kcore.c

嵌入式系统设计与实例开发源码

/*
 *	fs/proc/kcore.c kernel ELF/AOUT core dumper
 *
 *	Modelled on fs/exec.c:aout_core_dump()
 *	Jeremy Fitzhardinge <[e-mail]>
 *	ELF version written by David Howells <[e-mail]>
 *	Modified and incorporated into 2.3.x by Tigran Aivazian <[e-mail]>
 *	Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <[e-mail]>
 *	Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <[e-mail]>
 */

#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 <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 *, size_t, loff_t *);

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

#ifdef CONFIG_KCORE_AOUT
static ssize_t read_kcore(struct file *file, char *buf, size_t count, loff_t *ppos)
{
	unsigned long long p = *ppos, memsize;
	ssize_t read;
	ssize_t count1;
	char * pnt;
	struct user dump;
#if defined (__i386__) || defined (__mc68000__) || defined(__x86_64__)
#	define FIRST_MAPPED	PAGE_SIZE	/* we don't have page 0 mapped on x86.. */
#else
#	define FIRST_MAPPED	0
#endif

	memset(&dump, 0, sizeof(struct user));
	dump.magic = CMAGIC;
	dump.u_dsize = (virt_to_phys(high_memory) >> PAGE_SHIFT);
#if defined (__i386__) || defined(__x86_64__)
	dump.start_code = PAGE_OFFSET;
#endif
#ifdef __alpha__
	dump.start_data = PAGE_OFFSET;
#endif

	memsize = virt_to_phys(high_memory);
	if (p >= memsize)
		return 0;
	if (count > memsize - p)
		count = memsize - p;
	read = 0;

	if (p < sizeof(struct user) && count > 0) {
		count1 = count;
		if (p + count1 > sizeof(struct user))
			count1 = sizeof(struct user)-p;
		pnt = (char *) &dump + p;
		if (copy_to_user(buf,(void *) pnt, count1))
			return -EFAULT;
		buf += count1;
		p += count1;
		count -= count1;
		read += count1;
	}

	if (count > 0 && p < PAGE_SIZE + FIRST_MAPPED) {
		count1 = PAGE_SIZE + FIRST_MAPPED - p;
		if (count1 > count)
			count1 = count;
		if (clear_user(buf, count1))
			return -EFAULT;
		buf += count1;
		p += count1;
		count -= count1;
		read += count1;
	}
	if (count > 0) {
		if (copy_to_user(buf, (void *) (PAGE_OFFSET+p-PAGE_SIZE), count))
			return -EFAULT;
		read += count;
	}
	*ppos += read;
	return read;
}
#else /* CONFIG_KCORE_AOUT */

#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;
};

extern char saved_command_line[];

static size_t get_kcore_size(int *num_vma, size_t *elf_buflen)
{
	size_t try, size;
	struct vm_struct *m;

	*num_vma = 0;
	size = ((size_t)high_memory - PAGE_OFFSET + PAGE_SIZE);
	if (!vmlist) {
		*elf_buflen = PAGE_SIZE;
		return (size);
	}

	for (m=vmlist; m; m=m->next) {
		try = (size_t)m->addr + m->size;
		if (try > size)
			size = try;
		*num_vma = *num_vma + 1;
	}
	*elf_buflen =	sizeof(struct elfhdr) + 
			(*num_vma + 2)*sizeof(struct elf_phdr) + 
			3 * sizeof(struct memelfnote);
	*elf_buflen = PAGE_ALIGN(*elf_buflen);
	return (size - PAGE_OFFSET + *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
 * num_vma is the number of elements in vmlist
 */
static void elf_kcore_store_hdr(char *bufp, int num_vma, 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 vm_struct *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;
	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;
	elf->e_flags	= 0;
	elf->e_ehsize	= sizeof(struct elfhdr);
	elf->e_phentsize= sizeof(struct elf_phdr);
	elf->e_phnum	= 2 + num_vma;
	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 the 
	 * virtual range 0xc0000000 -> high_memory */
	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	= dataoff;
	phdr->p_vaddr	= PAGE_OFFSET;
	phdr->p_paddr	= __pa(PAGE_OFFSET);
	phdr->p_filesz	= phdr->p_memsz = ((unsigned long)high_memory - PAGE_OFFSET);
	phdr->p_align	= PAGE_SIZE;

	/* setup ELF PT_LOAD program header for every vmalloc'd area */
	for (m=vmlist; m; m=m->next) {
		if (m->flags & VM_IOREMAP) /* don't dump ioremap'd stuff! (TA) */
			continue;

		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	= (size_t)m->addr - PAGE_OFFSET + dataoff;
		phdr->p_vaddr	= (size_t)m->addr;
		phdr->p_paddr	= __pa(m->addr);
		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 *buffer, size_t buflen, loff_t *fpos)
{
	ssize_t acc = 0;
	size_t size, tsz;
	size_t elf_buflen;
	int num_vma;
	unsigned long start;

	read_lock(&vmlist_lock);
	proc_root_kcore->size = size = get_kcore_size(&num_vma, &elf_buflen);
	if (buflen == 0 || *fpos >= size) {
		read_unlock(&vmlist_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(&vmlist_lock);
			return -ENOMEM;
		}
		memset(elf_buf, 0, elf_buflen);
		elf_kcore_store_hdr(elf_buf, num_vma, elf_buflen);
		read_unlock(&vmlist_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(&vmlist_lock);

	/* where page 0 not mapped, write zeros into buffer */
#if defined (__i386__) || defined (__mc68000__) || defined(__x86_64__)
	if (*fpos < PAGE_SIZE + elf_buflen) {
		/* work out how much to clear */
		tsz = PAGE_SIZE + elf_buflen - *fpos;
		if (buflen < tsz)
			tsz = buflen;

		/* write zeros to buffer */
		if (clear_user(buffer, tsz))
			return -EFAULT;
		buflen -= tsz;
		*fpos += tsz;
		buffer += tsz;
		acc += tsz;

		/* leave now if filled buffer already */
		if (buflen == 0)
			return tsz;
	}
#endif
	/* fill the remainder of the buffer from kernel VM space */
	start = (unsigned long)__va(*fpos - elf_buflen);
	if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
		tsz = buflen;
		
	while (buflen) {
		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 ((start > PAGE_OFFSET) && (start < 
						(unsigned long)high_memory)) {
			if (kern_addr_valid(start)) {
				if (copy_to_user(buffer, (char *)start, tsz))
					return -EFAULT;
			} else {
				if (clear_user(buffer, tsz))
					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;
}
#endif /* CONFIG_KCORE_AOUT */