linux.git/kernel/kexec_core.c, branch v6.12.81

kexec: define functions to map and unmap segments

2026-03-13T16:20:27+00:00

[ Upstream commit 0091d9241ea24c5275be4a3e5a032862fd9de9ec ]

Implement kimage_map_segment() to enable IMA to map the measurement log
list to the kimage structure during the kexec 'load' stage. This function
gathers the source pages within the specified address range, and maps them
to a contiguous virtual address range.

This is a preparation for later usage.

Implement kimage_unmap_segment() for unmapping segments using vunmap().

Cc: Eric Biederman 
Cc: Baoquan He 
Cc: Vivek Goyal 
Cc: Dave Young 
Co-developed-by: Tushar Sugandhi 
Signed-off-by: Tushar Sugandhi 
Signed-off-by: Steven Chen 
Acked-by: Baoquan He 
Tested-by: Stefan Berger  # ppc64/kvm
Signed-off-by: Mimi Zohar 
Stable-dep-of: 10d1c75ed438 ("ima: verify the previous kernel's IMA buffer lies in addressable RAM")
Signed-off-by: Sasha Levin

sysctl: treewide: constify the ctl_table argument of proc_handlers

2024-07-24T18:59:29+00:00

const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.

This patch has been generated by the following coccinelle script:

```
  virtual patch

  @r1@
  identifier ctl, write, buffer, lenp, ppos;
  identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

  @r2@
  identifier func, ctl, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos)
  { ... }

  @r3@
  identifier func;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int , void *, size_t *, loff_t *);

  @r4@
  identifier func, ctl;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int , void *, size_t *, loff_t *);

  @r5@
  identifier func, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

```

* Code formatting was adjusted in xfs_sysctl.c to comply with code
  conventions. The xfs_stats_clear_proc_handler,
  xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
  adjusted.

* The ctl_table argument in proc_watchdog_common was const qualified.
  This is called from a proc_handler itself and is calling back into
  another proc_handler, making it necessary to change it as part of the
  proc_handler migration.

Co-developed-by: Thomas Weißschuh 
Signed-off-by: Thomas Weißschuh 
Co-developed-by: Joel Granados 
Signed-off-by: Joel Granados

kernel misc: Remove the now superfluous sentinel elements from ctl_table array

2024-04-24T07:43:53+00:00

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove the sentinel from ctl_table arrays. Reduce by one the values used
to compare the size of the adjusted arrays.

Signed-off-by: Joel Granados

Merge tag 'mm-nonmm-stable-2024-03-14-09-36' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-03-15T01:03:09+00:00

Pull non-MM updates from Andrew Morton:

 - Kuan-Wei Chiu has developed the well-named series "lib min_heap: Min
   heap optimizations".

 - Kuan-Wei Chiu has also sped up the library sorting code in the series
   "lib/sort: Optimize the number of swaps and comparisons".

 - Alexey Gladkov has added the ability for code running within an IPC
   namespace to alter its IPC and MQ limits. The series is "Allow to
   change ipc/mq sysctls inside ipc namespace".

 - Geert Uytterhoeven has contributed some dhrystone maintenance work in
   the series "lib: dhry: miscellaneous cleanups".

 - Ryusuke Konishi continues nilfs2 maintenance work in the series

	"nilfs2: eliminate kmap and kmap_atomic calls"
	"nilfs2: fix kernel bug at submit_bh_wbc()"

 - Nathan Chancellor has updated our build tools requirements in the
   series "Bump the minimum supported version of LLVM to 13.0.1".

 - Muhammad Usama Anjum continues with the selftests maintenance work in
   the series "selftests/mm: Improve run_vmtests.sh".

 - Oleg Nesterov has done some maintenance work against the signal code
   in the series "get_signal: minor cleanups and fix".

Plus the usual shower of singleton patches in various parts of the tree.
Please see the individual changelogs for details.

* tag 'mm-nonmm-stable-2024-03-14-09-36' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (77 commits)
  nilfs2: prevent kernel bug at submit_bh_wbc()
  nilfs2: fix failure to detect DAT corruption in btree and direct mappings
  ocfs2: enable ocfs2_listxattr for special files
  ocfs2: remove SLAB_MEM_SPREAD flag usage
  assoc_array: fix the return value in assoc_array_insert_mid_shortcut()
  buildid: use kmap_local_page()
  watchdog/core: remove sysctl handlers from public header
  nilfs2: use div64_ul() instead of do_div()
  mul_u64_u64_div_u64: increase precision by conditionally swapping a and b
  kexec: copy only happens before uchunk goes to zero
  get_signal: don't initialize ksig->info if SIGNAL_GROUP_EXIT/group_exec_task
  get_signal: hide_si_addr_tag_bits: fix the usage of uninitialized ksig
  get_signal: don't abuse ksig->info.si_signo and ksig->sig
  const_structs.checkpatch: add device_type
  Normalise "name (ad@dr)" MODULE_AUTHORs to "name "
  dyndbg: replace kstrdup() + strchr() with kstrdup_and_replace()
  list: leverage list_is_head() for list_entry_is_head()
  nilfs2: MAINTAINERS: drop unreachable project mirror site
  smp: make __smp_processor_id() 0-argument macro
  fat: fix uninitialized field in nostale filehandles
  ...

