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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Signal Handling for ARC
4 *
5 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
6 *
7 * vineetg: Jan 2010 (Restarting of timer related syscalls)
8 *
9 * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
10 * -do_signal() supports TIF_RESTORE_SIGMASK
11 * -do_signal() no longer needs oldset, required by OLD sys_sigsuspend
12 * -sys_rt_sigsuspend() now comes from generic code, so discard arch
13 * implementation
14 * -sys_sigsuspend() no longer needs to fudge ptregs, hence that arg removed
15 * -sys_sigsuspend() no longer loops for do_signal(), sets TIF_xxx and leaves
16 * the job to do_signal()
17 *
18 * vineetg: July 2009
19 * -Modified Code to support the uClibc provided userland sigreturn stub
20 * to avoid kernel synthesizing it on user stack at runtime, costing TLB
21 * probes and Cache line flushes.
22 *
23 * vineetg: July 2009
24 * -In stash_usr_regs( ) and restore_usr_regs( ), save/restore of user regs
25 * in done in block copy rather than one word at a time.
26 * This saves around 2K of code and improves LMBench lat_sig <catch>
27 *
28 * rajeshwarr: Feb 2009
29 * - Support for Realtime Signals
30 *
31 * vineetg: Aug 11th 2008: Bug #94183
32 * -ViXS were still seeing crashes when using insmod to load drivers.
33 * It turned out that the code to change Execute permssions for TLB entries
34 * of user was not guarded for interrupts (mod_tlb_permission)
35 * This was causing TLB entries to be overwritten on unrelated indexes
36 *
37 * Vineetg: July 15th 2008: Bug #94183
38 * -Exception happens in Delay slot of a JMP, and before user space resumes,
39 * Signal is delivered (Ctrl + C) = >SIGINT.
40 * setup_frame( ) sets up PC,SP,BLINK to enable user space signal handler
41 * to run, but doesn't clear the Delay slot bit from status32. As a result,
42 * on resuming user mode, signal handler branches off to BTA of orig JMP
43 * -FIX: clear the DE bit from status32 in setup_frame( )
44 *
45 * Rahul Trivedi, Kanika Nema: Codito Technologies 2004
46 */
47
48#include <linux/signal.h>
49#include <linux/ptrace.h>
50#include <linux/personality.h>
51#include <linux/uaccess.h>
52#include <linux/syscalls.h>
53#include <linux/resume_user_mode.h>
54#include <linux/sched/task_stack.h>
55
56#include <asm/ucontext.h>
57#include <asm/entry.h>
58
59struct rt_sigframe {
60 struct siginfo info;
61 struct ucontext uc;
62#define MAGIC_SIGALTSTK 0x07302004
63 unsigned int sigret_magic;
64};
65
66static int save_arcv2_regs(struct sigcontext __user *mctx, struct pt_regs *regs)
67{
68 int err = 0;
69#ifndef CONFIG_ISA_ARCOMPACT
70 struct user_regs_arcv2 v2abi;
71
72 v2abi.r30 = regs->r30;
73#ifdef CONFIG_ARC_HAS_ACCL_REGS
74 v2abi.r58 = regs->r58;
75 v2abi.r59 = regs->r59;
76#else
77 v2abi.r58 = v2abi.r59 = 0;
78#endif
79 err = __copy_to_user(&mctx->v2abi, (void const *)&v2abi, sizeof(v2abi));
80#endif
81 return err;
82}
83
84static int restore_arcv2_regs(struct sigcontext __user *mctx, struct pt_regs *regs)
85{
86 int err = 0;
87#ifndef CONFIG_ISA_ARCOMPACT
88 struct user_regs_arcv2 v2abi;
89
90 err = __copy_from_user(&v2abi, &mctx->v2abi, sizeof(v2abi));
91
92 regs->r30 = v2abi.r30;
93#ifdef CONFIG_ARC_HAS_ACCL_REGS
