xref: /openbmc/qemu/linux-user/arm/signal.c (revision e4082063)
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 
25 struct target_sigcontext {
26     abi_ulong trap_no;
27     abi_ulong error_code;
28     abi_ulong oldmask;
29     abi_ulong arm_r0;
30     abi_ulong arm_r1;
31     abi_ulong arm_r2;
32     abi_ulong arm_r3;
33     abi_ulong arm_r4;
34     abi_ulong arm_r5;
35     abi_ulong arm_r6;
36     abi_ulong arm_r7;
37     abi_ulong arm_r8;
38     abi_ulong arm_r9;
39     abi_ulong arm_r10;
40     abi_ulong arm_fp;
41     abi_ulong arm_ip;
42     abi_ulong arm_sp;
43     abi_ulong arm_lr;
44     abi_ulong arm_pc;
45     abi_ulong arm_cpsr;
46     abi_ulong fault_address;
47 };
48 
49 struct target_ucontext {
50     abi_ulong tuc_flags;
51     abi_ulong tuc_link;
52     target_stack_t tuc_stack;
53     struct target_sigcontext tuc_mcontext;
54     target_sigset_t  tuc_sigmask;       /* mask last for extensibility */
55     char __unused[128 - sizeof(target_sigset_t)];
56     abi_ulong tuc_regspace[128] __attribute__((__aligned__(8)));
57 };
58 
59 struct target_user_vfp {
60     uint64_t fpregs[32];
61     abi_ulong fpscr;
62 };
63 
64 struct target_user_vfp_exc {
65     abi_ulong fpexc;
66     abi_ulong fpinst;
67     abi_ulong fpinst2;
68 };
69 
70 struct target_vfp_sigframe {
71     abi_ulong magic;
72     abi_ulong size;
73     struct target_user_vfp ufp;
74     struct target_user_vfp_exc ufp_exc;
75 } __attribute__((__aligned__(8)));
76 
77 struct target_iwmmxt_sigframe {
78     abi_ulong magic;
79     abi_ulong size;
80     uint64_t regs[16];
81     /* Note that not all the coprocessor control registers are stored here */
82     uint32_t wcssf;
83     uint32_t wcasf;
84     uint32_t wcgr0;
85     uint32_t wcgr1;
86     uint32_t wcgr2;
87     uint32_t wcgr3;
88 } __attribute__((__aligned__(8)));
89 
90 #define TARGET_VFP_MAGIC 0x56465001
91 #define TARGET_IWMMXT_MAGIC 0x12ef842a
92 
93 struct sigframe
94 {
95     struct target_ucontext uc;
96     abi_ulong retcode[4];
97 };
98 
99 struct rt_sigframe
100 {
101     struct target_siginfo info;
102     struct sigframe sig;
103 };
104 
105 static abi_ptr sigreturn_fdpic_tramp;
106 
107 /*
108  * Up to 3 words of 'retcode' in the sigframe are code,
109  * with retcode[3] being used by fdpic for the function descriptor.
110  * This code is not actually executed, but is retained for ABI compat.
111  *
112  * We will create a table of 8 retcode variants in the sigtramp page.
113  * Let each table entry use 3 words.
