2 * arch/xtensa/kernel/signal.c
4 * Default platform functions.
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
10 * Copyright (C) 2005, 2006 Tensilica Inc.
11 * Copyright (C) 1991, 1992 Linus Torvalds
12 * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
14 * Chris Zankel <chris@zankel.net>
15 * Joe Taylor <joe@tensilica.com>
18 #include <linux/signal.h>
19 #include <linux/errno.h>
20 #include <linux/ptrace.h>
21 #include <linux/personality.h>
22 #include <linux/resume_user_mode.h>
23 #include <linux/sched/task_stack.h>
25 #include <asm/ucontext.h>
26 #include <linux/uaccess.h>
27 #include <asm/cacheflush.h>
28 #include <asm/coprocessor.h>
29 #include <asm/processor.h>
30 #include <asm/syscall.h>
31 #include <asm/unistd.h>
33 extern struct task_struct *coproc_owners[];
42 #if XTENSA_HAVE_COPROCESSORS
43 xtregs_coprocessor_t cp;
46 unsigned char retcode[6];
47 unsigned int window[4];
50 #if defined(USER_SUPPORT_WINDOWED)
52 * Flush register windows stored in pt_regs to stack.
53 * Returns 1 for errors.
57 flush_window_regs_user(struct pt_regs *regs)
59 const unsigned long ws = regs->windowstart;
60 const unsigned long wb = regs->windowbase;
66 /* Return if no other frames. */
71 /* Rotate windowmask and skip empty frames. */
73 wm = (ws >> wb) | (ws << (XCHAL_NUM_AREGS / 4 - wb));
74 base = (XCHAL_NUM_AREGS / 4) - (regs->wmask >> 4);
76 /* For call8 or call12 frames, we need the previous stack pointer. */
78 if ((regs->wmask & 2) == 0)
79 if (__get_user(sp, (int*)(regs->areg[base * 4 + 1] - 12)))
82 /* Spill frames to stack. */
84 while (base < XCHAL_NUM_AREGS / 4) {
89 /* Save registers a4..a7 (call8) or a4...a11 (call12) */
91 if (m & 2) { /* call4 */
94 } else if (m & 4) { /* call8 */
95 if (copy_to_user(&SPILL_SLOT_CALL8(sp, 4),
96 ®s->areg[(base + 1) * 4], 16))
100 } else if (m & 8) { /* call12 */
101 if (copy_to_user(&SPILL_SLOT_CALL12(sp, 4),
102 ®s->areg[(base + 1) * 4], 32))
107 /* Save current frame a0..a3 under next SP */
109 sp = regs->areg[((base + inc) * 4 + 1) % XCHAL_NUM_AREGS];
110 if (copy_to_user(&SPILL_SLOT(sp, 0), ®s->areg[base * 4], 16))
113 /* Get current stack pointer for next loop iteration. */
115 sp = regs->areg[base * 4 + 1];
120 regs->windowstart = 1 << wb;
129 flush_window_regs_user(struct pt_regs *regs)
136 * Note: We don't copy double exception 'regs', we have to finish double exc.
137 * first before we return to signal handler! This dbl.exc.handler might cause
138 * another double exception, but I think we are fine as the situation is the
139 * same as if we had returned to the signal handerl and got an interrupt
144 setup_sigcontext(struct rt_sigframe __user *frame, struct pt_regs *regs)
146 struct sigcontext __user *sc = &frame->uc.uc_mcontext;
147 struct thread_info *ti = current_thread_info();
150 #define COPY(x) err |= __put_user(regs->x, &sc->sc_##x)
159 err |= flush_window_regs_user(regs);
160 err |= __copy_to_user (sc->sc_a, regs->areg, 16 * 4);
161 err |= __put_user(0, &sc->sc_xtregs);
166 #if XTENSA_HAVE_COPROCESSORS
167 coprocessor_flush_release_all(ti);
168 err |= __copy_to_user(&frame->xtregs.cp, &ti->xtregs_cp,
169 sizeof (frame->xtregs.cp));
171 err |= __copy_to_user(&frame->xtregs.opt, ®s->xtregs_opt,
172 sizeof (xtregs_opt_t));
173 err |= __copy_to_user(&frame->xtregs.user, &ti->xtregs_user,
174 sizeof (xtregs_user_t));
176 err |= __put_user(err ? NULL : &frame->xtregs, &sc->sc_xtregs);
182 restore_sigcontext(struct pt_regs *regs, struct rt_sigframe __user *frame)
184 struct sigcontext __user *sc = &frame->uc.uc_mcontext;
185 struct thread_info *ti = current_thread_info();
186 unsigned int err = 0;
189 #define COPY(x) err |= __get_user(regs->x, &sc->sc_##x)
197 /* All registers were flushed to stack. Start with a pristine frame. */
200 regs->windowbase = 0;
201 regs->windowstart = 1;
203 regs->syscall = NO_SYSCALL; /* disable syscall checks */
205 /* For PS, restore only PS.CALLINC.
