFY_SWITCH
:
182 * On SMP, if VFP is enabled, save the old state in
183 * case the thread migrates to a different CPU. The
184 * restoring is done lazily.
186 if ((fpexc
& FPEXC_EN
) && vfp_current_hw_state
[cpu
])
187 vfp_save_state(vfp_current_hw_state
[cpu
], fpexc
);
191 * Always disable VFP so we can lazily save/restore the
194 fmxr(FPEXC
, fpexc
& ~FPEXC_EN
);
197 case THREAD_NOTIFY_FLUSH
:
198 vfp_thread_flush(thread
);
201 case THREAD_NOTIFY_EXIT
:
202 vfp_thread_exit(thread
);
205 case THREAD_NOTIFY_COPY
:
206 vfp_thread_copy(thread
);
213 static struct notifier_block vfp_notifier_block
= {
214 .notifier_call
= vfp_notifier
,
218 * Raise a SIGFPE for the current process.
219 * sicode describes the signal being raised.
221 static void vfp_raise_sigfpe(unsigned int sicode
, struct pt_regs
*regs
)
225 memset(&info
, 0, sizeof(info
));
227 info
.si_signo
= SIGFPE
;
228 info
.si_code
= sicode
;
229 info
.si_addr
= (void __user
*)(instruction_pointer(regs
) - 4);
232 * This is the same as NWFPE, because it's not clear what
235 current
->thread
.error_code
= 0;
236 current
->thread
.trap_no
= 6;
238 send_sig_info(SIGFPE
, &info
, current
);
241 static void vfp_panic(char *reason
, u32 inst
)
245 pr_err("VFP: Error: %s\n", reason
);
246 pr_err("VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n",
247 fmrx(FPEXC
), fmrx(FPSCR
), inst
);
248 for (i
= 0; i
< 32; i
+= 2)
249 pr_err("VFP: s%2u: 0x%08x s%2u: 0x%08x\n",
250 i
, vfp_get_float(i
), i
+1, vfp_get_float(i
+1));
254 * Process bitmask of exception conditions.
256 static void vfp_raise_exceptions(u32 exceptions
, u32 inst
, u32 fpscr
, struct pt_regs
*regs
)
260 pr_debug("VFP: raising exceptions %08x\n", exceptions
);
262 if (exceptions
== VFP_EXCEPTION_ERROR
) {
263 vfp_panic("unhandled bounce", inst
);
264 vfp_raise_sigfpe(0, regs
);
269 * If any of the status flags are set, update the FPSCR.
270 * Comparison instructions always return at least one of
273 if (exceptions
& (FPSCR_N
|FPSCR_Z
|FPSCR_C
|FPSCR_V
))
274 fpscr
&= ~(FPSCR_N
|FPSCR_Z
|FPSCR_C
|FPSCR_V
);
280 #define RAISE(stat,en,sig) \
281 if (exceptions & stat && fpscr & en) \
285 * These are arranged in priority order, least to highest.
287 RAISE(FPSCR_DZC
, FPSCR_DZE
, FPE_FLTDIV
);
288 RAISE(FPSCR_IXC
, FPSCR_IXE
, FPE_FLTRES
);
289 RAISE(FPSCR_UFC
, FPSCR_UFE
, FPE_FLTUND
);
290 RAISE(FPSCR_OFC
, FPSCR_OFE
, FPE_FLTOVF
);
291 RAISE(FPSCR_IOC
, FPSCR_IOE
, FPE_FLTINV
);
294 vfp_raise_sigfpe(si_code
, regs
);
298 * Emulate a VFP instruction.
300 static u32
vfp_emulate_instruction(u32 inst
, u32 fpscr
, struct pt_regs
*regs
)
302 u32 exceptions
= VFP_EXCEPTION_ERROR
;
304 pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst
, fpscr
);
306 if (INST_CPRTDO(inst
)) {
307 if (!INST_CPRT(inst
)) {
311 if (vfp_single(inst
)) {
312 exceptions
= vfp_single_cpdo(inst
, fpscr
);
314 exceptions
= vfp_double_cpdo(inst
, fpscr
);
318 * A CPRT instruction can not appear in FPINST2, nor
319 * can it cause an exception. Therefore, we do not
320 * have to emulate it.
