xref: /linux/arch/arm/kernel/process.c (revision 98817a84ff1c755c347ac633ff017a623a631fad) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/kernel/process.c
4  *
5  *  Copyright (C) 1996-2000 Russell King - Converted to ARM.
6  *  Original Copyright (C) 1995  Linus Torvalds
7  */
8 #include <stdarg.h>
9 
10 #include <linux/export.h>
11 #include <linux/sched.h>
12 #include <linux/sched/debug.h>
13 #include <linux/sched/task.h>
14 #include <linux/sched/task_stack.h>
15 #include <linux/kernel.h>
16 #include <linux/mm.h>
17 #include <linux/stddef.h>
18 #include <linux/unistd.h>
19 #include <linux/user.h>
20 #include <linux/interrupt.h>
21 #include <linux/init.h>
22 #include <linux/elfcore.h>
23 #include <linux/pm.h>
24 #include <linux/tick.h>
25 #include <linux/utsname.h>
26 #include <linux/uaccess.h>
27 #include <linux/random.h>
28 #include <linux/hw_breakpoint.h>
29 #include <linux/leds.h>
30 
31 #include <asm/processor.h>
32 #include <asm/thread_notify.h>
33 #include <asm/stacktrace.h>
34 #include <asm/system_misc.h>
35 #include <asm/mach/time.h>
36 #include <asm/tls.h>
37 #include <asm/vdso.h>
38 
39 #include "signal.h"
40 
41 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
42 #include <linux/stackprotector.h>
43 unsigned long __stack_chk_guard __read_mostly;
44 EXPORT_SYMBOL(__stack_chk_guard);
45 #endif
46 
47 static const char *processor_modes[] __maybe_unused = {
48   "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
49   "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
50   "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "MON_32" , "ABT_32" ,
51   "UK8_32" , "UK9_32" , "HYP_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
52 };
53 
54 static const char *isa_modes[] __maybe_unused = {
55   "ARM" , "Thumb" , "Jazelle", "ThumbEE"
56 };
57 
58 /*
59  * This is our default idle handler.
60  */
61 
62 void (*arm_pm_idle)(void);
63 
64 /*
65  * Called from the core idle loop.
66  */
67 
68 void arch_cpu_idle(void)
69 {
70 	if (arm_pm_idle)
71 		arm_pm_idle();
72 	else
73 		cpu_do_idle();
74 	local_irq_enable();
75 }
76 
77 void arch_cpu_idle_prepare(void)
78 {
79 	local_fiq_enable();
80 }
81 
82 void arch_cpu_idle_enter(void)
83 {
84 	ledtrig_cpu(CPU_LED_IDLE_START);
85 #ifdef CONFIG_PL310_ERRATA_769419
86 	wmb();
87 #endif
88 }
89 
90 void arch_cpu_idle_exit(void)
91 {
92 	ledtrig_cpu(CPU_LED_IDLE_END);
93 }
94 
95 void __show_regs(struct pt_regs *regs)
96 {
97 	unsigned long flags;
98 	char buf[64];
99 #ifndef CONFIG_CPU_V7M
100 	unsigned int domain, fs;
101 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
102 	/*
103 	 * Get the domain register for the parent context. In user
104 	 * mode, we don't save the DACR, so lets use what it should
105 	 * be. For other modes, we place it after the pt_regs struct.
106 	 */
107 	if (user_mode(regs)) {
108 		domain = DACR_UACCESS_ENABLE;
109 		fs = get_fs();
110 	} else {
111 		domain = to_svc_pt_regs(regs)->dacr;
112 		fs = to_svc_pt_regs(regs)->addr_limit;
113 	}
114 #else
115 	domain = get_domain();
116 	fs = get_fs();
117 #endif
118 #endif
119 
120 	show_regs_print_info(KERN_DEFAULT);
121 
122 	printk("PC is at %pS\n", (void *)instruction_pointer(regs));
123 	printk("LR is at %pS\n", (void *)regs->ARM_lr);
124 	printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n",
125 	       regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr);
126 	printk("sp : %08lx  ip : %08lx  fp : %08lx\n",
127 	       regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
128 	printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
129 		regs->ARM_r10, regs->ARM_r9,
130 		regs->ARM_r8);
131 	printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
132 		regs->ARM_r7, regs->ARM_r6,
133 		regs->ARM_r5, regs->ARM_r4);
134 	printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
135 		regs->ARM_r3, regs->ARM_r2,
136 		regs->ARM_r1, regs->ARM_r0);
137 
138 	flags = regs->ARM_cpsr;
139 	buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
140 	buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
141 	buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
142 	buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
143 	buf[4] = '\0';
144 
145 #ifndef CONFIG_CPU_V7M
146 	{
147 		const char *segment;
148 
149 		if ((domain & domain_mask(DOMAIN_USER)) ==
150 		    domain_val(DOMAIN_USER, DOMAIN_NOACCESS))
151 			segment = "none";
152 		else if (fs == KERNEL_DS)
153 			segment = "kernel";
154 		else
155 			segment = "user";
156 
157 		printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
158 			buf, interrupts_enabled(regs) ? "n" : "ff",
159 			fast_interrupts_enabled(regs) ? "n" : "ff",
160 			processor_modes[processor_mode(regs)],
161 			isa_modes[isa_mode(regs)], segment);
162 	}
163 #else
164 	printk("xPSR: %08lx\n", regs->ARM_cpsr);
165 #endif
166 
167 #ifdef CONFIG_CPU_CP15
168 	{
169 		unsigned int ctrl;
170 
171 		buf[0] = '\0';
172 #ifdef CONFIG_CPU_CP15_MMU
173 		{
174 			unsigned int transbase;
175 			asm("mrc p15, 0, %0, c2, c0\n\t"
176 			    : "=r" (transbase));
177 			snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
178 				transbase, domain);
179 		}
180 #endif
181 		asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));
182 
183 		printk("Control: %08x%s\n", ctrl, buf);
184 	}
185 #endif
186 }
187 
188 void show_regs(struct pt_regs * regs)
189 {
190 	__show_regs(regs);
191 	dump_stack();
192 }
193 
194 ATOMIC_NOTIFIER_HEAD(thread_notify_head);
195 
196 EXPORT_SYMBOL_GPL(thread_notify_head);
197 
198 /*
199  * Free current thread data structures etc..
