Merge master.kernel.org:/pub/scm/linux/kernel/git/davej/cpufreq
[linux-2.6] / arch / um / os-Linux / start_up.c
1 /*
2  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
3  * Licensed under the GPL
4  */
5
6 #include <stdio.h>
7 #include <stddef.h>
8 #include <stdarg.h>
9 #include <stdlib.h>
10 #include <string.h>
11 #include <unistd.h>
12 #include <signal.h>
13 #include <sched.h>
14 #include <fcntl.h>
15 #include <errno.h>
16 #include <setjmp.h>
17 #include <sys/time.h>
18 #include <sys/wait.h>
19 #include <sys/mman.h>
20 #include <asm/unistd.h>
21 #include <asm/page.h>
22 #include <sys/types.h>
23 #include "user_util.h"
24 #include "kern_util.h"
25 #include "user.h"
26 #include "signal_kern.h"
27 #include "sysdep/ptrace.h"
28 #include "sysdep/sigcontext.h"
29 #include "irq_user.h"
30 #include "ptrace_user.h"
31 #include "mem_user.h"
32 #include "init.h"
33 #include "os.h"
34 #include "uml-config.h"
35 #include "choose-mode.h"
36 #include "mode.h"
37 #include "tempfile.h"
38 #include "kern_constants.h"
39
40 #ifdef UML_CONFIG_MODE_SKAS
41 #include "skas.h"
42 #include "skas_ptrace.h"
43 #include "registers.h"
44 #endif
45
46 static int ptrace_child(void *arg)
47 {
48         int ret;
49         int pid = os_getpid(), ppid = getppid();
50         int sc_result;
51
52         if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
53                 perror("ptrace");
54                 os_kill_process(pid, 0);
55         }
56         os_stop_process(pid);
57
58         /*This syscall will be intercepted by the parent. Don't call more than
59          * once, please.*/
60         sc_result = os_getpid();
61
62         if (sc_result == pid)
63                 ret = 1; /*Nothing modified by the parent, we are running
64                            normally.*/
65         else if (sc_result == ppid)
66                 ret = 0; /*Expected in check_ptrace and check_sysemu when they
67                            succeed in modifying the stack frame*/
68         else
69                 ret = 2; /*Serious trouble! This could be caused by a bug in
70                            host 2.6 SKAS3/2.6 patch before release -V6, together
71                            with a bug in the UML code itself.*/
72         _exit(ret);
73 }
74
75 static int start_ptraced_child(void **stack_out)
76 {
77         void *stack;
78         unsigned long sp;
79         int pid, n, status;
80
81         stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
82                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
83         if(stack == MAP_FAILED)
84                 panic("check_ptrace : mmap failed, errno = %d", errno);
85         sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
86         pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
87         if(pid < 0)
88                 panic("start_ptraced_child : clone failed, errno = %d", errno);
89         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
90         if(n < 0)
91                 panic("check_ptrace : clone failed, errno = %d", errno);
92         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
93                 panic("check_ptrace : expected SIGSTOP, got status = %d",
94                       status);
95
96         *stack_out = stack;
97         return(pid);
98 }
99
100 /* When testing for SYSEMU support, if it is one of the broken versions, we
101  * must just avoid using sysemu, not panic, but only if SYSEMU features are
102  * broken.
103  * So only for SYSEMU features we test mustpanic, while normal host features
104  * must work anyway!