325 * A CPDT instruction can not appear in FPINST2, nor can
326 * it cause an exception. Therefore, we do not have to
330 return exceptions
& ~VFP_NAN_FLAG
;
334 * Package up a bounce condition.
336 void VFP_bounce(u32 trigger
, u32 fpexc
, struct pt_regs
*regs
)
338 u32 fpscr
, orig_fpscr
, fpsid
, exceptions
;
340 pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger
, fpexc
);
343 * At this point, FPEXC can have the following configuration:
346 * 0 1 x - synchronous exception
347 * 1 x 0 - asynchronous exception
348 * 1 x 1 - sychronous on VFP subarch 1 and asynchronous on later
349 * 0 0 1 - synchronous on VFP9 (non-standard subarch 1
350 * implementation), undefined otherwise
352 * Clear various bits and enable access to the VFP so we can
355 fmxr(FPEXC
, fpexc
& ~(FPEXC_EX
|FPEXC_DEX
|FPEXC_FP2V
|FPEXC_VV
|FPEXC_TRAP_MASK
));
358 orig_fpscr
= fpscr
= fmrx(FPSCR
);
361 * Check for the special VFP subarch 1 and FPSCR.IXE bit case
363 if ((fpsid
& FPSID_ARCH_MASK
) == (1 << FPSID_ARCH_BIT
)
364 && (fpscr
& FPSCR_IXE
)) {
366 * Synchronous exception, emulate the trigger instruction
371 if (fpexc
& FPEXC_EX
) {
372 #ifndef CONFIG_CPU_FEROCEON
374 * Asynchronous exception. The instruction is read from FPINST
375 * and the interrupted instruction has to be restarted.
377 trigger
= fmrx(FPINST
);
380 } else if (!(fpexc
& FPEXC_DEX
)) {
382 * Illegal combination of bits. It can be caused by an
383 * unallocated VFP instruction but with FPSCR.IXE set and not
386 vfp_raise_exceptions(VFP_EXCEPTION_ERROR
, trigger
, fpscr
, regs
);
391 * Modify fpscr to indicate the number of iterations remaining.
392 * If FPEXC.EX is 0, FPEXC.DEX is 1 and the FPEXC.VV bit indicates
393 * whether FPEXC.VECITR or FPSCR.LEN is used.
395 if (fpexc
& (FPEXC_EX
| FPEXC_VV
)) {
398 len
= fpexc
+ (1 << FPEXC_LENGTH_BIT
);
400 fpscr
&= ~FPSCR_LENGTH_MASK
;
401 fpscr
|= (len
& FPEXC_LENGTH_MASK
) << (FPSCR_LENGTH_BIT
- FPEXC_LENGTH_BIT
);
405 * Handle the first FP instruction. We used to take note of the
406 * FPEXC bounce reason, but this appears to be unreliable.
407 * Emulate the bounced instruction instead.
409 exceptions
= vfp_emulate_instruction(trigger
, fpscr
, regs
);
411 vfp_raise_exceptions(exceptions
, trigger
, orig_fpscr
, regs
);
414 * If there isn't a second FP instruction, exit now. Note that
415 * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1.
417 if ((fpexc
& (FPEXC_EX
| FPEXC_FP2V
)) != (FPEXC_EX
| FPEXC_FP2V
))
421 * The barrier() here prevents fpinst2 being read
422 * before the condition above.
