binfmt_elf.c

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 * These are the only things you should do on a core-file: use only these
 * functions to write out all the necessary info.
 */
static int dump_write(struct file *file, const void *addr, int nr)
{
	return file->f_op->write(file->f_inode, file, addr, nr) == nr;
}

static int dump_seek(struct file *file, off_t off)
{
	if (file->f_op->lseek) {
		if (file->f_op->lseek(file->f_inode, file, off, 0) != off)
			return 0;
	} else
		file->f_pos = off;
	return 1;
}

/*
 * Decide whether a segment is worth dumping; default is yes to be
 * sure (missing info is worse than too much; etc).
 * Personally I'd include everything, and use the coredump limit...
 *
 * I think we should skip something. But I am not sure how. H.J.
 */
static inline int maydump(struct vm_area_struct *vma)
{
	if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
		return 0;
#if 1
	if (vma->vm_flags & (VM_WRITE | VM_GROWSUP | VM_GROWSDOWN))
		return 1;
	if (vma->vm_flags & (VM_READ | VM_EXEC | VM_EXECUTABLE | VM_SHARED))
		return 0;
#endif
	return 1;
}

#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 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;
}

/* #define DEBUG */

#ifdef DEBUG
static void dump_regs(const char *str, elf_greg_t * r)
{
	int i;
	static const char *regs[] =
	{"ebx", "ecx", "edx", "esi", "edi", "ebp",
	 "eax", "ds", "es", "fs", "gs",
	 "orig_eax", "eip", "cs",
	 "efl", "uesp", "ss"};
	printk("Registers: %s\n", str);

	for (i = 0; i < ELF_NGREG; i++) {
		unsigned long val = r[i];
		printk("   %-2d %-5s=%08lx %lu\n", i, regs[i], val, val);
	}
}

#endif

#define DUMP_WRITE(addr, nr)	\
	do { if (!dump_write(file, (addr), (nr))) return 0; } while(0)
#define DUMP_SEEK(off)	\
	do { if (!dump_seek(file, (off))) return 0; } while(0)

static int writenote(struct memelfnote *men, struct file *file)
{
	struct elf_note en;

	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 */
	DUMP_SEEK(roundup((unsigned long) file->f_pos, 4));	/* XXX */
	DUMP_WRITE(men->data, men->datasz);
	DUMP_SEEK(roundup((unsigned long) file->f_pos, 4));	/* XXX */

	return 1;
}
#undef DUMP_WRITE
#undef DUMP_SEEK

#define DUMP_WRITE(addr, nr)	\
	if (!dump_write(&file, (addr), (nr))) \
		goto close_coredump;
#define DUMP_SEEK(off)	\
	if (!dump_seek(&file, (off))) \
		goto close_coredump;
/*
 * Actual dumper
 *
 * This is a two-pass process; first we find the offsets of the bits,
 * and then they are actually written out.  If we run out of core limit
 * we just truncate.
 */
static int elf_core_dump(long signr, struct pt_regs *regs)
{
	int has_dumped = 0;
	struct file file;
	struct inode *inode;
	unsigned short fs;
	char corefile[6 + sizeof(current->comm)];
	int segs;
	int i;
	size_t size;
	struct vm_area_struct *vma;
	struct elfhdr elf;
	off_t offset = 0, dataoff;
	int limit = current->rlim[RLIMIT_CORE].rlim_cur;
	int numnote = 4;
	struct memelfnote notes[4];
	struct elf_prstatus prstatus;	/* NT_PRSTATUS */
	elf_fpregset_t fpu;	/* NT_PRFPREG */
	struct elf_prpsinfo psinfo;	/* NT_PRPSINFO */

	if (!current->dumpable || limit < PAGE_SIZE || current->mm->count != 1)
		return 0;
	current->dumpable = 0;

#ifndef CONFIG_BINFMT_ELF
	MOD_INC_USE_COUNT;
#endif

	/* Count what's needed to dump, up to the limit of coredump size */
	segs = 0;
	size = 0;
	for (vma = current->mm->mmap; vma != NULL; vma = vma->vm_next) {
		if (maydump(vma)) {
			int sz = vma->vm_end - vma->vm_start;

			if (size + sz >= limit)
				break;
			else
				size += sz;
		}
		segs++;
	}
#ifdef DEBUG
	printk("elf_core_dump: %d segs taking %d bytes\n", segs, size);
#endif

