xref: /openbmc/qemu/linux-user/arm/signal.c (revision 235fe6d0)
1 /*
2  *  Emulation of Linux signals
3  *
4  *  Copyright (c) 2003 Fabrice Bellard
5  *
6  *  This program is free software; you can redistribute it and/or modify
7  *  it under the terms of the GNU General Public License as published by
8  *  the Free Software Foundation; either version 2 of the License, or
9  *  (at your option) any later version.
10  *
11  *  This program is distributed in the hope that it will be useful,
12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  *  GNU General Public License for more details.
15  *
16  *  You should have received a copy of the GNU General Public License
17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
18  */
19 #include "qemu/osdep.h"
20 #include "qemu.h"
21 #include "user-internals.h"
22 #include "signal-common.h"
23 #include "linux-user/trace.h"
24 #include "target/arm/cpu-features.h"
25 
26 struct target_sigcontext {
27     abi_ulong trap_no;
28     abi_ulong error_code;
29     abi_ulong oldmask;
30     abi_ulong arm_r0;
31     abi_ulong arm_r1;
32     abi_ulong arm_r2;
33     abi_ulong arm_r3;
34     abi_ulong arm_r4;
35     abi_ulong arm_r5;
36     abi_ulong arm_r6;
37     abi_ulong arm_r7;
38     abi_ulong arm_r8;
39     abi_ulong arm_r9;
40     abi_ulong arm_r10;
41     abi_ulong arm_fp;
42     abi_ulong arm_ip;
43     abi_ulong arm_sp;
44     abi_ulong arm_lr;
45     abi_ulong arm_pc;
46     abi_ulong arm_cpsr;
47     abi_ulong fault_address;
48 };
49 
50 struct target_ucontext {
51     abi_ulong tuc_flags;
52     abi_ulong tuc_link;
53     target_stack_t tuc_stack;
54     struct target_sigcontext tuc_mcontext;
55     target_sigset_t  tuc_sigmask;       /* mask last for extensibility */
56     char __unused[128 - sizeof(target_sigset_t)];
57     abi_ulong tuc_regspace[128] __attribute__((__aligned__(8)));
58 };
59 
60 struct target_user_vfp {
61     uint64_t fpregs[32];
62     abi_ulong fpscr;
63 };
64 
65 struct target_user_vfp_exc {
66     abi_ulong fpexc;
67     abi_ulong fpinst;
68     abi_ulong fpinst2;
69 };
70 
71 struct target_vfp_sigframe {
72     abi_ulong magic;
73     abi_ulong size;
74     struct target_user_vfp ufp;
75     struct target_user_vfp_exc ufp_exc;
76 } __attribute__((__aligned__(8)));
77 
78 struct target_iwmmxt_sigframe {
79     abi_ulong magic;
80     abi_ulong size;
81     uint64_t regs[16];
82     /* Note that not all the coprocessor control registers are stored here */
83     uint32_t wcssf;
84     uint32_t wcasf;
85     uint32_t wcgr0;
86     uint32_t wcgr1;
87     uint32_t wcgr2;
88     uint32_t wcgr3;
89 } __attribute__((__aligned__(8)));
90 
91 #define TARGET_VFP_MAGIC 0x56465001
92 #define TARGET_IWMMXT_MAGIC 0x12ef842a
93 
94 struct sigframe
95 {
96     struct target_ucontext uc;
97     abi_ulong retcode[4];
98 };
99 
100 struct rt_sigframe
101 {
102     struct target_siginfo info;
103     struct sigframe sig;
104 };
105 
106 static abi_ptr sigreturn_fdpic_tramp;
107 
108 /*
109  * Up to 3 words of 'retcode' in the sigframe are code,
110  * with retcode[3] being used by fdpic for the function descriptor.
111  * This code is not actually executed, but is retained for ABI compat.
112  *
113  * We will create a table of 8 retcode variants in the sigtramp page.
114  * Let each table entry use 3 words.