425 trigger
= fmrx(FPINST2
);
428 exceptions
= vfp_emulate_instruction(trigger
, orig_fpscr
, regs
);
430 vfp_raise_exceptions(exceptions
, trigger
, orig_fpscr
, regs
);
435 static void vfp_enable(void *unused
)
439 BUG_ON(preemptible());
440 access
= get_copro_access();
443 * Enable full access to VFP (cp10 and cp11)
445 set_copro_access(access
| CPACC_FULL(10) | CPACC_FULL(11));
449 static int vfp_pm_suspend(void)
451 struct thread_info
*ti
= current_thread_info();
452 u32 fpexc
= fmrx(FPEXC
);
454 /* if vfp is on, then save state for resumption */
455 if (fpexc
& FPEXC_EN
) {
456 pr_debug("%s: saving vfp state\n", __func__
);
457 vfp_save_state(&ti
->vfpstate
, fpexc
);
459 /* disable, just in case */
460 fmxr(FPEXC
, fmrx(FPEXC
) & ~FPEXC_EN
);
461 } else if (vfp_current_hw_state
[ti
->cpu
]) {
463 fmxr(FPEXC
, fpexc
| FPEXC_EN
);
464 vfp_save_state(vfp_current_hw_state
[ti
->cpu
], fpexc
);
469 /* clear any information we had about last context state */
470 vfp_current_hw_state
[ti
->cpu
] = NULL
;
475 static void vfp_pm_resume(void)
477 /* ensure we have access to the vfp */
480 /* and disable it to ensure the next usage restores the state */
481 fmxr(FPEXC
, fmrx(FPEXC
) & ~FPEXC_EN
);
484 static int vfp_cpu_pm_notifier(struct notifier_block
*self
, unsigned long cmd
,
491 case CPU_PM_ENTER_FAILED
:
499 static struct notifier_block vfp_cpu_pm_notifier_block
= {
500 .notifier_call
= vfp_cpu_pm_notifier
,
503 static void vfp_pm_init(void)
505 cpu_pm_register_notifier(&vfp_cpu_pm_notifier_block
);
509 static inline void vfp_pm_init(void) { }
510 #endif /* CONFIG_CPU_PM */
513 * Ensure that the VFP state stored in 'thread->vfpstate' is up to date
514 * with the hardware state.
516 void vfp_sync_hwstate(struct thread_info
*thread
)
518 unsigned int cpu
= get_cpu();
520 if (vfp_state_in_hw(cpu
, thread
)) {
521 u32 fpexc
= fmrx(FPEXC
);
524 * Save the last VFP state on this CPU.
526 fmxr(FPEXC
, fpexc
| FPEXC_EN
);
527 vfp_save_state(&thread
->vfpstate
, fpexc
| FPEXC_EN
);
534 /* Ensure that the thread reloads the hardware VFP state on the next use. */
535 void vfp_flush_hwstate(struct thread_info
*thread
)
537 unsigned int cpu
= get_cpu();
539 vfp_force_reload(cpu
, thread
);
545 * Save the current VFP state into the provided structures and prepare
546 * for entry into a new function (signal handler).
548 int vfp_preserve_user_clear_hwstate(struct user_vfp __user
*ufp
,
549 struct user_vfp_exc __user
*ufp_exc
)
551 struct thread_info
*thread
= current_thread_info();
552 struct vfp_hard_struct
*hwstate
= &thread
->vfpstate
.hard
;
555 /* Ensure that the saved hwstate is up-to-date. */
556 vfp_sync_hwstate(thread
);
559 * Copy the floating point registers. There can be unused
560 * registers see asm/hwcap.h for details.
562 err
|= __copy_to_user(&ufp
->fpregs
, &hwstate
->fpregs
,
563 sizeof(hwstate
->fpregs
));
565 * Copy the status and control register.
567 __put_user_error(hwstate
->fpscr
, &ufp
->fpscr
, err
);
570 * Copy the exception registers.