114  */
115 #define RETCODE_WORDS  3
116 #define RETCODE_BYTES  (RETCODE_WORDS * 4)
117 
118 static inline int valid_user_regs(CPUARMState *regs)
119 {
120     return 1;
121 }
122 
123 static void
124 setup_sigcontext(struct target_sigcontext *sc, /*struct _fpstate *fpstate,*/
125                  CPUARMState *env, abi_ulong mask)
126 {
127     __put_user(env->regs[0], &sc->arm_r0);
128     __put_user(env->regs[1], &sc->arm_r1);
129     __put_user(env->regs[2], &sc->arm_r2);
130     __put_user(env->regs[3], &sc->arm_r3);
131     __put_user(env->regs[4], &sc->arm_r4);
132     __put_user(env->regs[5], &sc->arm_r5);
133     __put_user(env->regs[6], &sc->arm_r6);
134     __put_user(env->regs[7], &sc->arm_r7);
135     __put_user(env->regs[8], &sc->arm_r8);
136     __put_user(env->regs[9], &sc->arm_r9);
137     __put_user(env->regs[10], &sc->arm_r10);
138     __put_user(env->regs[11], &sc->arm_fp);
139     __put_user(env->regs[12], &sc->arm_ip);
140     __put_user(env->regs[13], &sc->arm_sp);
141     __put_user(env->regs[14], &sc->arm_lr);
142     __put_user(env->regs[15], &sc->arm_pc);
143     __put_user(cpsr_read(env), &sc->arm_cpsr);
144 
145     __put_user(/* current->thread.trap_no */ 0, &sc->trap_no);
146     __put_user(/* current->thread.error_code */ 0, &sc->error_code);
147     __put_user(/* current->thread.address */ 0, &sc->fault_address);
148     __put_user(mask, &sc->oldmask);
149 }
150 
151 static inline abi_ulong
152 get_sigframe(struct target_sigaction *ka, CPUARMState *regs, int framesize)
153 {
154     unsigned long sp;
155 
156     sp = target_sigsp(get_sp_from_cpustate(regs), ka);
157     /*
158      * ATPCS B01 mandates 8-byte alignment
159      */
160     return (sp - framesize) & ~7;
161 }
162 
163 static int
164 setup_return(CPUARMState *env, struct target_sigaction *ka, int usig,
165              struct sigframe *frame, abi_ulong sp_addr)
166 {
167     abi_ulong handler = 0;
168     abi_ulong handler_fdpic_GOT = 0;
169     abi_ulong retcode;
170     int thumb, retcode_idx;
171     int is_fdpic = info_is_fdpic(((TaskState *)thread_cpu->opaque)->info);
172     bool copy_retcode;
173 
174     if (is_fdpic) {
175         /* In FDPIC mode, ka->_sa_handler points to a function
176          * descriptor (FD). The first word contains the address of the
177          * handler. The second word contains the value of the PIC
178          * register (r9).  */
179         abi_ulong funcdesc_ptr = ka->_sa_handler;
180         if (get_user_ual(handler, funcdesc_ptr)
181             || get_user_ual(handler_fdpic_GOT, funcdesc_ptr + 4)) {
182             return 1;
183         }
184     } else {
185         handler = ka->_sa_handler;
186     }
187 
188     thumb = handler & 1;
189     retcode_idx = thumb + (ka->sa_flags & TARGET_SA_SIGINFO ? 2 : 0);
190 
191     uint32_t cpsr = cpsr_read(env);
192 
193     cpsr &= ~CPSR_IT;
194     if (thumb) {
195         cpsr |= CPSR_T;
196     } else {
197         cpsr &= ~CPSR_T;
198     }
199     if (env->cp15.sctlr_el[1] & SCTLR_E0E) {
200         cpsr |= CPSR_E;
201     } else {
202         cpsr &= ~CPSR_E;
203     }
204 
205     if (ka->sa_flags & TARGET_SA_RESTORER) {
206         if (is_fdpic) {
207             __put_user((abi_ulong)ka->sa_restorer, &frame->retcode[3]);
208             retcode = (sigreturn_fdpic_tramp +
209                        retcode_idx * RETCODE_BYTES + thumb);
210             copy_retcode = true;
211         } else {
212             retcode = ka->sa_restorer;
213             copy_retcode = false;
214         }
215     } else {
216         retcode = default_sigreturn + retcode_idx * RETCODE_BYTES + thumb;
217         copy_retcode = true;
218     }
219 
220     /* Copy the code to the stack slot for ABI compatibility. */
221     if (copy_retcode) {
222         memcpy(frame->retcode, g2h_untagged(retcode & ~1), RETCODE_BYTES);
223     }
224 
225     env->regs[0] = usig;