	/* Set up header */
	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(elf);
	elf.e_shoff = 0;
	elf.e_flags = 0;
	elf.e_ehsize = sizeof(elf);
	elf.e_phentsize = sizeof(struct elf_phdr);
	elf.e_phnum = segs + 1;	/* Include notes */
	elf.e_shentsize = 0;
	elf.e_shnum = 0;
	elf.e_shstrndx = 0;

	fs = get_fs();
	set_fs(KERNEL_DS);
	memcpy(corefile, "core.", 5);
#if 0
	memcpy(corefile + 5, current->comm, sizeof(current->comm));
#else
	corefile[4] = '\0';
#endif
	if (open_namei(corefile, O_CREAT | 2 | O_TRUNC, 0600, &inode, NULL)) {
		inode = NULL;
		goto end_coredump;
	}
	if (!S_ISREG(inode->i_mode))
		goto end_coredump;
	if (!inode->i_op || !inode->i_op->default_file_ops)
		goto end_coredump;
	file.f_mode = 3;
	file.f_flags = 0;
	file.f_count = 1;
	file.f_inode = inode;
	file.f_pos = 0;
	file.f_reada = 0;
	file.f_op = inode->i_op->default_file_ops;
	if (file.f_op->open)
		if (file.f_op->open(inode, &file))
			goto end_coredump;
	if (!file.f_op->write)
		goto close_coredump;
	has_dumped = 1;
	current->flags |= PF_DUMPCORE;

	DUMP_WRITE(&elf, sizeof(elf));
	offset += sizeof(elf);	/* Elf header */
	offset += (segs + 1) * sizeof(struct elf_phdr);		/* Program headers */

	/*
	 * Set up the notes in similar form to SVR4 core dumps made
	 * with info from their /proc.
	 */
	memset(&psinfo, 0, sizeof(psinfo));
	memset(&prstatus, 0, sizeof(prstatus));

	notes[0].name = "CORE";
	notes[0].type = NT_PRSTATUS;
	notes[0].datasz = sizeof(prstatus);
	notes[0].data = &prstatus;
	prstatus.pr_info.si_signo = prstatus.pr_cursig = signr;
	prstatus.pr_sigpend = current->signal;
	prstatus.pr_sighold = current->blocked;
	psinfo.pr_pid = prstatus.pr_pid = current->pid;
	psinfo.pr_ppid = prstatus.pr_ppid = current->p_pptr->pid;
	psinfo.pr_pgrp = prstatus.pr_pgrp = current->pgrp;
	psinfo.pr_sid = prstatus.pr_sid = current->session;
	prstatus.pr_utime.tv_sec = CT_TO_SECS(current->utime);
	prstatus.pr_utime.tv_usec = CT_TO_USECS(current->utime);
	prstatus.pr_stime.tv_sec = CT_TO_SECS(current->stime);
	prstatus.pr_stime.tv_usec = CT_TO_USECS(current->stime);
	prstatus.pr_cutime.tv_sec = CT_TO_SECS(current->cutime);
	prstatus.pr_cutime.tv_usec = CT_TO_USECS(current->cutime);
	prstatus.pr_cstime.tv_sec = CT_TO_SECS(current->cstime);
	prstatus.pr_cstime.tv_usec = CT_TO_USECS(current->cstime);

	/*
	 * This transfers the registers from regs into the standard
	 * coredump arrangement, whatever that is.
	 */
#ifdef ELF_CORE_COPY_REGS
	ELF_CORE_COPY_REGS(prstatus.pr_reg, regs)
#else
	if (sizeof(elf_gregset_t) != sizeof(struct pt_regs)) {
		printk("sizeof(elf_gregset_t) (%d) != sizeof(struct pt_regs) (%d)\n",
		       sizeof(elf_gregset_t), sizeof(struct pt_regs));
	} else
		*(struct pt_regs *) &prstatus.pr_reg = *regs;
#endif

#ifdef DEBUG
	dump_regs("Passed in regs", (elf_greg_t *) regs);
	dump_regs("prstatus regs", (elf_greg_t *) & prstatus.pr_reg);
#endif

	notes[1].name = "CORE";
	notes[1].type = NT_PRPSINFO;
	notes[1].datasz = sizeof(psinfo);
	notes[1].data = &psinfo;
	psinfo.pr_state = current->state;
	psinfo.pr_sname = (current->state < 0 || current->state > 5) ? '.' : "RSDZTD"[current->state];
	psinfo.pr_zomb = psinfo.pr_sname == 'Z';
	psinfo.pr_nice = current->priority - 15;
	psinfo.pr_flag = current->flags;
	psinfo.pr_uid = current->uid;
	psinfo.pr_gid = current->gid;
	{
		int i, len;

