[net-next-2.6.git] / fs / proc / kcore.c

/*
 *	fs/proc/kcore.c kernel ELF core dumper
 *
 *	Modelled on fs/exec.c:aout_core_dump()
 *	Jeremy Fitzhardinge <jeremy@sw.oz.au>
 *	ELF version written by David Howells <David.Howells@nexor.co.uk>
 *	Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
 *	Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
 *	Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
 */

#include <linux/config.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/elf.h>
#include <linux/elfcore.h>
#include <linux/vmalloc.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <asm/io.h>


static int open_kcore(struct inode * inode, struct file * filp)
{
	return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
}

static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *);

struct file_operations proc_kcore_operations = {
	.read		= read_kcore,
	.open		= open_kcore,
};

#ifndef kc_vaddr_to_offset
#define	kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
#endif
#ifndef	kc_offset_to_vaddr
#define	kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
#endif

#define roundup(x, y)  ((((x)+((y)-1))/(y))*(y))

/* An ELF note in memory */
struct memelfnote
{
	const char *name;
	int type;
	unsigned int datasz;
	void *data;
};

static struct kcore_list *kclist;
static DEFINE_RWLOCK(kclist_lock);

void
kclist_add(struct kcore_list *new, void *addr, size_t size)
{
	new->addr = (unsigned long)addr;
	new->size = size;

	write_lock(&kclist_lock);
	new->next = kclist;
	kclist = new;
	write_unlock(&kclist_lock);
}

static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
{
	size_t try, size;
	struct kcore_list *m;

	*nphdr = 1; /* PT_NOTE */
	size = 0;

	for (m=kclist; m; m=m->next) {
		try = kc_vaddr_to_offset((size_t)m->addr + m->size);
		if (try > size)
			size = try;
		*nphdr = *nphdr + 1;
	}
	*elf_buflen =	sizeof(struct elfhdr) + 
			(*nphdr + 2)*sizeof(struct elf_phdr) + 
			3 * (sizeof(struct elf_note) + 4) +
			sizeof(struct elf_prstatus) +
			sizeof(struct elf_prpsinfo) +
			sizeof(struct task_struct);
	*elf_buflen = PAGE_ALIGN(*elf_buflen);
	return size + *elf_buflen;
}


/*****************************************************************************/
/*
 * determine size of ELF note
 */
static int notesize(struct memelfnote *en)
{
	int sz;

	sz = sizeof(struct elf_note);
	sz += roundup(strlen(en->name), 4);
	sz += roundup(en->datasz, 4);

	return sz;
} /* end notesize() */

/*****************************************************************************/
/*
 * store a note in the header buffer
 */
static char *storenote(struct memelfnote *men, char *bufp)
{
	struct elf_note en;

#define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)

	en.n_namesz = strlen(men->name);
	en.n_descsz = men->datasz;
	en.n_type = men->type;

	DUMP_WRITE(&en, sizeof(en));
	DUMP_WRITE(men->name, en.n_namesz);

	/* XXX - cast from long long to long to avoid need for libgcc.a */
	bufp = (char*) roundup((unsigned long)bufp,4);
	DUMP_WRITE(men->data, men->datasz);
	bufp = (char*) roundup((unsigned long)bufp,4);

#undef DUMP_WRITE

	return bufp;
} /* end storenote() */

/*
 * store an ELF coredump header in the supplied buffer
 * nphdr is the number of elf_phdr to insert
 */
static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
{
	struct elf_prstatus prstatus;	/* NT_PRSTATUS */
	struct elf_prpsinfo prpsinfo;	/* NT_PRPSINFO */
	struct elf_phdr *nhdr, *phdr;
	struct elfhdr *elf;
	struct memelfnote notes[3];
	off_t offset = 0;
	struct kcore_list *m;