94 regs->r58 = v2abi.r58;
95 regs->r59 = v2abi.r59;
96#endif
97#endif
98 return err;
99}
100
101static int
102stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
103 sigset_t *set)
104{
105 int err;
106 struct user_regs_struct uregs;
107
108 uregs.scratch.bta = regs->bta;
109 uregs.scratch.lp_start = regs->lp_start;
110 uregs.scratch.lp_end = regs->lp_end;
111 uregs.scratch.lp_count = regs->lp_count;
112 uregs.scratch.status32 = regs->status32;
113 uregs.scratch.ret = regs->ret;
114 uregs.scratch.blink = regs->blink;
115 uregs.scratch.fp = regs->fp;
116 uregs.scratch.gp = regs->r26;
117 uregs.scratch.r12 = regs->r12;
118 uregs.scratch.r11 = regs->r11;
119 uregs.scratch.r10 = regs->r10;
120 uregs.scratch.r9 = regs->r9;
121 uregs.scratch.r8 = regs->r8;
122 uregs.scratch.r7 = regs->r7;
123 uregs.scratch.r6 = regs->r6;
124 uregs.scratch.r5 = regs->r5;
125 uregs.scratch.r4 = regs->r4;
126 uregs.scratch.r3 = regs->r3;
127 uregs.scratch.r2 = regs->r2;
128 uregs.scratch.r1 = regs->r1;
129 uregs.scratch.r0 = regs->r0;
130 uregs.scratch.sp = regs->sp;
131
132 err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch,
133 sizeof(sf->uc.uc_mcontext.regs.scratch));
134
135 if (is_isa_arcv2())
136 err |= save_arcv2_regs(&(sf->uc.uc_mcontext), regs);
137
138 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
139
140 return err ? -EFAULT : 0;
141}
142
143static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
144{
145 sigset_t set;
146 int err;
147 struct user_regs_struct uregs;
148
149 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
150 err |= __copy_from_user(&uregs.scratch,
151 &(sf->uc.uc_mcontext.regs.scratch),
152 sizeof(sf->uc.uc_mcontext.regs.scratch));
153
154 if (is_isa_arcv2())
155 err |= restore_arcv2_regs(&(sf->uc.uc_mcontext), regs);
156
157 if (err)
158 return -EFAULT;
159
160 set_current_blocked(&set);
161 regs->bta = uregs.scratch.bta;
162 regs->lp_start = uregs.scratch.lp_start;
163 regs->lp_end = uregs.scratch.lp_end;
164 regs->lp_count = uregs.scratch.lp_count;
165 regs->status32 = uregs.scratch.status32;
166 regs->ret = uregs.scratch.ret;
167 regs->blink = uregs.scratch.blink;
168 regs->fp = uregs.scratch.fp;
169 regs->r26 = uregs.scratch.gp;
170 regs->r12 = uregs.scratch.r12;
171 regs->r11 = uregs.scratch.r11;
172 regs->r10 = uregs.scratch.r10;
173 regs->r9 = uregs.scratch.r9;
174 regs->r8 = uregs.scratch.r8;
175 regs->r7 = uregs.scratch.r7;
176 regs->r6 = uregs.scratch.r6;
177 regs->r5 = uregs.scratch.r5;
178 regs->r4 = uregs.scratch.r4;
179 regs->r3 = uregs.scratch.r3;
180 regs->r2 = uregs.scratch.r2;
181 regs->r1 = uregs.scratch.r1;
182 regs->r0 = uregs.scratch.r0;
183 regs->sp = uregs.scratch.sp;
184
185 return 0;
186}
187
188static inline int is_do_ss_needed(unsigned int magic)
189{
190 if (MAGIC_SIGALTSTK == magic)
191 return 1;
192 else
193 return 0;
194}
195
196SYSCALL_DEFINE0(rt_sigreturn)
197{
198 struct rt_sigframe __user *sf;
199 unsigned int magic;
200 struct pt_regs *regs = current_pt_regs();
201
202 /* Always make any pending restarted system calls return -EINTR */
203 current->restart_block.fn = do_no_restart_syscall;
204
205 /* Since we stacked the signal on a word boundary,
206 * then 'sp' should be word aligned here. If it's
207 * not, then the user is trying to mess with us.
