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

kexec: derive purgatory entry from symbol

2026-03-04T12:21:51+00:00

[ Upstream commit 480e1d5c64bb14441f79f2eb9421d5e26f91ea3d ]

kexec_load_purgatory() derives image->start by locating e_entry inside an
SHF_EXECINSTR section.  If the purgatory object contains multiple
executable sections with overlapping sh_addr, the entrypoint check can
match more than once and trigger a WARN.

Derive the entry section from the purgatory_start symbol when present and
compute image->start from its final placement.  Keep the existing e_entry
fallback for purgatories that do not expose the symbol.

WARNING: kernel/kexec_file.c:1009 at kexec_load_purgatory+0x395/0x3c0, CPU#10: kexec/1784
Call Trace:
 
 bzImage64_load+0x133/0xa00
 __do_sys_kexec_file_load+0x2b3/0x5c0
 do_syscall_64+0x81/0x610
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

[me@linux.beauty: move helper to avoid forward declaration, per Baoquan]
  Link: https://lkml.kernel.org/r/20260128043511.316860-1-me@linux.beauty
Link: https://lkml.kernel.org/r/20260120124005.148381-1-me@linux.beauty
Fixes: 8652d44f466a ("kexec: support purgatories with .text.hot sections")
Signed-off-by: Li Chen 
Acked-by: Baoquan He 
Cc: Alexander Graf 
Cc: Eric Biggers 
Cc: Li Chen 
Cc: Philipp Rudo 
Cc: Ricardo Ribalda Delgado 
Cc: Ross Zwisler 
Cc: Sourabh Jain 
Cc: Steven Rostedt 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Sasha Levin

kexec_file: fix elfcorehdr digest exclusion when CONFIG_CRASH_HOTPLUG=y

2024-09-02T00:59:01+00:00

Fix the condition to exclude the elfcorehdr segment from the SHA digest
calculation.

The j iterator is an index into the output sha_regions[] array, not into
the input image->segment[] array.  Once it reaches
image->elfcorehdr_index, all subsequent segments are excluded.  Besides,
if the purgatory segment precedes the elfcorehdr segment, the elfcorehdr
may be wrongly included in the calculation.

Link: https://lkml.kernel.org/r/20240805150750.170739-1-petr.tesarik@suse.com
Fixes: f7cc804a9fd4 ("kexec: exclude elfcorehdr from the segment digest")
Signed-off-by: Petr Tesarik 
Acked-by: Baoquan He 
Cc: Eric Biederman 
Cc: Hari Bathini 
Cc: Sourabh Jain 
Cc: Eric DeVolder 
Cc: 
Signed-off-by: Andrew Morton

crash: add a new kexec flag for hotplug support

2024-04-23T04:59:01+00:00

Commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
this flag to indicate to the kernel that it is safe to modify the
elfcorehdr of the kdump image loaded using the kexec_load system call.

However, it is possible that architectures may need to update kexec
segments other then elfcorehdr. For example, FDT (Flatten Device Tree)
on PowerPC. Introducing a new kexec flag for every new kexec segment
may not be a good solution. Hence, a generic kexec flag bit,
`KEXEC_CRASH_HOTPLUG_SUPPORT`, is introduced to share the CPU/Memory
hotplug support intent between the kexec tool and the kernel for the
kexec_load system call.

Now we have two kexec flags that enables crash hotplug support for
kexec_load system call. First is KEXEC_UPDATE_ELFCOREHDR (only used in
x86), and second is KEXEC_CRASH_HOTPLUG_SUPPORT (for all architectures).

To simplify the process of finding and reporting the crash hotplug
support the following changes are introduced.

1. Define arch specific function to process the kexec flags and
   determine crash hotplug support

2. Rename the @update_elfcorehdr member of struct kimage to
   @hotplug_support and populate it for both kexec_load and
   kexec_file_load syscalls, because architecture can update more than
   one kexec segment

3. Let generic function crash_check_hotplug_support report hotplug
   support for loaded kdump image based on value of @hotplug_support

To bring the x86 crash hotplug support in line with the above points,
the following changes have been made:

- Introduce the arch_crash_hotplug_support function to process kexec
  flags and determine crash hotplug support

- Remove the arch_crash_hotplug_[cpu|memory]_support functions

Signed-off-by: Sourabh Jain 
Acked-by: Baoquan He 
Acked-by: Hari Bathini 
Signed-off-by: Michael Ellerman 
Link: https://msgid.link/20240326055413.186534-3-sourabhjain@linux.ibm.com

arm64, crash: wrap crash dumping code into crash related ifdefs

2024-02-24T01:48:23+00:00

Now crash codes under kernel/ folder has been split out from kexec
code, crash dumping can be separated from kexec reboot in config
items on arm64 with some adjustments.

Here wrap up crash dumping codes with CONFIG_CRASH_DUMP ifdeffery.

[bhe@redhat.com: fix building error in generic codes]
  Link: https://lkml.kernel.org/r/20240129135033.157195-2-bhe@redhat.com
Link: https://lkml.kernel.org/r/20240124051254.67105-8-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

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_file: fix incorrect temp_start value in locate_mem_hole_top_down()

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

temp_end represents the address of the last available byte.  Therefore,
the starting address of the memory segment with temp_end as its last
available byte and a size of `kbuf->memsz`, that is, the value of
temp_start, should be `temp_end - kbuf->memsz + 1` instead of `temp_end -
kbuf->memsz`.

Additionally, use the ALIGN_DOWN macro instead of open-coding it directly
in locate_mem_hole_top_down() to improve code readability.

