summaryrefslogtreecommitdiffstats
path: root/arch/um/sys-x86_64/signal.c
blob: c98dd7f313969a8187852cb03a3a8bc21905a669 (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
/*
 * Copyright (C) 2003 PathScale, Inc.
 * Licensed under the GPL
 */

#include "linux/personality.h"
#include "linux/ptrace.h"
#include "asm/unistd.h"
#include "asm/uaccess.h"
#include "asm/ucontext.h"
#include "frame_kern.h"
#include "skas.h"

void copy_sc(struct uml_pt_regs *regs, void *from)
{
	struct sigcontext *sc = from;

#define GETREG(regs, regno, sc, regname)				\
	(regs)->gp[(regno) / sizeof(unsigned long)] = (sc)->regname

	GETREG(regs, R8, sc, r8);
	GETREG(regs, R9, sc, r9);
	GETREG(regs, R10, sc, r10);
	GETREG(regs, R11, sc, r11);
	GETREG(regs, R12, sc, r12);
	GETREG(regs, R13, sc, r13);
	GETREG(regs, R14, sc, r14);
	GETREG(regs, R15, sc, r15);
	GETREG(regs, RDI, sc, rdi);
	GETREG(regs, RSI, sc, rsi);
	GETREG(regs, RBP, sc, rbp);
	GETREG(regs, RBX, sc, rbx);
	GETREG(regs, RDX, sc, rdx);
	GETREG(regs, RAX, sc, rax);
	GETREG(regs, RCX, sc, rcx);
	GETREG(regs, RSP, sc, rsp);
	GETREG(regs, RIP, sc, rip);
	GETREG(regs, EFLAGS, sc, eflags);
	GETREG(regs, CS, sc, cs);

#undef GETREG
}

static int copy_sc_from_user(struct pt_regs *regs,
			     struct sigcontext __user *from)
{
	int err = 0;

#define GETREG(regs, regno, sc, regname)				\
	__get_user((regs)->regs.gp[(regno) / sizeof(unsigned long)],	\
		   &(sc)->regname)

	err |= GETREG(regs, R8, from, r8);
	err |= GETREG(regs, R9, from, r9);
	err |= GETREG(regs, R10, from, r10);
	err |= GETREG(regs, R11, from, r11);
	err |= GETREG(regs, R12, from, r12);
	err |= GETREG(regs, R13, from, r13);
	err |= GETREG(regs, R14, from, r14);
	err |= GETREG(regs, R15, from, r15);
	err |= GETREG(regs, RDI, from, rdi);
	err |= GETREG(regs, RSI, from, rsi);
	err |= GETREG(regs, RBP, from, rbp);
	err |= GETREG(regs, RBX, from, rbx);
	err |= GETREG(regs, RDX, from, rdx);
	err |= GETREG(regs, RAX, from, rax);
	err |= GETREG(regs, RCX, from, rcx);
	err |= GETREG(regs, RSP, from, rsp);
	err |= GETREG(regs, RIP, from, rip);
	err |= GETREG(regs, EFLAGS, from, eflags);
	err |= GETREG(regs, CS, from, cs);

#undef GETREG

	return err;
}

static int copy_sc_to_user(struct sigcontext __user *to,
			   struct _fpstate __user *to_fp, struct pt_regs *regs,
			   unsigned long mask, unsigned long sp)
{
	struct faultinfo * fi = &current->thread.arch.faultinfo;
	int err = 0;

	err |= __put_user(0, &to->gs);
	err |= __put_user(0, &to->fs);

#define PUTREG(regs, regno, sc, regname)				\
	__put_user((regs)->regs.gp[(regno) / sizeof(unsigned long)],	\
		   &(sc)->regname)

	err |= PUTREG(regs, RDI, to, rdi);
	err |= PUTREG(regs, RSI, to, rsi);
	err |= PUTREG(regs, RBP, to, rbp);
	/* Must use orignal RSP, which is passed in, rather than what's in
	 * the pt_regs, because that's already been updated to point at the
	 * signal frame.
	 */
	err |= __put_user(sp, &to->rsp);
	err |= PUTREG(regs, RBX, to, rbx);
	err |= PUTREG(regs, RDX, to, rdx);
	err |= PUTREG(regs, RCX, to, rcx);
	err |= PUTREG(regs, RAX, to, rax);
	err |= PUTREG(regs, R8, to, r8);
	err |= PUTREG(regs, R9, to, r9);
	err |= PUTREG(regs, R10, to, r10);
	err |= PUTREG(regs, R11, to, r11);
	err |= PUTREG(regs, R12, to, r12);
	err |= PUTREG(regs, R13, to, r13);
	err |= PUTREG(regs, R14, to, r14);
	err |= PUTREG(regs, R15, to, r15);
	err |= PUTREG(regs, CS, to, cs); /* XXX x86_64 doesn't do this */