105  */
106 static int stop_ptraced_child(int pid, void *stack, int exitcode,
107                               int mustpanic)
108 {
109         int status, n, ret = 0;
110
111         if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
112                 panic("check_ptrace : ptrace failed, errno = %d", errno);
113         CATCH_EINTR(n = waitpid(pid, &status, 0));
114         if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode)) {
115                 int exit_with = WEXITSTATUS(status);
116                 if (exit_with == 2)
117                         printf("check_ptrace : child exited with status 2. "
118                                "Serious trouble happening! Try updating your "
119                                "host skas patch!\nDisabling SYSEMU support.");
120                 printf("check_ptrace : child exited with exitcode %d, while "
121                       "expecting %d; status 0x%x", exit_with,
122                       exitcode, status);
123                 if (mustpanic)
124                         panic("\n");
125                 else
126                         printf("\n");
127                 ret = -1;
128         }
129
130         if(munmap(stack, PAGE_SIZE) < 0)
131                 panic("check_ptrace : munmap failed, errno = %d", errno);
132         return ret;
133 }
134
135 int ptrace_faultinfo = 1;
136 int ptrace_ldt = 1;
137 int proc_mm = 1;
138 int skas_needs_stub = 0;
139
140 static int __init skas0_cmd_param(char *str, int* add)
141 {
142         ptrace_faultinfo = proc_mm = 0;
143         return 0;
144 }
145
146 /* The two __uml_setup would conflict, without this stupid alias. */
147
148 static int __init mode_skas0_cmd_param(char *str, int* add)
149         __attribute__((alias("skas0_cmd_param")));
150
151 __uml_setup("skas0", skas0_cmd_param,
152                 "skas0\n"
153                 "    Disables SKAS3 usage, so that SKAS0 is used, unless \n"
154                 "    you specify mode=tt.\n\n");
155
156 __uml_setup("mode=skas0", mode_skas0_cmd_param,
157                 "mode=skas0\n"
158                 "    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
159                 "    specify mode=tt. Note that this was recently added - on \n"
160                 "    older kernels you must use simply \"skas0\".\n\n");
161
162 static int force_sysemu_disabled = 0;
163
164 static int __init nosysemu_cmd_param(char *str, int* add)
165 {
166         force_sysemu_disabled = 1;
167         return 0;
168 }
169
170 __uml_setup("nosysemu", nosysemu_cmd_param,
171 "nosysemu\n"
172 "    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
173 "    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
174 "    behaviour of ptrace() and helps reducing host context switch rate.\n"
175 "    To make it working, you need a kernel patch for your host, too.\n"
176 "    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
177 "    information.\n\n");
178
179 static void __init check_sysemu(void)
180 {
181         void *stack;
182         int pid, n, status, count=0;
183
184         printf("Checking syscall emulation patch for ptrace...");
185         sysemu_supported = 0;
186         pid = start_ptraced_child(&stack);
187
188         if(ptrace(PTRACE_SYSEMU, pid, 0, 0) < 0)
189                 goto fail;
190
191         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
192         if (n < 0)
193                 panic("check_sysemu : wait failed, errno = %d", errno);
194         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
195                 panic("check_sysemu : expected SIGTRAP, "
196                       "got status = %d", status);
197
198         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
199                    os_getpid());
200         if(n < 0)
201                 panic("check_sysemu : failed to modify system "
202                       "call return, errno = %d", errno);
203
204         if (stop_ptraced_child(pid, stack, 0, 0) < 0)
205                 goto fail_stopped;
206
207         sysemu_supported = 1;
208         printf("OK\n");
209         set_using_sysemu(!force_sysemu_disabled);
210
211         printf("Checking advanced syscall emulation patch for ptrace...");
212         pid = start_ptraced_child(&stack);
213
214         if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0,
215                   (void *) PTRACE_O_TRACESYSGOOD) < 0)
216                 panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d",
217                       errno);
218
219         while(1){
220                 count++;
221                 if(ptrace(PTRACE_SYSEMU_SINGLESTEP, pid, 0, 0) < 0)
222                         goto fail;
223                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
224                 if(n < 0)
225                         panic("check_ptrace : wait failed, errno = %d", errno);
226                 if(WIFSTOPPED(status) && (WSTOPSIG(status) == (SIGTRAP|0x80))){
227                         if (!count)
228                                 panic("check_ptrace : SYSEMU_SINGLESTEP "
229                                       "doesn't singlestep");
230                         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
231                                    os_getpid());
232                         if(n < 0)
233                                 panic("check_sysemu : failed to modify system "
234                                       "call return, errno = %d", errno);
235                         break;
236                 }
237                 else if(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGTRAP))
238                         count++;
239                 else
240                         panic("check_ptrace : expected SIGTRAP or "
241                               "(SIGTRAP|0x80), got status = %d", status);
242         }
243         if (stop_ptraced_child(pid, stack, 0, 0) < 0)
244                 goto fail_stopped;
245
246         sysemu_supported = 2;
247         printf("OK\n");
248
249         if ( !force_sysemu_disabled )
250                 set_using_sysemu(sysemu_supported);
251         return;