226     if (is_fdpic) {
227         env->regs[9] = handler_fdpic_GOT;
228     }
229     env->regs[13] = sp_addr;
230     env->regs[14] = retcode;
231     env->regs[15] = handler & (thumb ? ~1 : ~3);
232     cpsr_write(env, cpsr, CPSR_IT | CPSR_T | CPSR_E, CPSRWriteByInstr);
233 
234     return 0;
235 }
236 
237 static abi_ulong *setup_sigframe_vfp(abi_ulong *regspace, CPUARMState *env)
238 {
239     int i;
240     struct target_vfp_sigframe *vfpframe;
241     vfpframe = (struct target_vfp_sigframe *)regspace;
242     __put_user(TARGET_VFP_MAGIC, &vfpframe->magic);
243     __put_user(sizeof(*vfpframe), &vfpframe->size);
244     for (i = 0; i < 32; i++) {
245         __put_user(*aa32_vfp_dreg(env, i), &vfpframe->ufp.fpregs[i]);
246     }
247     __put_user(vfp_get_fpscr(env), &vfpframe->ufp.fpscr);
248     __put_user(env->vfp.xregs[ARM_VFP_FPEXC], &vfpframe->ufp_exc.fpexc);
249     __put_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
250     __put_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
251     return (abi_ulong*)(vfpframe+1);
252 }
253 
254 static abi_ulong *setup_sigframe_iwmmxt(abi_ulong *regspace, CPUARMState *env)
255 {
256     int i;
257     struct target_iwmmxt_sigframe *iwmmxtframe;
258     iwmmxtframe = (struct target_iwmmxt_sigframe *)regspace;
259     __put_user(TARGET_IWMMXT_MAGIC, &iwmmxtframe->magic);
260     __put_user(sizeof(*iwmmxtframe), &iwmmxtframe->size);
261     for (i = 0; i < 16; i++) {
262         __put_user(env->iwmmxt.regs[i], &iwmmxtframe->regs[i]);
263     }
264     __put_user(env->vfp.xregs[ARM_IWMMXT_wCSSF], &iwmmxtframe->wcssf);
265     __put_user(env->vfp.xregs[ARM_IWMMXT_wCASF], &iwmmxtframe->wcssf);
266     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR0], &iwmmxtframe->wcgr0);
267     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR1], &iwmmxtframe->wcgr1);
268     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR2], &iwmmxtframe->wcgr2);
269     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR3], &iwmmxtframe->wcgr3);
270     return (abi_ulong*)(iwmmxtframe+1);
271 }
272 
273 static void setup_sigframe(struct target_ucontext *uc,
274                            target_sigset_t *set, CPUARMState *env)
275 {
276     struct target_sigaltstack stack;
277     int i;
278     abi_ulong *regspace;
279 
280     /* Clear all the bits of the ucontext we don't use.  */
281     memset(uc, 0, offsetof(struct target_ucontext, tuc_mcontext));
282 
283     memset(&stack, 0, sizeof(stack));
284     target_save_altstack(&stack, env);
285     memcpy(&uc->tuc_stack, &stack, sizeof(stack));
286 
287     setup_sigcontext(&uc->tuc_mcontext, env, set->sig[0]);
288     /* Save coprocessor signal frame.  */
289     regspace = uc->tuc_regspace;
290     if (cpu_isar_feature(aa32_vfp_simd, env_archcpu(env))) {
291         regspace = setup_sigframe_vfp(regspace, env);
292     }
293     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
294         regspace = setup_sigframe_iwmmxt(regspace, env);
295     }
296 
297     /* Write terminating magic word */
298     __put_user(0, regspace);
299 
300     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
301         __put_user(set->sig[i], &uc->tuc_sigmask.sig[i]);
302     }
303 }
304 
305 void setup_frame(int usig, struct target_sigaction *ka,
306                  target_sigset_t *set, CPUARMState *regs)
307 {
308     struct sigframe *frame;
309     abi_ulong frame_addr = get_sigframe(ka, regs, sizeof(*frame));
310 
311     trace_user_setup_frame(regs, frame_addr);
312     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
313         goto sigsegv;
314     }
315 
316     setup_sigframe(&frame->uc, set, regs);
317 
318     if (setup_return(regs, ka, usig, frame, frame_addr)) {
319         goto sigsegv;
320     }
321 
322     unlock_user_struct(frame, frame_addr, 1);
323     return;
324 sigsegv:
325     unlock_user_struct(frame, frame_addr, 1);