	/* setup ELF header */
	elf = (struct elfhdr *) bufp;
	bufp += sizeof(struct elfhdr);
	offset += sizeof(struct elfhdr);
	memcpy(elf->e_ident, ELFMAG, SELFMAG);
	elf->e_ident[EI_CLASS]	= ELF_CLASS;
	elf->e_ident[EI_DATA]	= ELF_DATA;
	elf->e_ident[EI_VERSION]= EV_CURRENT;
	elf->e_ident[EI_OSABI] = ELF_OSABI;
	memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
	elf->e_type	= ET_CORE;
	elf->e_machine	= ELF_ARCH;
	elf->e_version	= EV_CURRENT;
	elf->e_entry	= 0;
	elf->e_phoff	= sizeof(struct elfhdr);
	elf->e_shoff	= 0;
#if defined(CONFIG_H8300)
	elf->e_flags	= ELF_FLAGS;
#else
	elf->e_flags	= 0;
#endif
	elf->e_ehsize	= sizeof(struct elfhdr);
	elf->e_phentsize= sizeof(struct elf_phdr);
	elf->e_phnum	= nphdr;
	elf->e_shentsize= 0;
	elf->e_shnum	= 0;
	elf->e_shstrndx	= 0;

	/* setup ELF PT_NOTE program header */
	nhdr = (struct elf_phdr *) bufp;
	bufp += sizeof(struct elf_phdr);
	offset += sizeof(struct elf_phdr);
	nhdr->p_type	= PT_NOTE;
	nhdr->p_offset	= 0;
	nhdr->p_vaddr	= 0;
	nhdr->p_paddr	= 0;
	nhdr->p_filesz	= 0;
	nhdr->p_memsz	= 0;
	nhdr->p_flags	= 0;
	nhdr->p_align	= 0;

	/* setup ELF PT_LOAD program header for every area */
	for (m=kclist; m; m=m->next) {
		phdr = (struct elf_phdr *) bufp;
		bufp += sizeof(struct elf_phdr);
		offset += sizeof(struct elf_phdr);

		phdr->p_type	= PT_LOAD;
		phdr->p_flags	= PF_R|PF_W|PF_X;
		phdr->p_offset	= kc_vaddr_to_offset(m->addr) + dataoff;
		phdr->p_vaddr	= (size_t)m->addr;
		phdr->p_paddr	= 0;
		phdr->p_filesz	= phdr->p_memsz	= m->size;
		phdr->p_align	= PAGE_SIZE;
	}

	/*
	 * Set up the notes in similar form to SVR4 core dumps made
	 * with info from their /proc.
	 */
	nhdr->p_offset	= offset;

	/* set up the process status */
	notes[0].name = "CORE";
	notes[0].type = NT_PRSTATUS;
	notes[0].datasz = sizeof(struct elf_prstatus);
	notes[0].data = &prstatus;

	memset(&prstatus, 0, sizeof(struct elf_prstatus));

	nhdr->p_filesz	= notesize(&notes[0]);
	bufp = storenote(&notes[0], bufp);

	/* set up the process info */
	notes[1].name	= "CORE";
	notes[1].type	= NT_PRPSINFO;
	notes[1].datasz	= sizeof(struct elf_prpsinfo);
	notes[1].data	= &prpsinfo;

	memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
	prpsinfo.pr_state	= 0;
	prpsinfo.pr_sname	= 'R';
	prpsinfo.pr_zomb	= 0;

	strcpy(prpsinfo.pr_fname, "vmlinux");
	strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);

	nhdr->p_filesz	+= notesize(&notes[1]);
	bufp = storenote(&notes[1], bufp);

	/* set up the task structure */
	notes[2].name	= "CORE";
	notes[2].type	= NT_TASKSTRUCT;
	notes[2].datasz	= sizeof(struct task_struct);
	notes[2].data	= current;

	nhdr->p_filesz	+= notesize(&notes[2]);
	bufp = storenote(&notes[2], bufp);

} /* end elf_kcore_store_hdr() */

/*****************************************************************************/
/*
 * read from the ELF header and then kernel memory
 */
static ssize_t
read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
{
	ssize_t acc = 0;
	size_t size, tsz;
	size_t elf_buflen;
	int nphdr;
	unsigned long start;

	read_lock(&kclist_lock);
	proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen);
	if (buflen == 0 || *fpos >= size) {
		read_unlock(&kclist_lock);
		return 0;
	}

