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TOMOYO Linux Cross Reference
Linux/arch/sparc/kernel/signal_64.c

Version: ~ [ linux-5.4-rc3 ] ~ [ linux-5.3.6 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.79 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.149 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.196 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.196 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.75 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /*
  2  *  arch/sparc64/kernel/signal.c
  3  *
  4  *  Copyright (C) 1991, 1992  Linus Torvalds
  5  *  Copyright (C) 1995, 2008 David S. Miller (davem@davemloft.net)
  6  *  Copyright (C) 1996 Miguel de Icaza (miguel@nuclecu.unam.mx)
  7  *  Copyright (C) 1997 Eddie C. Dost   (ecd@skynet.be)
  8  *  Copyright (C) 1997,1998 Jakub Jelinek   (jj@sunsite.mff.cuni.cz)
  9  */
 10 
 11 #ifdef CONFIG_COMPAT
 12 #include <linux/compat.h>       /* for compat_old_sigset_t */
 13 #endif
 14 #include <linux/sched.h>
 15 #include <linux/kernel.h>
 16 #include <linux/signal.h>
 17 #include <linux/errno.h>
 18 #include <linux/wait.h>
 19 #include <linux/ptrace.h>
 20 #include <linux/tracehook.h>
 21 #include <linux/unistd.h>
 22 #include <linux/mm.h>
 23 #include <linux/tty.h>
 24 #include <linux/binfmts.h>
 25 #include <linux/bitops.h>
 26 #include <linux/context_tracking.h>
 27 
 28 #include <linux/uaccess.h>
 29 #include <asm/ptrace.h>
 30 #include <asm/pgtable.h>
 31 #include <asm/fpumacro.h>
 32 #include <asm/uctx.h>
 33 #include <asm/siginfo.h>
 34 #include <asm/visasm.h>
 35 #include <asm/switch_to.h>
 36 #include <asm/cacheflush.h>
 37 
 38 #include "sigutil.h"
 39 #include "systbls.h"
 40 #include "kernel.h"
 41 #include "entry.h"
 42 
 43 /* {set, get}context() needed for 64-bit SparcLinux userland. */
 44 asmlinkage void sparc64_set_context(struct pt_regs *regs)
 45 {
 46         struct ucontext __user *ucp = (struct ucontext __user *)
 47                 regs->u_regs[UREG_I0];
 48         enum ctx_state prev_state = exception_enter();
 49         mc_gregset_t __user *grp;
 50         unsigned long pc, npc, tstate;
 51         unsigned long fp, i7;
 52         unsigned char fenab;
 53         int err;
 54 
 55         synchronize_user_stack();
 56         if (get_thread_wsaved()                                 ||
 57             (((unsigned long)ucp) & (sizeof(unsigned long)-1))  ||
 58             (!__access_ok(ucp, sizeof(*ucp))))
 59                 goto do_sigsegv;
 60         grp  = &ucp->uc_mcontext.mc_gregs;
 61         err  = __get_user(pc, &((*grp)[MC_PC]));
 62         err |= __get_user(npc, &((*grp)[MC_NPC]));
 63         if (err || ((pc | npc) & 3))
 64                 goto do_sigsegv;
 65         if (regs->u_regs[UREG_I1]) {
 66                 sigset_t set;
 67 
 68                 if (_NSIG_WORDS == 1) {
 69                         if (__get_user(set.sig[0], &ucp->uc_sigmask.sig[0]))
 70                                 goto do_sigsegv;
 71                 } else {
 72                         if (__copy_from_user(&set, &ucp->uc_sigmask, sizeof(sigset_t)))
 73                                 goto do_sigsegv;
 74                 }
 75                 set_current_blocked(&set);
 76         }
 77         if (test_thread_flag(TIF_32BIT)) {
 78                 pc &= 0xffffffff;
 79                 npc &= 0xffffffff;
 80         }
 81         regs->tpc = pc;
 82         regs->tnpc = npc;
 83         err |= __get_user(regs->y, &((*grp)[MC_Y]));
 84         err |= __get_user(tstate, &((*grp)[MC_TSTATE]));
 85         regs->tstate &= ~(TSTATE_ASI | TSTATE_ICC | TSTATE_XCC);
 86         regs->tstate |= (tstate & (TSTATE_ASI | TSTATE_ICC | TSTATE_XCC));
 87         err |= __get_user(regs->u_regs[UREG_G1], (&(*grp)[MC_G1]));