200  */
201 void exit_thread(struct task_struct *tsk)
202 {
203 	thread_notify(THREAD_NOTIFY_EXIT, task_thread_info(tsk));
204 }
205 
206 void flush_thread(void)
207 {
208 	struct thread_info *thread = current_thread_info();
209 	struct task_struct *tsk = current;
210 
211 	flush_ptrace_hw_breakpoint(tsk);
212 
213 	memset(thread->used_cp, 0, sizeof(thread->used_cp));
214 	memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
215 	memset(&thread->fpstate, 0, sizeof(union fp_state));
216 
217 	flush_tls();
218 
219 	thread_notify(THREAD_NOTIFY_FLUSH, thread);
220 }
221 
222 void release_thread(struct task_struct *dead_task)
223 {
224 }
225 
226 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
227 
228 int
229 copy_thread_tls(unsigned long clone_flags, unsigned long stack_start,
230 	    unsigned long stk_sz, struct task_struct *p, unsigned long tls)
231 {
232 	struct thread_info *thread = task_thread_info(p);
233 	struct pt_regs *childregs = task_pt_regs(p);
234 
235 	memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
236 
237 #ifdef CONFIG_CPU_USE_DOMAINS
238 	/*
239 	 * Copy the initial value of the domain access control register
240 	 * from the current thread: thread->addr_limit will have been
241 	 * copied from the current thread via setup_thread_stack() in
242 	 * kernel/fork.c
243 	 */
244 	thread->cpu_domain = get_domain();
245 #endif
246 
247 	if (likely(!(p->flags & PF_KTHREAD))) {
248 		*childregs = *current_pt_regs();
249 		childregs->ARM_r0 = 0;
250 		if (stack_start)
251 			childregs->ARM_sp = stack_start;
252 	} else {
253 		memset(childregs, 0, sizeof(struct pt_regs));
254 		thread->cpu_context.r4 = stk_sz;
255 		thread->cpu_context.r5 = stack_start;
256 		childregs->ARM_cpsr = SVC_MODE;
257 	}
258 	thread->cpu_context.pc = (unsigned long)ret_from_fork;
259 	thread->cpu_context.sp = (unsigned long)childregs;
260 
261 	clear_ptrace_hw_breakpoint(p);
262 
263 	if (clone_flags & CLONE_SETTLS)
264 		thread->tp_value[0] = tls;
265 	thread->tp_value[1] = get_tpuser();
266 
267 	thread_notify(THREAD_NOTIFY_COPY, thread);
268 
269 #ifdef CONFIG_STACKPROTECTOR_PER_TASK
270 	thread->stack_canary = p->stack_canary;
271 #endif
272 
273 	return 0;
274 }
275 
276 /*
277  * Fill in the task's elfregs structure for a core dump.
278  */
279 int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs)
280 {
281 	elf_core_copy_regs(elfregs, task_pt_regs(t));
282 	return 1;
283 }
284 
285 /*
286  * fill in the fpe structure for a core dump...