206 * Assume that all other bits are either the same as for the signal
207 * handler, or the user mode value doesn't matter (e.g. PS.OWB).
209 err |= __get_user(ps, &sc->sc_ps);
210 regs->ps = (regs->ps & ~PS_CALLINC_MASK) | (ps & PS_CALLINC_MASK);
212 /* Additional corruption checks */
214 if ((regs->lcount > 0)
215 && ((regs->lbeg > TASK_SIZE) || (regs->lend > TASK_SIZE)) )
218 err |= __copy_from_user(regs->areg, sc->sc_a, 16 * 4);
223 /* The signal handler may have used coprocessors in which
224 * case they are still enabled. We disable them to force a
225 * reloading of the original task's CP state by the lazy
226 * context-switching mechanisms of CP exception handling.
227 * Also, we essentially discard any coprocessor state that the
228 * signal handler created. */
230 #if XTENSA_HAVE_COPROCESSORS
231 coprocessor_release_all(ti);
232 err |= __copy_from_user(&ti->xtregs_cp, &frame->xtregs.cp,
233 sizeof (frame->xtregs.cp));
235 err |= __copy_from_user(&ti->xtregs_user, &frame->xtregs.user,
236 sizeof (xtregs_user_t));
237 err |= __copy_from_user(®s->xtregs_opt, &frame->xtregs.opt,
238 sizeof (xtregs_opt_t));
245 * Do a signal return; undo the signal stack.
248 asmlinkage long xtensa_rt_sigreturn(void)
250 struct pt_regs *regs = current_pt_regs();
251 struct rt_sigframe __user *frame;
255 /* Always make any pending restarted system calls return -EINTR */
256 current->restart_block.fn = do_no_restart_syscall;
259 panic("rt_sigreturn in double exception!\n");
261 frame = (struct rt_sigframe __user *) regs->areg[1];
263 if (!access_ok(frame, sizeof(*frame)))
266 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
269 set_current_blocked(&set);
271 if (restore_sigcontext(regs, frame))
276 if (restore_altstack(&frame->uc.uc_stack))
289 * Set up a signal frame.
293 gen_return_code(unsigned char *codemem)
298 * The 12-bit immediate is really split up within the 24-bit MOVI
299 * instruction. As long as the above system call numbers fit within
300 * 8-bits, the following code works fine. See the Xtensa ISA for
304 #if __NR_rt_sigreturn > 255
305 # error Generating the MOVI instruction below breaks!
308 #ifdef __XTENSA_EB__ /* Big Endian version */
309 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */
310 err |= __put_user(0x22, &codemem[0]);
311 err |= __put_user(0x0a, &codemem[1]);
312 err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
313 /* Generate instruction: SYSCALL */
314 err |= __put_user(0x00, &codemem[3]);
315 err |= __put_user(0x05, &codemem[4]);
316 err |= __put_user(0x00, &codemem[5]);
318 #elif defined __XTENSA_EL__ /* Little Endian version */
319 /* Generate instruction: MOVI a2, __NR_rt_sigreturn */
320 err |= __put_user(0x22, &codemem[0]);
321 err |= __put_user(0xa0, &codemem[1]);
322 err |= __put_user(__NR_rt_sigreturn, &codemem[2]);
323 /* Generate instruction: SYSCALL */
324 err |= __put_user(0x00, &codemem[3]);
325 err |= __put_user(0x50, &codemem[4]);
326 err |= __put_user(0x00, &codemem[5]);
328 # error Must use compiler for Xtensa processors.