208 */
209 if (regs->sp & 3)
210 goto badframe;
211
212 sf = (struct rt_sigframe __force __user *)(regs->sp);
213
214 if (!access_ok(sf, sizeof(*sf)))
215 goto badframe;
216
217 if (__get_user(magic, &sf->sigret_magic))
218 goto badframe;
219
220 if (unlikely(is_do_ss_needed(magic)))
221 if (restore_altstack(&sf->uc.uc_stack))
222 goto badframe;
223
224 if (restore_usr_regs(regs, sf))
225 goto badframe;
226
227 /* Don't restart from sigreturn */
228 syscall_wont_restart(regs);
229
230 /*
231 * Ensure that sigreturn always returns to user mode (in case the
232 * regs saved on user stack got fudged between save and sigreturn)
233 * Otherwise it is easy to panic the kernel with a custom
234 * signal handler and/or restorer which clobberes the status32/ret
235 * to return to a bogus location in kernel mode.
236 */
237 regs->status32 |= STATUS_U_MASK;
238
239 return regs->r0;
240
241badframe:
242 force_sig(SIGSEGV);
243 return 0;
244}
245
246/*
247 * Determine which stack to use..
248 */
249static inline void __user *get_sigframe(struct ksignal *ksig,
250 struct pt_regs *regs,
251 unsigned long framesize)
252{
253 unsigned long sp = sigsp(regs->sp, ksig);
254 void __user *frame;
255
256 /* No matter what happens, 'sp' must be word
257 * aligned otherwise nasty things could happen
258 */
259
260 /* ATPCS B01 mandates 8-byte alignment */
261 frame = (void __user *)((sp - framesize) & ~7);
262
263 /* Check that we can actually write to the signal frame */
264 if (!access_ok(frame, framesize))
265 frame = NULL;
266
267 return frame;
268}
269
270static int
271setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
272{
273 struct rt_sigframe __user *sf;
274 unsigned int magic = 0;
275 int err = 0;
276
277 sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
278 if (!sf)
279 return 1;
280
281 /*
282 * w/o SA_SIGINFO, struct ucontext is partially populated (only
283 * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
284 * during signal handler execution. This works for SA_SIGINFO as well
285 * although the semantics are now overloaded (the same reg state can be
286 * inspected by userland: but are they allowed to fiddle with it ?
287 */
288 err |= stash_usr_regs(sf, regs, set);
289
290 /*
291 * SA_SIGINFO requires 3 args to signal handler:
292 * #1: sig-no (common to any handler)
293 * #2: struct siginfo
294 * #3: struct ucontext (completely populated)
295 */
296 if (unlikely(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
297 err |= copy_siginfo_to_user(&sf->info, &ksig->info);
298 err |= __put_user(0, &sf->uc.uc_flags);
299 err |= __put_user(NULL, &sf->uc.uc_link);
300 err |= __save_altstack(&sf->uc.uc_stack, regs->sp);
301
302 /* setup args 2 and 3 for user mode handler */
303 regs->r1 = (unsigned long)&sf->info;
304 regs->r2 = (unsigned long)&sf->uc;
305
306 /*
307 * small optim to avoid unconditionally calling do_sigaltstack
308 * in sigreturn path, now that we only have rt_sigreturn
309 */
310 magic = MAGIC_SIGALTSTK;
311 }
312
313 err |= __put_user(magic, &sf->sigret_magic);
314 if (err)
315 return err;
316
317 /* #1 arg to the user Signal handler */
318 regs->r0 = ksig->sig;
319
320 /* setup PC of user space signal handler */
321 regs->ret = (unsigned long)ksig->ka.sa.sa_handler;
322
323 /*
324 * handler returns using sigreturn stub provided already by userspace
325 * If not, nuke the process right away
326 */
327 if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
328 return 1;
329
330 regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
331
332 /* User Stack for signal handler will be above the frame just carved */
333 regs->sp = (unsigned long)sf;
334
335 /*
336 * Bug 94183, Clear the DE bit, so that when signal handler
337 * starts to run, it doesn't use BTA
338 */
339 regs->status32 &= ~STATUS_DE_MASK;
340 regs->status32 |= STATUS_L_MASK;
341
342 return err;
343}
344
345static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs)
346{
347 switch (regs->r0) {
348 case -ERESTART_RESTARTBLOCK:
349 case -ERESTARTNOHAND:
350 /*
351 * ERESTARTNOHAND means that the syscall should
352 * only be restarted if there was no handler for
353 * the signal, and since we only get here if there
354 * is a handler, we don't restart
355 */
356 regs->r0 = -EINTR; /* ERESTART_xxx is internal */
357 break;
358
359 case -ERESTARTSYS:
360 /*
361 * ERESTARTSYS means to restart the syscall if
362 * there is no handler or the handler was
363 * registered with SA_RESTART
364 */
365 if (!(ka->sa.sa_flags & SA_RESTART)) {
366 regs->r0 = -EINTR;
367 break;
368 }
369 fallthrough;
370
371 case -ERESTARTNOINTR:
372 /*
373 * ERESTARTNOINTR means that the syscall should
374 * be called again after the signal handler returns.
