1 /*
2  *  Semihosting support for systems modeled on the Arm "Angel"
3  *  semihosting syscalls design. This includes Arm and RISC-V processors
4  *
5  *  Copyright (c) 2005, 2007 CodeSourcery.
6  *  Copyright (c) 2019 Linaro
7  *  Written by Paul Brook.
8  *
9  *  Copyright © 2020 by Keith Packard <keithp@keithp.com>
10  *  Adapted for systems other than ARM, including RISC-V, by Keith Packard
11  *
12  *  This program is free software; you can redistribute it and/or modify
13  *  it under the terms of the GNU General Public License as published by
14  *  the Free Software Foundation; either version 2 of the License, or
15  *  (at your option) any later version.
16  *
17  *  This program is distributed in the hope that it will be useful,
18  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
19  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20  *  GNU General Public License for more details.
21  *
22  *  You should have received a copy of the GNU General Public License
23  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
24  *
25  *  ARM Semihosting is documented in:
26  *     Semihosting for AArch32 and AArch64 Release 2.0
27  *     https://github.com/ARM-software/abi-aa/blob/main/semihosting/semihosting.rst
28  *
29  *  RISC-V Semihosting is documented in:
30  *     RISC-V Semihosting
31  *     https://github.com/riscv/riscv-semihosting-spec/blob/main/riscv-semihosting-spec.adoc
32  */
33 
34 #include "qemu/osdep.h"
35 #include "qemu/timer.h"
36 #include "exec/gdbstub.h"
37 #include "gdbstub/syscalls.h"
38 #include "semihosting/semihost.h"
39 #include "semihosting/console.h"
40 #include "semihosting/common-semi.h"
41 #include "semihosting/guestfd.h"
42 #include "semihosting/syscalls.h"
43 
44 #ifdef CONFIG_USER_ONLY
45 #include "qemu.h"
46 
47 #define COMMON_SEMI_HEAP_SIZE (128 * 1024 * 1024)
48 #else
49 #include "qemu/cutils.h"
50 #include "hw/loader.h"
51 #include "hw/boards.h"
52 #endif
53 
54 #define TARGET_SYS_OPEN        0x01
55 #define TARGET_SYS_CLOSE       0x02
56 #define TARGET_SYS_WRITEC      0x03
57 #define TARGET_SYS_WRITE0      0x04
58 #define TARGET_SYS_WRITE       0x05
59 #define TARGET_SYS_READ        0x06
60 #define TARGET_SYS_READC       0x07
61 #define TARGET_SYS_ISERROR     0x08
62 #define TARGET_SYS_ISTTY       0x09
63 #define TARGET_SYS_SEEK        0x0a
64 #define TARGET_SYS_FLEN        0x0c
65 #define TARGET_SYS_TMPNAM      0x0d
66 #define TARGET_SYS_REMOVE      0x0e
67 #define TARGET_SYS_RENAME      0x0f
68 #define TARGET_SYS_CLOCK       0x10
69 #define TARGET_SYS_TIME        0x11
70 #define TARGET_SYS_SYSTEM      0x12
71 #define TARGET_SYS_ERRNO       0x13
72 #define TARGET_SYS_GET_CMDLINE 0x15
73 #define TARGET_SYS_HEAPINFO    0x16
74 #define TARGET_SYS_EXIT        0x18
75 #define TARGET_SYS_SYNCCACHE   0x19
76 #define TARGET_SYS_EXIT_EXTENDED 0x20
77 #define TARGET_SYS_ELAPSED     0x30
78 #define TARGET_SYS_TICKFREQ    0x31
79 
80 /* ADP_Stopped_ApplicationExit is used for exit(0),
81  * anything else is implemented as exit(1) */
82 #define ADP_Stopped_ApplicationExit     (0x20026)
83 
84 #ifndef O_BINARY
85 #define O_BINARY 0
86 #endif
87 
88 static int gdb_open_modeflags[12] = {
89     GDB_O_RDONLY,
90     GDB_O_RDONLY,
91     GDB_O_RDWR,
92     GDB_O_RDWR,
93     GDB_O_WRONLY | GDB_O_CREAT | GDB_O_TRUNC,
94     GDB_O_WRONLY | GDB_O_CREAT | GDB_O_TRUNC,
95     GDB_O_RDWR | GDB_O_CREAT | GDB_O_TRUNC,
96     GDB_O_RDWR | GDB_O_CREAT | GDB_O_TRUNC,
97     GDB_O_WRONLY | GDB_O_CREAT | GDB_O_APPEND,
98     GDB_O_WRONLY | GDB_O_CREAT | GDB_O_APPEND,
99     GDB_O_RDWR | GDB_O_CREAT | GDB_O_APPEND,
100     GDB_O_RDWR | GDB_O_CREAT | GDB_O_APPEND,
101 };
102 
103 #ifndef CONFIG_USER_ONLY
104 
105 /**
106  * common_semi_find_bases: find information about ram and heap base
107  *
108  * This function attempts to provide meaningful numbers for RAM and
109  * HEAP base addresses. The rambase is simply the lowest addressable
110  * RAM position. For the heapbase we ask the loader to scan the
111  * address space and the largest available gap by querying the "ROM"
112  * regions.
