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