375 * Setup reg state just as it was before doing the trap
376 * r0 has been clobbered with sys call ret code thus it
377 * needs to be reloaded with orig first arg to syscall
378 * in orig_r0. Rest of relevant reg-file:
379 * r8 (syscall num) and (r1 - r7) will be reset to
380 * their orig user space value when we ret from kernel
381 */
382 regs->r0 = regs->orig_r0;
383 regs->ret -= is_isa_arcv2() ? 2 : 4;
384 break;
385 }
386}
387
388/*
389 * OK, we're invoking a handler
390 */
391static void
392handle_signal(struct ksignal *ksig, struct pt_regs *regs)
393{
394 sigset_t *oldset = sigmask_to_save();
395 int failed;
396
397 /* Set up the stack frame */
398 failed = setup_rt_frame(ksig, oldset, regs);
399
400 signal_setup_done(failed, ksig, 0);
401}
402
403void do_signal(struct pt_regs *regs)
404{
405 struct ksignal ksig;
406 int restart_scall;
407
408 restart_scall = in_syscall(regs) && syscall_restartable(regs);
409
410 if (test_thread_flag(TIF_SIGPENDING) && get_signal(&ksig)) {
411 if (restart_scall) {
412 arc_restart_syscall(&ksig.ka, regs);
413 syscall_wont_restart(regs); /* No more restarts */
414 }
415 handle_signal(&ksig, regs);
416 return;
417 }
418
419 if (restart_scall) {
420 /* No handler for syscall: restart it */
421 if (regs->r0 == -ERESTARTNOHAND ||
422 regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) {
423 regs->r0 = regs->orig_r0;
424 regs->ret -= is_isa_arcv2() ? 2 : 4;
425 } else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
426 regs->r8 = __NR_restart_syscall;
427 regs->ret -= is_isa_arcv2() ? 2 : 4;
428 }
429 syscall_wont_restart(regs); /* No more restarts */
430 }
431
432 /* If there's no signal to deliver, restore the saved sigmask back */
433 restore_saved_sigmask();
434}
435
436void do_notify_resume(struct pt_regs *regs)
437{
438 /*
439 * ASM glue guarantees that this is only called when returning to
440 * user mode
441 */
442 if (test_thread_flag(TIF_NOTIFY_RESUME))
443 resume_user_mode_work(regs);
444}
1/*
2 * Signal Handling for ARC
3 *
4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * vineetg: Jan 2010 (Restarting of timer related syscalls)
11 *
12 * vineetg: Nov 2009 (Everything needed for TIF_RESTORE_SIGMASK)
13 * -do_signal() supports TIF_RESTORE_SIGMASK
14 * -do_signal() no loner needs oldset, required by OLD sys_sigsuspend
15 * -sys_rt_sigsuspend() now comes from generic code, so discard arch implemen
16 * -sys_sigsuspend() no longer needs to fudge ptregs, hence that arg removed
17 * -sys_sigsuspend() no longer loops for do_signal(), sets TIF_xxx and leaves
18 * the job to do_signal()
19 *
20 * vineetg: July 2009
21 * -Modified Code to support the uClibc provided userland sigreturn stub
22 * to avoid kernel synthesing it on user stack at runtime, costing TLB
23 * probes and Cache line flushes.
24 *
25 * vineetg: July 2009
26 * -In stash_usr_regs( ) and restore_usr_regs( ), save/restore of user regs
27 * in done in block copy rather than one word at a time.
