summaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/signal32.c
blob: 331d1e5acad4aaa656fc2edb5cecbb8973044a9e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Based on arch/arm/kernel/signal.c
 *
 * Copyright (C) 1995-2009 Russell King
 * Copyright (C) 2012 ARM Ltd.
 * Modified by Will Deacon <will.deacon@arm.com>
 */

#include <linux/compat.h>
#include <linux/signal.h>
#include <linux/syscalls.h>
#include <linux/ratelimit.h>

#include <asm/esr.h>
#include <asm/fpsimd.h>
#include <asm/signal32.h>
#include <asm/traps.h>
#include <linux/uaccess.h>
#include <asm/unistd.h>

struct compat_sigcontext {
	/* We always set these two fields to 0 */
	compat_ulong_t			trap_no;
	compat_ulong_t			error_code;

	compat_ulong_t			oldmask;
	compat_ulong_t			arm_r0;
	compat_ulong_t			arm_r1;
	compat_ulong_t			arm_r2;
	compat_ulong_t			arm_r3;
	compat_ulong_t			arm_r4;
	compat_ulong_t			arm_r5;
	compat_ulong_t			arm_r6;
	compat_ulong_t			arm_r7;
	compat_ulong_t			arm_r8;
	compat_ulong_t			arm_r9;
	compat_ulong_t			arm_r10;
	compat_ulong_t			arm_fp;
	compat_ulong_t			arm_ip;
	compat_ulong_t			arm_sp;
	compat_ulong_t			arm_lr;
	compat_ulong_t			arm_pc;
	compat_ulong_t			arm_cpsr;
	compat_ulong_t			fault_address;
};

struct compat_ucontext {
	compat_ulong_t			uc_flags;
	compat_uptr_t			uc_link;
	compat_stack_t			uc_stack;
	struct compat_sigcontext	uc_mcontext;
	compat_sigset_t			uc_sigmask;
	int		__unused[32 - (sizeof (compat_sigset_t) / sizeof (int))];
	compat_ulong_t	uc_regspace[128] __attribute__((__aligned__(8)));
};

struct compat_vfp_sigframe {
	compat_ulong_t	magic;
	compat_ulong_t	size;
	struct compat_user_vfp {
		compat_u64	fpregs[32];
		compat_ulong_t	fpscr;
	} ufp;
	struct compat_user_vfp_exc {
		compat_ulong_t	fpexc;
		compat_ulong_t	fpinst;
		compat_ulong_t	fpinst2;
	} ufp_exc;
} __attribute__((__aligned__(8)));

#define VFP_MAGIC		0x56465001
#define VFP_STORAGE_SIZE	sizeof(struct compat_vfp_sigframe)

#define FSR_WRITE_SHIFT		(11)

struct compat_aux_sigframe {
	struct compat_vfp_sigframe	vfp;

	/* Something that isn't a valid magic number for any coprocessor.  */
	unsigned long			end_magic;
} __attribute__((__aligned__(8)));

struct compat_sigframe {
	struct compat_ucontext	uc;
	compat_ulong_t		retcode[2];
};

struct compat_rt_sigframe {
	struct compat_siginfo info;
	struct compat_sigframe sig;
};

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
{
	compat_sigset_t	cset;

	cset.sig[0] = set->sig[0] & 0xffffffffull;
	cset.sig[1] = set->sig[0] >> 32;

	return copy_to_user(uset, &cset, sizeof(*uset));
}

static inline int get_sigset_t(sigset_t *set,
			       const compat_sigset_t __user *uset)
{
	compat_sigset_t s32;

	if (copy_from_user(&s32, uset, sizeof(*uset)))
		return -EFAULT;

	set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
	return 0;
}

/*
 * VFP save/restore code.
 *
 * We have to be careful with endianness, since the fpsimd context-switch
 * code operates on 128-bit (Q) register values whereas the compat ABI
 * uses an array of 64-bit (D) registers. Consequently, we need to swap
 * the two halves of each Q register when running on a big-endian CPU.
 */
union __fpsimd_vreg {
	__uint128_t	raw;
	struct {
#ifdef __AARCH64EB__
		u64	hi;
		u64	lo;
#else
		u64	lo;
		u64	hi;
#endif
	};
};

static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
{
	struct user_fpsimd_state const *fpsimd =
		&current->thread.uw.fpsimd_state;
	compat_ulong_t magic = VFP_MAGIC;
	compat_ulong_t size = VFP_STORAGE_SIZE;
	compat_ulong_t fpscr, fpexc;
	int i, err = 0;