115  */
116 #define RETCODE_WORDS  3
117 #define RETCODE_BYTES  (RETCODE_WORDS * 4)
118 
119 static inline int valid_user_regs(CPUARMState *regs)
120 {
121     return 1;
122 }
123 
124 static void
125 setup_sigcontext(struct target_sigcontext *sc, /*struct _fpstate *fpstate,*/
126                  CPUARMState *env, abi_ulong mask)
127 {
128     __put_user(env->regs[0], &sc->arm_r0);
129     __put_user(env->regs[1], &sc->arm_r1);
130     __put_user(env->regs[2], &sc->arm_r2);
131     __put_user(env->regs[3], &sc->arm_r3);
132     __put_user(env->regs[4], &sc->arm_r4);
133     __put_user(env->regs[5], &sc->arm_r5);
134     __put_user(env->regs[6], &sc->arm_r6);
135     __put_user(env->regs[7], &sc->arm_r7);
136     __put_user(env->regs[8], &sc->arm_r8);
137     __put_user(env->regs[9], &sc->arm_r9);
138     __put_user(env->regs[10], &sc->arm_r10);
139     __put_user(env->regs[11], &sc->arm_fp);
140     __put_user(env->regs[12], &sc->arm_ip);
141     __put_user(env->regs[13], &sc->arm_sp);
142     __put_user(env->regs[14], &sc->arm_lr);
143     __put_user(env->regs[15], &sc->arm_pc);
144     __put_user(cpsr_read(env), &sc->arm_cpsr);
145 
146     __put_user(/* current->thread.trap_no */ 0, &sc->trap_no);
147     __put_user(/* current->thread.error_code */ 0, &sc->error_code);
148     __put_user(/* current->thread.address */ 0, &sc->fault_address);
149     __put_user(mask, &sc->oldmask);
150 }
151 
152 static inline abi_ulong
153 get_sigframe(struct target_sigaction *ka, CPUARMState *regs, int framesize)
154 {
155     unsigned long sp;
156 
157     sp = target_sigsp(get_sp_from_cpustate(regs), ka);
158     /*
159      * ATPCS B01 mandates 8-byte alignment
160      */
161     return (sp - framesize) & ~7;
162 }
163 
164 static int
165 setup_return(CPUARMState *env, struct target_sigaction *ka, int usig,
166              struct sigframe *frame, abi_ulong sp_addr)
167 {
168     abi_ulong handler = 0;
169     abi_ulong handler_fdpic_GOT = 0;
170     abi_ulong retcode;
171     int thumb, retcode_idx;
172     int is_fdpic = info_is_fdpic(((TaskState *)thread_cpu->opaque)->info);
173     bool copy_retcode;
174 
175     if (is_fdpic) {
176         /* In FDPIC mode, ka->_sa_handler points to a function
177          * descriptor (FD). The first word contains the address of the
178          * handler. The second word contains the value of the PIC
179          * register (r9).  */
180         abi_ulong funcdesc_ptr = ka->_sa_handler;
181         if (get_user_ual(handler, funcdesc_ptr)
182             || get_user_ual(handler_fdpic_GOT, funcdesc_ptr + 4)) {
183             return 1;
184         }
185     } else {
186         handler = ka->_sa_handler;
187     }
188 
189     thumb = handler & 1;
190     retcode_idx = thumb + (ka->sa_flags & TARGET_SA_SIGINFO ? 2 : 0);
191 
192     uint32_t cpsr = cpsr_read(env);
193 
194     cpsr &= ~CPSR_IT;
195     if (thumb) {
196         cpsr |= CPSR_T;
197     } else {
198         cpsr &= ~CPSR_T;
199     }
200     if (env->cp15.sctlr_el[1] & SCTLR_E0E) {
201         cpsr |= CPSR_E;
202     } else {
203         cpsr &= ~CPSR_E;
204     }
205 
206     if (ka->sa_flags & TARGET_SA_RESTORER) {
207         if (is_fdpic) {
208             __put_user((abi_ulong)ka->sa_restorer, &frame->retcode[3]);
209             retcode = (sigreturn_fdpic_tramp +
210                        retcode_idx * RETCODE_BYTES + thumb);
211             copy_retcode = true;
212         } else {
213             retcode = ka->sa_restorer;
214             copy_retcode = false;
215         }
216     } else {
217         retcode = default_sigreturn + retcode_idx * RETCODE_BYTES + thumb;
218         copy_retcode = true;
219     }
220 
221     /* Copy the code to the stack slot for ABI compatibility. */
222     if (copy_retcode) {
223         memcpy(frame->retcode, g2h_untagged(retcode & ~1), RETCODE_BYTES);
224     }
225 
226     env->regs[0] = usig;
