linux-stable.git/kernel/kexec_core.c, branch v6.5.2

kexec: enable kexec_crash_size to support two crash kernel regions

2023-06-10T00:44:24+00:00

The crashk_low_res should be considered by /sys/kernel/kexec_crash_size
to support two crash kernel regions shrinking if existing.

While doing it, crashk_low_res will only be shrunk when the entire
crashk_res is empty; and if the crashk_res is empty and crahk_low_res
is not, change crashk_low_res to be crashk_res.

[bhe@redhat.com: redo changelog]
Link: https://lkml.kernel.org/r/20230527123439.772-7-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei 
Acked-by: Baoquan He 
Cc: Cong Wang 
Cc: Eric W. Biederman 
Cc: Michael Holzheu 
Signed-off-by: Andrew Morton

kexec: add helper __crash_shrink_memory()

2023-06-10T00:44:24+00:00

No functional change, in preparation for the next patch so that it is
easier to review.

[akpm@linux-foundation.org: make  __crash_shrink_memory() static]
  Link: https://lore.kernel.org/oe-kbuild-all/202305280717.Pw06aLkz-lkp@intel.com/
Link: https://lkml.kernel.org/r/20230527123439.772-6-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei 
Acked-by: Baoquan He 
Cc: Cong Wang 
Cc: Eric W. Biederman 
Cc: Michael Holzheu 
Signed-off-by: Andrew Morton

kexec: improve the readability of crash_shrink_memory()

2023-06-10T00:44:24+00:00

The major adjustments are:
1. end = start + new_size.
   The 'end' here is not an accurate representation, because it is not the
   new end of crashk_res, but the start of ram_res, difference 1. So
   eliminate it and replace it with ram_res->start.
2. Use 'ram_res->start' and 'ram_res->end' as arguments to
   crash_free_reserved_phys_range() to indicate that the memory covered by
   'ram_res' is released from the crashk. And keep it close to
   insert_resource().
3. Replace 'if (start == end)' with 'if (!new_size)', clear indication that
   all crashk memory will be shrunken.

No functional change.

Link: https://lkml.kernel.org/r/20230527123439.772-5-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei 
Acked-by: Baoquan He 
Cc: Cong Wang 
Cc: Eric W. Biederman 
Cc: Michael Holzheu 
Signed-off-by: Andrew Morton

kexec: clear crashk_res if all its memory has been released

2023-06-10T00:44:23+00:00

If the resource of crashk_res has been released, it is better to clear
crashk_res.start and crashk_res.end.  Because 'end = start - 1' is not
reasonable, and in some places the test is based on crashk_res.end, not
resource_size(&crashk_res).

Link: https://lkml.kernel.org/r/20230527123439.772-4-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei 
Acked-by: Baoquan He 
Cc: Cong Wang 
Cc: Eric W. Biederman 
Cc: Michael Holzheu 
Signed-off-by: Andrew Morton

kexec: delete a useless check in crash_shrink_memory()

2023-06-10T00:44:23+00:00

The check '(crashk_res.parent != NULL)' is added by commit e05bd3367bd3
("kexec: fix Oops in crash_shrink_memory()"), but it's stale now.  Because
if 'crashk_res' is not reserved, it will be zero in size and will be
intercepted by the above 'if (new_size >= old_size)'.

Ago:
	if (new_size >= end - start + 1)

Now:
	old_size = (end == 0) ? 0 : end - start + 1;
	if (new_size >= old_size)

Link: https://lkml.kernel.org/r/20230527123439.772-3-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei 
Cc: Baoquan He 
Cc: Cong Wang 
Cc: Eric W. Biederman 
Cc: Michael Holzheu 
Signed-off-by: Andrew Morton

kexec: fix a memory leak in crash_shrink_memory()

2023-06-10T00:44:23+00:00

Patch series "kexec: enable kexec_crash_size to support two crash kernel
regions".

When crashkernel=X fails to reserve region under 4G, it will fall back to
reserve region above 4G and a region of the default size will also be
reserved under 4G.  Unfortunately, /sys/kernel/kexec_crash_size only
supports one crash kernel region now, the user cannot sense the low memory
reserved by reading /sys/kernel/kexec_crash_size.  Also, low memory cannot
be freed by writing this file.

For example:
resource_size(crashk_res) = 512M
resource_size(crashk_low_res) = 256M

The result of 'cat /sys/kernel/kexec_crash_size' is 512M, but it should be
768M.  When we execute 'echo 0 > /sys/kernel/kexec_crash_size', the size
of crashk_res becomes 0 and resource_size(crashk_low_res) is still 256 MB,
which is incorrect.

Since crashk_res manages the memory with high address and crashk_low_res
manages the memory with low address, crashk_low_res is shrunken only when
all crashk_res is shrunken.  And because when there is only one crash
kernel region, crashk_res is always used.  Therefore, if all crashk_res is
shrunken and crashk_low_res still exists, swap them.


This patch (of 6):

If the value of parameter 'new_size' is in the semi-open and semi-closed
interval (crashk_res.end - KEXEC_CRASH_MEM_ALIGN + 1, crashk_res.end], the
calculation result of ram_res is:

	ram_res->start = crashk_res.end + 1
	ram_res->end   = crashk_res.end

The operation of insert_resource() fails, and ram_res is not added to
iomem_resource.  As a result, the memory of the control block ram_res is
leaked.

In fact, on all architectures, the start address and size of crashk_res
are already aligned by KEXEC_CRASH_MEM_ALIGN.  Therefore, we do not need
to round up crashk_res.start again.  Instead, we should round up
'new_size' in advance.