	/*
	 * Save the hardware registers to the fpsimd_state structure.
	 * Note that this also saves V16-31, which aren't visible
	 * in AArch32.
	 */
	fpsimd_signal_preserve_current_state();

	/* Place structure header on the stack */
	__put_user_error(magic, &frame->magic, err);
	__put_user_error(size, &frame->size, err);

	/*
	 * Now copy the FP registers. Since the registers are packed,
	 * we can copy the prefix we want (V0-V15) as it is.
	 */
	for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
		union __fpsimd_vreg vreg = {
			.raw = fpsimd->vregs[i >> 1],
		};

		__put_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
		__put_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
	}

	/* Create an AArch32 fpscr from the fpsr and the fpcr. */
	fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) |
		(fpsimd->fpcr & VFP_FPSCR_CTRL_MASK);
	__put_user_error(fpscr, &frame->ufp.fpscr, err);

	/*
	 * The exception register aren't available so we fake up a
	 * basic FPEXC and zero everything else.
	 */
	fpexc = (1 << 30);
	__put_user_error(fpexc, &frame->ufp_exc.fpexc, err);
	__put_user_error(0, &frame->ufp_exc.fpinst, err);
	__put_user_error(0, &frame->ufp_exc.fpinst2, err);

	return err ? -EFAULT : 0;
}

static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
{
	struct user_fpsimd_state fpsimd;
	compat_ulong_t magic = VFP_MAGIC;
	compat_ulong_t size = VFP_STORAGE_SIZE;
	compat_ulong_t fpscr;
	int i, err = 0;

	__get_user_error(magic, &frame->magic, err);
	__get_user_error(size, &frame->size, err);

	if (err)
		return -EFAULT;
	if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
		return -EINVAL;

	/* Copy the FP registers into the start of the fpsimd_state. */
	for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
		union __fpsimd_vreg vreg;

		__get_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
		__get_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
		fpsimd.vregs[i >> 1] = vreg.raw;
	}

	/* Extract the fpsr and the fpcr from the fpscr */
	__get_user_error(fpscr, &frame->ufp.fpscr, err);
	fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK;
	fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK;

	/*
	 * We don't need to touch the exception register, so
	 * reload the hardware state.
	 */
	if (!err)
		fpsimd_update_current_state(&fpsimd);

	return err ? -EFAULT : 0;
}

static int compat_restore_sigframe(struct pt_regs *regs,
				   struct compat_sigframe __user *sf)
{
	int err;
	sigset_t set;
	struct compat_aux_sigframe __user *aux;
	unsigned long psr;

	err = get_sigset_t(&set, &sf->uc.uc_sigmask);
	if (err == 0) {
		sigdelsetmask(&set, ~_BLOCKABLE);
		set_current_blocked(&set);
	}

	__get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
	__get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
	__get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
	__get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
	__get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
	__get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
	__get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
	__get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
	__get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
	__get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
	__get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
	__get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
	__get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
	__get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
	__get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
	__get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
	__get_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);

	regs->pstate = compat_psr_to_pstate(psr);

	/*
	 * Avoid compat_sys_sigreturn() restarting.
	 */
	forget_syscall(regs);

	err |= !valid_user_regs(&regs->user_regs, current);

	aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
	if (err == 0)
		err |= compat_restore_vfp_context(&aux->vfp);

	return err;
}

COMPAT_SYSCALL_DEFINE0(sigreturn)
{
	struct pt_regs *regs = current_pt_regs();
	struct compat_sigframe __user *frame;

	/* Always make any pending restarted system calls return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	/*
	 * Since we stacked the signal on a 64-bit boundary,
	 * then 'sp' should be word aligned here.  If it's
	 * not, then the user is trying to mess with us.
	 */
	if (regs->compat_sp & 7)
		goto badframe;

	frame = (struct compat_sigframe __user *)regs->compat_sp;

	if (!access_ok(frame, sizeof (*frame)))
		goto badframe;

	if (compat_restore_sigframe(regs, frame))
		goto badframe;

	return regs->regs[0];

badframe:
	arm64_notify_segfault(regs->compat_sp);
	return 0;
}

COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
{
	struct pt_regs *regs = current_pt_regs();
	struct compat_rt_sigframe __user *frame;

	/* Always make any pending restarted system calls return -EINTR */
	current->restart_block.fn = do_no_restart_syscall;

