2 * Signal Handling for ARC
4 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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.
10 * vineetg: Jan 2010 (Restarting of timer related syscalls)
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()
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.
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>
30 * rajeshwarr: Feb 2009
31 * - Support for Realtime Signals
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
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( )
47 * Rahul Trivedi, Kanika Nema: Codito Technologies 2004
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>
58 #include <asm/ucontext.h>
63 #define MAGIC_SIGALTSTK 0x07302004
64 unsigned int sigret_magic;
67 static int save_arcv2_regs(struct sigcontext *mctx, struct pt_regs *regs)
70 #ifndef CONFIG_ISA_ARCOMPACT
71 struct user_regs_arcv2 v2abi;
73 v2abi.r30 = regs->r30;
74 #ifdef CONFIG_ARC_HAS_ACCL_REGS
75 v2abi.r58 = regs->r58;
76 v2abi.r59 = regs->r59;
78 v2abi.r58 = v2abi.r59 = 0;
80 err = __copy_to_user(&mctx->v2abi, &v2abi, sizeof(v2abi));
85 static int restore_arcv2_regs(struct sigcontext *mctx, struct pt_regs *regs)
88 #ifndef CONFIG_ISA_ARCOMPACT
89 struct user_regs_arcv2 v2abi;
91 err = __copy_from_user(&v2abi, &mctx->v2abi, sizeof(v2abi));
93 regs->r30 = v2abi.r30;
94 #ifdef CONFIG_ARC_HAS_ACCL_REGS
95 regs->r58 = v2abi.r58;
96 regs->r59 = v2abi.r59;
103 stash_usr_regs(struct rt_sigframe __user *sf, struct pt_regs *regs,
107 struct user_regs_struct uregs;
109 uregs.scratch.bta = regs->bta;
110 uregs.scratch.lp_start = regs->lp_start;
111 uregs.scratch.lp_end = regs->lp_end;
112 uregs.scratch.lp_count = regs->lp_count;
113 uregs.scratch.status32 = regs->status32;
114 uregs.scratch.ret = regs->ret;
115 uregs.scratch.blink = regs->blink;
116 uregs.scratch.fp = regs->fp;
117 uregs.scratch.gp = regs->r26;
118 uregs.scratch.r12 = regs->r12;
119 uregs.scratch.r11 = regs->r11;
120 uregs.scratch.r10 = regs->r10;
121 uregs.scratch.r9 = regs->r9;
122 uregs.scratch.r8 = regs->r8;
123 uregs.scratch.r7 = regs->r7;
124 uregs.scratch.r6 = regs->r6;
125 uregs.scratch.r5 = regs->r5;
126 uregs.scratch.r4 = regs->r4;
127 uregs.scratch.r3 = regs->r3;
128 uregs.scratch.r2 = regs->r2;
129 uregs.scratch.r1 = regs->r1;
130 uregs.scratch.r0 = regs->r0;
131 uregs.scratch.sp = regs->sp;
133 err = __copy_to_user(&(sf->uc.uc_mcontext.regs.scratch), &uregs.scratch,
134 sizeof(sf->uc.uc_mcontext.regs.scratch));
137 err |= save_arcv2_regs(&(sf->uc.uc_mcontext), regs);
139 err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(sigset_t));
141 return err ? -EFAULT : 0;
144 static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
148 struct user_regs_struct uregs;
150 err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
151 err |= __copy_from_user(&uregs.scratch,
152 &(sf->uc.uc_mcontext.regs.scratch),
153 sizeof(sf->uc.uc_mcontext.regs.scratch));
156 err |= restore_arcv2_regs(&(sf->uc.uc_mcontext), regs);
161 set_current_blocked(&set);
162 regs->bta = uregs.scratch.bta;
163 regs->lp_start = uregs.scratch.lp_start;