28 * This saves around 2K of code and improves LMBench lat_sig <catch>
29 *
30 * rajeshwarr: Feb 2009
31 * - Support for Realtime Signals
32 *
33 * vineetg: Aug 11th 2008: Bug #94183
34 * -ViXS were still seeing crashes when using insmod to load drivers.
35 * It turned out that the code to change Execute permssions for TLB entries
36 * of user was not guarded for interrupts (mod_tlb_permission)
37 * This was cauing TLB entries to be overwritten on unrelated indexes
38 *
39 * Vineetg: July 15th 2008: Bug #94183
40 * -Exception happens in Delay slot of a JMP, and before user space resumes,
41 * Signal is delivered (Ctrl + C) = >SIGINT.
42 * setup_frame( ) sets up PC,SP,BLINK to enable user space signal handler
43 * to run, but doesn't clear the Delay slot bit from status32. As a result,
44 * on resuming user mode, signal handler branches off to BTA of orig JMP
45 * -FIX: clear the DE bit from status32 in setup_frame( )
46 *
47 * Rahul Trivedi, Kanika Nema: Codito Technologies 2004
48 */
49
50#include <linux/signal.h>
51#include <linux/ptrace.h>
52#include <linux/personality.h>
53#include <linux/uaccess.h>
54#include <linux/syscalls.h>
55#include <linux/tracehook.h>
56#include <asm/ucontext.h>
57
58struct rt_sigframe {
59 struct siginfo info;
60 struct ucontext uc;
61#define MAGIC_SIGALTSTK 0x07302004
62 unsigned int sigret_magic;
63};
64
65static int
66stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
67 sigset_t *set)
68{
69 int err;
70 struct user_regs_struct uregs;
71
72 uregs.scratch.bta = regs->bta;
73 uregs.scratch.lp_start = regs->lp_start;
74 uregs.scratch.lp_end = regs->lp_end;
75 uregs.scratch.lp_count = regs->lp_count;
76 uregs.scratch.status32 = regs->status32;
77 uregs.scratch.ret = regs->ret;
78 uregs.scratch.blink = regs->blink;
79 uregs.scratch.fp = regs->fp;
80 uregs.scratch.gp = regs->r26;
81 uregs.scratch.r12 = regs->r12;
82 uregs.scratch.r11 = regs->r11;
83 uregs.scratch.r10 = regs->r10;
84 uregs.scratch.r9 = regs->r9;
85 uregs.scratch.r8 = regs->r8;
86 uregs.scratch.r7 = regs->r7;
87 uregs.scratch.r6 = regs->r6;
88 uregs.scratch.r5 = regs->r5;
89 uregs.scratch.r4 = regs->r4;
90 uregs.scratch.r3 = regs->r3;
91 uregs.scratch.r2 = regs->r2;
92 uregs.scratch.r1 = regs->r1;
93 uregs.scratch.r0 = regs->r0;
94 uregs.scratch.sp = regs->sp;
95
96 err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch,
97 sizeof(sf->uc.uc_mcontext.regs.scratch));
98 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
99
100 return err;
101}
102
103static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
104{
105 sigset_t set;
106 int err;
107 struct user_regs_struct uregs;
108
109 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
110 if (!err)
111 set_current_blocked(&set);
112
113 err |= __copy_from_user(&uregs.scratch,
114 &(sf->uc.uc_mcontext.regs.scratch),
115 sizeof(sf->uc.uc_mcontext.regs.scratch));
116
117 regs->bta = uregs.scratch.bta;
118 regs->lp_start = uregs.scratch.lp_start;
119 regs->lp_end = uregs.scratch.lp_end;
120 regs->lp_count = uregs.scratch.lp_count;
121 regs->status32 = uregs.scratch.status32;
122 regs->ret = uregs.scratch.ret;
123 regs->blink = uregs.scratch.blink;
124 regs->fp = uregs.scratch.fp;
125 regs->r26 = uregs.scratch.gp;
126 regs->r12 = uregs.scratch.r12;
127 regs->r11 = uregs.scratch.r11;
128 regs->r10 = uregs.scratch.r10;
129 regs->r9 = uregs.scratch.r9;
130 regs->r8 = uregs.scratch.r8;
131 regs->r7 = uregs.scratch.r7;
132 regs->r6 = uregs.scratch.r6;
133 regs->r5 = uregs.scratch.r5;
134 regs->r4 = uregs.scratch.r4;
135 regs->r3 = uregs.scratch.r3;
136 regs->r2 = uregs.scratch.r2;
137 regs->r1 = uregs.scratch.r1;
138 regs->r0 = uregs.scratch.r0;
139 regs->sp = uregs.scratch.sp;
140
141 return err;
142}
143
144static inline int is_do_ss_needed(unsigned int magic)
145{
146 if (MAGIC_SIGALTSTK == magic)
147 return 1;
148 else
149 return 0;
150}
151
152SYSCALL_DEFINE0(rt_sigreturn)
153{
154 struct rt_sigframe __user *sf;
155 unsigned int magic;
156 struct pt_regs *regs = current_pt_regs();
157
158 /* Always make any pending restarted system calls return -EINTR */
159 current->restart_block.fn = do_no_restart_syscall;
160
161 /* Since we stacked the signal on a word boundary,
162 * then 'sp' should be word aligned here. If it's
163 * not, then the user is trying to mess with us.
