Commit 4b692e86 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Linus Torvalds
Browse files

kexec: move locking into do_kexec_load 

Patch series "compat: remove compat_alloc_user_space", v5.

Going through compat_alloc_user_space() to convert indirect system call
arguments tends to add complexity compared to handling the native and
compat logic in the same code.

This patch (of 6):

The locking is the same between the native and compat version of
sys_kexec_load(), so it can be done in the common implementation to reduce
duplication.

Link: https://lkml.kernel.org/r/20210727144859.4150043-1-arnd@kernel.org
Link: https://lkml.kernel.org/r/20210727144859.4150043-2-arnd@kernel.org


Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Co-developed-by: default avatarEric Biederman <ebiederm@xmission.com>
Co-developed-by: default avatarChristoph Hellwig <hch@infradead.org>
Acked-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 213ecb31

kernel/kexec.c

+16 −28
Original line number Diff line number Diff line
@@ -110,6 +110,17 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments, 
	unsigned long i;

	int ret;



	/*

	 * 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;



	if (flags & KEXEC_ON_CRASH) {

		dest_image = &kexec_crash_image;

		if (kexec_crash_image)
@@ -121,7 +132,8 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments, 
	if (nr_segments == 0) {

		/* Uninstall image */

		kimage_free(xchg(dest_image, NULL));

		return 0;

		ret = 0;

		goto out_unlock;

	}

	if (flags & KEXEC_ON_CRASH) {

		/*
@@ -134,7 +146,7 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments, 


	ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags);

	if (ret)

		return ret;

		goto out_unlock;



	if (flags & KEXEC_PRESERVE_CONTEXT)

		image->preserve_context = 1;
@@ -171,6 +183,8 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments, 
		arch_kexec_protect_crashkres();



	kimage_free(image);

out_unlock:

	mutex_unlock(&kexec_mutex);

	return ret;

}
@@ -247,21 +261,8 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, 
		((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))

		return -EINVAL;



	/* 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;



	result = do_kexec_load(entry, nr_segments, segments, flags);



	mutex_unlock(&kexec_mutex);



	return result;

}
@@ -301,21 +302,8 @@ COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry, 
			return -EFAULT;

	}



	/* 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;



	result = do_kexec_load(entry, nr_segments, ksegments, flags);



	mutex_unlock(&kexec_mutex);



	return result;

}

#endif