113  *
114  * Returns: a structure with the numbers we need.
115  */
116 
117 typedef struct LayoutInfo {
118     target_ulong rambase;
119     size_t ramsize;
120     hwaddr heapbase;
121     hwaddr heaplimit;
122 } LayoutInfo;
123 
124 static bool find_ram_cb(Int128 start, Int128 len, const MemoryRegion *mr,
125                         hwaddr offset_in_region, void *opaque)
126 {
127     LayoutInfo *info = (LayoutInfo *) opaque;
128     uint64_t size = int128_get64(len);
129 
130     if (!mr->ram || mr->readonly) {
131         return false;
132     }
133 
134     if (size > info->ramsize) {
135         info->rambase = int128_get64(start);
136         info->ramsize = size;
137     }
138 
139     /* search exhaustively for largest RAM */
140     return false;
141 }
142 
143 static LayoutInfo common_semi_find_bases(CPUState *cs)
144 {
145     FlatView *fv;
146     LayoutInfo info = { 0, 0, 0, 0 };
147 
148     RCU_READ_LOCK_GUARD();
149 
150     fv = address_space_to_flatview(cs->as);
151     flatview_for_each_range(fv, find_ram_cb, &info);
152 
153     /*
154      * If we have found the RAM lets iterate through the ROM blobs to
155      * work out the best place for the remainder of RAM and split it
156      * equally between stack and heap.
157      */
158     if (info.rambase || info.ramsize > 0) {
159         RomGap gap = rom_find_largest_gap_between(info.rambase, info.ramsize);
160         info.heapbase = gap.base;
161         info.heaplimit = gap.base + gap.size;
162     }
163 
164     return info;
165 }
166 
167 #endif
168 
169 #include "common-semi-target.h"
170 
171 /*
172  * Read the input value from the argument block; fail the semihosting
173  * call if the memory read fails. Eventually we could use a generic
174  * CPUState helper function here.
175  * Note that GET_ARG() handles memory access errors by jumping to
176  * do_fault, so must be used as the first thing done in handling a
177  * semihosting call, to avoid accidentally leaking allocated resources.
178  * SET_ARG(), since it unavoidably happens late, instead returns an
179  * error indication (0 on success, non-0 for error) which the caller
180  * should check.
181  */
182 
183 #define GET_ARG(n) do {                                 \
184     if (is_64bit_semihosting(env)) {                    \
185         if (get_user_u64(arg ## n, args + (n) * 8)) {   \
186             goto do_fault;                              \
187         }                                               \
188     } else {                                            \
189         if (get_user_u32(arg ## n, args + (n) * 4)) {   \
190             goto do_fault;                              \
191         }                                               \
192     }                                                   \
193 } while (0)
194 
195 #define SET_ARG(n, val)                                 \
196     (is_64bit_semihosting(env) ?                        \
197      put_user_u64(val, args + (n) * 8) :                \
198      put_user_u32(val, args + (n) * 4))
199 
200 
201 /*
202  * The semihosting API has no concept of its errno being thread-safe,
203  * as the API design predates SMP CPUs and was intended as a simple
204  * real-hardware set of debug functionality. For QEMU, we make the
205  * errno be per-thread in linux-user mode; in softmmu it is a simple
206  * global, and we assume that the guest takes care of avoiding any races.