	/* trim buflen to not go beyond EOF */
	if (buflen > size - *fpos)
		buflen = size - *fpos;

	/* construct an ELF core header if we'll need some of it */
	if (*fpos < elf_buflen) {
		char * elf_buf;

		tsz = elf_buflen - *fpos;
		if (buflen < tsz)
			tsz = buflen;
		elf_buf = kmalloc(elf_buflen, GFP_ATOMIC);
		if (!elf_buf) {
			read_unlock(&kclist_lock);
			return -ENOMEM;
		}
		memset(elf_buf, 0, elf_buflen);
		elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
		read_unlock(&kclist_lock);
		if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
			kfree(elf_buf);
			return -EFAULT;
		}
		kfree(elf_buf);
		buflen -= tsz;
		*fpos += tsz;
		buffer += tsz;
		acc += tsz;

		/* leave now if filled buffer already */
		if (buflen == 0)
			return acc;
	} else
		read_unlock(&kclist_lock);

	/*
	 * Check to see if our file offset matches with any of
	 * the addresses in the elf_phdr on our list.
	 */
	start = kc_offset_to_vaddr(*fpos - elf_buflen);
	if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
		tsz = buflen;
		
	while (buflen) {
		struct kcore_list *m;

		read_lock(&kclist_lock);
		for (m=kclist; m; m=m->next) {
			if (start >= m->addr && start < (m->addr+m->size))
				break;
		}
		read_unlock(&kclist_lock);

		if (m == NULL) {
			if (clear_user(buffer, tsz))
				return -EFAULT;
		} else if ((start >= VMALLOC_START) && (start < VMALLOC_END)) {
			char * elf_buf;
			struct vm_struct *m;
			unsigned long curstart = start;
			unsigned long cursize = tsz;

			elf_buf = kmalloc(tsz, GFP_KERNEL);
			if (!elf_buf)
				return -ENOMEM;
			memset(elf_buf, 0, tsz);

			read_lock(&vmlist_lock);
			for (m=vmlist; m && cursize; m=m->next) {
				unsigned long vmstart;
				unsigned long vmsize;
				unsigned long msize = m->size - PAGE_SIZE;

				if (((unsigned long)m->addr + msize) < 
								curstart)
					continue;
				if ((unsigned long)m->addr > (curstart + 
								cursize))
					break;
				vmstart = (curstart < (unsigned long)m->addr ? 
					(unsigned long)m->addr : curstart);
				if (((unsigned long)m->addr + msize) > 
							(curstart + cursize))
					vmsize = curstart + cursize - vmstart;
				else
					vmsize = (unsigned long)m->addr + 
							msize - vmstart;
				curstart = vmstart + vmsize;
				cursize -= vmsize;
				/* don't dump ioremap'd stuff! (TA) */
				if (m->flags & VM_IOREMAP)
					continue;
				memcpy(elf_buf + (vmstart - start),
					(char *)vmstart, vmsize);
			}
			read_unlock(&vmlist_lock);
			if (copy_to_user(buffer, elf_buf, tsz)) {
				kfree(elf_buf);
				return -EFAULT;
			}
			kfree(elf_buf);
		} else {
			if (kern_addr_valid(start)) {
				unsigned long n;

				n = copy_to_user(buffer, (char *)start, tsz);
				/*
				 * We cannot distingush between fault on source
				 * and fault on destination. When this happens
				 * we clear too and hope it will trigger the
				 * EFAULT again.
				 */
				if (n) { 
					if (clear_user(buffer + tsz - n,
								tsz - n))
						return -EFAULT;
				}
			} else {
				if (clear_user(buffer, tsz))
					return -EFAULT;
			}
		}
		buflen -= tsz;
		*fpos += tsz;
		buffer += tsz;
		acc += tsz;
		start += tsz;
		tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
	}

