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 <linux/export.h>
9 #include <linux/sched.h>
10 #include <linux/sched/debug.h>
11 #include <linux/sched/task.h>
12 #include <linux/sched/task_stack.h>
13 #include <linux/kernel.h>
14 #include <linux/mm.h>
15 #include <linux/stddef.h>
16 #include <linux/unistd.h>
17 #include <linux/user.h>
18 #include <linux/interrupt.h>
19 #include <linux/init.h>
20 #include <linux/elfcore.h>
21 #include <linux/pm.h>
22 #include <linux/tick.h>
23 #include <linux/utsname.h>
24 #include <linux/uaccess.h>
25 #include <linux/random.h>
26 #include <linux/hw_breakpoint.h>
27 #include <linux/leds.h>
28 
29 #include <asm/processor.h>
30 #include <asm/thread_notify.h>
31 #include <asm/stacktrace.h>
32 #include <asm/system_misc.h>
33 #include <asm/mach/time.h>
34 #include <asm/tls.h>
35 #include <asm/vdso.h>
36 
37 #include "signal.h"
38 
39 #if defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
40 DEFINE_PER_CPU(struct task_struct *, __entry_task);
41 #endif
42 
43 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
44 #include <linux/stackprotector.h>
45 unsigned long __stack_chk_guard __read_mostly;
46 EXPORT_SYMBOL(__stack_chk_guard);
47 #endif
48 
49 #ifndef CONFIG_CURRENT_POINTER_IN_TPIDRURO
50 asmlinkage struct task_struct *__current;
51 EXPORT_SYMBOL(__current);
52 #endif
53 
54 static const char *processor_modes[] __maybe_unused = {
55   "USER_26", "FIQ_26" , "IRQ_26" , "SVC_26" , "UK4_26" , "UK5_26" , "UK6_26" , "UK7_26" ,
56   "UK8_26" , "UK9_26" , "UK10_26", "UK11_26", "UK12_26", "UK13_26", "UK14_26", "UK15_26",
57   "USER_32", "FIQ_32" , "IRQ_32" , "SVC_32" , "UK4_32" , "UK5_32" , "MON_32" , "ABT_32" ,
58   "UK8_32" , "UK9_32" , "HYP_32", "UND_32" , "UK12_32", "UK13_32", "UK14_32", "SYS_32"
59 };
60 
61 static const char *isa_modes[] __maybe_unused = {
62   "ARM" , "Thumb" , "Jazelle", "ThumbEE"
63 };
64 
65 /*
66  * This is our default idle handler.
67  */
68 
69 void (*arm_pm_idle)(void);
70 
71 /*
72  * Called from the core idle loop.
73  */
74 
arch_cpu_idle(void)75 void arch_cpu_idle(void)
76 {
77 	if (arm_pm_idle)
78 		arm_pm_idle();
79 	else
80 		cpu_do_idle();
81 	raw_local_irq_enable();
82 }
83 
arch_cpu_idle_prepare(void)84 void arch_cpu_idle_prepare(void)
85 {
86 	local_fiq_enable();
87 }
88 
arch_cpu_idle_enter(void)89 void arch_cpu_idle_enter(void)
90 {
91 	ledtrig_cpu(CPU_LED_IDLE_START);
92 #ifdef CONFIG_PL310_ERRATA_769419
93 	wmb();
94 #endif
95 }
96 
arch_cpu_idle_exit(void)97 void arch_cpu_idle_exit(void)
98 {
99 	ledtrig_cpu(CPU_LED_IDLE_END);
100 }
101 
__show_regs_alloc_free(struct pt_regs * regs)102 void __show_regs_alloc_free(struct pt_regs *regs)
103 {
104 	int i;
105 
106 	/* check for r0 - r12 only */
107 	for (i = 0; i < 13; i++) {
108 		pr_alert("Register r%d information:", i);
109 		mem_dump_obj((void *)regs->uregs[i]);
110 	}
111 }
112 
__show_regs(struct pt_regs * regs)113 void __show_regs(struct pt_regs *regs)
114 {
115 	unsigned long flags;
116 	char buf[64];
117 #ifndef CONFIG_CPU_V7M
118 	unsigned int domain;
119 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
120 	/*
121 	 * Get the domain register for the parent context. In user
122 	 * mode, we don't save the DACR, so lets use what it should
123 	 * be. For other modes, we place it after the pt_regs struct.