326     force_sigsegv(usig);
327 }
328 
329 void setup_rt_frame(int usig, struct target_sigaction *ka,
330                     target_siginfo_t *info,
331                     target_sigset_t *set, CPUARMState *env)
332 {
333     struct rt_sigframe *frame;
334     abi_ulong frame_addr = get_sigframe(ka, env, sizeof(*frame));
335     abi_ulong info_addr, uc_addr;
336 
337     trace_user_setup_rt_frame(env, frame_addr);
338     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
339         goto sigsegv;
340     }
341 
342     info_addr = frame_addr + offsetof(struct rt_sigframe, info);
343     uc_addr = frame_addr + offsetof(struct rt_sigframe, sig.uc);
344     tswap_siginfo(&frame->info, info);
345 
346     setup_sigframe(&frame->sig.uc, set, env);
347 
348     if (setup_return(env, ka, usig, &frame->sig, frame_addr)) {
349         goto sigsegv;
350     }
351 
352     env->regs[1] = info_addr;
353     env->regs[2] = uc_addr;
354 
355     unlock_user_struct(frame, frame_addr, 1);
356     return;
357 sigsegv:
358     unlock_user_struct(frame, frame_addr, 1);
359     force_sigsegv(usig);
360 }
361 
362 static int
363 restore_sigcontext(CPUARMState *env, struct target_sigcontext *sc)
364 {
365     int err = 0;
366     uint32_t cpsr;
367 
368     __get_user(env->regs[0], &sc->arm_r0);
369     __get_user(env->regs[1], &sc->arm_r1);
370     __get_user(env->regs[2], &sc->arm_r2);
371     __get_user(env->regs[3], &sc->arm_r3);
372     __get_user(env->regs[4], &sc->arm_r4);
373     __get_user(env->regs[5], &sc->arm_r5);
374     __get_user(env->regs[6], &sc->arm_r6);
375     __get_user(env->regs[7], &sc->arm_r7);
376     __get_user(env->regs[8], &sc->arm_r8);
377     __get_user(env->regs[9], &sc->arm_r9);
378     __get_user(env->regs[10], &sc->arm_r10);
379     __get_user(env->regs[11], &sc->arm_fp);
380     __get_user(env->regs[12], &sc->arm_ip);
381     __get_user(env->regs[13], &sc->arm_sp);
382     __get_user(env->regs[14], &sc->arm_lr);
383     __get_user(env->regs[15], &sc->arm_pc);
384     __get_user(cpsr, &sc->arm_cpsr);
385     cpsr_write(env, cpsr, CPSR_USER | CPSR_EXEC, CPSRWriteByInstr);
386 
387     err |= !valid_user_regs(env);
388 
389     return err;
390 }
391 
392 static abi_ulong *restore_sigframe_vfp(CPUARMState *env, abi_ulong *regspace)
393 {
394     int i;
395     abi_ulong magic, sz;
396     uint32_t fpscr, fpexc;
397     struct target_vfp_sigframe *vfpframe;
398     vfpframe = (struct target_vfp_sigframe *)regspace;
399 
400     __get_user(magic, &vfpframe->magic);
401     __get_user(sz, &vfpframe->size);
402     if (magic != TARGET_VFP_MAGIC || sz != sizeof(*vfpframe)) {
403         return 0;
404     }
405     for (i = 0; i < 32; i++) {
406         __get_user(*aa32_vfp_dreg(env, i), &vfpframe->ufp.fpregs[i]);
407     }
408     __get_user(fpscr, &vfpframe->ufp.fpscr);
409     vfp_set_fpscr(env, fpscr);
410     __get_user(fpexc, &vfpframe->ufp_exc.fpexc);
411     /* Sanitise FPEXC: ensure VFP is enabled, FPINST2 is invalid
412      * and the exception flag is cleared
413      */
414     fpexc |= (1 << 30);
415     fpexc &= ~((1 << 31) | (1 << 28));
416     env->vfp.xregs[ARM_VFP_FPEXC] = fpexc;
417     __get_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
418     __get_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
419     return (abi_ulong*)(vfpframe + 1);
420 }
421 
422 static abi_ulong *restore_sigframe_iwmmxt(CPUARMState *env,
423                                           abi_ulong *regspace)
424 {
425     int i;
426     abi_ulong magic, sz;
427     struct target_iwmmxt_sigframe *iwmmxtframe;
428     iwmmxtframe = (struct target_iwmmxt_sigframe *)regspace;
429 
430     __get_user(magic, &iwmmxtframe->magic);
431     __get_user(sz, &iwmmxtframe->size);
432     if (magic != TARGET_IWMMXT_MAGIC || sz != sizeof(*iwmmxtframe)) {
433         return 0;
434     }
435     for (i = 0; i < 16; i++) {
