1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * arch/sparc/kernel/traps.c
4  *
5  * Copyright 1995, 2008 David S. Miller (davem@davemloft.net)
6  * Copyright 2000 Jakub Jelinek (jakub@redhat.com)
7  */
8 
9 /*
10  * I hate traps on the sparc, grrr...
11  */
12 
13 #include <linux/sched/mm.h>
14 #include <linux/sched/debug.h>
15 #include <linux/mm_types.h>
16 #include <linux/kernel.h>
17 #include <linux/signal.h>
18 #include <linux/smp.h>
19 #include <linux/kdebug.h>
20 #include <linux/export.h>
21 #include <linux/pgtable.h>
22 
23 #include <asm/delay.h>
24 #include <asm/ptrace.h>
25 #include <asm/oplib.h>
26 #include <asm/page.h>
27 #include <asm/unistd.h>
28 #include <asm/traps.h>
29 
30 #include "entry.h"
31 #include "kernel.h"
32 
33 /* #define TRAP_DEBUG */
34 
instruction_dump(unsigned long * pc)35 static void instruction_dump(unsigned long *pc)
36 {
37 	int i;
38 
39 	if((((unsigned long) pc) & 3))
40                 return;
41 
42 	for(i = -3; i < 6; i++)
43 		printk("%c%08lx%c",i?' ':'<',pc[i],i?' ':'>');
44 	printk("\n");
45 }
46 
47 #define __SAVE __asm__ __volatile__("save %sp, -0x40, %sp\n\t")
48 #define __RESTORE __asm__ __volatile__("restore %g0, %g0, %g0\n\t")
49 
die_if_kernel(char * str,struct pt_regs * regs)50 void __noreturn die_if_kernel(char *str, struct pt_regs *regs)
51 {
52 	static int die_counter;
53 	int count = 0;
54 
55 	/* Amuse the user. */
56 	printk(
57 "              \\|/ ____ \\|/\n"
58 "              \"@'/ ,. \\`@\"\n"
59 "              /_| \\__/ |_\\\n"
60 "                 \\__U_/\n");
61 
62 	printk("%s(%d): %s [#%d]\n", current->comm, task_pid_nr(current), str, ++die_counter);
63 	show_regs(regs);
64 	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
65 
66 	__SAVE; __SAVE; __SAVE; __SAVE;
67 	__SAVE; __SAVE; __SAVE; __SAVE;
68 	__RESTORE; __RESTORE; __RESTORE; __RESTORE;
69 	__RESTORE; __RESTORE; __RESTORE; __RESTORE;
70 
71 	{
72 		struct reg_window32 *rw = (struct reg_window32 *)regs->u_regs[UREG_FP];
73 
74 		/* Stop the back trace when we hit userland or we
75 		 * find some badly aligned kernel stack. Set an upper
76 		 * bound in case our stack is trashed and we loop.
77 		 */
78 		while(rw					&&
79 		      count++ < 30				&&
80                       (((unsigned long) rw) >= PAGE_OFFSET)	&&
81 		      !(((unsigned long) rw) & 0x7)) {
82 			printk("Caller[%08lx]: %pS\n", rw->ins[7],
83 			       (void *) rw->ins[7]);
84 			rw = (struct reg_window32 *)rw->ins[6];
85 		}
86 	}
87 	printk("Instruction DUMP:");
88 	instruction_dump ((unsigned long *) regs->pc);
89 	make_task_dead((regs->psr & PSR_PS) ? SIGKILL : SIGSEGV);
90 }
91 
do_hw_interrupt(struct pt_regs * regs,unsigned long type)92 void do_hw_interrupt(struct pt_regs *regs, unsigned long type)
93 {
94 	if(type < 0x80) {
95 		/* Sun OS's puke from bad traps, Linux survives! */
96 		printk("Unimplemented Sparc TRAP, type = %02lx\n", type);
97 		die_if_kernel("Whee... Hello Mr. Penguin", regs);
98 	}
99 
100 	if(regs->psr & PSR_PS)
101 		die_if_kernel("Kernel bad trap", regs);
102 
103 	force_sig_fault_trapno(SIGILL, ILL_ILLTRP,
104 			       (void __user *)regs->pc, type - 0x80);
105 }
106 
do_illegal_instruction(struct pt_regs * regs,unsigned long pc,unsigned long npc,unsigned long psr)107 void do_illegal_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
108 			    unsigned long psr)
109 {
110 	if(psr & PSR_PS)
111 		die_if_kernel("Kernel illegal instruction", regs);
112 #ifdef TRAP_DEBUG
113 	printk("Ill instr. at pc=%08lx instruction is %08lx\n",
114 	       regs->pc, *(unsigned long *)regs->pc);
115 #endif
116 
117 	send_sig_fault(SIGILL, ILL_ILLOPC, (void __user *)pc, current);