227     if (is_fdpic) {
228         env->regs[9] = handler_fdpic_GOT;
229     }
230     env->regs[13] = sp_addr;
231     env->regs[14] = retcode;
232     env->regs[15] = handler & (thumb ? ~1 : ~3);
233     cpsr_write(env, cpsr, CPSR_IT | CPSR_T | CPSR_E, CPSRWriteByInstr);
234 
235     return 0;
236 }
237 
238 static abi_ulong *setup_sigframe_vfp(abi_ulong *regspace, CPUARMState *env)
239 {
240     int i;
241     struct target_vfp_sigframe *vfpframe;
242     vfpframe = (struct target_vfp_sigframe *)regspace;
243     __put_user(TARGET_VFP_MAGIC, &vfpframe->magic);
244     __put_user(sizeof(*vfpframe), &vfpframe->size);
245     for (i = 0; i < 32; i++) {
246         __put_user(*aa32_vfp_dreg(env, i), &vfpframe->ufp.fpregs[i]);
247     }
248     __put_user(vfp_get_fpscr(env), &vfpframe->ufp.fpscr);
249     __put_user(env->vfp.xregs[ARM_VFP_FPEXC], &vfpframe->ufp_exc.fpexc);
250     __put_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
251     __put_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
252     return (abi_ulong*)(vfpframe+1);
253 }
254 
255 static abi_ulong *setup_sigframe_iwmmxt(abi_ulong *regspace, CPUARMState *env)
256 {
257     int i;
258     struct target_iwmmxt_sigframe *iwmmxtframe;
259     iwmmxtframe = (struct target_iwmmxt_sigframe *)regspace;
260     __put_user(TARGET_IWMMXT_MAGIC, &iwmmxtframe->magic);
261     __put_user(sizeof(*iwmmxtframe), &iwmmxtframe->size);
262     for (i = 0; i < 16; i++) {
263         __put_user(env->iwmmxt.regs[i], &iwmmxtframe->regs[i]);
264     }
265     __put_user(env->vfp.xregs[ARM_IWMMXT_wCSSF], &iwmmxtframe->wcssf);
266     __put_user(env->vfp.xregs[ARM_IWMMXT_wCASF], &iwmmxtframe->wcssf);
267     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR0], &iwmmxtframe->wcgr0);
268     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR1], &iwmmxtframe->wcgr1);
269     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR2], &iwmmxtframe->wcgr2);
270     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR3], &iwmmxtframe->wcgr3);
271     return (abi_ulong*)(iwmmxtframe+1);
272 }
273 
274 static void setup_sigframe(struct target_ucontext *uc,
275                            target_sigset_t *set, CPUARMState *env)
276 {
277     struct target_sigaltstack stack;
278     int i;
279     abi_ulong *regspace;
280 
281     /* Clear all the bits of the ucontext we don't use.  */
282     memset(uc, 0, offsetof(struct target_ucontext, tuc_mcontext));
283 
284     memset(&stack, 0, sizeof(stack));
285     target_save_altstack(&stack, env);
286     memcpy(&uc->tuc_stack, &stack, sizeof(stack));
287 
288     setup_sigcontext(&uc->tuc_mcontext, env, set->sig[0]);
289     /* Save coprocessor signal frame.  */
290     regspace = uc->tuc_regspace;
291     if (cpu_isar_feature(aa32_vfp_simd, env_archcpu(env))) {
292         regspace = setup_sigframe_vfp(regspace, env);
293     }
294     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
295         regspace = setup_sigframe_iwmmxt(regspace, env);
296     }
297 
298     /* Write terminating magic word */
299     __put_user(0, regspace);
300 
301     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
302         __put_user(set->sig[i], &uc->tuc_sigmask.sig[i]);
303     }
304 }
305 
306 void setup_frame(int usig, struct target_sigaction *ka,
307                  target_sigset_t *set, CPUARMState *regs)
308 {
309     struct sigframe *frame;
310     abi_ulong frame_addr = get_sigframe(ka, regs, sizeof(*frame));
311 
312     trace_user_setup_frame(regs, frame_addr);
313     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
314         goto sigsegv;
315     }
316 
317     setup_sigframe(&frame->uc, set, regs);
318 
319     if (setup_return(regs, ka, usig, frame, frame_addr)) {
320         goto sigsegv;
321     }
322 
323     unlock_user_struct(frame, frame_addr, 1);
324     return;
325 sigsegv:
326     unlock_user_struct(frame, frame_addr, 1);
