/* * kexec.c - kexec_load system call * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com> * * This source code is licensed under the GNU General Public License, * Version 2.  See the file COPYING for more details. */ #include <linux/capability.h>#include <linux/mm.h>#include <linux/file.h>#include <linux/kexec.h>#include <linux/mutex.h>#include <linux/list.h>#include <linux/syscalls.h>#include <linux/vmalloc.h>#include <linux/slab.h> #include "kexec_internal.h" static int copy_user_segment_list(struct kimage *image,				  unsigned long nr_segments,				  struct kexec_segment __user *segments){	int ret;	size_t segment_bytes; 	/* Read in the segments */	image->nr_segments = nr_segments;	segment_bytes = nr_segments * sizeof(*segments);	ret = copy_from_user(image->segment, segments, segment_bytes);	if (ret)		ret = -EFAULT; 	return ret;} static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,			     unsigned long nr_segments,			     struct kexec_segment __user *segments,			     unsigned long flags){	int ret;	struct kimage *image;	bool kexec_on_panic = flags & KEXEC_ON_CRASH; 	if (kexec_on_panic) {		/* Verify we have a valid entry point */		if ((entry < crashk_res.start) || (entry > crashk_res.end))			return -EADDRNOTAVAIL;	} 	/* Allocate and initialize a controlling structure */	image = do_kimage_alloc_init();	if (!image)		return -ENOMEM; 	image->start = entry; 	ret = copy_user_segment_list(image, nr_segments, segments);	if (ret)		goto out_free_image; 	ret = sanity_check_segment_list(image);	if (ret)		goto out_free_image; 	 /* Enable the special crash kernel control page allocation policy. */	if (kexec_on_panic) {		image->control_page = crashk_res.start;		image->type = KEXEC_TYPE_CRASH;	} 	/*	 * Find a location for the control code buffer, and add it	 * the vector of segments so that it's pages will also be	 * counted as destination pages.	 */	ret = -ENOMEM;	image->control_code_page = kimage_alloc_control_pages(image,					   get_order(KEXEC_CONTROL_PAGE_SIZE));	if (!image->control_code_page) {		pr_err("Could not allocate control_code_buffer\n");		goto out_free_image;	} 	if (!kexec_on_panic) {		image->swap_page = kimage_alloc_control_pages(image, 0);		if (!image->swap_page) {			pr_err("Could not allocate swap buffer\n");			goto out_free_control_pages;		}	} 	*rimage = image;	return 0;out_free_control_pages:	kimage_free_page_list(&image->control_pages);out_free_image:	kfree(image);	return ret;} /* * Exec Kernel system call: for obvious reasons only root may call it. * * This call breaks up into three pieces. * - A generic part which loads the new kernel from the current *   address space, and very carefully places the data in the *   allocated pages. * * - A generic part that interacts with the kernel and tells all of *   the devices to shut down.  Preventing on-going dmas, and placing *   the devices in a consistent state so a later kernel can *   reinitialize them. * * - A machine specific part that includes the syscall number *   and then copies the image to it's final destination.  And *   jumps into the image at entry. * * kexec does not sync, or unmount filesystems so if you need * that to happen you need to do that yourself. */ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,		struct kexec_segment __user *, segments, unsigned long, flags){	struct kimage **dest_image, *image;	int result; 	/* We only trust the superuser with rebooting the system. */	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)		return -EPERM; 	/*	 * Verify we have a legal set of flags	 * This leaves us room for future extensions.	 */	if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK))		return -EINVAL; 	/* Verify we are on the appropriate architecture */	if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) &&		((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))		return -EINVAL; 	/* Put an artificial cap on the number	 * of segments passed to kexec_load.	 */	if (nr_segments > KEXEC_SEGMENT_MAX)		return -EINVAL; 	image = NULL;	result = 0; 	/* Because we write directly to the reserved memory	 * region when loading crash kernels we need a mutex here to	 * prevent multiple crash  kernels from attempting to load	 * simultaneously, and to prevent a crash kernel from loading	 * over the top of a in use crash kernel.	 *	 * KISS: always take the mutex.	 */	if (!mutex_trylock(&kexec_mutex))		return -EBUSY; 	dest_image = &kexec_image;	if (flags & KEXEC_ON_CRASH)		dest_image = &kexec_crash_image;	if (nr_segments > 0) {		unsigned long i; 		if (flags & KEXEC_ON_CRASH) {			/*			 * Loading another kernel to switch to if this one			 * crashes.  Free any current crash dump kernel before			 * we corrupt it.			 */ 			kimage_free(xchg(&kexec_crash_image, NULL));			result = kimage_alloc_init(&image, entry, nr_segments,						   segments, flags);			crash_map_reserved_pages();		} else {			/* Loading another kernel to reboot into. */ 			result = kimage_alloc_init(&image, entry, nr_segments,						   segments, flags);		}		if (result)			goto out; 		if (flags & KEXEC_PRESERVE_CONTEXT)			image->preserve_context = 1;		result = machine_kexec_prepare(image);		if (result)			goto out; 		for (i = 0; i < nr_segments; i++) {			result = kimage_load_segment(image, &image->segment[i]);			if (result)				goto out;		}		kimage_terminate(image);		if (flags & KEXEC_ON_CRASH)			crash_unmap_reserved_pages();	}	/* Install the new kernel, and  Uninstall the old */	image = xchg(dest_image, image); out:	mutex_unlock(&kexec_mutex);	kimage_free(image); 	return result;} #ifdef CONFIG_COMPATCOMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry,		       compat_ulong_t, nr_segments,		       struct compat_kexec_segment __user *, segments,		       compat_ulong_t, flags){	struct compat_kexec_segment in;	struct kexec_segment out, __user *ksegments;	unsigned long i, result; 	/* Don't allow clients that don't understand the native	 * architecture to do anything.	 */	if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)		return -EINVAL; 	if (nr_segments > KEXEC_SEGMENT_MAX)		return -EINVAL; 	ksegments = compat_alloc_user_space(nr_segments * sizeof(out));	for (i = 0; i < nr_segments; i++) {		result = copy_from_user(&in, &segments[i], sizeof(in));		if (result)			return -EFAULT; 		out.buf   = compat_ptr(in.buf);		out.bufsz = in.bufsz;		out.mem   = in.mem;		out.memsz = in.memsz; 		result = copy_to_user(&ksegments[i], &out, sizeof(out));		if (result)			return -EFAULT;	} 	return sys_kexec_load(entry, nr_segments, ksegments, flags);}#endif