118 }
119 
do_priv_instruction(struct pt_regs * regs,unsigned long pc,unsigned long npc,unsigned long psr)120 void do_priv_instruction(struct pt_regs *regs, unsigned long pc, unsigned long npc,
121 			 unsigned long psr)
122 {
123 	if(psr & PSR_PS)
124 		die_if_kernel("Penguin instruction from Penguin mode??!?!", regs);
125 	send_sig_fault(SIGILL, ILL_PRVOPC, (void __user *)pc, current);
126 }
127 
128 /* XXX User may want to be allowed to do this. XXX */
129 
do_memaccess_unaligned(struct pt_regs * regs,unsigned long pc,unsigned long npc,unsigned long psr)130 void do_memaccess_unaligned(struct pt_regs *regs, unsigned long pc, unsigned long npc,
131 			    unsigned long psr)
132 {
133 	if(regs->psr & PSR_PS) {
134 		printk("KERNEL MNA at pc %08lx npc %08lx called by %08lx\n", pc, npc,
135 		       regs->u_regs[UREG_RETPC]);
136 		die_if_kernel("BOGUS", regs);
137 		/* die_if_kernel("Kernel MNA access", regs); */
138 	}
139 #if 0
140 	show_regs (regs);
141 	instruction_dump ((unsigned long *) regs->pc);
142 	printk ("do_MNA!\n");
143 #endif
144 	send_sig_fault(SIGBUS, BUS_ADRALN,
145 		       /* FIXME: Should dig out mna address */ (void *)0,
146 		       current);
147 }
148 
149 static unsigned long init_fsr = 0x0UL;
150 static unsigned long init_fregs[32] __attribute__ ((aligned (8))) =
151                 { ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
152 		  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
153 		  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL,
154 		  ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL, ~0UL };
155 
do_fpd_trap(struct pt_regs * regs,unsigned long pc,unsigned long npc,unsigned long psr)156 void do_fpd_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
157 		 unsigned long psr)
158 {
159 	/* Sanity check... */
160 	if(psr & PSR_PS)
161 		die_if_kernel("Kernel gets FloatingPenguinUnit disabled trap", regs);
162 
163 	put_psr(get_psr() | PSR_EF);    /* Allow FPU ops. */
164 	regs->psr |= PSR_EF;
165 #ifndef CONFIG_SMP
166 	if(last_task_used_math == current)
167 		return;
168 	if(last_task_used_math) {
169 		/* Other processes fpu state, save away */
170 		struct task_struct *fptask = last_task_used_math;
171 		fpsave(&fptask->thread.float_regs[0], &fptask->thread.fsr,
172 		       &fptask->thread.fpqueue[0], &fptask->thread.fpqdepth);
173 	}
174 	last_task_used_math = current;
175 	if(used_math()) {
176 		fpload(&current->thread.float_regs[0], &current->thread.fsr);
177 	} else {
178 		/* Set initial sane state. */
179 		fpload(&init_fregs[0], &init_fsr);
180 		set_used_math();
181 	}
182 #else
183 	if(!used_math()) {
184 		fpload(&init_fregs[0], &init_fsr);
185 		set_used_math();
186 	} else {
187 		fpload(&current->thread.float_regs[0], &current->thread.fsr);
188 	}
189 	set_thread_flag(TIF_USEDFPU);
190 #endif
191 }
192 
193 static unsigned long fake_regs[32] __attribute__ ((aligned (8)));
194 static unsigned long fake_fsr;
195 static unsigned long fake_queue[32] __attribute__ ((aligned (8)));
196 static unsigned long fake_depth;
197 
do_fpe_trap(struct pt_regs * regs,unsigned long pc,unsigned long npc,unsigned long psr)198 void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc,
199 		 unsigned long psr)
200 {
201 	static int calls;
202 	unsigned long fsr;
203 	int ret = 0;
204 	int code;
205 #ifndef CONFIG_SMP
206 	struct task_struct *fpt = last_task_used_math;
207 #else
208 	struct task_struct *fpt = current;
209 #endif
210 	put_psr(get_psr() | PSR_EF);
211 	/* If nobody owns the fpu right now, just clear the
212 	 * error into our fake static buffer and hope it don't
213 	 * happen again.  Thank you crashme...
