From: Arnd Bergmann arnd@arndb.de

commit 4b692e861619353ce069e547a67c8d0e32d9ef3d upstream.

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: Arnd Bergmann arnd@arndb.de Co-developed-by: Eric Biederman ebiederm@xmission.com Co-developed-by: Christoph Hellwig hch@infradead.org Acked-by: "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: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: Wen Yang wenyang.linux@foxmail.com --- kernel/kexec.c | 44 ++++++++++++++++---------------------------- 1 file changed, 16 insertions(+), 28 deletions(-)

diff --git a/kernel/kexec.c b/kernel/kexec.c index c82c6c06f051..9c7aef8f4bb6 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -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