572 __put_user_error(hwstate
->fpexc
, &ufp_exc
->fpexc
, err
);
573 __put_user_error(hwstate
->fpinst
, &ufp_exc
->fpinst
, err
);
574 __put_user_error(hwstate
->fpinst2
, &ufp_exc
->fpinst2
, err
);
579 /* Ensure that VFP is disabled. */
580 vfp_flush_hwstate(thread
);
583 * As per the PCS, clear the length and stride bits for function
586 hwstate
->fpscr
&= ~(FPSCR_LENGTH_MASK
| FPSCR_STRIDE_MASK
);
590 /* Sanitise and restore the current VFP state from the provided structures. */
591 int vfp_restore_user_hwstate(struct user_vfp __user
*ufp
,
592 struct user_vfp_exc __user
*ufp_exc
)
594 struct thread_info
*thread
= current_thread_info();
595 struct vfp_hard_struct
*hwstate
= &thread
->vfpstate
.hard
;
599 /* Disable VFP to avoid corrupting the new thread state. */
600 vfp_flush_hwstate(thread
);
603 * Copy the floating point registers. There can be unused
604 * registers see asm/hwcap.h for details.
606 err
|= __copy_from_user(&hwstate
->fpregs
, &ufp
->fpregs
,
607 sizeof(hwstate
->fpregs
));
609 * Copy the status and control register.
611 __get_user_error(hwstate
->fpscr
, &ufp
->fpscr
, err
);
614 * Sanitise and restore the exception registers.
616 __get_user_error(fpexc
, &ufp_exc
->fpexc
, err
);
618 /* Ensure the VFP is enabled. */
621 /* Ensure FPINST2 is invalid and the exception flag is cleared. */
622 fpexc
&= ~(FPEXC_EX
| FPEXC_FP2V
);
623 hwstate
->fpexc
= fpexc
;
625 __get_user_error(hwstate
->fpinst
, &ufp_exc
->fpinst
, err
);
626 __get_user_error(hwstate
->fpinst2
, &ufp_exc
->fpinst2
, err
);
628 return err
? -EFAULT
: 0;
632 * VFP hardware can lose all context when a CPU goes offline.
633 * As we will be running in SMP mode with CPU hotplug, we will save the
634 * hardware state at every thread switch. We clear our held state when
635 * a CPU has been killed, indicating that the VFP hardware doesn't contain
636 * a threads VFP state. When a CPU starts up, we re-enable access to the
639 * Both CPU_DYING and CPU_STARTING are called on the CPU which
640 * is being offlined/onlined.
642 static int vfp_hotplug(struct notifier_block
*b
, unsigned long action
,
645 if (action
== CPU_DYING
|| action
== CPU_DYING_FROZEN
)
646 vfp_current_hw_state
[(long)hcpu
] = NULL
;
647 else if (action
== CPU_STARTING
|| action
== CPU_STARTING_FROZEN
)
652 void vfp_kmode_exception(void)
655 * If we reach this point, a floating point exception has been raised
656 * while running in kernel mode. If the NEON/VFP unit was enabled at the
657 * time, it means a VFP instruction has been issued that requires
658 * software assistance to complete, something which is not currently
659 * supported in kernel mode.
660 * If the NEON/VFP unit was disabled, and the location pointed to below
661 * is properly preceded by a call to kernel_neon_begin(), something has
662 * caused the task to be scheduled out and back in again. In this case,
663 * rebuilding and running with CONFIG_DEBUG_ATOMIC_SLEEP enabled should
664 * be helpful in localizing the problem.
666 if (fmrx(FPEXC
) & FPEXC_EN
)
667 pr_crit("BUG: unsupported FP instruction in kernel mode\n");
669 pr_crit("BUG: FP instruction issued in kernel mode with FP unit disabled\n");
672 #ifdef CONFIG_KERNEL_MODE_NEON
675 * Kernel-side NEON support functions
677 void kernel_neon_begin(void)
679 struct thread_info
*thread
= current_thread_info();
684 * Kernel mode NEON is only allowed outside of interrupt context
685 * with preemption disabled. This will make sure that the kernel
686 * mode NEON register contents never need to be preserved.
