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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 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/tracehook.h>
53#include <linux/sched/task_stack.h>
54
55#include <asm/ucontext.h>
56
57struct rt_sigframe {
58 struct siginfo info;
59 struct ucontext uc;
60#define MAGIC_SIGALTSTK 0x07302004
61 unsigned int sigret_magic;
62};
63
64static int
65stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
66 sigset_t *set)
67{
68 int err;
69 struct user_regs_struct uregs;
70
71 uregs.scratch.bta = regs->bta;
72 uregs.scratch.lp_start = regs->lp_start;
73 uregs.scratch.lp_end = regs->lp_end;
74 uregs.scratch.lp_count = regs->lp_count;
75 uregs.scratch.status32 = regs->status32;
76 uregs.scratch.ret = regs->ret;
77 uregs.scratch.blink = regs->blink;
78 uregs.scratch.fp = regs->fp;
79 uregs.scratch.gp = regs->r26;
80 uregs.scratch.r12 = regs->r12;
81 uregs.scratch.r11 = regs->r11;
82 uregs.scratch.r10 = regs->r10;
83 uregs.scratch.r9 = regs->r9;
84 uregs.scratch.r8 = regs->r8;
85 uregs.scratch.r7 = regs->r7;
86 uregs.scratch.r6 = regs->r6;
87 uregs.scratch.r5 = regs->r5;
88 uregs.scratch.r4 = regs->r4;
89 uregs.scratch.r3 = regs->r3;
90 uregs.scratch.r2 = regs->r2;
91 uregs.scratch.r1 = regs->r1;
92 uregs.scratch.r0 = regs->r0;
93 uregs.scratch.sp = regs->sp;
94
95 err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch,
96 sizeof(sf->uc.uc_mcontext.regs.scratch));
97 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
98
99 return err;
100}
101
102static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
103{
104 sigset_t set;
105 int err;
106 struct user_regs_struct uregs;
107
108 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
109 err |= __copy_from_user(&uregs.scratch,
110 &(sf->uc.uc_mcontext.regs.scratch),
111 sizeof(sf->uc.uc_mcontext.regs.scratch));
112 if (err)
113 return err;
114
115 set_current_blocked(&set);
116 regs->bta = uregs.scratch.bta;
117 regs->lp_start = uregs.scratch.lp_start;
118 regs->lp_end = uregs.scratch.lp_end;
119 regs->lp_count = uregs.scratch.lp_count;
120 regs->status32 = uregs.scratch.status32;
121 regs->ret = uregs.scratch.ret;
122 regs->blink = uregs.scratch.blink;
123 regs->fp = uregs.scratch.fp;
124 regs->r26 = uregs.scratch.gp;
125 regs->r12 = uregs.scratch.r12;
126 regs->r11 = uregs.scratch.r11;
127 regs->r10 = uregs.scratch.r10;
128 regs->r9 = uregs.scratch.r9;
129 regs->r8 = uregs.scratch.r8;
130 regs->r7 = uregs.scratch.r7;
131 regs->r6 = uregs.scratch.r6;
132 regs->r5 = uregs.scratch.r5;
133 regs->r4 = uregs.scratch.r4;
134 regs->r3 = uregs.scratch.r3;
135 regs->r2 = uregs.scratch.r2;
136 regs->r1 = uregs.scratch.r1;
137 regs->r0 = uregs.scratch.r0;
138 regs->sp = uregs.scratch.sp;
139
140 return 0;
141}
142
143static inline int is_do_ss_needed(unsigned int magic)
144{
145 if (MAGIC_SIGALTSTK == magic)
146 return 1;
147 else
148 return 0;
149}
150
151SYSCALL_DEFINE0(rt_sigreturn)
152{
153 struct rt_sigframe __user *sf;
154 unsigned int magic;
155 struct pt_regs *regs = current_pt_regs();
156
157 /* Always make any pending restarted system calls return -EINTR */
158 current->restart_block.fn = do_no_restart_syscall;
159
160 /* Since we stacked the signal on a word boundary,
161 * then 'sp' should be word aligned here. If it's
162 * not, then the user is trying to mess with us.
163 */
164 if (regs->sp & 3)
165 goto badframe;
166
167 sf = (struct rt_sigframe __force __user *)(regs->sp);
168
169 if (!access_ok(sf, sizeof(*sf)))
170 goto badframe;
171
172 if (__get_user(magic, &sf->sigret_magic))
173 goto badframe;
174
175 if (unlikely(is_do_ss_needed(magic)))
176 if (restore_altstack(&sf->uc.uc_stack))
177 goto badframe;
178
179 if (restore_usr_regs(regs, sf))
180 goto badframe;
181
182 /* Don't restart from sigreturn */
183 syscall_wont_restart(regs);
184
185 /*
186 * Ensure that sigreturn always returns to user mode (in case the
187 * regs saved on user stack got fudged between save and sigreturn)
188 * Otherwise it is easy to panic the kernel with a custom
189 * signal handler and/or restorer which clobberes the status32/ret
190 * to return to a bogus location in kernel mode.
191 */
192 regs->status32 |= STATUS_U_MASK;
193
194 return regs->r0;
195
196badframe:
197 force_sig(SIGSEGV);
198 return 0;
199}
200
201/*
202 * Determine which stack to use..