207  */
208 #ifndef CONFIG_USER_ONLY
209 static target_ulong syscall_err;
210 
211 #include "semihosting/softmmu-uaccess.h"
212 #endif
213 
214 static inline uint32_t get_swi_errno(CPUState *cs)
215 {
216 #ifdef CONFIG_USER_ONLY
217     TaskState *ts = cs->opaque;
218 
219     return ts->swi_errno;
220 #else
221     return syscall_err;
222 #endif
223 }
224 
225 static void common_semi_cb(CPUState *cs, uint64_t ret, int err)
226 {
227     if (err) {
228 #ifdef CONFIG_USER_ONLY
229         TaskState *ts = cs->opaque;
230         ts->swi_errno = err;
231 #else
232         syscall_err = err;
233 #endif
234     }
235     common_semi_set_ret(cs, ret);
236 }
237 
238 /*
239  * Use 0xdeadbeef as the return value when there isn't a defined
240  * return value for the call.
241  */
242 static void common_semi_dead_cb(CPUState *cs, uint64_t ret, int err)
243 {
244     common_semi_set_ret(cs, 0xdeadbeef);
245 }
246 
247 /*
248  * SYS_READ and SYS_WRITE always return the number of bytes not read/written.
249  * There is no error condition, other than returning the original length.
250  */
251 static void common_semi_rw_cb(CPUState *cs, uint64_t ret, int err)
252 {
253     /* Recover the original length from the third argument. */
254     CPUArchState *env G_GNUC_UNUSED = cpu_env(cs);
255     target_ulong args = common_semi_arg(cs, 1);
256     target_ulong arg2;
257     GET_ARG(2);
258 
259     if (err) {
260  do_fault:
261         ret = 0; /* error: no bytes transmitted */
262     }
263     common_semi_set_ret(cs, arg2 - ret);
264 }
265 
266 /*
267  * Convert from Posix ret+errno to Arm SYS_ISTTY return values.
268  * With gdbstub, err is only ever set for protocol errors to EIO.
269  */
270 static void common_semi_istty_cb(CPUState *cs, uint64_t ret, int err)
271 {
272     if (err) {
273         ret = (err == ENOTTY ? 0 : -1);
274     }
275     common_semi_cb(cs, ret, err);
276 }
277 
278 /*
279  * SYS_SEEK returns 0 on success, not the resulting offset.
280  */
281 static void common_semi_seek_cb(CPUState *cs, uint64_t ret, int err)
282 {
283     if (!err) {
284         ret = 0;
285     }
286     common_semi_cb(cs, ret, err);
287 }
288 
289 /*
290  * Return an address in target memory of 64 bytes where the remote
291  * gdb should write its stat struct. (The format of this structure
292  * is defined by GDB's remote protocol and is not target-specific.)
293  * We put this on the guest's stack just below SP.