164 */
165 if (regs->sp & 3)
166 goto badframe;
167
168 sf = (struct rt_sigframe __force __user *)(regs->sp);
169
170 if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
171 goto badframe;
172
173 if (__get_user(magic, &sf->sigret_magic))
174 goto badframe;
175
176 if (unlikely(is_do_ss_needed(magic)))
177 if (restore_altstack(&sf->uc.uc_stack))
178 goto badframe;
179
180 if (restore_usr_regs(regs, sf))
181 goto badframe;
182
183 /* Don't restart from sigreturn */
184 syscall_wont_restart(regs);
185
186 /*
187 * Ensure that sigreturn always returns to user mode (in case the
188 * regs saved on user stack got fudged between save and sigreturn)
189 * Otherwise it is easy to panic the kernel with a custom
190 * signal handler and/or restorer which clobberes the status32/ret
191 * to return to a bogus location in kernel mode.
192 */
193 regs->status32 |= STATUS_U_MASK;
194
195 return regs->r0;
196
197badframe:
198 force_sig(SIGSEGV, current);
199 return 0;
200}
201
202/*
203 * Determine which stack to use..
204 */
205static inline void __user *get_sigframe(struct ksignal *ksig,
206 struct pt_regs *regs,
207 unsigned long framesize)
208{
209 unsigned long sp = sigsp(regs->sp, ksig);
210 void __user *frame;
211
212 /* No matter what happens, 'sp' must be word
213 * aligned otherwise nasty things could happen
214 */
215
216 /* ATPCS B01 mandates 8-byte alignment */
217 frame = (void __user *)((sp - framesize) & ~7);
218
219 /* Check that we can actually write to the signal frame */
220 if (!access_ok(VERIFY_WRITE, frame, framesize))
221 frame = NULL;
222
223 return frame;
224}
225
226static int
227setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
228{
229 struct rt_sigframe __user *sf;
230 unsigned int magic = 0;
231 int err = 0;
232
233 sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
234 if (!sf)
235 return 1;
236
237 /*
238 * w/o SA_SIGINFO, struct ucontext is partially populated (only
239 * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
240 * during signal handler execution. This works for SA_SIGINFO as well
241 * although the semantics are now overloaded (the same reg state can be
242 * inspected by userland: but are they allowed to fiddle with it ?