164 regs->lp_end = uregs.scratch.lp_end;
165 regs->lp_count = uregs.scratch.lp_count;
166 regs->status32 = uregs.scratch.status32;
167 regs->ret = uregs.scratch.ret;
168 regs->blink = uregs.scratch.blink;
169 regs->fp = uregs.scratch.fp;
170 regs->r26 = uregs.scratch.gp;
171 regs->r12 = uregs.scratch.r12;
172 regs->r11 = uregs.scratch.r11;
173 regs->r10 = uregs.scratch.r10;
174 regs->r9 = uregs.scratch.r9;
175 regs->r8 = uregs.scratch.r8;
176 regs->r7 = uregs.scratch.r7;
177 regs->r6 = uregs.scratch.r6;
178 regs->r5 = uregs.scratch.r5;
179 regs->r4 = uregs.scratch.r4;
180 regs->r3 = uregs.scratch.r3;
181 regs->r2 = uregs.scratch.r2;
182 regs->r1 = uregs.scratch.r1;
183 regs->r0 = uregs.scratch.r0;
184 regs->sp = uregs.scratch.sp;
189 static inline int is_do_ss_needed(unsigned int magic)
191 if (MAGIC_SIGALTSTK == magic)
197 SYSCALL_DEFINE0(rt_sigreturn)
199 struct rt_sigframe __user *sf;
201 struct pt_regs *regs = current_pt_regs();
203 /* Always make any pending restarted system calls return -EINTR */
204 current->restart_block.fn = do_no_restart_syscall;
206 /* Since we stacked the signal on a word boundary,
207 * then 'sp' should be word aligned here. If it's
208 * not, then the user is trying to mess with us.
213 sf = (struct rt_sigframe __force __user *)(regs->sp);
215 if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
218 if (__get_user(magic, &sf->sigret_magic))
221 if (unlikely(is_do_ss_needed(magic)))
222 if (restore_altstack(&sf->uc.uc_stack))
225 if (restore_usr_regs(regs, sf))
228 /* Don't restart from sigreturn */
229 syscall_wont_restart(regs);
232 * Ensure that sigreturn always returns to user mode (in case the
233 * regs saved on user stack got fudged between save and sigreturn)
234 * Otherwise it is easy to panic the kernel with a custom
235 * signal handler and/or restorer which clobberes the status32/ret
236 * to return to a bogus location in kernel mode.
238 regs->status32 |= STATUS_U_MASK;
243 force_sig(SIGSEGV, current);
248 * Determine which stack to use..
250 static inline void __user *get_sigframe(struct ksignal *ksig,
251 struct pt_regs *regs,
252 unsigned long framesize)
254 unsigned long sp = sigsp(regs->sp, ksig);
257 /* No matter what happens, 'sp' must be word
258 * aligned otherwise nasty things could happen
261 /* ATPCS B01 mandates 8-byte alignment */
262 frame = (void __user *)((sp - framesize) & ~7);
264 /* Check that we can actually write to the signal frame */
265 if (!access_ok(VERIFY_WRITE, frame, framesize))
272 setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs)
274 struct rt_sigframe __user *sf;
275 unsigned int magic = 0;
278 sf = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
283 * w/o SA_SIGINFO, struct ucontext is partially populated (only
284 * uc_mcontext/uc_sigmask) for kernel's normal user state preservation
285 * during signal handler execution. This works for SA_SIGINFO as well
286 * although the semantics are now overloaded (the same reg state can be
287 * inspected by userland: but are they allowed to fiddle with it ?