294  */
295 static target_ulong common_semi_flen_buf(CPUState *cs)
296 {
297     target_ulong sp = common_semi_stack_bottom(cs);
298     return sp - 64;
299 }
300 
301 static void
302 common_semi_flen_fstat_cb(CPUState *cs, uint64_t ret, int err)
303 {
304     if (!err) {
305         /* The size is always stored in big-endian order, extract the value. */
306         uint64_t size;
307         if (cpu_memory_rw_debug(cs, common_semi_flen_buf(cs) +
308                                 offsetof(struct gdb_stat, gdb_st_size),
309                                 &size, 8, 0)) {
310             ret = -1, err = EFAULT;
311         } else {
312             size = be64_to_cpu(size);
313             if (ret != size) {
314                 ret = -1, err = EOVERFLOW;
315             }
316         }
317     }
318     common_semi_cb(cs, ret, err);
319 }
320 
321 static void
322 common_semi_readc_cb(CPUState *cs, uint64_t ret, int err)
323 {
324     if (!err) {
325         CPUArchState *env G_GNUC_UNUSED = cpu_env(cs);
326         uint8_t ch;
327 
328         if (get_user_u8(ch, common_semi_stack_bottom(cs) - 1)) {
329             ret = -1, err = EFAULT;
330         } else {
331             ret = ch;
332         }
333     }
334     common_semi_cb(cs, ret, err);
335 }
336 
337 #define SHFB_MAGIC_0 0x53
338 #define SHFB_MAGIC_1 0x48
339 #define SHFB_MAGIC_2 0x46
340 #define SHFB_MAGIC_3 0x42
341 
342 /* Feature bits reportable in feature byte 0 */
343 #define SH_EXT_EXIT_EXTENDED (1 << 0)
344 #define SH_EXT_STDOUT_STDERR (1 << 1)
345 
346 static const uint8_t featurefile_data[] = {
347     SHFB_MAGIC_0,
348     SHFB_MAGIC_1,
349     SHFB_MAGIC_2,
350     SHFB_MAGIC_3,
351     SH_EXT_EXIT_EXTENDED | SH_EXT_STDOUT_STDERR, /* Feature byte 0 */
352 };
353 
354 /*
355  * Do a semihosting call.
356  *
357  * The specification always says that the "return register" either
358  * returns a specific value or is corrupted, so we don't need to
359  * report to our caller whether we are returning a value or trying to
360  * leave the register unchanged.
361  */
362 void do_common_semihosting(CPUState *cs)
363 {
364     CPUArchState *env = cpu_env(cs);
365     target_ulong args;
366     target_ulong arg0, arg1, arg2, arg3;
367     target_ulong ul_ret;
368     char * s;
369     int nr;
370     uint32_t ret;
371     int64_t elapsed;
372 
373     nr = common_semi_arg(cs, 0) & 0xffffffffU;
374     args = common_semi_arg(cs, 1);
375 
376     switch (nr) {
377     case TARGET_SYS_OPEN:
378     {
379         int ret, err = 0;
380         int hostfd;
381 
382         GET_ARG(0);
383         GET_ARG(1);
384         GET_ARG(2);
385         s = lock_user_string(arg0);
386         if (!s) {
387             goto do_fault;
388         }
389         if (arg1 >= 12) {
390             unlock_user(s, arg0, 0);
391             common_semi_cb(cs, -1, EINVAL);
392             break;
393         }
394 
395         if (strcmp(s, ":tt") == 0) {
396             /*
397              * We implement SH_EXT_STDOUT_STDERR, so:
398              *  open for read == stdin
399              *  open for write == stdout
400              *  open for append == stderr
401              */
402             if (arg1 < 4) {
403                 hostfd = STDIN_FILENO;
404             } else if (arg1 < 8) {
405                 hostfd = STDOUT_FILENO;
406             } else {
407                 hostfd = STDERR_FILENO;
408             }
409             ret = alloc_guestfd();
410             associate_guestfd(ret, hostfd);
411         } else if (strcmp(s, ":semihosting-features") == 0) {
412             /* We must fail opens for modes other than 0 ('r') or 1 ('rb') */
413             if (arg1 != 0 && arg1 != 1) {
414                 ret = -1;
415                 err = EACCES;
416             } else {
417                 ret = alloc_guestfd();
418                 staticfile_guestfd(ret, featurefile_data,
419                                    sizeof(featurefile_data));
420             }
421         } else {
422             unlock_user(s, arg0, 0);
423             semihost_sys_open(cs, common_semi_cb, arg0, arg2 + 1,
424                               gdb_open_modeflags[arg1], 0644);
425             break;
426         }
427         unlock_user(s, arg0, 0);
428         common_semi_cb(cs, ret, err);
429         break;
430     }
431 
432     case TARGET_SYS_CLOSE:
433         GET_ARG(0);
434         semihost_sys_close(cs, common_semi_cb, arg0);
435         break;
436 
437     case TARGET_SYS_WRITEC:
438         /*
439          * FIXME: the byte to be written is in a target_ulong slot,
440          * which means this is wrong for a big-endian guest.