436         __get_user(env->iwmmxt.regs[i], &iwmmxtframe->regs[i]);
437     }
438     __get_user(env->vfp.xregs[ARM_IWMMXT_wCSSF], &iwmmxtframe->wcssf);
439     __get_user(env->vfp.xregs[ARM_IWMMXT_wCASF], &iwmmxtframe->wcssf);
440     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR0], &iwmmxtframe->wcgr0);
441     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR1], &iwmmxtframe->wcgr1);
442     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR2], &iwmmxtframe->wcgr2);
443     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR3], &iwmmxtframe->wcgr3);
444     return (abi_ulong*)(iwmmxtframe + 1);
445 }
446 
447 static int do_sigframe_return(CPUARMState *env,
448                               target_ulong context_addr,
449                               struct target_ucontext *uc)
450 {
451     sigset_t host_set;
452     abi_ulong *regspace;
453 
454     target_to_host_sigset(&host_set, &uc->tuc_sigmask);
455     set_sigmask(&host_set);
456 
457     if (restore_sigcontext(env, &uc->tuc_mcontext)) {
458         return 1;
459     }
460 
461     /* Restore coprocessor signal frame */
462     regspace = uc->tuc_regspace;
463     if (cpu_isar_feature(aa32_vfp_simd, env_archcpu(env))) {
464         regspace = restore_sigframe_vfp(env, regspace);
465         if (!regspace) {
466             return 1;
467         }
468     }
469     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
470         regspace = restore_sigframe_iwmmxt(env, regspace);
471         if (!regspace) {
472             return 1;
473         }
474     }
475 
476     target_restore_altstack(&uc->tuc_stack, env);
477 
478 #if 0
479     /* Send SIGTRAP if we're single-stepping */
480     if (ptrace_cancel_bpt(current))
481         send_sig(SIGTRAP, current, 1);
482 #endif
483 
484     return 0;
485 }
486 
487 long do_sigreturn(CPUARMState *env)
488 {
489     abi_ulong frame_addr;
490     struct sigframe *frame = NULL;
491 
492     /*
493      * Since we stacked the signal on a 64-bit boundary,
494      * then 'sp' should be word aligned here.  If it's
495      * not, then the user is trying to mess with us.
496      */
497     frame_addr = env->regs[13];
498     trace_user_do_sigreturn(env, frame_addr);
499     if (frame_addr & 7) {
500         goto badframe;
501     }
502 
503     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
504         goto badframe;
505     }
506 
507     if (do_sigframe_return(env,
508                            frame_addr + offsetof(struct sigframe, uc),
509                            &frame->uc)) {
510         goto badframe;
511     }
512 
513     unlock_user_struct(frame, frame_addr, 0);
514     return -QEMU_ESIGRETURN;
515 
516 badframe:
517     unlock_user_struct(frame, frame_addr, 0);
518     force_sig(TARGET_SIGSEGV);
519     return -QEMU_ESIGRETURN;
520 }
521 
522 long do_rt_sigreturn(CPUARMState *env)
523 {
524     abi_ulong frame_addr;
525     struct rt_sigframe *frame = NULL;
526 
527     /*
528      * Since we stacked the signal on a 64-bit boundary,
529      * then 'sp' should be word aligned here.  If it's
530      * not, then the user is trying to mess with us.
531      */
532     frame_addr = env->regs[13];
533     trace_user_do_rt_sigreturn(env, frame_addr);
534     if (frame_addr & 7) {
535         goto badframe;
536     }
537 
538     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
539         goto badframe;
540     }
541 
542     if (do_sigframe_return(env,
543                            frame_addr + offsetof(struct rt_sigframe, sig.uc),
544                            &frame->sig.uc)) {
545         goto badframe;
546     }
547 
548     unlock_user_struct(frame, frame_addr, 0);
549     return -QEMU_ESIGRETURN;
550 
551 badframe:
552     unlock_user_struct(frame, frame_addr, 0);
553     force_sig(TARGET_SIGSEGV);
554     return -QEMU_ESIGRETURN;
555 }
556 
557 /*
558  * EABI syscalls pass the number via r7.