289 err |= stash_usr_regs(sf, regs, set);
292 * SA_SIGINFO requires 3 args to signal handler:
293 * #1: sig-no (common to any handler)
295 * #3: struct ucontext (completely populated)
297 if (unlikely(ksig->ka.sa.sa_flags & SA_SIGINFO)) {
298 err |= copy_siginfo_to_user(&sf->info, &ksig->info);
299 err |= __put_user(0, &sf->uc.uc_flags);
300 err |= __put_user(NULL, &sf->uc.uc_link);
301 err |= __save_altstack(&sf->uc.uc_stack, regs->sp);
303 /* setup args 2 and 3 for user mode handler */
304 regs->r1 = (unsigned long)&sf->info;
305 regs->r2 = (unsigned long)&sf->uc;
308 * small optim to avoid unconditonally calling do_sigaltstack
309 * in sigreturn path, now that we only have rt_sigreturn
311 magic = MAGIC_SIGALTSTK;
314 err |= __put_user(magic, &sf->sigret_magic);
318 /* #1 arg to the user Signal handler */
319 regs->r0 = ksig->sig;
321 /* setup PC of user space signal handler */
322 regs->ret = (unsigned long)ksig->ka.sa.sa_handler;
325 * handler returns using sigreturn stub provided already by userpsace
326 * If not, nuke the process right away
328 if(!(ksig->ka.sa.sa_flags & SA_RESTORER))
331 regs->blink = (unsigned long)ksig->ka.sa.sa_restorer;
333 /* User Stack for signal handler will be above the frame just carved */
334 regs->sp = (unsigned long)sf;
337 * Bug 94183, Clear the DE bit, so that when signal handler
338 * starts to run, it doesn't use BTA
340 regs->status32 &= ~STATUS_DE_MASK;
341 regs->status32 |= STATUS_L_MASK;
346 static void arc_restart_syscall(struct k_sigaction *ka, struct pt_regs *regs)
349 case -ERESTART_RESTARTBLOCK:
350 case -ERESTARTNOHAND:
352 * ERESTARTNOHAND means that the syscall should
353 * only be restarted if there was no handler for
354 * the signal, and since we only get here if there
355 * is a handler, we don't restart
357 regs->r0 = -EINTR; /* ERESTART_xxx is internal */
362 * ERESTARTSYS means to restart the syscall if
363 * there is no handler or the handler was
364 * registered with SA_RESTART
366 if (!(ka->sa.sa_flags & SA_RESTART)) {
372 case -ERESTARTNOINTR:
374 * ERESTARTNOINTR means that the syscall should
375 * be called again after the signal handler returns.
376 * Setup reg state just as it was before doing the trap
377 * r0 has been clobbered with sys call ret code thus it
378 * needs to be reloaded with orig first arg to syscall
379 * in orig_r0. Rest of relevant reg-file:
380 * r8 (syscall num) and (r1 - r7) will be reset to
381 * their orig user space value when we ret from kernel
383 regs->r0 = regs->orig_r0;
384 regs->ret -= is_isa_arcv2() ? 2 : 4;
390 * OK, we're invoking a handler
393 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
395 sigset_t *oldset = sigmask_to_save();
398 /* Set up the stack frame */
399 failed = setup_rt_frame(ksig, oldset, regs);
401 signal_setup_done(failed, ksig, 0);
404 void do_signal(struct pt_regs *regs)
409 restart_scall = in_syscall(regs) && syscall_restartable(regs);
411 if (get_signal(&ksig)) {
413 arc_restart_syscall(&ksig.ka, regs);
414 syscall_wont_restart(regs); /* No more restarts */
416 handle_signal(&ksig, regs);
421 /* No handler for syscall: restart it */
422 if (regs->r0 == -ERESTARTNOHAND ||
423 regs->r0 == -ERESTARTSYS || regs->r0 == -ERESTARTNOINTR) {
424 regs->r0 = regs->orig_r0;
425 regs->ret -= is_isa_arcv2() ? 2 : 4;
426 } else if (regs->r0 == -ERESTART_RESTARTBLOCK) {
427 regs->r8 = __NR_restart_syscall;
428 regs->ret -= is_isa_arcv2() ? 2 : 4;
430 syscall_wont_restart(regs); /* No more restarts */
433 /* If there's no signal to deliver, restore the saved sigmask back */
434 restore_saved_sigmask();
437 void do_notify_resume(struct pt_regs *regs)
440 * ASM glue gaurantees that this is only called when returning to
443 if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
444 tracehook_notify_resume(regs);