243 */
244 err |= stash_usr_regs(sf, regs, set);
245
246 /*
247 * SA_SIGINFO requires 3 args to signal handler:
248 * #1: sig-no (common to any handler)
249 * #2: struct siginfo
250 * #3: struct ucontext (completely populated)
251 */
252 if (unlikely(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
253 err |= copy_siginfo_to_user(&sf->info, &ksig->info);
254 err |= __put_user(0, &sf->uc.uc_flags);
255 err |= __put_user(NULL, &sf->uc.uc_link);
256 err |= __save_altstack(&sf->uc.uc_stack, regs->sp);
257
258 /* setup args 2 and 3 for user mode handler */
259 regs->r1 = (unsigned long)&sf->info;
260 regs->r2 = (unsigned long)&sf->uc;
261
262 /*
263 * small optim to avoid unconditonally calling do_sigaltstack
264 * in sigreturn path, now that we only have rt_sigreturn
265 */
266 magic = MAGIC_SIGALTSTK;
267 }
268
269 err |= __put_user(magic, &sf->sigret_magic);
270 if (err)
271 return err;
272
273 /* #1 arg to the user Signal handler */
274 regs->r0 = ksig->sig;
275
276 /* setup PC of user space signal handler */
277 regs->ret = (unsigned long)ksig->ka.sa.sa_handler;
278
279 /*
280 * handler returns using sigreturn stub provided already by userpsace
281 * If not, nuke the process right away
282 */
283 if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
284 return 1;
285
286 regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
287
288 /* User Stack for signal handler will be above the frame just carved */
289 regs->sp = (unsigned long)sf;
290
291 /*
292 * Bug 94183, Clear the DE bit, so that when signal handler
293 * starts to run, it doesn't use BTA
294 */
295 regs->status32 &= ~STATUS_DE_MASK;
296 regs->status32 |= STATUS_L_MASK;
297
298 return err;
299}
300
301static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs)
302{
303 switch (regs->r0) {
304 case -ERESTART_RESTARTBLOCK:
305 case -ERESTARTNOHAND:
306 /*
307 * ERESTARTNOHAND means that the syscall should
308 * only be restarted if there was no handler for
309 * the signal, and since we only get here if there
310 * is a handler, we don't restart
311 */
312 regs->r0 = -EINTR; /* ERESTART_xxx is internal */
313 break;
314
315 case -ERESTARTSYS:
316 /*
317 * ERESTARTSYS means to restart the syscall if
318 * there is no handler or the handler was
319 * registered with SA_RESTART
320 */
321 if (!(ka->sa.sa_flags & SA_RESTART)) {
322 regs->r0 = -EINTR;
323 break;
324 }
325 /* fallthrough */
326
327 case -ERESTARTNOINTR:
328 /*
329 * ERESTARTNOINTR means that the syscall should
330 * be called again after the signal handler returns.
331 * Setup reg state just as it was before doing the trap
332 * r0 has been clobbered with sys call ret code thus it
333 * needs to be reloaded with orig first arg to syscall
334 * in orig_r0. Rest of relevant reg-file:
335 * r8 (syscall num) and (r1 - r7) will be reset to
336 * their orig user space value when we ret from kernel
337 */
338 regs->r0 = regs->orig_r0;
339 regs->ret -= is_isa_arcv2() ? 2 : 4;
340 break;
341 }
342}
343
344/*
345 * OK, we're invoking a handler
346 */
347static void
348handle_signal(struct ksignal *ksig, struct pt_regs *regs)
349{
350 sigset_t *oldset = sigmask_to_save();
351 int failed;
352
353 /* Set up the stack frame */
354 failed = setup_rt_frame(ksig, oldset, regs);
355
356 signal_setup_done(failed, ksig, 0);
357}
358
359void do_signal(struct pt_regs *regs)
360{
361 struct ksignal ksig;
362 int restart_scall;
363
364 restart_scall = in_syscall(regs) && syscall_restartable(regs);
365
366 if (get_signal(&ksig)) {
367 if (restart_scall) {
368 arc_restart_syscall(&ksig.ka, regs);
369 syscall_wont_restart(regs); /* No more restarts */
370 }
371 handle_signal(&ksig, regs);
372 return;
373 }
374
375 if (restart_scall) {
376 /* No handler for syscall: restart it */
377 if (regs->r0 == -ERESTARTNOHAND ||
378 regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) {
379 regs->r0 = regs->orig_r0;
380 regs->ret -= is_isa_arcv2() ? 2 : 4;
381 } else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
382 regs->r8 = __NR_restart_syscall;
383 regs->ret -= is_isa_arcv2() ? 2 : 4;
384 }
385 syscall_wont_restart(regs); /* No more restarts */
386 }
387
388 /* If there's no signal to deliver, restore the saved sigmask back */
389 restore_saved_sigmask();
390}
391
392void do_notify_resume(struct pt_regs *regs)
393{
394 /*
395 * ASM glue gaurantees that this is only called when returning to
396 * user mode
397 */
398 if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
399 tracehook_notify_resume(regs);
400}