203 */
204static inline void __user *get_sigframe(struct ksignal *ksig,
205 struct pt_regs *regs,
206 unsigned long framesize)
207{
208 unsigned long sp = sigsp(regs->sp, ksig);
209 void __user *frame;
210
211 /* No matter what happens, 'sp' must be word
212 * aligned otherwise nasty things could happen
213 */
214
215 /* ATPCS B01 mandates 8-byte alignment */
216 frame = (void __user *)((sp - framesize) & ~7);
217
218 /* Check that we can actually write to the signal frame */
219 if (!access_ok(frame, framesize))
220 frame = NULL;
221
222 return frame;
223}
224
225static int
226setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
227{
228 struct rt_sigframe __user *sf;
229 unsigned int magic = 0;
230 int err = 0;
231
232 sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
233 if (!sf)
234 return 1;
235
236 /*
237 * w/o SA_SIGINFO, struct ucontext is partially populated (only
238 * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
239 * during signal handler execution. This works for SA_SIGINFO as well
240 * although the semantics are now overloaded (the same reg state can be
241 * inspected by userland: but are they allowed to fiddle with it ?
242 */
243 err |= stash_usr_regs(sf, regs, set);
244
245 /*
246 * SA_SIGINFO requires 3 args to signal handler:
247 * #1: sig-no (common to any handler)
248 * #2: struct siginfo
249 * #3: struct ucontext (completely populated)
250 */
251 if (unlikely(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
252 err |= copy_siginfo_to_user(&sf->info, &ksig->info);
253 err |= __put_user(0, &sf->uc.uc_flags);
254 err |= __put_user(NULL, &sf->uc.uc_link);
255 err |= __save_altstack(&sf->uc.uc_stack, regs->sp);
256
257 /* setup args 2 and 3 for user mode handler */
258 regs->r1 = (unsigned long)&sf->info;
259 regs->r2 = (unsigned long)&sf->uc;
260
261 /*
262 * small optim to avoid unconditonally calling do_sigaltstack
263 * in sigreturn path, now that we only have rt_sigreturn
264 */
265 magic = MAGIC_SIGALTSTK;
266 }
267
268 err |= __put_user(magic, &sf->sigret_magic);
269 if (err)
270 return err;
271
272 /* #1 arg to the user Signal handler */
273 regs->r0 = ksig->sig;
274
275 /* setup PC of user space signal handler */
276 regs->ret = (unsigned long)ksig->ka.sa.sa_handler;
277
278 /*
279 * handler returns using sigreturn stub provided already by userpsace
280 * If not, nuke the process right away
281 */
282 if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
283 return 1;
284
285 regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
286
287 /* User Stack for signal handler will be above the frame just carved */
288 regs->sp = (unsigned long)sf;
289
290 /*
291 * Bug 94183, Clear the DE bit, so that when signal handler
292 * starts to run, it doesn't use BTA
293 */
294 regs->status32 &= ~STATUS_DE_MASK;
295 regs->status32 |= STATUS_L_MASK;
296
297 return err;
298}
299
300static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs)
301{
302 switch (regs->r0) {
303 case -ERESTART_RESTARTBLOCK:
304 case -ERESTARTNOHAND:
305 /*
306 * ERESTARTNOHAND means that the syscall should
307 * only be restarted if there was no handler for
308 * the signal, and since we only get here if there
309 * is a handler, we don't restart
310 */
311 regs->r0 = -EINTR; /* ERESTART_xxx is internal */
312 break;
313
314 case -ERESTARTSYS:
315 /*
316 * ERESTARTSYS means to restart the syscall if
317 * there is no handler or the handler was
318 * registered with SA_RESTART
319 */
320 if (!(ka->sa.sa_flags & SA_RESTART)) {
321 regs->r0 = -EINTR;
322 break;
323 }
324 /* fallthrough */
325
326 case -ERESTARTNOINTR:
327 /*
328 * ERESTARTNOINTR means that the syscall should
329 * be called again after the signal handler returns.
330 * Setup reg state just as it was before doing the trap
331 * r0 has been clobbered with sys call ret code thus it
332 * needs to be reloaded with orig first arg to syscall
333 * in orig_r0. Rest of relevant reg-file:
334 * r8 (syscall num) and (r1 - r7) will be reset to
335 * their orig user space value when we ret from kernel
336 */
337 regs->r0 = regs->orig_r0;
338 regs->ret -= is_isa_arcv2() ? 2 : 4;
339 break;
340 }
341}
342
343/*
344 * OK, we're invoking a handler
345 */
346static void
347handle_signal(struct ksignal *ksig, struct pt_regs *regs)
348{
349 sigset_t *oldset = sigmask_to_save();
350 int failed;
351
352 /* Set up the stack frame */
353 failed = setup_rt_frame(ksig, oldset, regs);
354
355 signal_setup_done(failed, ksig, 0);
356}
357
358void do_signal(struct pt_regs *regs)
359{
360 struct ksignal ksig;
361 int restart_scall;
362
363 restart_scall = in_syscall(regs) && syscall_restartable(regs);
364
365 if (get_signal(&ksig)) {
366 if (restart_scall) {
367 arc_restart_syscall(&ksig.ka, regs);
368 syscall_wont_restart(regs); /* No more restarts */
369 }
370 handle_signal(&ksig, regs);
371 return;
372 }
373
374 if (restart_scall) {
375 /* No handler for syscall: restart it */
376 if (regs->r0 == -ERESTARTNOHAND ||
377 regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) {
378 regs->r0 = regs->orig_r0;
379 regs->ret -= is_isa_arcv2() ? 2 : 4;
380 } else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
381 regs->r8 = __NR_restart_syscall;
382 regs->ret -= is_isa_arcv2() ? 2 : 4;
383 }
384 syscall_wont_restart(regs); /* No more restarts */
385 }
386
387 /* If there's no signal to deliver, restore the saved sigmask back */
388 restore_saved_sigmask();
389}
390
391void do_notify_resume(struct pt_regs *regs)
392{
393 /*
394 * ASM glue gaurantees that this is only called when returning to
395 * user mode
396 */
397 if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
398 tracehook_notify_resume(regs);
399}
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}