	return acc;
}
Commit	Line	Data
1da177e4 LT	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/config.h>
	13	#include <linux/mm.h>
	14	#include <linux/proc_fs.h>
	15	#include <linux/user.h>
	16	#include <linux/a.out.h>
	17	#include <linux/elf.h>
	18	#include <linux/elfcore.h>
	19	#include <linux/vmalloc.h>
	20	#include <linux/highmem.h>
	21	#include <linux/init.h>
	22	#include <asm/uaccess.h>
	23	#include <asm/io.h>
	24
	25
	26	static int open_kcore(struct inode * inode, struct file * filp)
	27	{
	28	return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
	29	}
	30
	31	static ssize_t read_kcore(struct file , char __user , size_t, loff_t *);
	32
	33	struct file_operations proc_kcore_operations = {
	34	.read = read_kcore,
	35	.open = open_kcore,
	36	};
	37
	38	#ifndef kc_vaddr_to_offset
	39	#define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
	40	#endif
	41	#ifndef kc_offset_to_vaddr
	42	#define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
	43	#endif
	44
	45	#define roundup(x, y) ((((x)+((y)-1))/(y))*(y))
	46
	47	/* An ELF note in memory */
	48	struct memelfnote
	49	{
	50	const char *name;
	51	int type;
	52	unsigned int datasz;
	53	void *data;
	54	};
	55
	56	static struct kcore_list *kclist;
	57	static DEFINE_RWLOCK(kclist_lock);
	58
	59	void
	60	kclist_add(struct kcore_list new, void addr, size_t size)
	61	{
	62	new->addr = (unsigned long)addr;
	63	new->size = size;
	64
65	write_lock(&kclist_lock);
66	new->next = kclist;
67	kclist = new;
68	write_unlock(&kclist_lock);
69	}
70
71	static size_t get_kcore_size(int nphdr, size_t elf_buflen)
72	{
73	size_t try, size;
74	struct kcore_list *m;
75
76	nphdr = 1; / PT_NOTE */
77	size = 0;
78
79	for (m=kclist; m; m=m->next) {
80	try = kc_vaddr_to_offset((size_t)m->addr + m->size);
81	if (try > size)
82	size = try;
83	nphdr = nphdr + 1;
84	}
85	*elf_buflen = sizeof(struct elfhdr) +
86	(nphdr + 2)sizeof(struct elf_phdr) +
87	3 * (sizeof(struct elf_note) + 4) +
88	sizeof(struct elf_prstatus) +
89	sizeof(struct elf_prpsinfo) +
90	sizeof(struct task_struct);
91	elf_buflen = PAGE_ALIGN(elf_buflen);
92	return size + *elf_buflen;
93	}
94
95
96	/*****************************************************************************/
97	/*
98	* determine size of ELF note
99	*/
100	static int notesize(struct memelfnote *en)
101	{
102	int sz;
103
104	sz = sizeof(struct elf_note);
105	sz += roundup(strlen(en->name), 4);
106	sz += roundup(en->datasz, 4);
107
108	return sz;
109	} /* end notesize() */
110
111	/*****************************************************************************/
112	/*
113	* store a note in the header buffer
114	*/
115	static char storenote(struct memelfnote men, char *bufp)
116	{
117	struct elf_note en;
118
119	#define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
120
121	en.n_namesz = strlen(men->name);
122	en.n_descsz = men->datasz;
123	en.n_type = men->type;
124
125	DUMP_WRITE(&en, sizeof(en));
126	DUMP_WRITE(men->name, en.n_namesz);
127
128	/* XXX - cast from long long to long to avoid need for libgcc.a */
129	bufp = (char*) roundup((unsigned long)bufp,4);
130	DUMP_WRITE(men->data, men->datasz);
131	bufp = (char*) roundup((unsigned long)bufp,4);
132
133	#undef DUMP_WRITE
134
135	return bufp;
