Root/arch/avr32/kernel/signal.c

1/*
2 * Copyright (C) 2004-2006 Atmel Corporation
3 *
4 * Based on linux/arch/sh/kernel/signal.c
5 * Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
6 * Copyright (C) 1991, 1992 Linus Torvalds
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/sched.h>
14#include <linux/mm.h>
15#include <linux/errno.h>
16#include <linux/ptrace.h>
17#include <linux/unistd.h>
18#include <linux/tracehook.h>
19
20#include <asm/uaccess.h>
21#include <asm/ucontext.h>
22#include <asm/syscalls.h>
23
24struct rt_sigframe
25{
26    struct siginfo info;
27    struct ucontext uc;
28    unsigned long retcode;
29};
30
31static int
32restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
33{
34    int err = 0;
35
36#define COPY(x) err |= __get_user(regs->x, &sc->x)
37    COPY(sr);
38    COPY(pc);
39    COPY(lr);
40    COPY(sp);
41    COPY(r12);
42    COPY(r11);
43    COPY(r10);
44    COPY(r9);
45    COPY(r8);
46    COPY(r7);
47    COPY(r6);
48    COPY(r5);
49    COPY(r4);
50    COPY(r3);
51    COPY(r2);
52    COPY(r1);
53    COPY(r0);
54#undef COPY
55
56    /*
57     * Don't allow anyone to pretend they're running in supervisor
58     * mode or something...
59     */
60    err |= !valid_user_regs(regs);
61
62    return err;
63}
64
65
66asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
67{
68    struct rt_sigframe __user *frame;
69    sigset_t set;
70
71    /* Always make any pending restarted system calls return -EINTR */
72    current_thread_info()->restart_block.fn = do_no_restart_syscall;
73
74    frame = (struct rt_sigframe __user *)regs->sp;
75    pr_debug("SIG return: frame = %p\n", frame);
76
77    if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
78        goto badframe;
79
80    if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
81        goto badframe;
82
83    set_current_blocked(&set);
84
85    if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
86        goto badframe;
87
88    if (restore_altstack(&frame->uc.uc_stack))
89        goto badframe;
90
91    pr_debug("Context restored: pc = %08lx, lr = %08lx, sp = %08lx\n",
92         regs->pc, regs->lr, regs->sp);
93
94    return regs->r12;
95
96badframe:
97    force_sig(SIGSEGV, current);
98    return 0;
99}
100
101static int
102setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs)
103{
104    int err = 0;
105
106#define COPY(x) err |= __put_user(regs->x, &sc->x)
107    COPY(sr);
108    COPY(pc);
109    COPY(lr);
110    COPY(sp);
111    COPY(r12);
112    COPY(r11);
113    COPY(r10);
114    COPY(r9);
115    COPY(r8);
116    COPY(r7);
117    COPY(r6);
118    COPY(r5);
119    COPY(r4);
120    COPY(r3);
121    COPY(r2);
122    COPY(r1);
123    COPY(r0);
124#undef COPY
125
126    return err;
127}
128
129static inline void __user *
130get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize)
131{
132    unsigned long sp = sigsp(regs->sp, ksig);
133
134    return (void __user *)((sp - framesize) & ~3);
135}
136
137static int
138setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
139{
140    struct rt_sigframe __user *frame;
141    int err = 0;
142
143    frame = get_sigframe(ksig, regs, sizeof(*frame));
144    err = -EFAULT;
145    if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
146        goto out;
147
148    /*
149     * Set up the return code:
150     *
151     * mov r8, __NR_rt_sigreturn
152     * scall
153     *
154     * Note: This will blow up since we're using a non-executable
155     * stack. Better use SA_RESTORER.
