summaryrefslogtreecommitdiffstats
path: root/arch/x86/ia32/ia32_signal.c
blob: 0e2a5edbce00111f6a41f1b3070610b5316d1e71 (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
/*
 *  linux/arch/x86_64/ia32/ia32_signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
 *  2000-12-*   x86-64 compatibility mode signal handling by Andi Kleen
 */

#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/compat.h>
#include <linux/binfmts.h>
#include <asm/ucontext.h>
#include <linux/uaccess.h>
#include <asm/fpu/internal.h>
#include <asm/fpu/signal.h>
#include <asm/ptrace.h>
#include <asm/ia32_unistd.h>
#include <asm/user32.h>
#include <uapi/asm/sigcontext.h>
#include <asm/proto.h>
#include <asm/vdso.h>
#include <asm/sigframe.h>
#include <asm/sighandling.h>
#include <asm/sys_ia32.h>
#include <asm/smap.h>

/*
 * Do a signal return; undo the signal stack.
 */
#define loadsegment_gs(v)	load_gs_index(v)
#define loadsegment_fs(v)	loadsegment(fs, v)
#define loadsegment_ds(v)	loadsegment(ds, v)
#define loadsegment_es(v)	loadsegment(es, v)

#define get_user_seg(seg)	({ unsigned int v; savesegment(seg, v); v; })
#define set_user_seg(seg, v)	loadsegment_##seg(v)

#define COPY(x)			{		\
	get_user_ex(regs->x, &sc->x);		\
}

#define GET_SEG(seg)		({			\
	unsigned short tmp;				\
	get_user_ex(tmp, &sc->seg);			\
	tmp;						\
})

#define COPY_SEG_CPL3(seg)	do {			\
	regs->seg = GET_SEG(seg) | 3;			\
} while (0)

#define RELOAD_SEG(seg)		{		\
	unsigned int pre = GET_SEG(seg);	\
	unsigned int cur = get_user_seg(seg);	\
	pre |= 3;				\
	if (pre != cur)				\
		set_user_seg(seg, pre);		\
}

static int ia32_restore_sigcontext(struct pt_regs *regs,
				   struct sigcontext_32 __user *sc)
{
	unsigned int tmpflags, err = 0;
	void __user *buf;
	u32 tmp;

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

	get_user_try {
		/*
		 * Reload fs and gs if they have changed in the signal
		 * handler.  This does not handle long fs/gs base changes in
		 * the handler, but does not clobber them at least in the
		 * normal case.
		 */
		RELOAD_SEG(gs);
		RELOAD_SEG(fs);
		RELOAD_SEG(ds);
		RELOAD_SEG(es);

		COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
		COPY(dx); COPY(cx); COPY(ip); COPY(ax);
		/* Don't touch extended registers */

		COPY_SEG_CPL3(cs);
		COPY_SEG_CPL3(ss);

		get_user_ex(tmpflags, &sc->flags);
		regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
		/* disable syscall checks */
		regs->orig_ax = -1;

		get_user_ex(tmp, &sc->fpstate);
		buf = compat_ptr(tmp);
	} get_user_catch(err);

	err |= fpu__restore_sig(buf, 1);

	force_iret();

	return err;
}

asmlinkage long sys32_sigreturn(void)
{
	struct pt_regs *regs = current_pt_regs();
	struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
	sigset_t set;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;
	if (__get_user(set.sig[0], &frame->sc.oldmask)
	    || (_COMPAT_NSIG_WORDS > 1
		&& __copy_from_user((((char *) &set.sig) + 4),
				    &frame->extramask,
				    sizeof(frame->extramask))))
		goto badframe;

	set_current_blocked(&set);

	if (ia32_restore_sigcontext(regs, &frame->sc))
		goto badframe;
	return regs->ax;

badframe:
	signal_fault(regs, frame, "32bit sigreturn");
	return 0;
}

asmlinkage long sys32_rt_sigreturn(void)
{
	struct pt_regs *regs = current_pt_regs();
	struct rt_sigframe_ia32 __user *frame;
	sigset_t set;

	frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;
	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	set_current_blocked(&set);

	if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
		goto badframe;

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

	return regs->ax;

badframe:
	signal_fault(regs, frame, "32bit rt sigreturn");
	return 0;
}

/*
 * Set up a signal frame.
 */

static int ia32_setup_sigcontext(struct sigcontext_32 __user *sc,
				 void __user *fpstate,
				 struct pt_regs *regs, unsigned int mask)
{
	int err = 0;

	put_user_try {
		put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
		put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
		put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
		put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);

		put_user_ex(regs->di, &sc->di);
		put_user_ex(regs->si, &sc->si);
		put_user_ex(regs->bp, &sc->bp);
		put_user_ex(regs->sp, &sc->sp);
		put_user_ex(regs->bx, &sc->bx);
		put_user_ex(regs->dx, &sc->dx);
		put_user_ex(regs->cx, &sc->cx);
		put_user_ex(regs->ax, &sc->ax);
		put_user_ex(current->thread.trap_nr, &sc->trapno);
		put_user_ex(current->thread.error_code, &sc->err);
		put_user_ex(regs->ip, &sc->ip);
		put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
		put_user_ex(regs->flags, &sc->flags);
		put_user_ex(regs->sp, &sc->sp_at_signal);
		put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);

		put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);