136	} /* end storenote() */
137
138	/*
139	* store an ELF coredump header in the supplied buffer
140	* nphdr is the number of elf_phdr to insert
141	*/
142	static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
143	{
144	struct elf_prstatus prstatus; /* NT_PRSTATUS */
145	struct elf_prpsinfo prpsinfo; /* NT_PRPSINFO */
146	struct elf_phdr nhdr, phdr;
147	struct elfhdr *elf;
148	struct memelfnote notes[3];
149	off_t offset = 0;
150	struct kcore_list *m;
151
152	/* setup ELF header */
153	elf = (struct elfhdr *) bufp;
154	bufp += sizeof(struct elfhdr);
155	offset += sizeof(struct elfhdr);
156	memcpy(elf->e_ident, ELFMAG, SELFMAG);
157	elf->e_ident[EI_CLASS] = ELF_CLASS;
158	elf->e_ident[EI_DATA] = ELF_DATA;
159	elf->e_ident[EI_VERSION]= EV_CURRENT;
160	elf->e_ident[EI_OSABI] = ELF_OSABI;
161	memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
162	elf->e_type = ET_CORE;
163	elf->e_machine = ELF_ARCH;
164	elf->e_version = EV_CURRENT;
165	elf->e_entry = 0;
166	elf->e_phoff = sizeof(struct elfhdr);
167	elf->e_shoff = 0;
168	#if defined(CONFIG_H8300)
169	elf->e_flags = ELF_FLAGS;
170	#else
171	elf->e_flags = 0;
172	#endif
173	elf->e_ehsize = sizeof(struct elfhdr);
174	elf->e_phentsize= sizeof(struct elf_phdr);
175	elf->e_phnum = nphdr;
176	elf->e_shentsize= 0;
177	elf->e_shnum = 0;
178	elf->e_shstrndx = 0;
179
180	/* setup ELF PT_NOTE program header */
181	nhdr = (struct elf_phdr *) bufp;
182	bufp += sizeof(struct elf_phdr);
183	offset += sizeof(struct elf_phdr);
184	nhdr->p_type = PT_NOTE;
185	nhdr->p_offset = 0;
186	nhdr->p_vaddr = 0;
187	nhdr->p_paddr = 0;
188	nhdr->p_filesz = 0;
189	nhdr->p_memsz = 0;
190	nhdr->p_flags = 0;
191	nhdr->p_align = 0;
192
193	/* setup ELF PT_LOAD program header for every area */
194	for (m=kclist; m; m=m->next) {
195	phdr = (struct elf_phdr *) bufp;
196	bufp += sizeof(struct elf_phdr);
197	offset += sizeof(struct elf_phdr);
198
199	phdr->p_type = PT_LOAD;
200	phdr->p_flags = PF_R\|PF_W\|PF_X;
201	phdr->p_offset = kc_vaddr_to_offset(m->addr) + dataoff;
202	phdr->p_vaddr = (size_t)m->addr;
203	phdr->p_paddr = 0;
204	phdr->p_filesz = phdr->p_memsz = m->size;
205	phdr->p_align = PAGE_SIZE;
206	}
207
208	/*
209	* Set up the notes in similar form to SVR4 core dumps made
210	* with info from their /proc.
211	*/
212	nhdr->p_offset = offset;
213
214	/* set up the process status */
215	notes[0].name = "CORE";
216	notes[0].type = NT_PRSTATUS;
217	notes[0].datasz = sizeof(struct elf_prstatus);
218	notes[0].data = &prstatus;
219
220	memset(&prstatus, 0, sizeof(struct elf_prstatus));
221
222	nhdr->p_filesz = notesize(&notes[0]);
223	bufp = storenote(&notes[0], bufp);
224
225	/* set up the process info */
226	notes[1].name = "CORE";
227	notes[1].type = NT_PRPSINFO;
228	notes[1].datasz = sizeof(struct elf_prpsinfo);
229	notes[1].data = &prpsinfo;
230
231	memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
232	prpsinfo.pr_state = 0;
233	prpsinfo.pr_sname = 'R';
234	prpsinfo.pr_zomb = 0;
235
236	strcpy(prpsinfo.pr_fname, "vmlinux");
237	strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
238
239	nhdr->p_filesz += notesize(&notes[1]);
240	bufp = storenote(&notes[1], bufp);
241
242	/* set up the task structure */