327     force_sigsegv(usig);
328 }
329 
330 void setup_rt_frame(int usig, struct target_sigaction *ka,
331                     target_siginfo_t *info,
332                     target_sigset_t *set, CPUARMState *env)
333 {
334     struct rt_sigframe *frame;
335     abi_ulong frame_addr = get_sigframe(ka, env, sizeof(*frame));
336     abi_ulong info_addr, uc_addr;
337 
338     trace_user_setup_rt_frame(env, frame_addr);
339     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
340         goto sigsegv;
341     }
342 
343     info_addr = frame_addr + offsetof(struct rt_sigframe, info);
344     uc_addr = frame_addr + offsetof(struct rt_sigframe, sig.uc);
345     tswap_siginfo(&frame->info, info);
346 
347     setup_sigframe(&frame->sig.uc, set, env);
348 
349     if (setup_return(env, ka, usig, &frame->sig, frame_addr)) {
350         goto sigsegv;
351     }
352 
353     env->regs[1] = info_addr;
354     env->regs[2] = uc_addr;
355 
356     unlock_user_struct(frame, frame_addr, 1);
357     return;
358 sigsegv:
359     unlock_user_struct(frame, frame_addr, 1);
360     force_sigsegv(usig);
361 }
362 
363 static int
364 restore_sigcontext(CPUARMState *env, struct target_sigcontext *sc)
365 {
366     int err = 0;
367     uint32_t cpsr;
368 
369     __get_user(env->regs[0], &sc->arm_r0);
370     __get_user(env->regs[1], &sc->arm_r1);
371     __get_user(env->regs[2], &sc->arm_r2);
372     __get_user(env->regs[3], &sc->arm_r3);
373     __get_user(env->regs[4], &sc->arm_r4);
374     __get_user(env->regs[5], &sc->arm_r5);
375     __get_user(env->regs[6], &sc->arm_r6);
376     __get_user(env->regs[7], &sc->arm_r7);
377     __get_user(env->regs[8], &sc->arm_r8);
378     __get_user(env->regs[9], &sc->arm_r9);
379     __get_user(env->regs[10], &sc->arm_r10);
380     __get_user(env->regs[11], &sc->arm_fp);
381     __get_user(env->regs[12], &sc->arm_ip);
382     __get_user(env->regs[13], &sc->arm_sp);
383     __get_user(env->regs[14], &sc->arm_lr);
384     __get_user(env->regs[15], &sc->arm_pc);
385     __get_user(cpsr, &sc->arm_cpsr);
386     cpsr_write(env, cpsr, CPSR_USER | CPSR_EXEC, CPSRWriteByInstr);
387 
388     err |= !valid_user_regs(env);
389 
390     return err;
391 }
392 
393 static abi_ulong *restore_sigframe_vfp(CPUARMState *env, abi_ulong *regspace)
394 {
395     int i;
396     abi_ulong magic, sz;
397     uint32_t fpscr, fpexc;
398     struct target_vfp_sigframe *vfpframe;
399     vfpframe = (struct target_vfp_sigframe *)regspace;
400 
401     __get_user(magic, &vfpframe->magic);
402     __get_user(sz, &vfpframe->size);
403     if (magic != TARGET_VFP_MAGIC || sz != sizeof(*vfpframe)) {
404         return 0;
405     }
406     for (i = 0; i < 32; i++) {
407         __get_user(*aa32_vfp_dreg(env, i), &vfpframe->ufp.fpregs[i]);
408     }
409     __get_user(fpscr, &vfpframe->ufp.fpscr);
410     vfp_set_fpscr(env, fpscr);
411     __get_user(fpexc, &vfpframe->ufp_exc.fpexc);
412     /* Sanitise FPEXC: ensure VFP is enabled, FPINST2 is invalid
413      * and the exception flag is cleared
414      */
415     fpexc |= (1 << 30);
416     fpexc &= ~((1 << 31) | (1 << 28));
417     env->vfp.xregs[ARM_VFP_FPEXC] = fpexc;
418     __get_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
419     __get_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
420     return (abi_ulong*)(vfpframe + 1);
421 }
422 
423 static abi_ulong *restore_sigframe_iwmmxt(CPUARMState *env,
424                                           abi_ulong *regspace)
425 {
426     int i;
427     abi_ulong magic, sz;
428     struct target_iwmmxt_sigframe *iwmmxtframe;
429     iwmmxtframe = (struct target_iwmmxt_sigframe *)regspace;
430 
431     __get_user(magic, &iwmmxtframe->magic);
432     __get_user(sz, &iwmmxtframe->size);
433     if (magic != TARGET_IWMMXT_MAGIC || sz != sizeof(*iwmmxtframe)) {
434         return 0;
435     }
436     for (i = 0; i < 16; i++) {