124 	 */
125 	if (user_mode(regs)) {
126 		domain = DACR_UACCESS_ENABLE;
127 	} else {
128 		domain = to_svc_pt_regs(regs)->dacr;
129 	}
130 #else
131 	domain = get_domain();
132 #endif
133 #endif
134 
135 	show_regs_print_info(KERN_DEFAULT);
136 
137 	printk("PC is at %pS\n", (void *)instruction_pointer(regs));
138 	printk("LR is at %pS\n", (void *)regs->ARM_lr);
139 	printk("pc : [<%08lx>]    lr : [<%08lx>]    psr: %08lx\n",
140 	       regs->ARM_pc, regs->ARM_lr, regs->ARM_cpsr);
141 	printk("sp : %08lx  ip : %08lx  fp : %08lx\n",
142 	       regs->ARM_sp, regs->ARM_ip, regs->ARM_fp);
143 	printk("r10: %08lx  r9 : %08lx  r8 : %08lx\n",
144 		regs->ARM_r10, regs->ARM_r9,
145 		regs->ARM_r8);
146 	printk("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
147 		regs->ARM_r7, regs->ARM_r6,
148 		regs->ARM_r5, regs->ARM_r4);
149 	printk("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
150 		regs->ARM_r3, regs->ARM_r2,
151 		regs->ARM_r1, regs->ARM_r0);
152 
153 	flags = regs->ARM_cpsr;
154 	buf[0] = flags & PSR_N_BIT ? 'N' : 'n';
155 	buf[1] = flags & PSR_Z_BIT ? 'Z' : 'z';
156 	buf[2] = flags & PSR_C_BIT ? 'C' : 'c';
157 	buf[3] = flags & PSR_V_BIT ? 'V' : 'v';
158 	buf[4] = '\0';
159 
160 #ifndef CONFIG_CPU_V7M
161 	{
162 		const char *segment;
163 
164 		if ((domain & domain_mask(DOMAIN_USER)) ==
165 		    domain_val(DOMAIN_USER, DOMAIN_NOACCESS))
166 			segment = "none";
167 		else
168 			segment = "user";
169 
170 		printk("Flags: %s  IRQs o%s  FIQs o%s  Mode %s  ISA %s  Segment %s\n",
171 			buf, interrupts_enabled(regs) ? "n" : "ff",
172 			fast_interrupts_enabled(regs) ? "n" : "ff",
173 			processor_modes[processor_mode(regs)],
174 			isa_modes[isa_mode(regs)], segment);
175 	}
176 #else
177 	printk("xPSR: %08lx\n", regs->ARM_cpsr);
178 #endif
179 
180 #ifdef CONFIG_CPU_CP15
181 	{
182 		unsigned int ctrl;
183 
184 		buf[0] = '\0';
185 #ifdef CONFIG_CPU_CP15_MMU
186 		{
187 			unsigned int transbase;
188 			asm("mrc p15, 0, %0, c2, c0\n\t"
189 			    : "=r" (transbase));
190 			snprintf(buf, sizeof(buf), "  Table: %08x  DAC: %08x",
191 				transbase, domain);
192 		}
193 #endif
194 		asm("mrc p15, 0, %0, c1, c0\n" : "=r" (ctrl));
195 
196 		printk("Control: %08x%s\n", ctrl, buf);
197 	}
198 #endif
199 }
200 
show_regs(struct pt_regs * regs)201 void show_regs(struct pt_regs * regs)
202 {
203 	__show_regs(regs);
204 	dump_stack();
205 }
206 
207 ATOMIC_NOTIFIER_HEAD(thread_notify_head);
208 
209 EXPORT_SYMBOL_GPL(thread_notify_head);
210 
211 /*
212  * Free current thread data structures etc..
