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/module.h>
12 #include <linux/config.h>
13 #include <linux/types.h>
14 #include <linux/kernel.h>
15 #include <linux/signal.h>
16 #include <linux/sched.h>
17 #include <linux/init.h>
19 #include <asm/thread_notify.h>
26 * Our undef handlers (in entry.S)
28 void vfp_testing_entry(void);
29 void vfp_support_entry(void);
31 void (*vfp_vector)(void) = vfp_testing_entry;
32 union vfp_state *last_VFP_context;
36 * Used in startup: set to non-zero if VFP checks fail
37 * After startup, holds VFP architecture
39 unsigned int VFP_arch;
41 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)
43 struct thread_info *thread = v;
44 union vfp_state *vfp = &thread->vfpstate;
47 case THREAD_NOTIFY_FLUSH:
49 * Per-thread VFP initialisation.
51 memset(vfp, 0, sizeof(union vfp_state));
53 vfp->hard.fpexc = FPEXC_ENABLE;
54 vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
57 * Disable VFP to ensure we initialise it first.
59 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
62 * FALLTHROUGH: Ensure we don't try to overwrite our newly
63 * initialised state information on the first fault.
66 case THREAD_NOTIFY_RELEASE:
68 * Per-thread VFP cleanup.
70 if (last_VFP_context == vfp)
71 last_VFP_context = NULL;
74 case THREAD_NOTIFY_SWITCH:
76 * Always disable VFP so we can lazily save/restore the
79 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_ENABLE);
86 static struct notifier_block vfp_notifier_block = {
87 .notifier_call = vfp_notifier,
91 * Raise a SIGFPE for the current process.
92 * sicode describes the signal being raised.
94 void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)
98 memset(&info, 0, sizeof(info));
100 info.si_signo = SIGFPE;
101 info.si_code = sicode;
102 info.si_addr = (void *)(instruction_pointer(regs) - 4);
105 * This is the same as NWFPE, because it's not clear what
108 current->thread.error_code = 0;
109 current->thread.trap_no = 6;
111 send_sig_info(SIGFPE, &info, current);
114 static void vfp_panic(char *reason)
118 printk(KERN_ERR "VFP: Error: %s\n", reason);
119 printk(KERN_ERR "VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n",
120 fmrx(FPEXC), fmrx(FPSCR), fmrx(FPINST));
121 for (i = 0; i < 32; i += 2)
122 printk(KERN_ERR "VFP: s%2u: 0x%08x s%2u: 0x%08x\n",
123 i, vfp_get_float(i), i+1, vfp_get_float(i+1));
127 * Process bitmask of exception conditions.
129 static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs)
133 pr_debug("VFP: raising exceptions %08x\n", exceptions);
135 if (exceptions == (u32)-1) {
136 vfp_panic("unhandled bounce");
137 vfp_raise_sigfpe(0, regs);
142 * If any of the status flags are set, update the FPSCR.
143 * Comparison instructions always return at least one of
146 if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
147 fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V);
153 #define RAISE(stat,en,sig) \
154 if (exceptions & stat && fpscr & en) \
158 * These are arranged in priority order, least to highest.
160 RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES);
161 RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND);
162 RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF);
163 RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV);
166 vfp_raise_sigfpe(si_code, regs);
170 * Emulate a VFP instruction.
172 static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
174 u32 exceptions = (u32)-1;
176 pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr);
178 if (INST_CPRTDO(inst)) {
179 if (!INST_CPRT(inst)) {
183 if (vfp_single(inst)) {
184 exceptions = vfp_single_cpdo(inst, fpscr);
186 exceptions = vfp_double_cpdo(inst, fpscr);
190 * A CPRT instruction can not appear in FPINST2, nor
191 * can it cause an exception. Therefore, we do not
192 * have to emulate it.
197 * A CPDT instruction can not appear in FPINST2, nor can
198 * it cause an exception. Therefore, we do not have to
202 return exceptions & ~VFP_NAN_FLAG;
206 * Package up a bounce condition.
208 void VFP9_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)
210 u32 fpscr, orig_fpscr, exceptions, inst;
212 pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc);
215 * Enable access to the VFP so we can handle the bounce.
217 fmxr(FPEXC, fpexc & ~(FPEXC_EXCEPTION|FPEXC_INV|FPEXC_UFC|FPEXC_IOC));
219 orig_fpscr = fpscr = fmrx(FPSCR);
222 * If we are running with inexact exceptions enabled, we need to
223 * emulate the trigger instruction. Note that as we're emulating
224 * the trigger instruction, we need to increment PC.
226 if (fpscr & FPSCR_IXE) {
234 * Modify fpscr to indicate the number of iterations remaining
236 if (fpexc & FPEXC_EXCEPTION) {
239 len = fpexc + (1 << FPEXC_LENGTH_BIT);
241 fpscr &= ~FPSCR_LENGTH_MASK;
242 fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT);
246 * Handle the first FP instruction. We used to take note of the
247 * FPEXC bounce reason, but this appears to be unreliable.
248 * Emulate the bounced instruction instead.
251 exceptions = vfp_emulate_instruction(inst, fpscr, regs);
253 vfp_raise_exceptions(exceptions, inst, orig_fpscr, regs);
256 * If there isn't a second FP instruction, exit now.
258 if (!(fpexc & FPEXC_FPV2))
262 * The barrier() here prevents fpinst2 being read
263 * before the condition above.
266 trigger = fmrx(FPINST2);
267 orig_fpscr = fpscr = fmrx(FPSCR);
270 exceptions = vfp_emulate_instruction(trigger, fpscr, regs);
272 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);
276 * VFP support code initialisation.
278 static int __init vfp_init(void)
283 * First check that there is a VFP that we can use.
284 * The handler is already setup to just log calls, so
285 * we just need to read the VFPSID register.
287 vfpsid = fmrx(FPSID);
289 printk(KERN_INFO "VFP support v0.3: ");
291 printk("not present\n");
292 } else if (vfpsid & FPSID_NODOUBLE) {
293 printk("no double precision support\n");
295 VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT; /* Extract the architecture version */
296 printk("implementor %02x architecture %d part %02x variant %x rev %x\n",
297 (vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT,
298 (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT,
299 (vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT,
300 (vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT,
301 (vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT);
302 vfp_vector = vfp_support_entry;
304 thread_register_notifier(&vfp_notifier_block);
309 late_initcall(vfp_init);