559  * Note that the kernel still adds the OABI syscall number to the trap,
560  * presumably for backward ABI compatibility with unwinders.
561  */
562 #define ARM_MOV_R7_IMM(X)       (0xe3a07000 | (X))
563 #define ARM_SWI_SYS(X)          (0xef000000 | (X) | ARM_SYSCALL_BASE)
564 
565 #define THUMB_MOVS_R7_IMM(X)    (0x2700 | (X))
566 #define THUMB_SWI_SYS           0xdf00
567 
568 static void write_arm_sigreturn(uint32_t *rc, int syscall)
569 {
570     __put_user(ARM_MOV_R7_IMM(syscall), rc);
571     __put_user(ARM_SWI_SYS(syscall), rc + 1);
572     /* Wrote 8 of 12 bytes */
573 }
574 
575 static void write_thm_sigreturn(uint32_t *rc, int syscall)
576 {
577     __put_user(THUMB_SWI_SYS << 16 | THUMB_MOVS_R7_IMM(syscall), rc);
578     /* Wrote 4 of 12 bytes */
579 }
580 
581 /*
582  * Stub needed to make sure the FD register (r9) contains the right value.
583  * Use the same instruction sequence as the kernel.
584  */
585 static void write_arm_fdpic_sigreturn(uint32_t *rc, int ofs)
586 {
587     assert(ofs <= 0xfff);
588     __put_user(0xe59d3000 | ofs, rc + 0);   /* ldr r3, [sp, #ofs] */
589     __put_user(0xe8930908, rc + 1);         /* ldm r3, { r3, r9 } */
590     __put_user(0xe12fff13, rc + 2);         /* bx  r3 */
591     /* Wrote 12 of 12 bytes */
592 }
593 
594 static void write_thm_fdpic_sigreturn(void *vrc, int ofs)
595 {
596     uint16_t *rc = vrc;
597 
598     assert((ofs & ~0x3fc) == 0);
599     __put_user(0x9b00 | (ofs >> 2), rc + 0);      /* ldr r3, [sp, #ofs] */
600     __put_user(0xcb0c, rc + 1);                   /* ldm r3, { r2, r3 } */
601     __put_user(0x4699, rc + 2);                   /* mov r9, r3 */
602     __put_user(0x4710, rc + 3);                   /* bx  r2 */
603     /* Wrote 8 of 12 bytes */
604 }
605 
606 void setup_sigtramp(abi_ulong sigtramp_page)
607 {
608     uint32_t total_size = 8 * RETCODE_BYTES;
609     uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, total_size, 0);
610 
611     assert(tramp != NULL);
612 
613     default_sigreturn = sigtramp_page;
614     write_arm_sigreturn(&tramp[0 * RETCODE_WORDS], TARGET_NR_sigreturn);
615     write_thm_sigreturn(&tramp[1 * RETCODE_WORDS], TARGET_NR_sigreturn);
616     write_arm_sigreturn(&tramp[2 * RETCODE_WORDS], TARGET_NR_rt_sigreturn);
617     write_thm_sigreturn(&tramp[3 * RETCODE_WORDS], TARGET_NR_rt_sigreturn);
618 
619     sigreturn_fdpic_tramp = sigtramp_page + 4 * RETCODE_BYTES;
620     write_arm_fdpic_sigreturn(tramp + 4 * RETCODE_WORDS,
621                               offsetof(struct sigframe, retcode[3]));
622     write_thm_fdpic_sigreturn(tramp + 5 * RETCODE_WORDS,
623                                 offsetof(struct sigframe, retcode[3]));
624     write_arm_fdpic_sigreturn(tramp + 6 * RETCODE_WORDS,
625                               offsetof(struct rt_sigframe, sig.retcode[3]));
626     write_thm_fdpic_sigreturn(tramp + 7 * RETCODE_WORDS,
627                               offsetof(struct rt_sigframe, sig.retcode[3]));
628 
629     unlock_user(tramp, sigtramp_page, total_size);
630 }
631