linux-stable.git/include/linux/kexec.h, branch v5.15.208

kexec: turn all kexec_mutex acquisitions into trylocks

2023-04-20T10:13:57+00:00

commit 7bb5da0d490b2d836c5218f5186ee588d2145310 upstream.

Patch series "kexec, panic: Making crash_kexec() NMI safe", v4.


This patch (of 2):

Most acquistions of kexec_mutex are done via mutex_trylock() - those were
a direct "translation" from:

  8c5a1cf0ad3a ("kexec: use a mutex for locking rather than xchg()")

there have however been two additions since then that use mutex_lock():
crash_get_memory_size() and crash_shrink_memory().

A later commit will replace said mutex with an atomic variable, and
locking operations will become atomic_cmpxchg().  Rather than having those
mutex_lock() become while (atomic_cmpxchg(&lock, 0, 1)), turn them into
trylocks that can return -EBUSY on acquisition failure.

This does halve the printable size of the crash kernel, but that's still
neighbouring 2G for 32bit kernels which should be ample enough.

Link: https://lkml.kernel.org/r/20220630223258.4144112-1-vschneid@redhat.com
Link: https://lkml.kernel.org/r/20220630223258.4144112-2-vschneid@redhat.com
Signed-off-by: Valentin Schneider 
Cc: Arnd Bergmann 
Cc: "Eric W . Biederman" 
Cc: Juri Lelli 
Cc: Luis Claudio R. Goncalves 
Cc: Miaohe Lin 
Cc: Petr Mladek 
Cc: Sebastian Andrzej Siewior 
Cc: Thomas Gleixner 
Cc: Baoquan He 
Signed-off-by: Andrew Morton 
Signed-off-by: Wen Yang 
Signed-off-by: Greg Kroah-Hartman

ima: force signature verification when CONFIG_KEXEC_SIG is configured

2022-07-21T19:24:29+00:00

[ Upstream commit af16df54b89dee72df253abc5e7b5e8a6d16c11c ]

Currently, an unsigned kernel could be kexec'ed when IMA arch specific
policy is configured unless lockdown is enabled. Enforce kernel
signature verification check in the kexec_file_load syscall when IMA
arch specific policy is configured.

Fixes: 99d5cadfde2b ("kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE")
Reported-and-suggested-by: Mimi Zohar 
Signed-off-by: Coiby Xu 
Signed-off-by: Mimi Zohar 
Signed-off-by: Sasha Levin

kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add]

2022-06-09T08:23:27+00:00

commit 3e35142ef99fe6b4fe5d834ad43ee13cca10a2dc upstream.

Since commit d1bcae833b32f1 ("ELF: Don't generate unused section
symbols") [1], binutils (v2.36+) started dropping section symbols that
it thought were unused.  This isn't an issue in general, but with
kexec_file.c, gcc is placing kexec_arch_apply_relocations[_add] into a
separate .text.unlikely section and the section symbol ".text.unlikely"
is being dropped. Due to this, recordmcount is unable to find a non-weak
symbol in .text.unlikely to generate a relocation record against.

Address this by dropping the weak attribute from these functions.
Instead, follow the existing pattern of having architectures #define the
name of the function they want to override in their headers.

[1] https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d1bcae833b32f1

[akpm@linux-foundation.org: arch/s390/include/asm/kexec.h needs linux/module.h]
Link: https://lkml.kernel.org/r/20220519091237.676736-1-naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Michael Ellerman 
Signed-off-by: Naveen N. Rao 
Cc: "Eric W. Biederman" 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Greg Kroah-Hartman

powerpc: Move ima buffer fields to struct kimage

2021-03-08T19:06:29+00:00

The fields ima_buffer_addr and ima_buffer_size in "struct kimage_arch"
for powerpc are used to carry forward the IMA measurement list across
kexec system call.  These fields are not architecture specific, but are
currently limited to powerpc.

arch_ima_add_kexec_buffer() defined in "arch/powerpc/kexec/ima.c"
sets ima_buffer_addr and ima_buffer_size for the kexec system call.
This function does not have architecture specific code, but is
currently limited to powerpc.

Move ima_buffer_addr and ima_buffer_size to "struct kimage".
Set ima_buffer_addr and ima_buffer_size in ima_add_kexec_buffer()
in security/integrity/ima/ima_kexec.c.

Co-developed-by: Prakhar Srivastava 
Signed-off-by: Prakhar Srivastava 
Signed-off-by: Lakshmi Ramasubramanian 
Suggested-by: Will Deacon 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Rob Herring 
Link: https://lore.kernel.org/r/20210221174930.27324-9-nramas@linux.microsoft.com

kexec: Move ELF fields to struct kimage

2021-03-08T19:06:28+00:00

ELF related fields elf_headers, elf_headers_sz, and elf_load_addr are
defined in architecture specific 'struct kimage_arch' for x86, powerpc,
and arm64.  The name of these fields are different in these
architectures that makes it hard to have a common code for setting up
the device tree for kexec system call.