243	notes[2].name = "CORE";
244	notes[2].type = NT_TASKSTRUCT;
245	notes[2].datasz = sizeof(struct task_struct);
246	notes[2].data = current;
247
248	nhdr->p_filesz += notesize(&notes[2]);
249	bufp = storenote(&notes[2], bufp);
250
251	} /* end elf_kcore_store_hdr() */
252
253	/*****************************************************************************/
254	/*
255	* read from the ELF header and then kernel memory
256	*/
257	static ssize_t
258	read_kcore(struct file file, char __user buffer, size_t buflen, loff_t *fpos)
259	{
260	ssize_t acc = 0;
261	size_t size, tsz;
262	size_t elf_buflen;
263	int nphdr;
264	unsigned long start;
265
266	read_lock(&kclist_lock);
267	proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen);
268	if (buflen == 0 \|\| *fpos >= size) {
269	read_unlock(&kclist_lock);
270	return 0;
271	}
272
273	/* trim buflen to not go beyond EOF */
274	if (buflen > size - *fpos)
275	buflen = size - *fpos;
276
277	/* construct an ELF core header if we'll need some of it */
278	if (*fpos < elf_buflen) {
279	char * elf_buf;
280
281	tsz = elf_buflen - *fpos;
282	if (buflen < tsz)
283	tsz = buflen;
284	elf_buf = kmalloc(elf_buflen, GFP_ATOMIC);
285	if (!elf_buf) {
286	read_unlock(&kclist_lock);
287	return -ENOMEM;
288	}
289	memset(elf_buf, 0, elf_buflen);
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 ((start >= VMALLOC_START) && (start < VMALLOC_END)) {
330	char * elf_buf;
331	struct vm_struct *m;
332	unsigned long curstart = start;
333	unsigned long cursize = tsz;
334
335	elf_buf = kmalloc(tsz, GFP_KERNEL);
336	if (!elf_buf)
337	return -ENOMEM;
338	memset(elf_buf, 0, tsz);
339
340	read_lock(&vmlist_lock);
341	for (m=vmlist; m && cursize; m=m->next) {
342	unsigned long vmstart;
343	unsigned long vmsize;
344	unsigned long msize = m->size - PAGE_SIZE;
345
346	if (((unsigned long)m->addr + msize) <
347	curstart)
348	continue;
349	if ((unsigned long)m->addr > (curstart +
350	cursize))
351	break;
352	vmstart = (curstart < (unsigned long)m->addr ?
353	(unsigned long)m->addr : curstart);
354	if (((unsigned long)m->addr + msize) >
355	(curstart + cursize))
356	vmsize = curstart + cursize - vmstart;
357	else
358	vmsize = (unsigned long)m->addr +
359	msize - vmstart;
360	curstart = vmstart + vmsize;
361	cursize -= vmsize;
362	/* don't dump ioremap'd stuff! (TA) */
363	if (m->flags & VM_IOREMAP)
364	continue;
365	memcpy(elf_buf + (vmstart - start),
366	(char *)vmstart, vmsize);
367	}
368	read_unlock(&vmlist_lock);
369	if (copy_to_user(buffer, elf_buf, tsz)) {
370	kfree(elf_buf);
371	return -EFAULT;
372	}
373	kfree(elf_buf);
374	} else {
375	if (kern_addr_valid(start)) {
376	unsigned long n;
377
378	n = copy_to_user(buffer, (char *)start, tsz);
379	/*
380	* We cannot distingush between fault on source
381	* and fault on destination. When this happens
382	* we clear too and hope it will trigger the
383	* EFAULT again.
384	*/
385	if (n) {
386	if (clear_user(buffer + tsz - n,
387	tsz - n))
388	return -EFAULT;
389	}
390	} else {
391	if (clear_user(buffer, tsz))
392	return -EFAULT;
393	}
394	}
395	buflen -= tsz;
396	*fpos += tsz;
397	buffer += tsz;
398	acc += tsz;
399	start += tsz;
400	tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
401	}
402
403	return acc;
404	}