437         __get_user(env->iwmmxt.regs[i], &iwmmxtframe->regs[i]);
438     }
439     __get_user(env->vfp.xregs[ARM_IWMMXT_wCSSF], &iwmmxtframe->wcssf);
440     __get_user(env->vfp.xregs[ARM_IWMMXT_wCASF], &iwmmxtframe->wcssf);
441     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR0], &iwmmxtframe->wcgr0);
442     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR1], &iwmmxtframe->wcgr1);
443     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR2], &iwmmxtframe->wcgr2);
444     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR3], &iwmmxtframe->wcgr3);
445     return (abi_ulong*)(iwmmxtframe + 1);
446 }
447 
448 static int do_sigframe_return(CPUARMState *env,
449                               target_ulong context_addr,
450                               struct target_ucontext *uc)
451 {
452     sigset_t host_set;
453     abi_ulong *regspace;
454 
455     target_to_host_sigset(&host_set, &uc->tuc_sigmask);
456     set_sigmask(&host_set);
457 
458     if (restore_sigcontext(env, &uc->tuc_mcontext)) {
459         return 1;
460     }
461 
462     /* Restore coprocessor signal frame */
463     regspace = uc->tuc_regspace;
464     if (cpu_isar_feature(aa32_vfp_simd, env_archcpu(env))) {
465         regspace = restore_sigframe_vfp(env, regspace);
466         if (!regspace) {
467             return 1;
468         }
469     }
470     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
471         regspace = restore_sigframe_iwmmxt(env, regspace);
472         if (!regspace) {
473             return 1;
474         }
475     }
476 
477     target_restore_altstack(&uc->tuc_stack, env);
478 
479 #if 0
480     /* Send SIGTRAP if we're single-stepping */
481     if (ptrace_cancel_bpt(current))
482         send_sig(SIGTRAP, current, 1);
483 #endif
484 
485     return 0;
486 }
487 
488 long do_sigreturn(CPUARMState *env)
489 {
490     abi_ulong frame_addr;
491     struct sigframe *frame = NULL;
492 
493     /*
494      * Since we stacked the signal on a 64-bit boundary,
495      * then 'sp' should be word aligned here.  If it's
496      * not, then the user is trying to mess with us.
497      */
498     frame_addr = env->regs[13];
499     trace_user_do_sigreturn(env, frame_addr);
500     if (frame_addr & 7) {
501         goto badframe;
502     }
503 
504     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
505         goto badframe;
506     }
507 
508     if (do_sigframe_return(env,
509                            frame_addr + offsetof(struct sigframe, uc),
510                            &frame->uc)) {
511         goto badframe;
512     }
513 
514     unlock_user_struct(frame, frame_addr, 0);
515     return -QEMU_ESIGRETURN;
516 
517 badframe:
518     unlock_user_struct(frame, frame_addr, 0);
519     force_sig(TARGET_SIGSEGV);
520     return -QEMU_ESIGRETURN;
521 }
522 
523 long do_rt_sigreturn(CPUARMState *env)
524 {
525     abi_ulong frame_addr;
526     struct rt_sigframe *frame = NULL;
527 
528     /*
529      * Since we stacked the signal on a 64-bit boundary,
530      * then 'sp' should be word aligned here.  If it's
531      * not, then the user is trying to mess with us.
532      */
533     frame_addr = env->regs[13];
534     trace_user_do_rt_sigreturn(env, frame_addr);
535     if (frame_addr & 7) {
536         goto badframe;
537     }
538 
539     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
540         goto badframe;
541     }
542 
543     if (do_sigframe_return(env,
544                            frame_addr + offsetof(struct rt_sigframe, sig.uc),
545                            &frame->sig.uc)) {
546         goto badframe;
547     }
548 
549     unlock_user_struct(frame, frame_addr, 0);
550     return -QEMU_ESIGRETURN;
551 
552 badframe:
553     unlock_user_struct(frame, frame_addr, 0);
554     force_sig(TARGET_SIGSEGV);
555     return -QEMU_ESIGRETURN;
556 }
557 
558 /*
559  * EABI syscalls pass the number via r7.