 88         err |= __get_user(regs->u_regs[UREG_G2], (&(*grp)[MC_G2]));
 89         err |= __get_user(regs->u_regs[UREG_G3], (&(*grp)[MC_G3]));
 90         err |= __get_user(regs->u_regs[UREG_G4], (&(*grp)[MC_G4]));
 91         err |= __get_user(regs->u_regs[UREG_G5], (&(*grp)[MC_G5]));
 92         err |= __get_user(regs->u_regs[UREG_G6], (&(*grp)[MC_G6]));
 93 
 94         /* Skip %g7 as that's the thread register in userspace.  */
 95 
 96         err |= __get_user(regs->u_regs[UREG_I0], (&(*grp)[MC_O0]));
 97         err |= __get_user(regs->u_regs[UREG_I1], (&(*grp)[MC_O1]));
 98         err |= __get_user(regs->u_regs[UREG_I2], (&(*grp)[MC_O2]));
 99         err |= __get_user(regs->u_regs[UREG_I3], (&(*grp)[MC_O3]));
100         err |= __get_user(regs->u_regs[UREG_I4], (&(*grp)[MC_O4]));
101         err |= __get_user(regs->u_regs[UREG_I5], (&(*grp)[MC_O5]));
102         err |= __get_user(regs->u_regs[UREG_I6], (&(*grp)[MC_O6]));
103         err |= __get_user(regs->u_regs[UREG_I7], (&(*grp)[MC_O7]));
104 
105         err |= __get_user(fp, &(ucp->uc_mcontext.mc_fp));
106         err |= __get_user(i7, &(ucp->uc_mcontext.mc_i7));
107         err |= __put_user(fp,
108               (&(((struct reg_window __user *)(STACK_BIAS+regs->u_regs[UREG_I6]))->ins[6])));
109         err |= __put_user(i7,
110               (&(((struct reg_window __user *)(STACK_BIAS+regs->u_regs[UREG_I6]))->ins[7])));
111 
112         err |= __get_user(fenab, &(ucp->uc_mcontext.mc_fpregs.mcfpu_enab));
113         if (fenab) {
114                 unsigned long *fpregs = current_thread_info()->fpregs;
115                 unsigned long fprs;
116                 
117                 fprs_write(0);
118                 err |= __get_user(fprs, &(ucp->uc_mcontext.mc_fpregs.mcfpu_fprs));
119                 if (fprs & FPRS_DL)
120                         err |= copy_from_user(fpregs,
121                                               &(ucp->uc_mcontext.mc_fpregs.mcfpu_fregs),
122                                               (sizeof(unsigned int) * 32));
123                 if (fprs & FPRS_DU)
124                         err |= copy_from_user(fpregs+16,
125                          ((unsigned long __user *)&(ucp->uc_mcontext.mc_fpregs.mcfpu_fregs))+16,
126                          (sizeof(unsigned int) * 32));
127                 err |= __get_user(current_thread_info()->xfsr[0],
128                                   &(ucp->uc_mcontext.mc_fpregs.mcfpu_fsr));
129                 err |= __get_user(current_thread_info()->gsr[0],
130                                   &(ucp->uc_mcontext.mc_fpregs.mcfpu_gsr));
131                 regs->tstate &= ~TSTATE_PEF;
132         }
133         if (err)
134                 goto do_sigsegv;
135 out:
136         exception_exit(prev_state);
137         return;
138 do_sigsegv:
139         force_sig(SIGSEGV, current);
140         goto out;
141 }
142 
143 asmlinkage void sparc64_get_context(struct pt_regs *regs)
144 {
145         struct ucontext __user *ucp = (struct ucontext __user *)
146                 regs->u_regs[UREG_I0];
147         enum ctx_state prev_state = exception_enter();
148         mc_gregset_t __user *grp;
149         mcontext_t __user *mcp;
150         unsigned long fp, i7;
151         unsigned char fenab;
152         int err;
153 
154         synchronize_user_stack();
155         if (get_thread_wsaved() || clear_user(ucp, sizeof(*ucp)))
156                 goto do_sigsegv;
157 
158 #if 1
159         fenab = 0; /* IMO get_context is like any other system call, thus modifies FPU state -jj */
160 #else
161         fenab = (current_thread_info()->fpsaved[0] & FPRS_FEF);
162 #endif
163                 
164         mcp = &ucp->uc_mcontext;
165         grp = &mcp->mc_gregs;
166 
167         /* Skip over the trap instruction, first. */
168         if (test_thread_flag(TIF_32BIT)) {
169                 regs->tpc   = (regs->tnpc & 0xffffffff);
170                 regs->tnpc  = (regs->tnpc + 4) & 0xffffffff;
171         } else {
172                 regs->tpc   = regs->tnpc;
173                 regs->tnpc += 4;
174         }
175         err = 0;
176         if (_NSIG_WORDS == 1)
177                 err |= __put_user(current->blocked.sig[0],
178                                   (unsigned long __user *)&ucp->uc_sigmask);
179         else
180                 err |= __copy_to_user(&ucp->uc_sigmask, &current->blocked,
181                                       sizeof(sigset_t));
182 
183         err |= __put_user(regs->tstate, &((*grp)[MC_TSTATE]));
184         err |= __put_user(regs->tpc, &((*grp)[MC_PC]));
185         err |= __put_user(regs->tnpc, &((*grp)[MC_NPC]));
186         err |= __put_user(regs->y, &((*grp)[MC_Y]));
187         err |= __put_user(regs->u_regs[UREG_G1], &((*grp)[MC_G1]));
188         err |= __put_user(regs->u_regs[UREG_G2], &((*grp)[MC_G2]));
189         err |= __put_user(regs->u_regs[UREG_G3], &((*grp)[MC_G3]));
190         err |= __put_user(regs->u_regs[UREG_G4], &((*grp)[MC_G4]));
191         err |= __put_user(regs->u_regs[UREG_G5], &((*grp)[MC_G5]));
192         err |= __put_user(regs->u_regs[UREG_G6], &((*grp)[MC_G6]));
193         err |= __put_user(regs->u_regs[UREG_G7], &((*grp)[MC_G7]));
194         err |= __put_user(regs->u_regs[UREG_I0], &((*grp)[MC_O0]));
195         err |= __put_user(regs->u_regs[UREG_I1], &((*grp)[MC_O1]));
196         err |= __put_user(regs->u_regs[UREG_I2], &((*grp)[MC_O2]));
197         err |= __put_user(regs->u_regs[UREG_I3], &((*grp)[MC_O3]));
198         err |= __put_user(regs->u_regs[UREG_I4], &((*grp)[MC_O4]));
199         err |= __put_user(regs->u_regs[UREG_I5], &((*grp)[MC_O5]));
200         err |= __put_user(regs->u_regs[UREG_I6], &((*grp)[MC_O6]));
201         err |= __put_user(regs->u_regs[UREG_I7], &((*grp)[MC_O7]));
202 
203         err |= __get_user(fp,
204                  (&(((struct reg_window __user *)(STACK_BIAS+regs->u_regs[UREG_I6]))->ins[6])));
205         err |= __get_user(i7,
206                  (&(((struct reg_window __user *)(STACK_BIAS+regs->u_regs[UREG_I6]))->ins[7])));
207         err |= __put_user(fp, &(mcp->mc_fp));
208         err |= __put_user(i7, &(mcp->mc_i7));
209 
210         err |= __put_user(fenab, &(mcp->mc_fpregs.mcfpu_enab));
211         if (fenab) {
212                 unsigned long *fpregs = current_thread_info()->fpregs;
213                 unsigned long fprs;
214                 
215                 fprs = current_thread_info()->fpsaved[0];
216                 if (fprs & FPRS_DL)
217                         err |= copy_to_user(&(mcp->mc_fpregs.mcfpu_fregs), fpregs,
218                                             (sizeof(unsigned int) * 32));
219                 if (fprs & FPRS_DU)
220                         err |= copy_to_user(
221                           ((unsigned long __user *)&(mcp->mc_fpregs.mcfpu_fregs))+16, fpregs+16,
222                           (sizeof(unsigned int) * 32));
223                 err |= __put_user(current_thread_info()->xfsr[0], &(mcp->mc_fpregs.mcfpu_fsr));
224                 err |= __put_user(current_thread_info()->gsr[0], &(mcp->mc_fpregs.mcfpu_gsr));
225                 err |= __put_user(fprs, &(mcp->mc_fpregs.mcfpu_fprs));
226         }
227         if (err)
228                 goto do_sigsegv;
229 out:
230         exception_exit(prev_state);
231         return;
232 do_sigsegv:
233         force_sig(SIGSEGV, current);
234         goto out;
235 }
236 
237 /* Checks if the fp is valid.  We always build rt signal frames which
238  * are 16-byte aligned, therefore we can always enforce that the
239  * restore frame has that property as well.
240  */
241 static bool invalid_frame_pointer(void __user *fp)
242 {
243         if (((unsigned long) fp) & 15)
244                 return true;
245         return false;
246 }
247 
248 struct rt_signal_frame {
249         struct sparc_stackf     ss;
250         siginfo_t               info;
251         struct pt_regs          regs;
252         __siginfo_fpu_t __user  *fpu_save;
253         stack_t                 stack;
254         sigset_t                mask;
255         __siginfo_rwin_t        *rwin_save;
256 };
257 
258 void do_rt_sigreturn(struct pt_regs *regs)
259 {
260         unsigned long tpc, tnpc, tstate, ufp;
261         struct rt_signal_frame __user *sf;
262         __siginfo_fpu_t __user *fpu_save;
263         __siginfo_rwin_t __user *rwin_save;
264         sigset_t set;
265         int err;
266 
267         /* Always make any pending restarted system calls return -EINTR */
268         current->restart_block.fn = do_no_restart_syscall;
269 
270         synchronize_user_stack ();
271         sf = (struct rt_signal_frame __user *)
272                 (regs->u_regs [UREG_FP] + STACK_BIAS);
273 
274         /* 1. Make sure we are not getting garbage from the user */
275         if (invalid_frame_pointer(sf))
276                 goto segv;
277 
278         if (get_user(ufp, &sf->regs.u_regs[UREG_FP]))
279                 goto segv;
280 
281         if ((ufp + STACK_BIAS) & 0x7)
282                 goto segv;
283 
284         err = __get_user(tpc, &sf->regs.tpc);
285         err |= __get_user(tnpc, &sf->regs.tnpc);
286         if (test_thread_flag(TIF_32BIT)) {
287                 tpc &= 0xffffffff;
288                 tnpc &= 0xffffffff;
289         }
290         err |= ((tpc | tnpc) & 3);
291 
292         /* 2. Restore the state */
293         err |= __get_user(regs->y, &sf->regs.y);
294         err |= __get_user(tstate, &sf->regs.tstate);
295         err |= copy_from_user(regs->u_regs, sf->regs.u_regs, sizeof(regs->u_regs));
296 
297         /* User can only change condition codes and %asi in %tstate. */
298         regs->tstate &= ~(TSTATE_ASI | TSTATE_ICC | TSTATE_XCC);
299         regs->tstate |= (tstate & (TSTATE_ASI | TSTATE_ICC | TSTATE_XCC));
300 
301         err |= __get_user(fpu_save, &sf->fpu_save);
302         if (!err && fpu_save)
303                 err |= restore_fpu_state(regs, fpu_save);
304 
305         err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
306         err |= restore_altstack(&sf->stack);
307         if (err)
308                 goto segv;
309 
310         err |= __get_user(rwin_save, &sf->rwin_save);
311         if (!err && rwin_save) {
312                 if (restore_rwin_state(rwin_save))
313                         goto segv;
314         }
315 
316         regs->tpc = tpc;
317         regs->tnpc = tnpc;
318 
319         /* Prevent syscall restart.  */
320         pt_regs_clear_syscall(regs);
321 
322         set_current_blocked(&set);
323         return;
324 segv:
325         force_sig(SIGSEGV, current);
326 }
327 
328 static inline void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs, unsigned long framesize)
329 {
330         unsigned long sp = regs->u_regs[UREG_FP] + STACK_BIAS;
331 
332         /*
333          * If we are on the alternate signal stack and would overflow it, don't.
334          * Return an always-bogus address instead so we will die with SIGSEGV.