156     */
157#if __NR_rt_sigreturn > 127
158# error __NR_rt_sigreturn must be < 127 to fit in a short mov
159#endif
160    err = __put_user(0x3008d733 | (__NR_rt_sigreturn << 20),
161             &frame->retcode);
162
163    err |= copy_siginfo_to_user(&frame->info, &ksig->info);
164
165    /* Set up the ucontext */
166    err |= __put_user(0, &frame->uc.uc_flags);
167    err |= __put_user(NULL, &frame->uc.uc_link);
168    err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
169    err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
170    err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
171
172    if (err)
173        goto out;
174
175    regs->r12 = ksig->sig;
176    regs->r11 = (unsigned long) &frame->info;
177    regs->r10 = (unsigned long) &frame->uc;
178    regs->sp = (unsigned long) frame;
179    if (ksig->ka.sa.sa_flags & SA_RESTORER)
180        regs->lr = (unsigned long)ksig->ka.sa.sa_restorer;
181    else {
182        printk(KERN_NOTICE "[%s:%d] did not set SA_RESTORER\n",
183               current->comm, current->pid);
184        regs->lr = (unsigned long) &frame->retcode;
185    }
186
187    pr_debug("SIG deliver [%s:%d]: sig=%d sp=0x%lx pc=0x%lx->0x%p lr=0x%lx\n",
188         current->comm, current->pid, ksig->sig, regs->sp,
189         regs->pc, ksig->ka.sa.sa_handler, regs->lr);
190
191    regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
192
193out:
194    return err;
195}
196
197static inline void setup_syscall_restart(struct pt_regs *regs)
198{
199    if (regs->r12 == -ERESTART_RESTARTBLOCK)
200        regs->r8 = __NR_restart_syscall;
201    else
202        regs->r12 = regs->r12_orig;
203    regs->pc -= 2;
204}
205
206static inline void
207handle_signal(struct ksignal *ksig, struct pt_regs *regs, int syscall)
208{
209    int ret;
210
211    /*
212     * Set up the stack frame
213     */
214    ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
215
216    /*
217     * Check that the resulting registers are sane
218     */
219    ret |= !valid_user_regs(regs);
220
221    /*
222     * Block the signal if we were successful.
223     */
224    signal_setup_done(ret, ksig, 0);
225}
226
227/*
228 * Note that 'init' is a special process: it doesn't get signals it
229 * doesn't want to handle. Thus you cannot kill init even with a
230 * SIGKILL even by mistake.
231 */
232static void do_signal(struct pt_regs *regs, int syscall)
233{
234    struct ksignal ksig;
235
236    /*
237     * We want the common case to go fast, which is why we may in
238     * certain cases get here from kernel mode. Just return
239     * without doing anything if so.
240     */
241    if (!user_mode(regs))
242        return;
243
244    get_signal(&ksig);
245    if (syscall) {
246        switch (regs->r12) {
247        case -ERESTART_RESTARTBLOCK:
248        case -ERESTARTNOHAND:
249            if (ksig.sig > 0) {
250                regs->r12 = -EINTR;
251                break;
252            }
253            /* fall through */
254        case -ERESTARTSYS:
255            if (ksig.sig > 0 && !(ksig.ka.sa.sa_flags & SA_RESTART)) {
256                regs->r12 = -EINTR;
257                break;
258            }
259            /* fall through */
260        case -ERESTARTNOINTR:
261            setup_syscall_restart(regs);
262        }
263    }
264
265    if (!ksig.sig) {
266        /* No signal to deliver -- put the saved sigmask back */
267        restore_saved_sigmask();
268        return;
269    }
270
271    handle_signal(&ksig, regs, syscall);
272}
273
274asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
275{
276    int syscall = 0;
277
278    if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
279        syscall = 1;
280
281    if (ti->flags & _TIF_SIGPENDING)
282        do_signal(regs, syscall);
283
284    if (ti->flags & _TIF_NOTIFY_RESUME) {
285        clear_thread_flag(TIF_NOTIFY_RESUME);
286        tracehook_notify_resume(regs);
287    }
288}
289

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