560  * Note that the kernel still adds the OABI syscall number to the trap,
561  * presumably for backward ABI compatibility with unwinders.
562  */
563 #define ARM_MOV_R7_IMM(X)       (0xe3a07000 | (X))
564 #define ARM_SWI_SYS(X)          (0xef000000 | (X) | ARM_SYSCALL_BASE)
565 
566 #define THUMB_MOVS_R7_IMM(X)    (0x2700 | (X))
567 #define THUMB_SWI_SYS           0xdf00
568 
569 static void write_arm_sigreturn(uint32_t *rc, int syscall)
570 {
571     __put_user(ARM_MOV_R7_IMM(syscall), rc);
572     __put_user(ARM_SWI_SYS(syscall), rc + 1);
573     /* Wrote 8 of 12 bytes */
574 }
575 
576 static void write_thm_sigreturn(uint32_t *rc, int syscall)
577 {
578     __put_user(THUMB_SWI_SYS << 16 | THUMB_MOVS_R7_IMM(syscall), rc);
579     /* Wrote 4 of 12 bytes */
580 }
581 
582 /*
583  * Stub needed to make sure the FD register (r9) contains the right value.
584  * Use the same instruction sequence as the kernel.
585  */
586 static void write_arm_fdpic_sigreturn(uint32_t *rc, int ofs)
587 {
588     assert(ofs <= 0xfff);
589     __put_user(0xe59d3000 | ofs, rc + 0);   /* ldr r3, [sp, #ofs] */
590     __put_user(0xe8930908, rc + 1);         /* ldm r3, { r3, r9 } */
591     __put_user(0xe12fff13, rc + 2);         /* bx  r3 */
592     /* Wrote 12 of 12 bytes */
593 }
594 
595 static void write_thm_fdpic_sigreturn(void *vrc, int ofs)
596 {
597     uint16_t *rc = vrc;
598 
599     assert((ofs & ~0x3fc) == 0);
600     __put_user(0x9b00 | (ofs >> 2), rc + 0);      /* ldr r3, [sp, #ofs] */
601     __put_user(0xcb0c, rc + 1);                   /* ldm r3, { r2, r3 } */
602     __put_user(0x4699, rc + 2);                   /* mov r9, r3 */
603     __put_user(0x4710, rc + 3);                   /* bx  r2 */
604     /* Wrote 8 of 12 bytes */
605 }
606 
607 void setup_sigtramp(abi_ulong sigtramp_page)
608 {
609     uint32_t total_size = 8 * RETCODE_BYTES;
610     uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, total_size, 0);
611 
612     assert(tramp != NULL);
613 
614     default_sigreturn = sigtramp_page;
615     write_arm_sigreturn(&tramp[0 * RETCODE_WORDS], TARGET_NR_sigreturn);
616     write_thm_sigreturn(&tramp[1 * RETCODE_WORDS], TARGET_NR_sigreturn);
617     write_arm_sigreturn(&tramp[2 * RETCODE_WORDS], TARGET_NR_rt_sigreturn);
618     write_thm_sigreturn(&tramp[3 * RETCODE_WORDS], TARGET_NR_rt_sigreturn);
619 
620     sigreturn_fdpic_tramp = sigtramp_page + 4 * RETCODE_BYTES;
621     write_arm_fdpic_sigreturn(tramp + 4 * RETCODE_WORDS,
622                               offsetof(struct sigframe, retcode[3]));
623     write_thm_fdpic_sigreturn(tramp + 5 * RETCODE_WORDS,
624                                 offsetof(struct sigframe, retcode[3]));
625     write_arm_fdpic_sigreturn(tramp + 6 * RETCODE_WORDS,
626                               offsetof(struct rt_sigframe, sig.retcode[3]));
627     write_thm_fdpic_sigreturn(tramp + 7 * RETCODE_WORDS,
628                               offsetof(struct rt_sigframe, sig.retcode[3]));
629 
630     unlock_user(tramp, sigtramp_page, total_size);
631 }
632