kexec: copy only happens before uchunk goes to zero

2024-03-06T21:07:39+00:00

When loading segments, ubytes is <= mbytes.  When ubytes is exhausted,
there could be remaining mbytes.  Then in the while loop, the buf pointer
advancing with mchunk will causing meaningless reading even though it
doesn't harm.

So let's change to make sure that all of the copying and the rest only
happens before uchunk goes to zero.

Link: https://lkml.kernel.org/r/20240222092119.5602-1-gaoshanliukou@163.com
Signed-off-by: yang.zhang 
Acked-by: Baoquan He 
Signed-off-by: Andrew Morton

crash: split crash dumping code out from kexec_core.c

2024-02-24T01:48:22+00:00

Currently, KEXEC_CORE select CRASH_CORE automatically because crash codes
need be built in to avoid compiling error when building kexec code even
though the crash dumping functionality is not enabled. E.g
--------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_KEXEC=y
CONFIG_KEXEC_FILE=y
---------------------

After splitting out crashkernel reservation code and vmcoreinfo exporting
code, there's only crash related code left in kernel/crash_core.c. Now
move crash related codes from kexec_core.c to crash_core.c and only build it
in when CONFIG_CRASH_DUMP=y.

And also wrap up crash codes inside CONFIG_CRASH_DUMP ifdeffery scope,
or replace inappropriate CONFIG_KEXEC_CORE ifdef with CONFIG_CRASH_DUMP
ifdef in generic kernel files.

With these changes, crash_core codes are abstracted from kexec codes and
can be disabled at all if only kexec reboot feature is wanted.

Link: https://lkml.kernel.org/r/20240124051254.67105-5-bhe@redhat.com
Signed-off-by: Baoquan He 
Cc: Al Viro 
Cc: Eric W. Biederman 
Cc: Hari Bathini 
Cc: Pingfan Liu 
Cc: Klara Modin 
Cc: Michael Kelley 
Cc: Nathan Chancellor 
Cc: Stephen Rothwell 
Cc: Yang Li 
Signed-off-by: Andrew Morton

kexec: do syscore_shutdown() in kernel_kexec

2024-01-12T23:20:47+00:00

syscore_shutdown() runs driver and module callbacks to get the system into
a state where it can be correctly shut down.  In commit 6f389a8f1dd2 ("PM
/ reboot: call syscore_shutdown() after disable_nonboot_cpus()")
syscore_shutdown() was removed from kernel_restart_prepare() and hence got
(incorrectly?) removed from the kexec flow.  This was innocuous until
commit 6735150b6997 ("KVM: Use syscore_ops instead of reboot_notifier to
hook restart/shutdown") changed the way that KVM registered its shutdown
callbacks, switching from reboot notifiers to syscore_ops.shutdown.  As
syscore_shutdown() is missing from kexec, KVM's shutdown hook is not run
and virtualisation is left enabled on the boot CPU which results in triple
faults when switching to the new kernel on Intel x86 VT-x with VMXE
enabled.

Fix this by adding syscore_shutdown() to the kexec sequence.  In terms of
where to add it, it is being added after migrating the kexec task to the
boot CPU, but before APs are shut down.  It is not totally clear if this
is the best place: in commit 6f389a8f1dd2 ("PM / reboot: call
syscore_shutdown() after disable_nonboot_cpus()") it is stated that
"syscore_ops operations should be carried with one CPU on-line and
interrupts disabled." APs are only offlined later in machine_shutdown(),
so this syscore_shutdown() is being run while APs are still online.  This
seems to be the correct place as it matches where syscore_shutdown() is
run in the reboot and halt flows - they also run it before APs are shut
down.  The assumption is that the commit message in commit 6f389a8f1dd2
("PM / reboot: call syscore_shutdown() after disable_nonboot_cpus()") is
no longer valid.