335          */
336         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
337                 return (void __user *) -1L;
338 
339         /* This is the X/Open sanctioned signal stack switching.  */
340         sp = sigsp(sp, ksig) - framesize;
341 
342         /* Always align the stack frame.  This handles two cases.  First,
343          * sigaltstack need not be mindful of platform specific stack
344          * alignment.  Second, if we took this signal because the stack
345          * is not aligned properly, we'd like to take the signal cleanly
346          * and report that.
347          */
348         sp &= ~15UL;
349 
350         return (void __user *) sp;
351 }
352 
353 static inline int
354 setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs)
355 {
356         struct rt_signal_frame __user *sf;
357         int wsaved, err, sf_size;
358         void __user *tail;
359 
360         /* 1. Make sure everything is clean */
361         synchronize_user_stack();
362         save_and_clear_fpu();
363         
364         wsaved = get_thread_wsaved();
365 
366         sf_size = sizeof(struct rt_signal_frame);
367         if (current_thread_info()->fpsaved[0] & FPRS_FEF)
368                 sf_size += sizeof(__siginfo_fpu_t);
369         if (wsaved)
370                 sf_size += sizeof(__siginfo_rwin_t);
371         sf = (struct rt_signal_frame __user *)
372                 get_sigframe(ksig, regs, sf_size);
373 
374         if (invalid_frame_pointer (sf)) {
375                 do_exit(SIGILL);        /* won't return, actually */
376                 return -EINVAL;
377         }
378 
379         tail = (sf + 1);
380 
381         /* 2. Save the current process state */
382         err = copy_to_user(&sf->regs, regs, sizeof (*regs));
383 
384         if (current_thread_info()->fpsaved[0] & FPRS_FEF) {
385                 __siginfo_fpu_t __user *fpu_save = tail;
386                 tail += sizeof(__siginfo_fpu_t);
387                 err |= save_fpu_state(regs, fpu_save);
388                 err |= __put_user((u64)fpu_save, &sf->fpu_save);
389         } else {
390                 err |= __put_user(0, &sf->fpu_save);
391         }
392         if (wsaved) {
393                 __siginfo_rwin_t __user *rwin_save = tail;
394                 tail += sizeof(__siginfo_rwin_t);
395                 err |= save_rwin_state(wsaved, rwin_save);
396                 err |= __put_user((u64)rwin_save, &sf->rwin_save);
397                 set_thread_wsaved(0);
398         } else {
399                 err |= __put_user(0, &sf->rwin_save);
400         }
401         
402         /* Setup sigaltstack */
403         err |= __save_altstack(&sf->stack, regs->u_regs[UREG_FP]);
404 
405         err |= copy_to_user(&sf->mask, sigmask_to_save(), sizeof(sigset_t));
406 
407         if (!wsaved) {
408                 err |= copy_in_user((u64 __user *)sf,
409                                     (u64 __user *)(regs->u_regs[UREG_FP] +
410                                                    STACK_BIAS),
411                                     sizeof(struct reg_window));
412         } else {
413                 struct reg_window *rp;
414 
415                 rp = &current_thread_info()->reg_window[wsaved - 1];
416                 err |= copy_to_user(sf, rp, sizeof(struct reg_window));
417         }
418         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
419                 err |= copy_siginfo_to_user(&sf->info, &ksig->info);
420         else {
421                 err |= __put_user(ksig->sig, &sf->info.si_signo);
422                 err |= __put_user(SI_NOINFO, &sf->info.si_code);
423         }
424         if (err)
425                 return err;
426         
427         /* 3. signal handler back-trampoline and parameters */
428         regs->u_regs[UREG_FP] = ((unsigned long) sf) - STACK_BIAS;
429         regs->u_regs[UREG_I0] = ksig->sig;
430         regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
431 
432         /* The sigcontext is passed in this way because of how it
433          * is defined in GLIBC's /usr/include/bits/sigcontext.h
434          * for sparc64.  It includes the 128 bytes of siginfo_t.