	/*
	 * Since we stacked the signal on a 64-bit boundary,
	 * then 'sp' should be word aligned here.  If it's
	 * not, then the user is trying to mess with us.
	 */
	if (regs->compat_sp & 7)
		goto badframe;

	frame = (struct compat_rt_sigframe __user *)regs->compat_sp;

	if (!access_ok(frame, sizeof (*frame)))
		goto badframe;

	if (compat_restore_sigframe(regs, &frame->sig))
		goto badframe;

	if (compat_restore_altstack(&frame->sig.uc.uc_stack))
		goto badframe;

	return regs->regs[0];

badframe:
	arm64_notify_segfault(regs->compat_sp);
	return 0;
}

static void __user *compat_get_sigframe(struct ksignal *ksig,
					struct pt_regs *regs,
					int framesize)
{
	compat_ulong_t sp = sigsp(regs->compat_sp, ksig);
	void __user *frame;

	/*
	 * ATPCS B01 mandates 8-byte alignment
	 */
	frame = compat_ptr((compat_uptr_t)((sp - framesize) & ~7));

	/*
	 * Check that we can actually write to the signal frame.
	 */
	if (!access_ok(frame, framesize))
		frame = NULL;

	return frame;
}

static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
				compat_ulong_t __user *rc, void __user *frame,
				int usig)
{
	compat_ulong_t handler = ptr_to_compat(ka->sa.sa_handler);
	compat_ulong_t retcode;
	compat_ulong_t spsr = regs->pstate & ~(PSR_f | PSR_AA32_E_BIT);
	int thumb;

	/* Check if the handler is written for ARM or Thumb */
	thumb = handler & 1;

	if (thumb)
		spsr |= PSR_AA32_T_BIT;
	else
		spsr &= ~PSR_AA32_T_BIT;

	/* The IT state must be cleared for both ARM and Thumb-2 */
	spsr &= ~PSR_AA32_IT_MASK;

	/* Restore the original endianness */
	spsr |= PSR_AA32_ENDSTATE;

	if (ka->sa.sa_flags & SA_RESTORER) {
		retcode = ptr_to_compat(ka->sa.sa_restorer);
	} else {
		/* Set up sigreturn pointer */
		unsigned int idx = thumb << 1;

		if (ka->sa.sa_flags & SA_SIGINFO)
			idx += 3;

		retcode = (unsigned long)current->mm->context.vdso +
			  (idx << 2) + thumb;
	}

	regs->regs[0]	= usig;
	regs->compat_sp	= ptr_to_compat(frame);
	regs->compat_lr	= retcode;
	regs->pc	= handler;
	regs->pstate	= spsr;
}

static int compat_setup_sigframe(struct compat_sigframe __user *sf,
				 struct pt_regs *regs, sigset_t *set)
{
	struct compat_aux_sigframe __user *aux;
	unsigned long psr = pstate_to_compat_psr(regs->pstate);
	int err = 0;

	__put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
	__put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
	__put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
	__put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
	__put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
	__put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
	__put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
	__put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
	__put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
	__put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
	__put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
	__put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
	__put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
	__put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
	__put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
	__put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
	__put_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);

	__put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
	/* set the compat FSR WnR */
	__put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) <<
			 FSR_WRITE_SHIFT, &sf->uc.uc_mcontext.error_code, err);
	__put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
	__put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);

	err |= put_sigset_t(&sf->uc.uc_sigmask, set);

	aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;

	if (err == 0)
		err |= compat_preserve_vfp_context(&aux->vfp);
	__put_user_error(0, &aux->end_magic, err);

	return err;
}

/*
 * 32-bit signal handling routines called from signal.c
 */
int compat_setup_rt_frame(int usig, struct ksignal *ksig,
			  sigset_t *set, struct pt_regs *regs)
{
	struct compat_rt_sigframe __user *frame;
	int err = 0;

	frame = compat_get_sigframe(ksig, regs, sizeof(*frame));

	if (!frame)
		return 1;

	err |= copy_siginfo_to_user32(&frame->info, &ksig->info);

	__put_user_error(0, &frame->sig.uc.uc_flags, err);
	__put_user_error(0, &frame->sig.uc.uc_link, err);

	err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);

	err |= compat_setup_sigframe(&frame->sig, regs, set);

	if (err == 0) {
		compat_setup_return(regs, &ksig->ka, frame->sig.retcode, frame, usig);
		regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
		regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
	}

	return err;
}

int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set,
		       struct pt_regs *regs)
{
	struct compat_sigframe __user *frame;
	int err = 0;

	frame = compat_get_sigframe(ksig, regs, sizeof(*frame));

	if (!frame)
		return 1;

	__put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);

	err |= compat_setup_sigframe(frame, regs, set);
	if (err == 0)
		compat_setup_return(regs, &ksig->ka, frame->retcode, frame, usig);

	return err;
}

void compat_setup_restart_syscall(struct pt_regs *regs)
{
       regs->regs[7] = __NR_compat_restart_syscall;
}