KVM has been discussed here as it is what broke loudly by not having
syscore_shutdown() in kexec, but this change impacts more than just KVM;
all drivers/modules which register a syscore_ops.shutdown callback will
now be invoked in the kexec flow.  Looking at some of them like x86 MCE it
is probably more correct to also shut these down during kexec. 
Maintainers of all drivers which use syscore_ops.shutdown are added on CC
for visibility.  They are:

arch/powerpc/platforms/cell/spu_base.c  .shutdown = spu_shutdown,
arch/x86/kernel/cpu/mce/core.c	        .shutdown = mce_syscore_shutdown,
arch/x86/kernel/i8259.c                 .shutdown = i8259A_shutdown,
drivers/irqchip/irq-i8259.c	        .shutdown = i8259A_shutdown,
drivers/irqchip/irq-sun6i-r.c	        .shutdown = sun6i_r_intc_shutdown,
drivers/leds/trigger/ledtrig-cpu.c	.shutdown = ledtrig_cpu_syscore_shutdown,
drivers/power/reset/sc27xx-poweroff.c	.shutdown = sc27xx_poweroff_shutdown,
kernel/irq/generic-chip.c	        .shutdown = irq_gc_shutdown,
virt/kvm/kvm_main.c	                .shutdown = kvm_shutdown,

This has been tested by doing a kexec on x86_64 and aarch64.

Link: https://lkml.kernel.org/r/20231213064004.2419447-1-jgowans@amazon.com
Fixes: 6735150b6997 ("KVM: Use syscore_ops instead of reboot_notifier to hook restart/shutdown")
Signed-off-by: James Gowans 
Cc: Baoquan He 
Cc: Eric Biederman 
Cc: Paolo Bonzini 
Cc: Sean Christopherson 
Cc: Marc Zyngier 
Cc: Arnd Bergmann 
Cc: Tony Luck 
Cc: Borislav Petkov 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Chen-Yu Tsai 
Cc: Jernej Skrabec 
Cc: Samuel Holland 
Cc: Pavel Machek 
Cc: Sebastian Reichel 
Cc: Orson Zhai 
Cc: Alexander Graf 
Cc: Jan H. Schoenherr 
Cc: 
Signed-off-by: Andrew Morton

kexec_core: fix the assignment to kimage->control_page

2023-12-29T20:22:29+00:00

image->control_page represents the starting address for allocating the
next control page, while hole_end represents the address of the last valid
byte of the currently allocated control page.

This bug actually does not affect the correctness of allocating control
pages, because image->control_page is currently only used in
kimage_alloc_crash_control_pages(), and this function, when allocating
control pages, will first align image->control_page up to the nearest
`(1 << order) << PAGE_SHIFT` boundary, then use this value as the
starting address of the next control page.  This ensures that the newly
allocated control page will use the correct starting address and not
overlap with previously allocated control pages.

Although it does not affect the correctness of the final result, it is
better for us to set image->control_page to the correct value, in case
it might be used elsewhere in the future, potentially causing errors.

Therefore, after successfully allocating a control page,
image->control_page should be updated to `hole_end + 1`, rather than
hole_end.

Link: https://lkml.kernel.org/r/20231221042308.11076-1-ytcoode@gmail.com
Signed-off-by: Yuntao Wang 
Cc: Baoquan He 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton

kexec: modify the meaning of the end parameter in kimage_is_destination_range()

2023-12-29T20:22:25+00:00

The end parameter received by kimage_is_destination_range() should be the
last valid byte address of the target memory segment plus 1.  However, in
the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
the corresponding value passed to kimage_is_destination_range() is the
last valid byte address of the target memory segment, which is 1 less.

There are two ways to fix this bug.  We can either correct the logic of
the locate_mem_hole_bottom_up() and locate_mem_hole_top_down() functions,
or we can fix kimage_is_destination_range() by making the end parameter
represent the last valid byte address of the target memory segment.  Here,
we choose the second approach.

Due to the modification to kimage_is_destination_range(), we also need to
adjust its callers, such as kimage_alloc_normal_control_pages() and
kimage_alloc_page().

Link: https://lkml.kernel.org/r/20231217033528.303333-2-ytcoode@gmail.com
Signed-off-by: Yuntao Wang 
Acked-by: Baoquan He 
Cc: Borislav Petkov (AMD) 
Cc: Dave Hansen 
Cc: "Eric W. Biederman" 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Jonathan Corbet 
Cc: Thomas Gleixner 
Signed-off-by: Andrew Morton

kexec: use ALIGN macro instead of open-coding it

2023-12-20T23:02:58+00:00

Use ALIGN macro instead of open-coding it to improve code readability.

Link: https://lkml.kernel.org/r/20231212142706.25149-1-ytcoode@gmail.com
Signed-off-by: Yuntao Wang 
Acked-by: Baoquan He 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton