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Linux/arch/s390/kernel/compat_signal.c

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  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *    Copyright IBM Corp. 2000, 2006
  4  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
  5  *               Gerhard Tonn (ton@de.ibm.com)                  
  6  *
  7  *  Copyright (C) 1991, 1992  Linus Torvalds
  8  *
  9  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 10  */
 11 
 12 #include <linux/compat.h>
 13 #include <linux/sched.h>
 14 #include <linux/sched/task_stack.h>
 15 #include <linux/mm.h>
 16 #include <linux/smp.h>
 17 #include <linux/kernel.h>
 18 #include <linux/signal.h>
 19 #include <linux/errno.h>
 20 #include <linux/wait.h>
 21 #include <linux/ptrace.h>
 22 #include <linux/unistd.h>
 23 #include <linux/stddef.h>
 24 #include <linux/tty.h>
 25 #include <linux/personality.h>
 26 #include <linux/binfmts.h>
 27 #include <asm/ucontext.h>
 28 #include <linux/uaccess.h>
 29 #include <asm/lowcore.h>
 30 #include <asm/switch_to.h>
 31 #include "compat_linux.h"
 32 #include "compat_ptrace.h"
 33 #include "entry.h"
 34 
 35 typedef struct 
 36 {
 37         __u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
 38         struct sigcontext32 sc;
 39         _sigregs32 sregs;
 40         int signo;
 41         _sigregs_ext32 sregs_ext;
 42         __u16 svc_insn;         /* Offset of svc_insn is NOT fixed! */
 43 } sigframe32;
 44 
 45 typedef struct 
 46 {
 47         __u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
 48         __u16 svc_insn;
 49         compat_siginfo_t info;
 50         struct ucontext32 uc;
 51 } rt_sigframe32;
 52 
 53 /* Store registers needed to create the signal frame */
 54 static void store_sigregs(void)
 55 {
 56         save_access_regs(current->thread.acrs);
 57         save_fpu_regs();
 58 }
 59 
 60 /* Load registers after signal return */
 61 static void load_sigregs(void)
 62 {
 63         restore_access_regs(current->thread.acrs);
 64 }
 65 
 66 static int save_sigregs32(struct pt_regs *regs, _sigregs32 __user *sregs)
 67 {
 68         _sigregs32 user_sregs;
 69         int i;
 70 
 71         user_sregs.regs.psw.mask = (__u32)(regs->psw.mask >> 32);
 72         user_sregs.regs.psw.mask &= PSW32_MASK_USER | PSW32_MASK_RI;
 73         user_sregs.regs.psw.mask |= PSW32_USER_BITS;
 74         user_sregs.regs.psw.addr = (__u32) regs->psw.addr |
 75                 (__u32)(regs->psw.mask & PSW_MASK_BA);
 76         for (i = 0; i < NUM_GPRS; i++)
 77                 user_sregs.regs.gprs[i] = (__u32) regs->gprs[i];
 78         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
 79                sizeof(user_sregs.regs.acrs));
 80         fpregs_store((_s390_fp_regs *) &user_sregs.fpregs, &current->thread.fpu);
 81         if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs32)))
 82                 return -EFAULT;
 83         return 0;
 84 }
 85 
 86 static int restore_sigregs32(struct pt_regs *regs,_sigregs32 __user *sregs)
 87 {
 88         _sigregs32 user_sregs;
 89         int i;
 90 
 91         /* Alwys make any pending restarted system call return -EINTR */
 92         current->restart_block.fn = do_no_restart_syscall;
 93 
 94         if (__copy_from_user(&user_sregs, &sregs->regs, sizeof(user_sregs)))
 95                 return -EFAULT;
 96 
 97         if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW32_MASK_RI))
 98                 return -EINVAL;
 99 
100         /* Test the floating-point-control word. */
101         if (test_fp_ctl(user_sregs.fpregs.fpc))
102                 return -EINVAL;
103 
104         /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
105         regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
106                 (__u64)(user_sregs.regs.psw.mask & PSW32_MASK_USER) << 32 |
107                 (__u64)(user_sregs.regs.psw.mask & PSW32_MASK_RI) << 32 |
108                 (__u64)(user_sregs.regs.psw.addr & PSW32_ADDR_AMODE);
109         /* Check for invalid user address space control. */
110         if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
111                 regs->psw.mask = PSW_ASC_PRIMARY |
112                         (regs->psw.mask & ~PSW_MASK_ASC);
113         regs->psw.addr = (__u64)(user_sregs.regs.psw.addr & PSW32_ADDR_INSN);
114         for (i = 0; i < NUM_GPRS; i++)
115                 regs->gprs[i] = (__u64) user_sregs.regs.gprs[i];
116         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
117                sizeof(current->thread.acrs));
118         fpregs_load((_s390_fp_regs *) &user_sregs.fpregs, &current->thread.fpu);
119 
120         clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
121         clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART);
122         return 0;
123 }
124 
125 static int save_sigregs_ext32(struct pt_regs *regs,
126                               _sigregs_ext32 __user *sregs_ext)
127 {
128         __u32 gprs_high[NUM_GPRS];
129         __u64 vxrs[__NUM_VXRS_LOW];
130         int i;
131 
132         /* Save high gprs to signal stack */
133         for (i = 0; i < NUM_GPRS; i++)
134                 gprs_high[i] = regs->gprs[i] >> 32;
135         if (__copy_to_user(&sregs_ext->gprs_high, &gprs_high,
136                            sizeof(sregs_ext->gprs_high)))
137                 return -EFAULT;
138 
139         /* Save vector registers to signal stack */
140         if (MACHINE_HAS_VX) {
141                 for (i = 0; i < __NUM_VXRS_LOW; i++)
142                         vxrs[i] = *((__u64 *)(current->thread.fpu.vxrs + i) + 1);
143                 if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
144                                    sizeof(sregs_ext->vxrs_low)) ||
145                     __copy_to_user(&sregs_ext->vxrs_high,
146                                    current->thread.fpu.vxrs + __NUM_VXRS_LOW,
147                                    sizeof(sregs_ext->vxrs_high)))
148                         return -EFAULT;
149         }
150         return 0;
151 }
152 
153 static int restore_sigregs_ext32(struct pt_regs *regs,
154                                  _sigregs_ext32 __user *sregs_ext)
155 {
156         __u32 gprs_high[NUM_GPRS];
157         __u64 vxrs[__NUM_VXRS_LOW];
158         int i;
159 
160         /* Restore high gprs from signal stack */
161         if (__copy_from_user(&gprs_high, &sregs_ext->gprs_high,
162                              sizeof(sregs_ext->gprs_high)))
163                 return -EFAULT;
164         for (i = 0; i < NUM_GPRS; i++)
165                 *(__u32 *)&regs->gprs[i] = gprs_high[i];
166 
167         /* Restore vector registers from signal stack */
168         if (MACHINE_HAS_VX) {
169                 if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
170                                      sizeof(sregs_ext->vxrs_low)) ||
171                     __copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW,
172                                      &sregs_ext->vxrs_high,
173                                      sizeof(sregs_ext->vxrs_high)))
174                         return -EFAULT;
175                 for (i = 0; i < __NUM_VXRS_LOW; i++)
176                         *((__u64 *)(current->thread.fpu.vxrs + i) + 1) = vxrs[i];
177         }
178         return 0;
179 }
180 
181 COMPAT_SYSCALL_DEFINE0(sigreturn)
182 {
183         struct pt_regs *regs = task_pt_regs(current);
184         sigframe32 __user *frame = (sigframe32 __user *)regs->gprs[15];
185         sigset_t set;
186 
187         if (get_compat_sigset(&set, (compat_sigset_t __user *)frame->sc.oldmask))
188                 goto badframe;
189         set_current_blocked(&set);
190         save_fpu_regs();
191         if (restore_sigregs32(regs, &frame->sregs))
192                 goto badframe;
193         if (restore_sigregs_ext32(regs, &frame->sregs_ext))
194                 goto badframe;
195         load_sigregs();
196         return regs->gprs[2];
197 badframe:
198         force_sig(SIGSEGV);
199         return 0;
200 }
201 
202 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
203 {
204         struct pt_regs *regs = task_pt_regs(current);
205         rt_sigframe32 __user *frame = (rt_sigframe32 __user *)regs->gprs[15];
206         sigset_t set;
207 
208         if (get_compat_sigset(&set, &frame->uc.uc_sigmask))
209                 goto badframe;
210         set_current_blocked(&set);
211         if (compat_restore_altstack(&frame->uc.uc_stack))
212                 goto badframe;
213         save_fpu_regs();
214         if (restore_sigregs32(regs, &frame->uc.uc_mcontext))
215                 goto badframe;
216         if (restore_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))
217                 goto badframe;
218         load_sigregs();
219         return regs->gprs[2];
220 badframe:
221         force_sig(SIGSEGV);
222         return 0;
223 }       
224 
225 /*
226  * Set up a signal frame.
227  */
228 
229 
230 /*
231  * Determine which stack to use..
232  */
233 static inline void __user *
234 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
235 {
236         unsigned long sp;
237 
238         /* Default to using normal stack */
239         sp = (unsigned long) A(regs->gprs[15]);
240 
241         /* Overflow on alternate signal stack gives SIGSEGV. */
242         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
243                 return (void __user *) -1UL;
244 
245         /* This is the X/Open sanctioned signal stack switching.  */
246         if (ka->sa.sa_flags & SA_ONSTACK) {
247                 if (! sas_ss_flags(sp))
248                         sp = current->sas_ss_sp + current->sas_ss_size;
249         }
250 
251         return (void __user *)((sp - frame_size) & -8ul);
252 }
253 
254 static int setup_frame32(struct ksignal *ksig, sigset_t *set,
255                          struct pt_regs *regs)
256 {
257         int sig = ksig->sig;
258         sigframe32 __user *frame;
259         unsigned long restorer;
260         size_t frame_size;
261 
262         /*
263          * gprs_high are always present for 31-bit compat tasks.
264          * The space for vector registers is only allocated if
265          * the machine supports it
266          */
267         frame_size = sizeof(*frame) - sizeof(frame->sregs_ext.__reserved);
268         if (!MACHINE_HAS_VX)
269                 frame_size -= sizeof(frame->sregs_ext.vxrs_low) +
270                               sizeof(frame->sregs_ext.vxrs_high);
271         frame = get_sigframe(&ksig->ka, regs, frame_size);
272         if (frame == (void __user *) -1UL)
273                 return -EFAULT;
274 
275         /* Set up backchain. */
276         if (__put_user(regs->gprs[15], (unsigned int __user *) frame))
277                 return -EFAULT;
278 
279         /* Create struct sigcontext32 on the signal stack */
280         if (put_compat_sigset((compat_sigset_t __user *)frame->sc.oldmask,
281                               set, sizeof(compat_sigset_t)))
282                 return -EFAULT;
283         if (__put_user(ptr_to_compat(&frame->sregs), &frame->sc.sregs))
284                 return -EFAULT;
285 
286         /* Store registers needed to create the signal frame */
287         store_sigregs();
288 
289         /* Create _sigregs32 on the signal stack */
290         if (save_sigregs32(regs, &frame->sregs))
291                 return -EFAULT;
292 
293         /* Place signal number on stack to allow backtrace from handler.  */
294         if (__put_user(regs->gprs[2], (int __force __user *) &frame->signo))
295                 return -EFAULT;
296 
297         /* Create _sigregs_ext32 on the signal stack */
298         if (save_sigregs_ext32(regs, &frame->sregs_ext))
299                 return -EFAULT;
300 
301         /* Set up to return from userspace.  If provided, use a stub
302            already in userspace.  */
303         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
304                 restorer = (unsigned long __force)
305                         ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE;
306         } else {
307                 /* Signal frames without vectors registers are short ! */
308                 __u16 __user *svc = (void __user *) frame + frame_size - 2;
309                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc))
310                         return -EFAULT;
311                 restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE;
312         }
313 
314         /* Set up registers for signal handler */
315         regs->gprs[14] = restorer;
316         regs->gprs[15] = (__force __u64) frame;
317         /* Force 31 bit amode and default user address space control. */
318         regs->psw.mask = PSW_MASK_BA |
319                 (PSW_USER_BITS & PSW_MASK_ASC) |
320                 (regs->psw.mask & ~PSW_MASK_ASC);
321         regs->psw.addr = (__force __u64) ksig->ka.sa.sa_handler;
322 
323         regs->gprs[2] = sig;
324         regs->gprs[3] = (__force __u64) &frame->sc;
325 
326         /* We forgot to include these in the sigcontext.