688 BUG_ON(in_interrupt());
691 fpexc
= fmrx(FPEXC
) | FPEXC_EN
;
695 * Save the userland NEON/VFP state. Under UP,
696 * the owner could be a task other than 'current'
698 if (vfp_state_in_hw(cpu
, thread
))
699 vfp_save_state(&thread
->vfpstate
, fpexc
);
701 else if (vfp_current_hw_state
[cpu
] != NULL
)
702 vfp_save_state(vfp_current_hw_state
[cpu
], fpexc
);
704 vfp_current_hw_state
[cpu
] = NULL
;
706 EXPORT_SYMBOL(kernel_neon_begin
);
708 void kernel_neon_end(void)
710 /* Disable the NEON/VFP unit. */
711 fmxr(FPEXC
, fmrx(FPEXC
) & ~FPEXC_EN
);
714 EXPORT_SYMBOL(kernel_neon_end
);
716 #endif /* CONFIG_KERNEL_MODE_NEON */
719 * VFP support code initialisation.
721 static int __init
vfp_init(void)
724 unsigned int cpu_arch
= cpu_architecture();
726 if (cpu_arch
>= CPU_ARCH_ARMv6
)
727 on_each_cpu(vfp_enable
, NULL
, 1);
730 * First check that there is a VFP that we can use.
731 * The handler is already setup to just log calls, so
732 * we just need to read the VFPSID register.
734 vfp_vector
= vfp_testing_entry
;
736 vfpsid
= fmrx(FPSID
);
738 vfp_vector
= vfp_null_entry
;
740 pr_info("VFP support v0.3: ");
742 pr_cont("not present\n");
743 else if (vfpsid
& FPSID_NODOUBLE
) {
744 pr_cont("no double precision support\n");
746 hotcpu_notifier(vfp_hotplug
, 0);
748 VFP_arch
= (vfpsid
& FPSID_ARCH_MASK
) >> FPSID_ARCH_BIT
; /* Extract the architecture version */
749 pr_cont("implementor %02x architecture %d part %02x variant %x rev %x\n",
750 (vfpsid
& FPSID_IMPLEMENTER_MASK
) >> FPSID_IMPLEMENTER_BIT
,
751 (vfpsid
& FPSID_ARCH_MASK
) >> FPSID_ARCH_BIT
,
752 (vfpsid
& FPSID_PART_MASK
) >> FPSID_PART_BIT
,
753 (vfpsid
& FPSID_VARIANT_MASK
) >> FPSID_VARIANT_BIT
,
754 (vfpsid
& FPSID_REV_MASK
) >> FPSID_REV_BIT
);
756 vfp_vector
= vfp_support_entry
;
758 thread_register_notifier(&vfp_notifier_block
);
762 * We detected VFP, and the support code is
763 * in place; report VFP support to userspace.
765 elf_hwcap
|= HWCAP_VFP
;
768 elf_hwcap
|= HWCAP_VFPv3
;
771 * Check for VFPv3 D16 and VFPv4 D16. CPUs in
772 * this configuration only have 16 x 64bit
775 if (((fmrx(MVFR0
) & MVFR0_A_SIMD_MASK
)) == 1)
776 elf_hwcap
|= HWCAP_VFPv3D16
; /* also v4-D16 */
778 elf_hwcap
|= HWCAP_VFPD32
;
782 * Check for the presence of the Advanced SIMD
783 * load/store instructions, integer and single
784 * precision floating point operations. Only check
785 * for NEON if the hardware has the MVFR registers.
787 if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) {
789 if ((fmrx(MVFR1
) & 0x000fff00) == 0x00011100)
790 elf_hwcap
|= HWCAP_NEON
;
793 if ((fmrx(MVFR1
) & 0xf0000000) == 0x10000000)
794 elf_hwcap
|= HWCAP_VFPv4
;
801 core_initcall(vfp_init
);