Link: https://lkml.kernel.org/r/20230527123439.772-1-thunder.leizhen@huawei.com
Link: https://lkml.kernel.org/r/20230527123439.772-2-thunder.leizhen@huawei.com
Fixes: 6480e5a09237 ("kdump: add missing RAM resource in crash_shrink_memory()")
Fixes: 06a7f711246b ("kexec: premit reduction of the reserved memory size")
Signed-off-by: Zhen Lei 
Acked-by: Baoquan He 
Cc: Cong Wang 
Cc: Eric W. Biederman 
Cc: Michael Holzheu 
Signed-off-by: Andrew Morton

Merge tag 'mm-nonmm-stable-2023-02-20-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-02-24T01:55:40+00:00

Pull non-MM updates from Andrew Morton:
 "There is no particular theme here - mainly quick hits all over the
  tree.

  Most notable is a set of zlib changes from Mikhail Zaslonko which
  enhances and fixes zlib's use of S390 hardware support: 'lib/zlib: Set
  of s390 DFLTCC related patches for kernel zlib'"

* tag 'mm-nonmm-stable-2023-02-20-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (55 commits)
  Update CREDITS file entry for Jesper Juhl
  sparc: allow PM configs for sparc32 COMPILE_TEST
  hung_task: print message when hung_task_warnings gets down to zero.
  arch/Kconfig: fix indentation
  scripts/tags.sh: fix the Kconfig tags generation when using latest ctags
  nilfs2: prevent WARNING in nilfs_dat_commit_end()
  lib/zlib: remove redundation assignement of avail_in dfltcc_gdht()
  lib/Kconfig.debug: do not enable DEBUG_PREEMPT by default
  lib/zlib: DFLTCC always switch to software inflate for Z_PACKET_FLUSH option
  lib/zlib: DFLTCC support inflate with small window
  lib/zlib: Split deflate and inflate states for DFLTCC
  lib/zlib: DFLTCC not writing header bits when avail_out == 0
  lib/zlib: fix DFLTCC ignoring flush modes when avail_in == 0
  lib/zlib: fix DFLTCC not flushing EOBS when creating raw streams
  lib/zlib: implement switching between DFLTCC and software
  lib/zlib: adjust offset calculation for dfltcc_state
  nilfs2: replace WARN_ONs for invalid DAT metadata block requests
  scripts/spelling.txt: add "exsits" pattern and fix typo instances
  fs: gracefully handle ->get_block not mapping bh in __mpage_writepage
  cramfs: Kconfig: fix spelling & punctuation
  ...

kexec: introduce sysctl parameters kexec_load_limit_*

2023-02-03T06:50:05+00:00

kexec allows replacing the current kernel with a different one.  This is
usually a source of concerns for sysadmins that want to harden a system.

Linux already provides a way to disable loading new kexec kernel via
kexec_load_disabled, but that control is very coard, it is all or nothing
and does not make distinction between a panic kexec and a normal kexec.

This patch introduces new sysctl parameters, with finer tuning to specify
how many times a kexec kernel can be loaded.  The sysadmin can set
different limits for kexec panic and kexec reboot kernels.  The value can
be modified at runtime via sysctl, but only with a stricter value.

With these new parameters on place, a system with loadpin and verity
enabled, using the following kernel parameters:
sysctl.kexec_load_limit_reboot=0 sysct.kexec_load_limit_panic=1 can have a
good warranty that if initrd tries to load a panic kernel, a malitious
user will have small chances to replace that kernel with a different one,
even if they can trigger timeouts on the disk where the panic kernel
lives.

Link: https://lkml.kernel.org/r/20221114-disable-kexec-reset-v6-3-6a8531a09b9a@chromium.org
Signed-off-by: Ricardo Ribalda 
Reviewed-by: Steven Rostedt (Google) 
Acked-by: Baoquan He 
Cc: Bagas Sanjaya 
Cc: "Eric W. Biederman" 
Cc: Guilherme G. Piccoli  # Steam Deck
Cc: Joel Fernandes (Google) 
Cc: Jonathan Corbet 
Cc: Philipp Rudo 
Cc: Ross Zwisler 
Cc: Sergey Senozhatsky 
Signed-off-by: Andrew Morton

kexec: factor out kexec_load_permitted

2023-02-03T06:50:04+00:00

Both syscalls (kexec and kexec_file) do the same check, let's factor it
out.

Link: https://lkml.kernel.org/r/20221114-disable-kexec-reset-v6-2-6a8531a09b9a@chromium.org
Signed-off-by: Ricardo Ribalda 
Reviewed-by: Steven Rostedt (Google) 
Acked-by: Baoquan He 
Cc: Bagas Sanjaya 
Cc: "Eric W. Biederman" 
Cc: Guilherme G. Piccoli 
Cc: Joel Fernandes (Google) 
Cc: Jonathan Corbet 
Cc: Philipp Rudo 
Cc: Ross Zwisler 
Cc: Sergey Senozhatsky 
Signed-off-by: Andrew Morton

bpf: Add __bpf_kfunc tag to all kfuncs

2023-02-01T23:25:14+00:00

Now that we have the __bpf_kfunc tag, we should use add it to all
existing kfuncs to ensure that they'll never be elided in LTO builds.

Signed-off-by: David Vernet 
Signed-off-by: Daniel Borkmann 
Acked-by: Stanislav Fomichev 
Link: https://lore.kernel.org/bpf/20230201173016.342758-4-void@manifault.com