	err |= __put_user(fi->cr2, &to->cr2);
	err |= __put_user(fi->error_code, &to->err);
	err |= __put_user(fi->trap_no, &to->trapno);

	err |= PUTREG(regs, RIP, to, rip);
	err |= PUTREG(regs, EFLAGS, to, eflags);
#undef PUTREG

	err |= __put_user(mask, &to->oldmask);

	return(err);
}

struct rt_sigframe
{
	char __user *pretcode;
	struct ucontext uc;
	struct siginfo info;
};

#define round_down(m, n) (((m) / (n)) * (n))

int setup_signal_stack_si(unsigned long stack_top, int sig,
			  struct k_sigaction *ka, struct pt_regs * regs,
			  siginfo_t *info, sigset_t *set)
{
	struct rt_sigframe __user *frame;
	struct _fpstate __user *fp = NULL;
	unsigned long save_sp = PT_REGS_RSP(regs);
	int err = 0;
	struct task_struct *me = current;

	frame = (struct rt_sigframe __user *)
		round_down(stack_top - sizeof(struct rt_sigframe), 16);
	/* Subtract 128 for a red zone and 8 for proper alignment */
	frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8);

	if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
		goto out;

#if 0 /* XXX */
	if (save_i387(fp) < 0)
		err |= -1;
#endif
	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
		goto out;

	if (ka->sa.sa_flags & SA_SIGINFO) {
		err |= copy_siginfo_to_user(&frame->info, info);
		if (err)
			goto out;
	}

	/* Update SP now because the page fault handler refuses to extend
	 * the stack if the faulting address is too far below the current
	 * SP, which frame now certainly is.  If there's an error, the original
	 * value is restored on the way out.
	 * When writing the sigcontext to the stack, we have to write the
	 * original value, so that's passed to copy_sc_to_user, which does
	 * the right thing with it.
	 */
	PT_REGS_RSP(regs) = (unsigned long) frame;

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(save_sp),
			  &frame->uc.uc_stack.ss_flags);
	err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= copy_sc_to_user(&frame->uc.uc_mcontext, fp, regs, set->sig[0],
		save_sp);
	err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
	if (sizeof(*set) == 16) {
		__put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
		__put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
	}
	else
		err |= __copy_to_user(&frame->uc.uc_sigmask, set,
				      sizeof(*set));

	/* Set up to return from userspace.  If provided, use a stub
	   already in userspace.  */
	/* x86-64 should always use SA_RESTORER. */
	if (ka->sa.sa_flags & SA_RESTORER)
		err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
	else
		/* could use a vstub here */
		goto restore_sp;

	if (err)
		goto restore_sp;

	/* Set up registers for signal handler */
	{
		struct exec_domain *ed = current_thread_info()->exec_domain;
		if (unlikely(ed && ed->signal_invmap && sig < 32))
			sig = ed->signal_invmap[sig];
	}

	PT_REGS_RDI(regs) = sig;
	/* In case the signal handler was declared without prototypes */
	PT_REGS_RAX(regs) = 0;

	/* This also works for non SA_SIGINFO handlers because they expect the
	   next argument after the signal number on the stack. */
	PT_REGS_RSI(regs) = (unsigned long) &frame->info;
	PT_REGS_RDX(regs) = (unsigned long) &frame->uc;
	PT_REGS_RIP(regs) = (unsigned long) ka->sa.sa_handler;
 out:
	return err;

restore_sp:
	PT_REGS_RSP(regs) = save_sp;
	return err;
}

long sys_rt_sigreturn(struct pt_regs *regs)
{
	unsigned long sp = PT_REGS_SP(&current->thread.regs);
	struct rt_sigframe __user *frame =
		(struct rt_sigframe __user *)(sp - 8);
	struct ucontext __user *uc = &frame->uc;
	sigset_t set;

	if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
		goto segfault;

	sigdelsetmask(&set, ~_BLOCKABLE);

	spin_lock_irq(&current->sighand->siglock);
	current->blocked = set;
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
		goto segfault;

	/* Avoid ERESTART handling */
	PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
	return(PT_REGS_SYSCALL_RET(&current->thread.regs));

 segfault:
	force_sig(SIGSEGV, current);
	return 0;
}