327            To avoid breaking binary compatibility, they are passed as args. */
328         if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
329             sig == SIGTRAP || sig == SIGFPE) {
330                 /* set extra registers only for synchronous signals */
331                 regs->gprs[4] = regs->int_code & 127;
332                 regs->gprs[5] = regs->int_parm_long;
333                 regs->gprs[6] = current->thread.last_break;
334         }
335 
336         return 0;
337 }
338 
339 static int setup_rt_frame32(struct ksignal *ksig, sigset_t *set,
340                             struct pt_regs *regs)
341 {
342         rt_sigframe32 __user *frame;
343         unsigned long restorer;
344         size_t frame_size;
345         u32 uc_flags;
346 
347         frame_size = sizeof(*frame) -
348                      sizeof(frame->uc.uc_mcontext_ext.__reserved);
349         /*
350          * gprs_high are always present for 31-bit compat tasks.
351          * The space for vector registers is only allocated if
352          * the machine supports it
353          */
354         uc_flags = UC_GPRS_HIGH;
355         if (MACHINE_HAS_VX) {
356                 uc_flags |= UC_VXRS;
357         } else
358                 frame_size -= sizeof(frame->uc.uc_mcontext_ext.vxrs_low) +
359                               sizeof(frame->uc.uc_mcontext_ext.vxrs_high);
360         frame = get_sigframe(&ksig->ka, regs, frame_size);
361         if (frame == (void __user *) -1UL)
362                 return -EFAULT;
363 
364         /* Set up backchain. */
365         if (__put_user(regs->gprs[15], (unsigned int __force __user *) frame))
366                 return -EFAULT;
367 
368         /* Set up to return from userspace.  If provided, use a stub
369            already in userspace.  */
370         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
371                 restorer = (unsigned long __force)
372                         ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE;
373         } else {
374                 __u16 __user *svc = &frame->svc_insn;
375                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc))
376                         return -EFAULT;
377                 restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE;
378         }
379 
380         /* Create siginfo on the signal stack */
381         if (copy_siginfo_to_user32(&frame->info, &ksig->info))
382                 return -EFAULT;
383 
384         /* Store registers needed to create the signal frame */
385         store_sigregs();
386 
387         /* Create ucontext on the signal stack. */
388         if (__put_user(uc_flags, &frame->uc.uc_flags) ||
389             __put_user(0, &frame->uc.uc_link) ||
390             __compat_save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
391             save_sigregs32(regs, &frame->uc.uc_mcontext) ||
392             put_compat_sigset(&frame->uc.uc_sigmask, set, sizeof(compat_sigset_t)) ||
393             save_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))
394                 return -EFAULT;
395 
396         /* Set up registers for signal handler */
397         regs->gprs[14] = restorer;
398         regs->gprs[15] = (__force __u64) frame;
399         /* Force 31 bit amode and default user address space control. */
400         regs->psw.mask = PSW_MASK_BA |
401                 (PSW_USER_BITS & PSW_MASK_ASC) |
402                 (regs->psw.mask & ~PSW_MASK_ASC);
403         regs->psw.addr = (__u64 __force) ksig->ka.sa.sa_handler;
404 
405         regs->gprs[2] = ksig->sig;
406         regs->gprs[3] = (__force __u64) &frame->info;
407         regs->gprs[4] = (__force __u64) &frame->uc;
408         regs->gprs[5] = current->thread.last_break;
409         return 0;
410 }
411 
412 /*
413  * OK, we're invoking a handler
414  */     
415 
416 void handle_signal32(struct ksignal *ksig, sigset_t *oldset,
417                      struct pt_regs *regs)
418 {
419         int ret;
420 
421         /* Set up the stack frame */
422         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
423                 ret = setup_rt_frame32(ksig, oldset, regs);
424         else
425                 ret = setup_frame32(ksig, oldset, regs);
426 
427         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
428 }
429 
430 

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