214 	 */
215 #ifndef CONFIG_SMP
216 	if(!fpt) {
217 #else
218 	if (!test_tsk_thread_flag(fpt, TIF_USEDFPU)) {
219 #endif
220 		fpsave(&fake_regs[0], &fake_fsr, &fake_queue[0], &fake_depth);
221 		regs->psr &= ~PSR_EF;
222 		return;
223 	}
224 	fpsave(&fpt->thread.float_regs[0], &fpt->thread.fsr,
225 	       &fpt->thread.fpqueue[0], &fpt->thread.fpqdepth);
226 #ifdef DEBUG_FPU
227 	printk("Hmm, FP exception, fsr was %016lx\n", fpt->thread.fsr);
228 #endif
229 
230 	switch ((fpt->thread.fsr & 0x1c000)) {
231 	/* switch on the contents of the ftt [floating point trap type] field */
232 #ifdef DEBUG_FPU
233 	case (1 << 14):
234 		printk("IEEE_754_exception\n");
235 		break;
236 #endif
237 	case (2 << 14):  /* unfinished_FPop (underflow & co) */
238 	case (3 << 14):  /* unimplemented_FPop (quad stuff, maybe sqrt) */
239 		ret = do_mathemu(regs, fpt);
240 		break;
241 #ifdef DEBUG_FPU
242 	case (4 << 14):
243 		printk("sequence_error (OS bug...)\n");
244 		break;
245 	case (5 << 14):
246 		printk("hardware_error (uhoh!)\n");
247 		break;
248 	case (6 << 14):
249 		printk("invalid_fp_register (user error)\n");
250 		break;
251 #endif /* DEBUG_FPU */
252 	}
253 	/* If we successfully emulated the FPop, we pretend the trap never happened :-> */
254 	if (ret) {
255 		fpload(&current->thread.float_regs[0], &current->thread.fsr);
256 		return;
257 	}
258 	/* nope, better SIGFPE the offending process... */
259 
260 #ifdef CONFIG_SMP
261 	clear_tsk_thread_flag(fpt, TIF_USEDFPU);
262 #endif
263 	if(psr & PSR_PS) {
264 		/* The first fsr store/load we tried trapped,
265 		 * the second one will not (we hope).
266 		 */
267 		printk("WARNING: FPU exception from kernel mode. at pc=%08lx\n",
268 		       regs->pc);
269 		regs->pc = regs->npc;
270 		regs->npc += 4;
271 		calls++;
272 		if(calls > 2)
273 			die_if_kernel("Too many Penguin-FPU traps from kernel mode",
274 				      regs);
275 		return;
276 	}
277 
278 	fsr = fpt->thread.fsr;
279 	code = FPE_FLTUNK;
280 	if ((fsr & 0x1c000) == (1 << 14)) {
281 		if (fsr & 0x10)
282 			code = FPE_FLTINV;
283 		else if (fsr & 0x08)
284 			code = FPE_FLTOVF;
285 		else if (fsr & 0x04)
286 			code = FPE_FLTUND;
287 		else if (fsr & 0x02)
288 			code = FPE_FLTDIV;
289 		else if (fsr & 0x01)
290 			code = FPE_FLTRES;
291 	}
292 	send_sig_fault(SIGFPE, code, (void __user *)pc, fpt);
293 #ifndef CONFIG_SMP
294 	last_task_used_math = NULL;
295 #endif
296 	regs->psr &= ~PSR_EF;
297 	if(calls > 0)
298 		calls=0;
299 }
300 
301 void handle_tag_overflow(struct pt_regs *regs, unsigned long pc, unsigned long npc,
302 			 unsigned long psr)
303 {
304 	if(psr & PSR_PS)
305 		die_if_kernel("Penguin overflow trap from kernel mode", regs);
306 	send_sig_fault(SIGEMT, EMT_TAGOVF, (void __user *)pc, current);
307 }
308 
309 void handle_watchpoint(struct pt_regs *regs, unsigned long pc, unsigned long npc,
310 		       unsigned long psr)
311 {
312 #ifdef TRAP_DEBUG
313 	printk("Watchpoint detected at PC %08lx NPC %08lx PSR %08lx\n",
314 	       pc, npc, psr);