213  */
exit_thread(struct task_struct * tsk)214 void exit_thread(struct task_struct *tsk)
215 {
216 	thread_notify(THREAD_NOTIFY_EXIT, task_thread_info(tsk));
217 }
218 
flush_thread(void)219 void flush_thread(void)
220 {
221 	struct thread_info *thread = current_thread_info();
222 	struct task_struct *tsk = current;
223 
224 	flush_ptrace_hw_breakpoint(tsk);
225 
226 	memset(thread->used_cp, 0, sizeof(thread->used_cp));
227 	memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
228 	memset(&thread->fpstate, 0, sizeof(union fp_state));
229 
230 	flush_tls();
231 
232 	thread_notify(THREAD_NOTIFY_FLUSH, thread);
233 }
234 
release_thread(struct task_struct * dead_task)235 void release_thread(struct task_struct *dead_task)
236 {
237 }
238 
239 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
240 
copy_thread(struct task_struct * p,const struct kernel_clone_args * args)241 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
242 {
243 	unsigned long clone_flags = args->flags;
244 	unsigned long stack_start = args->stack;
245 	unsigned long tls = args->tls;
246 	struct thread_info *thread = task_thread_info(p);
247 	struct pt_regs *childregs = task_pt_regs(p);
248 
249 	memset(&thread->cpu_context, 0, sizeof(struct cpu_context_save));
250 
251 #ifdef CONFIG_CPU_USE_DOMAINS
252 	/*
253 	 * Copy the initial value of the domain access control register
254 	 * from the current thread: thread->addr_limit will have been
255 	 * copied from the current thread via setup_thread_stack() in
256 	 * kernel/fork.c
257 	 */
258 	thread->cpu_domain = get_domain();
259 #endif
260 
261 	if (likely(!args->fn)) {
262 		*childregs = *current_pt_regs();
263 		childregs->ARM_r0 = 0;
264 		if (stack_start)
265 			childregs->ARM_sp = stack_start;
266 	} else {
267 		memset(childregs, 0, sizeof(struct pt_regs));
268 		thread->cpu_context.r4 = (unsigned long)args->fn_arg;
269 		thread->cpu_context.r5 = (unsigned long)args->fn;
270 		childregs->ARM_cpsr = SVC_MODE;
271 	}
272 	thread->cpu_context.pc = (unsigned long)ret_from_fork;
273 	thread->cpu_context.sp = (unsigned long)childregs;
274 
275 	clear_ptrace_hw_breakpoint(p);
276 
277 	if (clone_flags & CLONE_SETTLS)
278 		thread->tp_value[0] = tls;
279 	thread->tp_value[1] = get_tpuser();
280 
281 	thread_notify(THREAD_NOTIFY_COPY, thread);
282 
283 	return 0;
284 }
285 
__get_wchan(struct task_struct * p)286 unsigned long __get_wchan(struct task_struct *p)
287 {
288 	struct stackframe frame;
289 	unsigned long stack_page;
290 	int count = 0;
291 
292 	frame.fp = thread_saved_fp(p);
293 	frame.sp = thread_saved_sp(p);
294 	frame.lr = 0;			/* recovered from the stack */
295 	frame.pc = thread_saved_pc(p);
296 	stack_page = (unsigned long)task_stack_page(p);
297 	do {
298 		if (frame.sp < stack_page ||
299 		    frame.sp >= stack_page + THREAD_SIZE ||
300 		    unwind_frame(&frame) < 0)
301 			return 0;
302 		if (!in_sched_functions(frame.pc))
303 			return frame.pc;
304 	} while (count ++ < 16);
305 	return 0;
306 }
307 
308 #ifdef CONFIG_MMU
309 #ifdef CONFIG_KUSER_HELPERS
310 /*
311  * The vectors page is always readable from user space for the
312  * atomic helpers. Insert it into the gate_vma so that it is visible
313  * through ptrace and /proc/<pid>/mem.
