Merge branch 'i7300_idle' into release
[linux-2.6] / fs / proc / kcore.c
1 /*
2  *      fs/proc/kcore.c kernel ELF core dumper
3  *
4  *      Modelled on fs/exec.c:aout_core_dump()
5  *      Jeremy Fitzhardinge <jeremy@sw.oz.au>
6  *      ELF version written by David Howells <David.Howells@nexor.co.uk>
7  *      Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
8  *      Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
9  *      Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
10  */
11
12 #include <linux/mm.h>
13 #include <linux/proc_fs.h>
14 #include <linux/user.h>
15 #include <linux/capability.h>
16 #include <linux/elf.h>
17 #include <linux/elfcore.h>
18 #include <linux/vmalloc.h>
19 #include <linux/highmem.h>
20 #include <linux/init.h>
21 #include <asm/uaccess.h>
22 #include <asm/io.h>
23
24 #define CORE_STR "CORE"
25
26 #ifndef ELF_CORE_EFLAGS
27 #define ELF_CORE_EFLAGS 0
28 #endif
29
30 static struct proc_dir_entry *proc_root_kcore;
31
32 static int open_kcore(struct inode * inode, struct file * filp)
33 {
34         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
35 }
36
37 static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);
38
39 static const struct file_operations proc_kcore_operations = {
40         .read           = read_kcore,
41         .open           = open_kcore,
42 };
43
44 #ifndef kc_vaddr_to_offset
45 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
46 #endif
47 #ifndef kc_offset_to_vaddr
48 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
49 #endif
50
51 /* An ELF note in memory */
52 struct memelfnote
53 {
54         const char *name;
55         int type;
56         unsigned int datasz;
57         void *data;
58 };
59
60 static struct kcore_list *kclist;
61 static DEFINE_RWLOCK(kclist_lock);
62
63 void
64 kclist_add(struct kcore_list *new, void *addr, size_t size)
65 {
66         new->addr = (unsigned long)addr;
67         new->size = size;
68
69         write_lock(&kclist_lock);
70         new->next = kclist;
71         kclist = new;
72         write_unlock(&kclist_lock);
73 }
74
75 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
76 {
77         size_t try, size;
78         struct kcore_list *m;
79
80         *nphdr = 1; /* PT_NOTE */
81         size = 0;
82
83         for (m=kclist; m; m=m->next) {
84                 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
85                 if (try > size)
86                         size = try;
87                 *nphdr = *nphdr + 1;
88         }
89         *elf_buflen =   sizeof(struct elfhdr) + 
90                         (*nphdr + 2)*sizeof(struct elf_phdr) + 
91                         3 * ((sizeof(struct elf_note)) +
92                              roundup(sizeof(CORE_STR), 4)) +
93                         roundup(sizeof(struct elf_prstatus), 4) +
94                         roundup(sizeof(struct elf_prpsinfo), 4) +
95                         roundup(sizeof(struct task_struct), 4);
96         *elf_buflen = PAGE_ALIGN(*elf_buflen);
97         return size + *elf_buflen;
98 }
99
100
101 /*****************************************************************************/
102 /*
103  * determine size of ELF note
104  */
105 static int notesize(struct memelfnote *en)
106 {
107         int sz;
108
109         sz = sizeof(struct elf_note);
110         sz += roundup((strlen(en->name) + 1), 4);
111         sz += roundup(en->datasz, 4);
112
113         return sz;
114 } /* end notesize() */
115
116 /*****************************************************************************/
117 /*
118  * store a note in the header buffer
119  */
120 static char *storenote(struct memelfnote *men, char *bufp)
121 {
122         struct elf_note en;
123
124 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
125
126         en.n_namesz = strlen(men->name) + 1;
127         en.n_descsz = men->datasz;
128         en.n_type = men->type;
129
130         DUMP_WRITE(&en, sizeof(en));
131         DUMP_WRITE(men->name, en.n_namesz);
132
133         /* XXX - cast from long long to long to avoid need for libgcc.a */
134         bufp = (char*) roundup((unsigned long)bufp,4);
135         DUMP_WRITE(men->data, men->datasz);
136         bufp = (char*) roundup((unsigned long)bufp,4);
137
138 #undef DUMP_WRITE
139
140         return bufp;
141 } /* end storenote() */
142
143 /*
144  * store an ELF coredump header in the supplied buffer
145  * nphdr is the number of elf_phdr to insert
146  */
147 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
148 {
149         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
150         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
151         struct elf_phdr *nhdr, *phdr;
152         struct elfhdr *elf;
153         struct memelfnote notes[3];
154         off_t offset = 0;
155         struct kcore_list *m;
156
157         /* setup ELF header */
158         elf = (struct elfhdr *) bufp;
159         bufp += sizeof(struct elfhdr);
160         offset += sizeof(struct elfhdr);
161         memcpy(elf->e_ident, ELFMAG, SELFMAG);
162         elf->e_ident[EI_CLASS]  = ELF_CLASS;
163         elf->e_ident[EI_DATA]   = ELF_DATA;
164         elf->e_ident[EI_VERSION]= EV_CURRENT;
165         elf->e_ident[EI_OSABI] = ELF_OSABI;
166         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
167         elf->e_type     = ET_CORE;