		set_fs(fs);

		len = current->mm->arg_end - current->mm->arg_start;
		len = (len >= ELF_PRARGSZ - 1) ? ELF_PRARGSZ - 1 : len;
		memcpy_fromfs(&psinfo.pr_psargs,
			      (const char *) current->mm->arg_start, len);
		for (i = 0; i < len; i++)
			if (psinfo.pr_psargs[i] == 0)
				psinfo.pr_psargs[i] = ' ';
		psinfo.pr_psargs[len] = 0;

		set_fs(KERNEL_DS);
	}
	strncpy(psinfo.pr_fname, current->comm, sizeof(psinfo.pr_fname));

	notes[2].name = "CORE";
	notes[2].type = NT_TASKSTRUCT;
	notes[2].datasz = sizeof(*current);
	notes[2].data = current;

	/* Try to dump the fpu. */
	prstatus.pr_fpvalid = dump_fpu(regs, &fpu);
	if (!prstatus.pr_fpvalid) {
		numnote--;
	} else {
		notes[3].name = "CORE";
		notes[3].type = NT_PRFPREG;
		notes[3].datasz = sizeof(fpu);
		notes[3].data = &fpu;
	}

	/* Write notes phdr entry */
	{
		struct elf_phdr phdr;
		int sz = 0;

		for (i = 0; i < numnote; i++)
			sz += notesize(&notes[i]);

		phdr.p_type = PT_NOTE;
		phdr.p_offset = offset;
		phdr.p_vaddr = 0;
		phdr.p_paddr = 0;
		phdr.p_filesz = sz;
		phdr.p_memsz = 0;
		phdr.p_flags = 0;
		phdr.p_align = 0;

		offset += phdr.p_filesz;
		DUMP_WRITE(&phdr, sizeof(phdr));
	}

	/* Page-align dumped data */
	dataoff = offset = roundup(offset, PAGE_SIZE);

	/* Write program headers for segments dump */
	for (vma = current->mm->mmap, i = 0;
	     i < segs && vma != NULL; vma = vma->vm_next) {
		struct elf_phdr phdr;
		size_t sz;

		i++;

		sz = vma->vm_end - vma->vm_start;

		phdr.p_type = PT_LOAD;
		phdr.p_offset = offset;
		phdr.p_vaddr = vma->vm_start;
		phdr.p_paddr = 0;
		phdr.p_filesz = maydump(vma) ? sz : 0;
		phdr.p_memsz = sz;
		offset += phdr.p_filesz;
		phdr.p_flags = vma->vm_flags & VM_READ ? PF_R : 0;
		if (vma->vm_flags & VM_WRITE)
			phdr.p_flags |= PF_W;
		if (vma->vm_flags & VM_EXEC)
			phdr.p_flags |= PF_X;
		phdr.p_align = PAGE_SIZE;

		DUMP_WRITE(&phdr, sizeof(phdr));
	}

	for (i = 0; i < numnote; i++)
		if (!writenote(&notes[i], &file))
			goto close_coredump;

	set_fs(fs);

	DUMP_SEEK(dataoff);

	for (i = 0, vma = current->mm->mmap;
	     i < segs && vma != NULL;
	     vma = vma->vm_next) {
		unsigned long addr = vma->vm_start;
		unsigned long len = vma->vm_end - vma->vm_start;

		i++;
		if (!maydump(vma))
			continue;
#ifdef DEBUG
		printk("elf_core_dump: writing %08lx %lx\n", addr, len);
#endif
		DUMP_WRITE((void *) addr, len);
	}

	if ((off_t) file.f_pos != offset) {
		/* Sanity check */
		printk("elf_core_dump: file.f_pos (%ld) != offset (%ld)\n",
		       (off_t) file.f_pos, offset);
	}
      close_coredump:
	if (file.f_op->release)
		file.f_op->release(inode, &file);

      end_coredump:
	set_fs(fs);
	iput(inode);
#ifndef CONFIG_BINFMT_ELF
	MOD_DEC_USE_COUNT;
#endif
	return has_dumped;
}
#endif				/* USE_ELF_CORE_DUMP */

int init_elf_binfmt(void)
{
	return register_binfmt(&elf_format);
}

#ifdef MODULE

int init_module(void)
{
	/* Install the COFF, ELF and XOUT loaders.
	 * N.B. We *rely* on the table being the right size with the
	 * right number of free slots...
	 */
	return init_elf_binfmt();
}


void cleanup_module(void)
{
	/* Remove the COFF and ELF loaders. */
	unregister_binfmt(&elf_format);
}

#endif