441          */
442         semihost_sys_write_gf(cs, common_semi_dead_cb,
443                               &console_out_gf, args, 1);
444         break;
445 
446     case TARGET_SYS_WRITE0:
447         {
448             ssize_t len = target_strlen(args);
449             if (len < 0) {
450                 common_semi_dead_cb(cs, -1, EFAULT);
451             } else {
452                 semihost_sys_write_gf(cs, common_semi_dead_cb,
453                                       &console_out_gf, args, len);
454             }
455         }
456         break;
457 
458     case TARGET_SYS_WRITE:
459         GET_ARG(0);
460         GET_ARG(1);
461         GET_ARG(2);
462         semihost_sys_write(cs, common_semi_rw_cb, arg0, arg1, arg2);
463         break;
464 
465     case TARGET_SYS_READ:
466         GET_ARG(0);
467         GET_ARG(1);
468         GET_ARG(2);
469         semihost_sys_read(cs, common_semi_rw_cb, arg0, arg1, arg2);
470         break;
471 
472     case TARGET_SYS_READC:
473         semihost_sys_read_gf(cs, common_semi_readc_cb, &console_in_gf,
474                              common_semi_stack_bottom(cs) - 1, 1);
475         break;
476 
477     case TARGET_SYS_ISERROR:
478         GET_ARG(0);
479         common_semi_set_ret(cs, (target_long)arg0 < 0);
480         break;
481 
482     case TARGET_SYS_ISTTY:
483         GET_ARG(0);
484         semihost_sys_isatty(cs, common_semi_istty_cb, arg0);
485         break;
486 
487     case TARGET_SYS_SEEK:
488         GET_ARG(0);
489         GET_ARG(1);
490         semihost_sys_lseek(cs, common_semi_seek_cb, arg0, arg1, GDB_SEEK_SET);
491         break;
492 
493     case TARGET_SYS_FLEN:
494         GET_ARG(0);
495         semihost_sys_flen(cs, common_semi_flen_fstat_cb, common_semi_cb,
496                           arg0, common_semi_flen_buf(cs));
497         break;
498 
499     case TARGET_SYS_TMPNAM:
500     {
501         int len;
502         char *p;
503 
504         GET_ARG(0);
505         GET_ARG(1);
506         GET_ARG(2);
507         len = asprintf(&s, "%s/qemu-%x%02x", g_get_tmp_dir(),
508                        getpid(), (int)arg1 & 0xff);
509         if (len < 0) {
510             common_semi_set_ret(cs, -1);
511             break;
512         }
513 
514         /* Allow for trailing NUL */
515         len++;
516         /* Make sure there's enough space in the buffer */
517         if (len > arg2) {
518             free(s);
519             common_semi_set_ret(cs, -1);
520             break;
521         }
522         p = lock_user(VERIFY_WRITE, arg0, len, 0);
523         if (!p) {
524             free(s);
525             goto do_fault;
526         }
527         memcpy(p, s, len);
528         unlock_user(p, arg0, len);
529         free(s);
530         common_semi_set_ret(cs, 0);
531         break;
532     }
533 
534     case TARGET_SYS_REMOVE:
535         GET_ARG(0);
536         GET_ARG(1);
537         semihost_sys_remove(cs, common_semi_cb, arg0, arg1 + 1);
538         break;
539 
540     case TARGET_SYS_RENAME:
541         GET_ARG(0);
542         GET_ARG(1);
543         GET_ARG(2);
544         GET_ARG(3);
545         semihost_sys_rename(cs, common_semi_cb, arg0, arg1 + 1, arg2, arg3 + 1);
546         break;
547 
548     case TARGET_SYS_CLOCK:
549         common_semi_set_ret(cs, clock() / (CLOCKS_PER_SEC / 100));
550         break;
551 
552     case TARGET_SYS_TIME:
553         ul_ret = time(NULL);
554         common_semi_cb(cs, ul_ret, ul_ret == -1 ? errno : 0);
555         break;
556 
557     case TARGET_SYS_SYSTEM:
558         GET_ARG(0);
559         GET_ARG(1);
560         semihost_sys_system(cs, common_semi_cb, arg0, arg1 + 1);
561         break;
562 
563     case TARGET_SYS_ERRNO:
564         common_semi_set_ret(cs, get_swi_errno(cs));
565         break;
566 
567     case TARGET_SYS_GET_CMDLINE:
568         {
569             /* Build a command-line from the original argv.