315 #endif
316 	if(psr & PSR_PS)
317 		panic("Tell me what a watchpoint trap is, and I'll then deal "
318 		      "with such a beast...");
319 }
320 
321 void handle_reg_access(struct pt_regs *regs, unsigned long pc, unsigned long npc,
322 		       unsigned long psr)
323 {
324 #ifdef TRAP_DEBUG
325 	printk("Register Access Exception at PC %08lx NPC %08lx PSR %08lx\n",
326 	       pc, npc, psr);
327 #endif
328 	force_sig_fault(SIGBUS, BUS_OBJERR, (void __user *)pc);
329 }
330 
331 void handle_cp_disabled(struct pt_regs *regs, unsigned long pc, unsigned long npc,
332 			unsigned long psr)
333 {
334 	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
335 }
336 
337 void handle_cp_exception(struct pt_regs *regs, unsigned long pc, unsigned long npc,
338 			 unsigned long psr)
339 {
340 #ifdef TRAP_DEBUG
341 	printk("Co-Processor Exception at PC %08lx NPC %08lx PSR %08lx\n",
342 	       pc, npc, psr);
343 #endif
344 	send_sig_fault(SIGILL, ILL_COPROC, (void __user *)pc, current);
345 }
346 
347 void handle_hw_divzero(struct pt_regs *regs, unsigned long pc, unsigned long npc,
348 		       unsigned long psr)
349 {
350 	send_sig_fault(SIGFPE, FPE_INTDIV, (void __user *)pc, current);
351 }
352 
353 #ifdef CONFIG_DEBUG_BUGVERBOSE
354 void do_BUG(const char *file, int line)
355 {
356         // bust_spinlocks(1);   XXX Not in our original BUG()
357         printk("kernel BUG at %s:%d!\n", file, line);
358 }
359 EXPORT_SYMBOL(do_BUG);
360 #endif
361 
362 /* Since we have our mappings set up, on multiprocessors we can spin them
363  * up here so that timer interrupts work during initialization.
364  */
365 
366 void trap_init(void)
367 {
368 	extern void thread_info_offsets_are_bolixed_pete(void);
369 
370 	/* Force linker to barf if mismatched */
371 	if (TI_UWINMASK    != offsetof(struct thread_info, uwinmask) ||
372 	    TI_TASK        != offsetof(struct thread_info, task) ||
373 	    TI_FLAGS       != offsetof(struct thread_info, flags) ||
374 	    TI_CPU         != offsetof(struct thread_info, cpu) ||
375 	    TI_PREEMPT     != offsetof(struct thread_info, preempt_count) ||
376 	    TI_SOFTIRQ     != offsetof(struct thread_info, softirq_count) ||
377 	    TI_HARDIRQ     != offsetof(struct thread_info, hardirq_count) ||
378 	    TI_KSP         != offsetof(struct thread_info, ksp) ||
379 	    TI_KPC         != offsetof(struct thread_info, kpc) ||
380 	    TI_KPSR        != offsetof(struct thread_info, kpsr) ||
381 	    TI_KWIM        != offsetof(struct thread_info, kwim) ||
382 	    TI_REG_WINDOW  != offsetof(struct thread_info, reg_window) ||
383 	    TI_RWIN_SPTRS  != offsetof(struct thread_info, rwbuf_stkptrs) ||
384 	    TI_W_SAVED     != offsetof(struct thread_info, w_saved))
385 		thread_info_offsets_are_bolixed_pete();
386 
387 	/* Attach to the address space of init_task. */
388 	mmgrab(&init_mm);
389 	current->active_mm = &init_mm;
390 
391 	/* NOTE: Other cpus have this done as they are started
392 	 *       up on SMP.
393 	 */
394 }
395