252
253 fail:
254         stop_ptraced_child(pid, stack, 1, 0);
255 fail_stopped:
256         printf("missing\n");
257 }
258
259 static void __init check_ptrace(void)
260 {
261         void *stack;
262         int pid, syscall, n, status;
263
264         printf("Checking that ptrace can change system call numbers...");
265         pid = start_ptraced_child(&stack);
266
267         if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
268                 panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", errno);
269
270         while(1){
271                 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
272                         panic("check_ptrace : ptrace failed, errno = %d",
273                               errno);
274                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
275                 if(n < 0)
276                         panic("check_ptrace : wait failed, errno = %d", errno);
277                 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != (SIGTRAP|0x80)))
278                         panic("check_ptrace : expected (SIGTRAP|0x80), "
279                               "got status = %d", status);
280
281                 syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
282                                  0);
283                 if(syscall == __NR_getpid){
284                         n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
285                                    __NR_getppid);
286                         if(n < 0)
287                                 panic("check_ptrace : failed to modify system "
288                                       "call, errno = %d", errno);
289                         break;
290                 }
291         }
292         stop_ptraced_child(pid, stack, 0, 1);
293         printf("OK\n");
294         check_sysemu();
295 }
296
297 extern int create_tmp_file(unsigned long long len);
298
299 static void check_tmpexec(void)
300 {
301         void *addr;
302         int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE);
303
304         addr = mmap(NULL, UM_KERN_PAGE_SIZE,
305                     PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0);
306         printf("Checking PROT_EXEC mmap in /tmp...");
307         fflush(stdout);
308         if(addr == MAP_FAILED){
309                 err = errno;
310                 perror("failed");
311                 if(err == EPERM)
312                         printf("/tmp must be not mounted noexec\n");
313                 exit(1);
314         }
315         printf("OK\n");
316         munmap(addr, UM_KERN_PAGE_SIZE);
317
318         close(fd);
319 }
320
321 void os_early_checks(void)
322 {
323         check_ptrace();
324
325         /* Need to check this early because mmapping happens before the
326          * kernel is running.
327          */
328         check_tmpexec();
329 }
330
331 static int __init noprocmm_cmd_param(char *str, int* add)
332 {
333         proc_mm = 0;
334         return 0;
335 }
336
337 __uml_setup("noprocmm", noprocmm_cmd_param,
338 "noprocmm\n"
339 "    Turns off usage of /proc/mm, even if host supports it.\n"
340 "    To support /proc/mm, the host needs to be patched using\n"
341 "    the current skas3 patch.\n\n");
342
343 static int __init noptracefaultinfo_cmd_param(char *str, int* add)
344 {
345         ptrace_faultinfo = 0;
346         return 0;
347 }
348
349 __uml_setup("noptracefaultinfo", noptracefaultinfo_cmd_param,
350 "noptracefaultinfo\n"
351 "    Turns off usage of PTRACE_FAULTINFO, even if host supports\n"
352 "    it. To support PTRACE_FAULTINFO, the host needs to be patched\n"
353 "    using the current skas3 patch.\n\n");
354
355 static int __init noptraceldt_cmd_param(char *str, int* add)
356 {
357         ptrace_ldt = 0;
358         return 0;
359 }
360
361 __uml_setup("noptraceldt", noptraceldt_cmd_param,
362 "noptraceldt\n"
363 "    Turns off usage of PTRACE_LDT, even if host supports it.\n"
364 "    To support PTRACE_LDT, the host needs to be patched using\n"
365 "    the current skas3 patch.\n\n");
366
367 #ifdef UML_CONFIG_MODE_SKAS
368 static inline void check_skas3_ptrace_faultinfo(void)
369 {
370         struct ptrace_faultinfo fi;
371         void *stack;
372         int pid, n;
373
374         printf("  - PTRACE_FAULTINFO...");
375         pid = start_ptraced_child(&stack);
376
377         n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
378         if (n < 0) {
379                 ptrace_faultinfo = 0;
380                 if(errno == EIO)
381                         printf("not found\n");
382                 else
383                         perror("not found");
384         }
385         else {
386                 if (!ptrace_faultinfo)
387                         printf("found but disabled on command line\n");
388                 else
389                         printf("found\n");
390         }
391
392         init_registers(pid);
393         stop_ptraced_child(pid, stack, 1, 1);
394 }
395
396 static inline void check_skas3_ptrace_ldt(void)
397 {
398 #ifdef PTRACE_LDT
399         void *stack;
400         int pid, n;
401         unsigned char ldtbuf[40];
402         struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
403                 .func = 2, /* read default ldt */
404                 .ptr = ldtbuf,
405                 .bytecount = sizeof(ldtbuf)};
406
407         printf("  - PTRACE_LDT...");
408         pid = start_ptraced_child(&stack);
409
410         n = ptrace(PTRACE_LDT, pid, 0, (unsigned long) &ldt_op);
411         if (n < 0) {
412                 if(errno == EIO)
413                         printf("not found\n");
414                 else {
415                         perror("not found");
416                 }
417                 ptrace_ldt = 0;
418         }
419         else {
420                 if(ptrace_ldt)
421                         printf("found\n");
422                 else
423                         printf("found, but use is disabled\n");
424         }
425
426         stop_ptraced_child(pid, stack, 1, 1);
427 #else
428         /* PTRACE_LDT might be disabled via cmdline option.