570              *
571              * The inputs are:
572              *     * arg0, pointer to a buffer of at least the size
573              *               specified in arg1.
574              *     * arg1, size of the buffer pointed to by arg0 in
575              *               bytes.
576              *
577              * The outputs are:
578              *     * arg0, pointer to null-terminated string of the
579              *               command line.
580              *     * arg1, length of the string pointed to by arg0.
581              */
582 
583             char *output_buffer;
584             size_t input_size;
585             size_t output_size;
586             int status = 0;
587 #if !defined(CONFIG_USER_ONLY)
588             const char *cmdline;
589 #else
590             TaskState *ts = cs->opaque;
591 #endif
592             GET_ARG(0);
593             GET_ARG(1);
594             input_size = arg1;
595             /* Compute the size of the output string.  */
596 #if !defined(CONFIG_USER_ONLY)
597             cmdline = semihosting_get_cmdline();
598             if (cmdline == NULL) {
599                 cmdline = ""; /* Default to an empty line. */
600             }
601             output_size = strlen(cmdline) + 1; /* Count terminating 0. */
602 #else
603             unsigned int i;
604 
605             output_size = ts->info->env_strings - ts->info->arg_strings;
606             if (!output_size) {
607                 /*
608                  * We special-case the "empty command line" case (argc==0).
609                  * Just provide the terminating 0.
610                  */
611                 output_size = 1;
612             }
613 #endif
614 
615             if (output_size > input_size) {
616                 /* Not enough space to store command-line arguments.  */
617                 common_semi_cb(cs, -1, E2BIG);
618                 break;
619             }
620 
621             /* Adjust the command-line length.  */
622             if (SET_ARG(1, output_size - 1)) {
623                 /* Couldn't write back to argument block */
624                 goto do_fault;
625             }
626 
627             /* Lock the buffer on the ARM side.  */
628             output_buffer = lock_user(VERIFY_WRITE, arg0, output_size, 0);
629             if (!output_buffer) {
630                 goto do_fault;
631             }
632 
633             /* Copy the command-line arguments.  */
634 #if !defined(CONFIG_USER_ONLY)
635             pstrcpy(output_buffer, output_size, cmdline);
636 #else
637             if (output_size == 1) {
638                 /* Empty command-line.  */
639                 output_buffer[0] = '\0';
640                 goto out;
641             }
642 
643             if (copy_from_user(output_buffer, ts->info->arg_strings,
644                                output_size)) {
645                 unlock_user(output_buffer, arg0, 0);
646                 goto do_fault;
647             }
648 
649             /* Separate arguments by white spaces.  */
650             for (i = 0; i < output_size - 1; i++) {
651                 if (output_buffer[i] == 0) {
652                     output_buffer[i] = ' ';
653                 }
654             }
655         out:
656 #endif
657             /* Unlock the buffer on the ARM side.  */
658             unlock_user(output_buffer, arg0, output_size);
659             common_semi_cb(cs, status, 0);
660         }
661         break;
662 
663     case TARGET_SYS_HEAPINFO:
664         {
665             target_ulong retvals[4];
666             int i;
667 #ifdef CONFIG_USER_ONLY
668             TaskState *ts = cs->opaque;
669             target_ulong limit;
670 #else
671             LayoutInfo info = common_semi_find_bases(cs);
672 #endif
673 
674             GET_ARG(0);
675 
676 #ifdef CONFIG_USER_ONLY
677             /*
678              * Some C libraries assume the heap immediately follows .bss, so
679              * allocate it using sbrk.