168         elf->e_machine  = ELF_ARCH;
169         elf->e_version  = EV_CURRENT;
170         elf->e_entry    = 0;
171         elf->e_phoff    = sizeof(struct elfhdr);
172         elf->e_shoff    = 0;
173         elf->e_flags    = ELF_CORE_EFLAGS;
174         elf->e_ehsize   = sizeof(struct elfhdr);
175         elf->e_phentsize= sizeof(struct elf_phdr);
176         elf->e_phnum    = nphdr;
177         elf->e_shentsize= 0;
178         elf->e_shnum    = 0;
179         elf->e_shstrndx = 0;
180
181         /* setup ELF PT_NOTE program header */
182         nhdr = (struct elf_phdr *) bufp;
183         bufp += sizeof(struct elf_phdr);
184         offset += sizeof(struct elf_phdr);
185         nhdr->p_type    = PT_NOTE;
186         nhdr->p_offset  = 0;
187         nhdr->p_vaddr   = 0;
188         nhdr->p_paddr   = 0;
189         nhdr->p_filesz  = 0;
190         nhdr->p_memsz   = 0;
191         nhdr->p_flags   = 0;
192         nhdr->p_align   = 0;
193
194         /* setup ELF PT_LOAD program header for every area */
195         for (m=kclist; m; m=m->next) {
196                 phdr = (struct elf_phdr *) bufp;
197                 bufp += sizeof(struct elf_phdr);
198                 offset += sizeof(struct elf_phdr);
199
200                 phdr->p_type    = PT_LOAD;
201                 phdr->p_flags   = PF_R|PF_W|PF_X;
202                 phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
203                 phdr->p_vaddr   = (size_t)m->addr;
204                 phdr->p_paddr   = 0;
205                 phdr->p_filesz  = phdr->p_memsz = m->size;
206                 phdr->p_align   = PAGE_SIZE;
207         }
208
209         /*
210          * Set up the notes in similar form to SVR4 core dumps made
211          * with info from their /proc.
212          */
213         nhdr->p_offset  = offset;
214
215         /* set up the process status */
216         notes[0].name = CORE_STR;
217         notes[0].type = NT_PRSTATUS;
218         notes[0].datasz = sizeof(struct elf_prstatus);
219         notes[0].data = &prstatus;
220
221         memset(&prstatus, 0, sizeof(struct elf_prstatus));
222
223         nhdr->p_filesz  = notesize(&notes[0]);
224         bufp = storenote(&notes[0], bufp);
225
226         /* set up the process info */
227         notes[1].name   = CORE_STR;
228         notes[1].type   = NT_PRPSINFO;
229         notes[1].datasz = sizeof(struct elf_prpsinfo);
230         notes[1].data   = &prpsinfo;
231
232         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
233         prpsinfo.pr_state       = 0;
234         prpsinfo.pr_sname       = 'R';
235         prpsinfo.pr_zomb        = 0;
236
237         strcpy(prpsinfo.pr_fname, "vmlinux");
238         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
239
240         nhdr->p_filesz  += notesize(&notes[1]);
241         bufp = storenote(&notes[1], bufp);
242
243         /* set up the task structure */
244         notes[2].name   = CORE_STR;
245         notes[2].type   = NT_TASKSTRUCT;
246         notes[2].datasz = sizeof(struct task_struct);
247         notes[2].data   = current;
248
249         nhdr->p_filesz  += notesize(&notes[2]);
250         bufp = storenote(&notes[2], bufp);
251
252 } /* end elf_kcore_store_hdr() */
253
254 /*****************************************************************************/
255 /*
256  * read from the ELF header and then kernel memory
257  */
258 static ssize_t
259 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
260 {
261         ssize_t acc = 0;
262         size_t size, tsz;
263         size_t elf_buflen;
264         int nphdr;
265         unsigned long start;
266
267         read_lock(&kclist_lock);
268         proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen);
269         if (buflen == 0 || *fpos >= size) {
270                 read_unlock(&kclist_lock);
271                 return 0;
272         }
273
274         /* trim buflen to not go beyond EOF */
275         if (buflen > size - *fpos)
276                 buflen = size - *fpos;
277
278         /* construct an ELF core header if we'll need some of it */
279         if (*fpos < elf_buflen) {
280                 char * elf_buf;
281
282                 tsz = elf_buflen - *fpos;
283                 if (buflen < tsz)
284                         tsz = buflen;
285                 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
286                 if (!elf_buf) {
287                         read_unlock(&kclist_lock);
288                         return -ENOMEM;
289                 }
290                 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
291                 read_unlock(&kclist_lock);
292                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
293                         kfree(elf_buf);
294                         return -EFAULT;
295                 }
296                 kfree(elf_buf);
297                 buflen -= tsz;
298                 *fpos += tsz;
299                 buffer += tsz;
300                 acc += tsz;
301
302                 /* leave now if filled buffer already */
303                 if (buflen == 0)
304                         return acc;
305         } else
306                 read_unlock(&kclist_lock);
307
308         /*
309          * Check to see if our file offset matches with any of
310          * the addresses in the elf_phdr on our list.