331 /* Flush generated code out of the data cache */
334 __invalidate_icache_range((unsigned long)codemem, 6UL);
335 __flush_invalidate_dcache_range((unsigned long)codemem, 6UL);
342 static int setup_frame(struct ksignal *ksig, sigset_t *set,
343 struct pt_regs *regs)
345 struct rt_sigframe *frame;
346 int err = 0, sig = ksig->sig;
347 unsigned long sp, ra, tp, ps;
348 unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler;
349 unsigned long handler_fdpic_GOT = 0;
351 bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) &&
352 (current->personality & FDPIC_FUNCPTRS);
355 unsigned long __user *fdpic_func_desc =
356 (unsigned long __user *)handler;
357 if (__get_user(handler, &fdpic_func_desc[0]) ||
358 __get_user(handler_fdpic_GOT, &fdpic_func_desc[1]))
364 if ((ksig->ka.sa.sa_flags & SA_ONSTACK) != 0 && sas_ss_flags(sp) == 0) {
365 sp = current->sas_ss_sp + current->sas_ss_size;
368 frame = (void *)((sp - sizeof(*frame)) & -16ul);
371 panic ("Double exception sys_sigreturn\n");
373 if (!access_ok(frame, sizeof(*frame))) {
377 if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
378 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
381 /* Create the user context. */
383 err |= __put_user(0, &frame->uc.uc_flags);
384 err |= __put_user(0, &frame->uc.uc_link);
385 err |= __save_altstack(&frame->uc.uc_stack, regs->areg[1]);
386 err |= setup_sigcontext(frame, regs);
387 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
389 if (ksig->ka.sa.sa_flags & SA_RESTORER) {
391 unsigned long __user *fdpic_func_desc =
392 (unsigned long __user *)ksig->ka.sa.sa_restorer;
394 err |= __get_user(ra, fdpic_func_desc);
396 ra = (unsigned long)ksig->ka.sa.sa_restorer;
400 /* Create sys_rt_sigreturn syscall in stack frame */
402 err |= gen_return_code(frame->retcode);
403 ra = (unsigned long) frame->retcode;
410 * Create signal handler execution context.
411 * Return context not modified until this point.
414 /* Set up registers for signal handler; preserve the threadptr */
415 tp = regs->threadptr;
417 start_thread(regs, handler, (unsigned long)frame);
419 /* Set up a stack frame for a call4 if userspace uses windowed ABI */
420 if (ps & PS_WOE_MASK) {
423 (((unsigned long) ra) & 0x3fffffff) | 0x40000000;
424 ps = (ps & ~(PS_CALLINC_MASK | PS_OWB_MASK)) |
425 (1 << PS_CALLINC_SHIFT);
428 regs->areg[base] = (unsigned long) ra;
430 regs->areg[base + 2] = (unsigned long) sig;
431 regs->areg[base + 3] = (unsigned long) &frame->info;
432 regs->areg[base + 4] = (unsigned long) &frame->uc;
433 regs->threadptr = tp;
436 regs->areg[base + 11] = handler_fdpic_GOT;
438 pr_debug("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08lx\n",
439 current->comm, current->pid, sig, frame, regs->pc);
445 * Note that 'init' is a special process: it doesn't get signals it doesn't
446 * want to handle. Thus you cannot kill init even with a SIGKILL even by
449 * Note that we go through the signals twice: once to check the signals that
450 * the kernel can handle, and then we build all the user-level signal handling
451 * stack-frames in one go after that.
453 static void do_signal(struct pt_regs *regs)
457 task_pt_regs(current)->icountlevel = 0;
459 if (get_signal(&ksig)) {
462 /* Are we from a system call? */
464 if (regs->syscall != NO_SYSCALL) {
466 /* If so, check system call restarting.. */
468 switch (regs->areg[2]) {
469 case -ERESTARTNOHAND:
470 case -ERESTART_RESTARTBLOCK:
471 regs->areg[2] = -EINTR;
475 if (!(ksig.ka.sa.sa_flags & SA_RESTART)) {
476 regs->areg[2] = -EINTR;
480 case -ERESTARTNOINTR:
481 regs->areg[2] = regs->syscall;
487 if (regs->areg[2] != 0)
492 /* Whee! Actually deliver the signal. */
493 /* Set up the stack frame */
494 ret = setup_frame(&ksig, sigmask_to_save(), regs);
495 signal_setup_done(ret, &ksig, 0);
496 if (test_thread_flag(TIF_SINGLESTEP))
497 task_pt_regs(current)->icountlevel = 1;
502 /* Did we come from a system call? */
503 if (regs->syscall != NO_SYSCALL) {
504 /* Restart the system call - no handlers present */
505 switch (regs->areg[2]) {
506 case -ERESTARTNOHAND:
508 case -ERESTARTNOINTR:
509 regs->areg[2] = regs->syscall;
512 case -ERESTART_RESTARTBLOCK:
513 regs->areg[2] = __NR_restart_syscall;
519 /* If there's no signal to deliver, we just restore the saved mask. */
520 restore_saved_sigmask();
522 if (test_thread_flag(TIF_SINGLESTEP))
523 task_pt_regs(current)->icountlevel = 1;
527 void do_notify_resume(struct pt_regs *regs)
529 if (test_thread_flag(TIF_SIGPENDING) ||
530 test_thread_flag(TIF_NOTIFY_SIGNAL))
533 if (test_thread_flag(TIF_NOTIFY_RESUME))
534 resume_user_mode_work(regs);