680              */
681             if (!ts->heap_limit) {
682                 abi_ulong ret;
683 
684                 ts->heap_base = do_brk(0);
685                 limit = ts->heap_base + COMMON_SEMI_HEAP_SIZE;
686                 /* Try a big heap, and reduce the size if that fails.  */
687                 for (;;) {
688                     ret = do_brk(limit);
689                     if (ret >= limit) {
690                         break;
691                     }
692                     limit = (ts->heap_base >> 1) + (limit >> 1);
693                 }
694                 ts->heap_limit = limit;
695             }
696 
697             retvals[0] = ts->heap_base;
698             retvals[1] = ts->heap_limit;
699             retvals[2] = ts->stack_base;
700             retvals[3] = 0; /* Stack limit.  */
701 #else
702             retvals[0] = info.heapbase;  /* Heap Base */
703             retvals[1] = info.heaplimit; /* Heap Limit */
704             retvals[2] = info.heaplimit; /* Stack base */
705             retvals[3] = info.heapbase;  /* Stack limit.  */
706 #endif
707 
708             for (i = 0; i < ARRAY_SIZE(retvals); i++) {
709                 bool fail;
710 
711                 if (is_64bit_semihosting(env)) {
712                     fail = put_user_u64(retvals[i], arg0 + i * 8);
713                 } else {
714                     fail = put_user_u32(retvals[i], arg0 + i * 4);
715                 }
716 
717                 if (fail) {
718                     /* Couldn't write back to argument block */
719                     goto do_fault;
720                 }
721             }
722             common_semi_set_ret(cs, 0);
723         }
724         break;
725 
726     case TARGET_SYS_EXIT:
727     case TARGET_SYS_EXIT_EXTENDED:
728         if (common_semi_sys_exit_extended(cs, nr)) {
729             /*
730              * The A64 version of SYS_EXIT takes a parameter block,
731              * so the application-exit type can return a subcode which
732              * is the exit status code from the application.
733              * SYS_EXIT_EXTENDED is an a new-in-v2.0 optional function
734              * which allows A32/T32 guests to also provide a status code.
735              */
736             GET_ARG(0);
737             GET_ARG(1);
738 
739             if (arg0 == ADP_Stopped_ApplicationExit) {
740                 ret = arg1;
741             } else {
742                 ret = 1;
743             }
744         } else {
745             /*
746              * The A32/T32 version of SYS_EXIT specifies only
747              * Stopped_ApplicationExit as normal exit, but does not
748              * allow the guest to specify the exit status code.
749              * Everything else is considered an error.
750              */
751             ret = (args == ADP_Stopped_ApplicationExit) ? 0 : 1;
752         }
753         gdb_exit(ret);
754         exit(ret);
755 
756     case TARGET_SYS_ELAPSED:
757         elapsed = get_clock() - clock_start;
758         if (sizeof(target_ulong) == 8) {
759             if (SET_ARG(0, elapsed)) {
760                 goto do_fault;
761             }
762         } else {
763             if (SET_ARG(0, (uint32_t) elapsed) ||
764                 SET_ARG(1, (uint32_t) (elapsed >> 32))) {
765                 goto do_fault;
766             }
767         }
768         common_semi_set_ret(cs, 0);
769         break;
770 
771     case TARGET_SYS_TICKFREQ:
772         /* qemu always uses nsec */
773         common_semi_set_ret(cs, 1000000000);
774         break;
775 
776     case TARGET_SYS_SYNCCACHE:
777         /*
778          * Clean the D-cache and invalidate the I-cache for the specified
779          * virtual address range. This is a nop for us since we don't
780          * implement caches. This is only present on A64.
781          */
782         if (common_semi_has_synccache(env)) {
783             common_semi_set_ret(cs, 0);
784             break;
785         }
786         /* fall through */
787     default:
788         fprintf(stderr, "qemu: Unsupported SemiHosting SWI 0x%02x\n", nr);
789         cpu_dump_state(cs, stderr, 0);
790         abort();
791 
792     do_fault:
793         common_semi_cb(cs, -1, EFAULT);
794         break;
795     }
796 }
797