311          */
312         start = kc_offset_to_vaddr(*fpos - elf_buflen);
313         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
314                 tsz = buflen;
315                 
316         while (buflen) {
317                 struct kcore_list *m;
318
319                 read_lock(&kclist_lock);
320                 for (m=kclist; m; m=m->next) {
321                         if (start >= m->addr && start < (m->addr+m->size))
322                                 break;
323                 }
324                 read_unlock(&kclist_lock);
325
326                 if (m == NULL) {
327                         if (clear_user(buffer, tsz))
328                                 return -EFAULT;
329                 } else if (is_vmalloc_addr((void *)start)) {
330                         char * elf_buf;
331                         struct vm_struct *m;
332                         unsigned long curstart = start;
333                         unsigned long cursize = tsz;
334
335                         elf_buf = kzalloc(tsz, GFP_KERNEL);
336                         if (!elf_buf)
337                                 return -ENOMEM;
338
339                         read_lock(&vmlist_lock);
340                         for (m=vmlist; m && cursize; m=m->next) {
341                                 unsigned long vmstart;
342                                 unsigned long vmsize;
343                                 unsigned long msize = m->size - PAGE_SIZE;
344
345                                 if (((unsigned long)m->addr + msize) < 
346                                                                 curstart)
347                                         continue;
348                                 if ((unsigned long)m->addr > (curstart + 
349                                                                 cursize))
350                                         break;
351                                 vmstart = (curstart < (unsigned long)m->addr ? 
352                                         (unsigned long)m->addr : curstart);
353                                 if (((unsigned long)m->addr + msize) > 
354                                                         (curstart + cursize))
355                                         vmsize = curstart + cursize - vmstart;
356                                 else
357                                         vmsize = (unsigned long)m->addr + 
358                                                         msize - vmstart;
359                                 curstart = vmstart + vmsize;
360                                 cursize -= vmsize;
361                                 /* don't dump ioremap'd stuff! (TA) */
362                                 if (m->flags & VM_IOREMAP)
363                                         continue;
364                                 memcpy(elf_buf + (vmstart - start),
365                                         (char *)vmstart, vmsize);
366                         }
367                         read_unlock(&vmlist_lock);
368                         if (copy_to_user(buffer, elf_buf, tsz)) {
369                                 kfree(elf_buf);
370                                 return -EFAULT;
371                         }
372                         kfree(elf_buf);
373                 } else {
374                         if (kern_addr_valid(start)) {
375                                 unsigned long n;
376
377                                 n = copy_to_user(buffer, (char *)start, tsz);
378                                 /*
379                                  * We cannot distingush between fault on source
380                                  * and fault on destination. When this happens
381                                  * we clear too and hope it will trigger the
382                                  * EFAULT again.
383                                  */
384                                 if (n) { 
385                                         if (clear_user(buffer + tsz - n,
386                                                                 n))
387                                                 return -EFAULT;
388                                 }
389                         } else {
390                                 if (clear_user(buffer, tsz))
391                                         return -EFAULT;
392                         }
393                 }
394                 buflen -= tsz;
395                 *fpos += tsz;
396                 buffer += tsz;
397                 acc += tsz;
398                 start += tsz;
399                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
400         }
401
402         return acc;
403 }
404
405 static int __init proc_kcore_init(void)
406 {
407         proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &proc_kcore_operations);
408         if (proc_root_kcore)
409                 proc_root_kcore->size =
410                                 (size_t)high_memory - PAGE_OFFSET + PAGE_SIZE;
411         return 0;
412 }
413 module_init(proc_kcore_init);