287  */
288 int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
289 {
290 	struct thread_info *thread = current_thread_info();
291 	int used_math = thread->used_cp[1] | thread->used_cp[2];
292 
293 	if (used_math)
294 		memcpy(fp, &thread->fpstate.soft, sizeof (*fp));
295 
296 	return used_math != 0;
297 }
298 EXPORT_SYMBOL(dump_fpu);
299 
300 unsigned long get_wchan(struct task_struct *p)
301 {
302 	struct stackframe frame;
303 	unsigned long stack_page;
304 	int count = 0;
305 	if (!p || p == current || p->state == TASK_RUNNING)
306 		return 0;
307 
308 	frame.fp = thread_saved_fp(p);
309 	frame.sp = thread_saved_sp(p);
310 	frame.lr = 0;			/* recovered from the stack */
311 	frame.pc = thread_saved_pc(p);
312 	stack_page = (unsigned long)task_stack_page(p);
313 	do {
314 		if (frame.sp < stack_page ||
315 		    frame.sp >= stack_page + THREAD_SIZE ||
316 		    unwind_frame(&frame) < 0)
317 			return 0;
318 		if (!in_sched_functions(frame.pc))
319 			return frame.pc;
320 	} while (count ++ < 16);
321 	return 0;
322 }
323 
324 #ifdef CONFIG_MMU
325 #ifdef CONFIG_KUSER_HELPERS
326 /*
327  * The vectors page is always readable from user space for the
328  * atomic helpers. Insert it into the gate_vma so that it is visible
329  * through ptrace and /proc/<pid>/mem.
330  */
331 static struct vm_area_struct gate_vma;
332 
333 static int __init gate_vma_init(void)
334 {
335 	vma_init(&gate_vma, NULL);
336 	gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
337 	gate_vma.vm_start = 0xffff0000;
338 	gate_vma.vm_end	= 0xffff0000 + PAGE_SIZE;
339 	gate_vma.vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC;
340 	return 0;
341 }
342 arch_initcall(gate_vma_init);
343 
344 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
345 {
346 	return &gate_vma;
347 }
348 
349 int in_gate_area(struct mm_struct *mm, unsigned long addr)
350 {
351 	return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
352 }
353 
354 int in_gate_area_no_mm(unsigned long addr)
355 {
356 	return in_gate_area(NULL, addr);
357 }
358 #define is_gate_vma(vma)	((vma) == &gate_vma)
359 #else
360 #define is_gate_vma(vma)	0
361 #endif
362 
363 const char *arch_vma_name(struct vm_area_struct *vma)
364 {
365 	return is_gate_vma(vma) ? "[vectors]" : NULL;
366 }
367 
368 /* If possible, provide a placement hint at a random offset from the
369  * stack for the sigpage and vdso pages.
370  */
371 static unsigned long sigpage_addr(const struct mm_struct *mm,
372 				  unsigned int npages)
373 {
374 	unsigned long offset;
375 	unsigned long first;
376 	unsigned long last;
377 	unsigned long addr;
378 	unsigned int slots;
379 
380 	first = PAGE_ALIGN(mm->start_stack);
381 
382 	last = TASK_SIZE - (npages << PAGE_SHIFT);
383 
384 	/* No room after stack? */
385 	if (first > last)
386 		return 0;
387 
388 	/* Just enough room? */
389 	if (first == last)
390 		return first;
391 
392 	slots = ((last - first) >> PAGE_SHIFT) + 1;
393 
394 	offset = get_random_int() % slots;
395 
396 	addr = first + (offset << PAGE_SHIFT);
397 
398 	return addr;
399 }
400 
401 static struct page *signal_page;
402 extern struct page *get_signal_page(void);
403 
404 static int sigpage_mremap(const struct vm_special_mapping *sm,
405 		struct vm_area_struct *new_vma)
406 {
407 	current->mm->context.sigpage = new_vma->vm_start;
408 	return 0;
409 }
410 
411 static const struct vm_special_mapping sigpage_mapping = {
412 	.name = "[sigpage]",
413 	.pages = &signal_page,
414 	.mremap = sigpage_mremap,
415 };
416 
417 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
418 {
419 	struct mm_struct *mm = current->mm;
420 	struct vm_area_struct *vma;
421 	unsigned long npages;
422 	unsigned long addr;
423 	unsigned long hint;
424 	int ret = 0;
425 
426 	if (!signal_page)
427 		signal_page = get_signal_page();
428 	if (!signal_page)
429 		return -ENOMEM;
430 
431 	npages = 1; /* for sigpage */
432 	npages += vdso_total_pages;
433 
434 	if (mmap_write_lock_killable(mm))
435 		return -EINTR;
436 	hint = sigpage_addr(mm, npages);
437 	addr = get_unmapped_area(NULL, hint, npages << PAGE_SHIFT, 0, 0);
438 	if (IS_ERR_VALUE(addr)) {
439 		ret = addr;
440 		goto up_fail;
441 	}
442 
443 	vma = _install_special_mapping(mm, addr, PAGE_SIZE,
444 		VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
445 		&sigpage_mapping);
446 
447 	if (IS_ERR(vma)) {
448 		ret = PTR_ERR(vma);
449 		goto up_fail;
450 	}
451 
452 	mm->context.sigpage = addr;
453 
454 	/* Unlike the sigpage, failure to install the vdso is unlikely
455 	 * to be fatal to the process, so no error check needed
456 	 * here.
457 	 */
458 	arm_install_vdso(mm, addr + PAGE_SIZE);
459 
460  up_fail:
461 	mmap_write_unlock(mm);
462 	return ret;
463 }
464 #endif
465