314  */
315 static struct vm_area_struct gate_vma;
316 
gate_vma_init(void)317 static int __init gate_vma_init(void)
318 {
319 	vma_init(&gate_vma, NULL);
320 	gate_vma.vm_page_prot = PAGE_READONLY_EXEC;
321 	gate_vma.vm_start = 0xffff0000;
322 	gate_vma.vm_end	= 0xffff0000 + PAGE_SIZE;
323 	gate_vma.vm_flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYEXEC;
324 	return 0;
325 }
326 arch_initcall(gate_vma_init);
327 
get_gate_vma(struct mm_struct * mm)328 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
329 {
330 	return &gate_vma;
331 }
332 
in_gate_area(struct mm_struct * mm,unsigned long addr)333 int in_gate_area(struct mm_struct *mm, unsigned long addr)
334 {
335 	return (addr >= gate_vma.vm_start) && (addr < gate_vma.vm_end);
336 }
337 
in_gate_area_no_mm(unsigned long addr)338 int in_gate_area_no_mm(unsigned long addr)
339 {
340 	return in_gate_area(NULL, addr);
341 }
342 #define is_gate_vma(vma)	((vma) == &gate_vma)
343 #else
344 #define is_gate_vma(vma)	0
345 #endif
346 
arch_vma_name(struct vm_area_struct * vma)347 const char *arch_vma_name(struct vm_area_struct *vma)
348 {
349 	return is_gate_vma(vma) ? "[vectors]" : NULL;
350 }
351 
352 /* If possible, provide a placement hint at a random offset from the
353  * stack for the sigpage and vdso pages.
354  */
sigpage_addr(const struct mm_struct * mm,unsigned int npages)355 static unsigned long sigpage_addr(const struct mm_struct *mm,
356 				  unsigned int npages)
357 {
358 	unsigned long offset;
359 	unsigned long first;
360 	unsigned long last;
361 	unsigned long addr;
362 	unsigned int slots;
363 
364 	first = PAGE_ALIGN(mm->start_stack);
365 
366 	last = TASK_SIZE - (npages << PAGE_SHIFT);
367 
368 	/* No room after stack? */
369 	if (first > last)
370 		return 0;
371 
372 	/* Just enough room? */
373 	if (first == last)
374 		return first;
375 
376 	slots = ((last - first) >> PAGE_SHIFT) + 1;
377 
378 	offset = get_random_int() % slots;
379 
380 	addr = first + (offset << PAGE_SHIFT);
381 
382 	return addr;
383 }
384 
385 static struct page *signal_page;
386 extern struct page *get_signal_page(void);
387 
sigpage_mremap(const struct vm_special_mapping * sm,struct vm_area_struct * new_vma)388 static int sigpage_mremap(const struct vm_special_mapping *sm,
389 		struct vm_area_struct *new_vma)
390 {
391 	current->mm->context.sigpage = new_vma->vm_start;
392 	return 0;
393 }
394 
395 static const struct vm_special_mapping sigpage_mapping = {
396 	.name = "[sigpage]",
397 	.pages = &signal_page,
398 	.mremap = sigpage_mremap,
399 };
400 
arch_setup_additional_pages(struct linux_binprm * bprm,int uses_interp)401 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
402 {
403 	struct mm_struct *mm = current->mm;
404 	struct vm_area_struct *vma;
405 	unsigned long npages;
406 	unsigned long addr;
407 	unsigned long hint;
408 	int ret = 0;
409 
410 	if (!signal_page)
411 		signal_page = get_signal_page();
412 	if (!signal_page)
413 		return -ENOMEM;
414 
415 	npages = 1; /* for sigpage */
416 	npages += vdso_total_pages;
417 
418 	if (mmap_write_lock_killable(mm))
419 		return -EINTR;
420 	hint = sigpage_addr(mm, npages);
421 	addr = get_unmapped_area(NULL, hint, npages << PAGE_SHIFT, 0, 0);
422 	if (IS_ERR_VALUE(addr)) {
423 		ret = addr;
424 		goto up_fail;
425 	}
426 
427 	vma = _install_special_mapping(mm, addr, PAGE_SIZE,
428 		VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC,
429 		&sigpage_mapping);
430 
431 	if (IS_ERR(vma)) {
432 		ret = PTR_ERR(vma);
433 		goto up_fail;
434 	}
435 
436 	mm->context.sigpage = addr;
437 
438 	/* Unlike the sigpage, failure to install the vdso is unlikely
439 	 * to be fatal to the process, so no error check needed
440 	 * here.
441 	 */
442 	arm_install_vdso(mm, addr + PAGE_SIZE);
443 
444  up_fail:
445 	mmap_write_unlock(mm);
446 	return ret;
447 }
448 #endif
449