Move the ELF fields to 'struct kimage' defined in include/linux/kexec.h
so common code can use it.

Suggested-by: Rob Herring 
Reported-by: kernel test robot 
Signed-off-by: Lakshmi Ramasubramanian 
Reviewed-by: Thiago Jung Bauermann 
Signed-off-by: Rob Herring 
Link: https://lore.kernel.org/r/20210221174930.27324-2-nramas@linux.microsoft.com

Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

2021-02-26T18:19:03+00:00

Pull arm64 fixes from Will Deacon:
 "The big one is a fix for the VHE enabling path during early boot,
  where the code enabling the MMU wasn't necessarily in the identity map
  of the new page-tables, resulting in a consistent crash with 64k
  pages. In fixing that, we noticed some missing barriers too, so we
  added those for the sake of architectural compliance.

  Other than that, just the usual merge window trickle. There'll be more
  to come, too.

  Summary:

   - Fix lockdep false alarm on resume-from-cpuidle path

   - Fix memory leak in kexec_file

   - Fix module linker script to work with GDB

   - Fix error code when trying to use uprobes with AArch32 instructions

   - Fix late VHE enabling with 64k pages

   - Add missing ISBs after TLB invalidation

   - Fix seccomp when tracing syscall -1

   - Fix stacktrace return code at end of stack

   - Fix inconsistent whitespace for pointer return values

   - Fix compiler warnings when building with W=1"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: stacktrace: Report when we reach the end of the stack
  arm64: ptrace: Fix seccomp of traced syscall -1 (NO_SYSCALL)
  arm64: Add missing ISB after invalidating TLB in enter_vhe
  arm64: Add missing ISB after invalidating TLB in __primary_switch
  arm64: VHE: Enable EL2 MMU from the idmap
  KVM: arm64: make the hyp vector table entries local
  arm64/mm: Fixed some coding style issues
  arm64: uprobe: Return EOPNOTSUPP for AARCH32 instruction probing
  kexec: move machine_kexec_post_load() to public interface
  arm64 module: set plt* section addresses to 0x0
  arm64: kexec_file: fix memory leakage in create_dtb() when fdt_open_into() fails
  arm64: spectre: Prevent lockdep splat on v4 mitigation enable path

kexec: move machine_kexec_post_load() to public interface

2021-02-22T12:33:26+00:00

The kernel test robot reports the following compiler warning:

  | arch/arm64/kernel/machine_kexec.c:62:5: warning: no previous prototype for
  | function 'machine_kexec_post_load' [-Wmissing-prototypes]
  |    int machine_kexec_post_load(struct kimage *kimage)

Fix it by moving the declaration of machine_kexec_post_load() from
kexec_internal.h to the public header instead.

Reported-by: kernel test robot 
Link: https://lore.kernel.org/linux-arm-kernel/202102030727.gqTokACH-lkp@intel.com
Signed-off-by: Pavel Tatashin 
Link: https://lore.kernel.org/r/20210219195142.13571-1-pasha.tatashin@soleen.com
Fixes: 4c3c31230c91 ("arm64: kexec: move relocation function setup")
Signed-off-by: Will Deacon

ima: Free IMA measurement buffer after kexec syscall

2021-02-10T20:49:38+00:00

IMA allocates kernel virtual memory to carry forward the measurement
list, from the current kernel to the next kernel on kexec system call,
in ima_add_kexec_buffer() function.  This buffer is not freed before
completing the kexec system call resulting in memory leak.

Add ima_buffer field in "struct kimage" to store the virtual address
of the buffer allocated for the IMA measurement list.
Free the memory allocated for the IMA measurement list in
kimage_file_post_load_cleanup() function.

Signed-off-by: Lakshmi Ramasubramanian 
Suggested-by: Tyler Hicks 
Reviewed-by: Thiago Jung Bauermann 
Reviewed-by: Tyler Hicks 
Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")
Signed-off-by: Mimi Zohar

kexec_file: Allow archs to handle special regions while locating memory hole

2020-07-29T13:47:53+00:00

Some architectures may have special memory regions, within the given
memory range, which can't be used for the buffer in a kexec segment.
Implement weak arch_kexec_locate_mem_hole() definition which arch code
may override, to take care of special regions, while trying to locate
a memory hole.

Also, add the missing declarations for arch overridable functions and
and drop the __weak descriptors in the declarations to avoid non-weak
definitions from becoming weak.

Signed-off-by: Hari Bathini 
Tested-by: Pingfan Liu 
Reviewed-by: Thiago Jung Bauermann 
Acked-by: Dave Young 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/159602273603.575379.17665852963340380839.stgit@hbathini

kexec: Replace zero-length array with flexible-array

2020-06-16T04:08:31+00:00

There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].

[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21

Signed-off-by: Gustavo A. R. Silva