435          */
436         regs->u_regs[UREG_I2] = (unsigned long) &sf->info;
437 
438         /* 5. signal handler */
439         regs->tpc = (unsigned long) ksig->ka.sa.sa_handler;
440         regs->tnpc = (regs->tpc + 4);
441         if (test_thread_flag(TIF_32BIT)) {
442                 regs->tpc &= 0xffffffff;
443                 regs->tnpc &= 0xffffffff;
444         }
445         /* 4. return to kernel instructions */
446         regs->u_regs[UREG_I7] = (unsigned long)ksig->ka.ka_restorer;
447         return 0;
448 }
449 
450 static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
451                                    struct sigaction *sa)
452 {
453         switch (regs->u_regs[UREG_I0]) {
454         case ERESTART_RESTARTBLOCK:
455         case ERESTARTNOHAND:
456         no_system_call_restart:
457                 regs->u_regs[UREG_I0] = EINTR;
458                 regs->tstate |= (TSTATE_ICARRY|TSTATE_XCARRY);
459                 break;
460         case ERESTARTSYS:
461                 if (!(sa->sa_flags & SA_RESTART))
462                         goto no_system_call_restart;
463                 /* fallthrough */
464         case ERESTARTNOINTR:
465                 regs->u_regs[UREG_I0] = orig_i0;
466                 regs->tpc -= 4;
467                 regs->tnpc -= 4;
468         }
469 }
470 
471 /* Note that 'init' is a special process: it doesn't get signals it doesn't
472  * want to handle. Thus you cannot kill init even with a SIGKILL even by
473  * mistake.
474  */
475 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
476 {
477         struct ksignal ksig;
478         int restart_syscall;
479         bool has_handler;
480         
481         /* It's a lot of work and synchronization to add a new ptrace
482          * register for GDB to save and restore in order to get
483          * orig_i0 correct for syscall restarts when debugging.
484          *
485          * Although it should be the case that most of the global
486          * registers are volatile across a system call, glibc already
487          * depends upon that fact that we preserve them.  So we can't
488          * just use any global register to save away the orig_i0 value.
489          *
490          * In particular %g2, %g3, %g4, and %g5 are all assumed to be
491          * preserved across a system call trap by various pieces of
492          * code in glibc.
493          *
494          * %g7 is used as the "thread register".   %g6 is not used in
495          * any fixed manner.  %g6 is used as a scratch register and
496          * a compiler temporary, but it's value is never used across
497          * a system call.  Therefore %g6 is usable for orig_i0 storage.
498          */
499         if (pt_regs_is_syscall(regs) &&
500             (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY)))
501                 regs->u_regs[UREG_G6] = orig_i0;
502 
503 #ifdef CONFIG_COMPAT
504         if (test_thread_flag(TIF_32BIT)) {
505                 do_signal32(regs);
506                 return;
507         }
508 #endif  
509 
510         has_handler = get_signal(&ksig);
511 
512         restart_syscall = 0;
513         if (pt_regs_is_syscall(regs) &&
514             (regs->tstate & (TSTATE_XCARRY | TSTATE_ICARRY))) {
515                 restart_syscall = 1;
516                 orig_i0 = regs->u_regs[UREG_G6];
517         }
518 
519         if (has_handler) {
520                 if (restart_syscall)
521                         syscall_restart(orig_i0, regs, &ksig.ka.sa);
522                 signal_setup_done(setup_rt_frame(&ksig, regs), &ksig, 0);
523         } else {
524                 if (restart_syscall) {
525                         switch (regs->u_regs[UREG_I0]) {
526                         case ERESTARTNOHAND:
527                         case ERESTARTSYS:
528                         case ERESTARTNOINTR:
529                                 /* replay the system call when we are done */
530                                 regs->u_regs[UREG_I0] = orig_i0;
531                                 regs->tpc -= 4;
532                                 regs->tnpc -= 4;
533                                 pt_regs_clear_syscall(regs);
534                         case ERESTART_RESTARTBLOCK:
535                                 regs->u_regs[UREG_G1] = __NR_restart_syscall;
536                                 regs->tpc -= 4;
537                                 regs->tnpc -= 4;
538                                 pt_regs_clear_syscall(regs);
539                         }
540                 }
541                 restore_saved_sigmask();
542         }
543 }
544 
545 void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long thread_info_flags)
546 {
547         user_exit();
548         if (thread_info_flags & _TIF_UPROBE)
549                 uprobe_notify_resume(regs);
550         if (thread_info_flags & _TIF_SIGPENDING)
551                 do_signal(regs, orig_i0);
552         if (thread_info_flags & _TIF_NOTIFY_RESUME) {
553                 clear_thread_flag(TIF_NOTIFY_RESUME);
554                 tracehook_notify_resume(regs);
555         }
556         user_enter();
557 }
558 
559 

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