429          * We want to override this, else we might use the stub
430          * without real need
431          */
432         ptrace_ldt = 1;
433 #endif
434 }
435
436 static inline void check_skas3_proc_mm(void)
437 {
438         printf("  - /proc/mm...");
439         if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
440                 proc_mm = 0;
441                 printf("not found\n");
442         }
443         else {
444                 if (!proc_mm)
445                         printf("found but disabled on command line\n");
446                 else
447                         printf("found\n");
448         }
449 }
450
451 int can_do_skas(void)
452 {
453         printf("Checking for the skas3 patch in the host:\n");
454
455         check_skas3_proc_mm();
456         check_skas3_ptrace_faultinfo();
457         check_skas3_ptrace_ldt();
458
459         if(!proc_mm || !ptrace_faultinfo || !ptrace_ldt)
460                 skas_needs_stub = 1;
461
462         return 1;
463 }
464 #else
465 int can_do_skas(void)
466 {
467         return(0);
468 }
469 #endif
470
471 int have_devanon = 0;
472
473 /* Runs on boot kernel stack - already safe to use printk. */
474
475 void check_devanon(void)
476 {
477         int fd;
478
479         printk("Checking for /dev/anon on the host...");
480         fd = open("/dev/anon", O_RDWR);
481         if(fd < 0){
482                 printk("Not available (open failed with errno %d)\n", errno);
483                 return;
484         }
485
486         printk("OK\n");
487         have_devanon = 1;
488 }
489
490 int __init parse_iomem(char *str, int *add)
491 {
492         struct iomem_region *new;
493         struct uml_stat buf;
494         char *file, *driver;
495         int fd, err, size;
496
497         driver = str;
498         file = strchr(str,',');
499         if(file == NULL){
500                 printf("parse_iomem : failed to parse iomem\n");
501                 goto out;
502         }
503         *file = '\0';
504         file++;
505         fd = os_open_file(file, of_rdwr(OPENFLAGS()), 0);
506         if(fd < 0){
507                 os_print_error(fd, "parse_iomem - Couldn't open io file");
508                 goto out;
509         }
510
511         err = os_stat_fd(fd, &buf);
512         if(err < 0){
513                 os_print_error(err, "parse_iomem - cannot stat_fd file");
514                 goto out_close;
515         }
516
517         new = malloc(sizeof(*new));
518         if(new == NULL){
519                 perror("Couldn't allocate iomem_region struct");
520                 goto out_close;
521         }
522
523         size = (buf.ust_size + UM_KERN_PAGE_SIZE) & ~(UM_KERN_PAGE_SIZE - 1);
524
525         *new = ((struct iomem_region) { .next           = iomem_regions,
526                                         .driver         = driver,
527                                         .fd             = fd,
528                                         .size           = size,
529                                         .phys           = 0,
530                                         .virt           = 0 });
531         iomem_regions = new;
532         iomem_size += new->size + UM_KERN_PAGE_SIZE;
533
534         return(0);
535  out_close:
536         os_close_file(fd);
537  out:
538         return(1);
539 }
540