		/* non-iBCS2 extensions.. */
		put_user_ex(mask, &sc->oldmask);
		put_user_ex(current->thread.cr2, &sc->cr2);
	} put_user_catch(err);

	return err;
}

/*
 * Determine which stack to use..
 */
static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
				 size_t frame_size,
				 void __user **fpstate)
{
	struct fpu *fpu = &current->thread.fpu;
	unsigned long sp;

	/* Default to using normal stack */
	sp = regs->sp;

	/* This is the X/Open sanctioned signal stack switching.  */
	if (ksig->ka.sa.sa_flags & SA_ONSTACK)
		sp = sigsp(sp, ksig);
	/* This is the legacy signal stack switching. */
	else if (regs->ss != __USER32_DS &&
		!(ksig->ka.sa.sa_flags & SA_RESTORER) &&
		 ksig->ka.sa.sa_restorer)
		sp = (unsigned long) ksig->ka.sa.sa_restorer;

	if (fpu->initialized) {
		unsigned long fx_aligned, math_size;

		sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
		*fpstate = (struct _fpstate_32 __user *) sp;
		if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
				    math_size) < 0)
			return (void __user *) -1L;
	}

	sp -= frame_size;
	/* Align the stack pointer according to the i386 ABI,
	 * i.e. so that on function entry ((sp + 4) & 15) == 0. */
	sp = ((sp + 4) & -16ul) - 4;
	return (void __user *) sp;
}

int ia32_setup_frame(int sig, struct ksignal *ksig,
		     compat_sigset_t *set, struct pt_regs *regs)
{
	struct sigframe_ia32 __user *frame;
	void __user *restorer;
	int err = 0;
	void __user *fpstate = NULL;

	/* copy_to_user optimizes that into a single 8 byte store */
	static const struct {
		u16 poplmovl;
		u32 val;
		u16 int80;
	} __attribute__((packed)) code = {
		0xb858,		 /* popl %eax ; movl $...,%eax */
		__NR_ia32_sigreturn,
		0x80cd,		/* int $0x80 */
	};

	frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		return -EFAULT;

	if (__put_user(sig, &frame->sig))
		return -EFAULT;

	if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
		return -EFAULT;

	if (_COMPAT_NSIG_WORDS > 1) {
		if (__copy_to_user(frame->extramask, &set->sig[1],
				   sizeof(frame->extramask)))
			return -EFAULT;
	}

	if (ksig->ka.sa.sa_flags & SA_RESTORER) {
		restorer = ksig->ka.sa.sa_restorer;
	} else {
		/* Return stub is in 32bit vsyscall page */
		if (current->mm->context.vdso)
			restorer = current->mm->context.vdso +
				vdso_image_32.sym___kernel_sigreturn;
		else
			restorer = &frame->retcode;
	}

	put_user_try {
		put_user_ex(ptr_to_compat(restorer), &frame->pretcode);

		/*
		 * These are actually not used anymore, but left because some
		 * gdb versions depend on them as a marker.
		 */
		put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
	} put_user_catch(err);

	if (err)
		return -EFAULT;

	/* Set up registers for signal handler */
	regs->sp = (unsigned long) frame;
	regs->ip = (unsigned long) ksig->ka.sa.sa_handler;

	/* Make -mregparm=3 work */
	regs->ax = sig;
	regs->dx = 0;
	regs->cx = 0;

	loadsegment(ds, __USER32_DS);
	loadsegment(es, __USER32_DS);

	regs->cs = __USER32_CS;
	regs->ss = __USER32_DS;

	return 0;
}

int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
			compat_sigset_t *set, struct pt_regs *regs)
{
	struct rt_sigframe_ia32 __user *frame;
	void __user *restorer;
	int err = 0;
	void __user *fpstate = NULL;

	/* __copy_to_user optimizes that into a single 8 byte store */
	static const struct {
		u8 movl;
		u32 val;
		u16 int80;
		u8  pad;
	} __attribute__((packed)) code = {
		0xb8,
		__NR_ia32_rt_sigreturn,
		0x80cd,
		0,
	};

	frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);

	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		return -EFAULT;

	put_user_try {
		put_user_ex(sig, &frame->sig);
		put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
		put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);

		/* Create the ucontext.  */
		if (boot_cpu_has(X86_FEATURE_XSAVE))
			put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
		else
			put_user_ex(0, &frame->uc.uc_flags);
		put_user_ex(0, &frame->uc.uc_link);
		compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);

		if (ksig->ka.sa.sa_flags & SA_RESTORER)
			restorer = ksig->ka.sa.sa_restorer;
		else
			restorer = current->mm->context.vdso +
				vdso_image_32.sym___kernel_rt_sigreturn;
		put_user_ex(ptr_to_compat(restorer), &frame->pretcode);

		/*
		 * Not actually used anymore, but left because some gdb
		 * versions need it.
		 */
		put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
	} put_user_catch(err);

	err |= __copy_siginfo_to_user32(&frame->info, &ksig->info, false);
	err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
				     regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	if (err)
		return -EFAULT;

	/* Set up registers for signal handler */
	regs->sp = (unsigned long) frame;
	regs->ip = (unsigned long) ksig->ka.sa.sa_handler;

	/* Make -mregparm=3 work */
	regs->ax = sig;
	regs->dx = (unsigned long) &frame->info;
	regs->cx = (unsigned long) &frame->uc;

	loadsegment(ds, __USER32_DS);
	loadsegment(es, __USER32_DS);

	regs->cs = __USER32_CS;
	regs->ss = __USER32_DS;

	return 0;
}
OpenPOWER on IntegriCloud