Link: https://lkml.kernel.org/r/20231217033528.303333-3-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_file: print out debugging message if required

2023-12-20T23:02:57+00:00

Then when specifying '-d' for kexec_file_load interface, loaded locations
of kernel/initrd/cmdline etc can be printed out to help debug.

Here replace pr_debug() with the newly added kexec_dprintk() in kexec_file
loading related codes.

And also print out type/start/head of kimage and flags to help debug.

Link: https://lkml.kernel.org/r/20231213055747.61826-3-bhe@redhat.com
Signed-off-by: Baoquan He 
Cc: Conor Dooley 
Cc: Joe Perches 
Cc: Nathan Chancellor 
Signed-off-by: Andrew Morton

kexec_file: add kexec_file flag to control debug printing

2023-12-20T23:02:57+00:00

Patch series "kexec_file: print out debugging message if required", v4.

Currently, specifying '-d' on kexec command will print a lot of debugging
informationabout kexec/kdump loading with kexec_load interface.

However, kexec_file_load prints nothing even though '-d' is specified. 
It's very inconvenient to debug or analyze the kexec/kdump loading when
something wrong happened with kexec/kdump itself or develper want to check
the kexec/kdump loading.

In this patchset, a kexec_file flag is KEXEC_FILE_DEBUG added and checked
in code.  If it's passed in, debugging message of kexec_file code will be
printed out and can be seen from console and dmesg.  Otherwise, the
debugging message is printed like beofre when pr_debug() is taken.

Note:
****
=====
1) The code in kexec-tools utility also need be changed to support
passing KEXEC_FILE_DEBUG to kernel when 'kexec -s -d' is specified.
The patch link is here:
=========
[PATCH] kexec_file: add kexec_file flag to support debug printing
http://lists.infradead.org/pipermail/kexec/2023-November/028505.html

2) s390 also has kexec_file code, while I am not sure what debugging
information is necessary. So leave it to s390 developer.

Test:
****
====
Testing was done in v1 on x86_64 and arm64. For v4, tested on x86_64
again. And on x86_64, the printed messages look like below:
--------------------------------------------------------------
kexec measurement buffer for the loaded kernel at 0x207fffe000.
Loaded purgatory at 0x207fff9000
Loaded boot_param, command line and misc at 0x207fff3000 bufsz=0x1180 memsz=0x1180
Loaded 64bit kernel at 0x207c000000 bufsz=0xc88200 memsz=0x3c4a000
Loaded initrd at 0x2079e79000 bufsz=0x2186280 memsz=0x2186280
Final command line is: root=/dev/mapper/fedora_intel--knightslanding--lb--02-root ro
rd.lvm.lv=fedora_intel-knightslanding-lb-02/root console=ttyS0,115200N81 crashkernel=256M
E820 memmap:
0000000000000000-000000000009a3ff (1)
000000000009a400-000000000009ffff (2)
00000000000e0000-00000000000fffff (2)
0000000000100000-000000006ff83fff (1)
000000006ff84000-000000007ac50fff (2)
......
000000207fff6150-000000207fff615f (128)
000000207fff6160-000000207fff714f (1)
000000207fff7150-000000207fff715f (128)
000000207fff7160-000000207fff814f (1)
000000207fff8150-000000207fff815f (128)
000000207fff8160-000000207fffffff (1)
nr_segments = 5
segment[0]: buf=0x000000004e5ece74 bufsz=0x211 mem=0x207fffe000 memsz=0x1000
segment[1]: buf=0x000000009e871498 bufsz=0x4000 mem=0x207fff9000 memsz=0x5000
segment[2]: buf=0x00000000d879f1fe bufsz=0x1180 mem=0x207fff3000 memsz=0x2000
segment[3]: buf=0x000000001101cd86 bufsz=0xc88200 mem=0x207c000000 memsz=0x3c4a000
segment[4]: buf=0x00000000c6e38ac7 bufsz=0x2186280 mem=0x2079e79000 memsz=0x2187000
kexec_file_load: type:0, start:0x207fff91a0 head:0x109e004002 flags:0x8
---------------------------------------------------------------------------


This patch (of 7):

When specifying 'kexec -c -d', kexec_load interface will print loading
information, e.g the regions where kernel/initrd/purgatory/cmdline are
put, the memmap passed to 2nd kernel taken as system RAM ranges, and
printing all contents of struct kexec_segment, etc.  These are very
helpful for analyzing or positioning what's happening when kexec/kdump
itself failed.  The debugging printing for kexec_load interface is made in
user space utility kexec-tools.

Whereas, with kexec_file_load interface, 'kexec -s -d' print nothing. 
Because kexec_file code is mostly implemented in kernel space, and the
debugging printing functionality is missed.  It's not convenient when
debugging kexec/kdump loading and jumping with kexec_file_load interface.

Now add KEXEC_FILE_DEBUG to kexec_file flag to control the debugging
message printing.  And add global variable kexec_file_dbg_print and macro
kexec_dprintk() to facilitate the printing.

This is a preparation, later kexec_dprintk() will be used to replace the
existing pr_debug().  Once 'kexec -s -d' is specified, it will print out
kexec/kdump loading information.  If '-d' is not specified, it regresses
to pr_debug().

Link: https://lkml.kernel.org/r/20231213055747.61826-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20231213055747.61826-2-bhe@redhat.com
Signed-off-by: Baoquan He 
Cc: Conor Dooley 
Cc: Joe Perches 
Cc: Nathan Chancellor 
Signed-off-by: Andrew Morton

kexec_file: load kernel at top of system RAM if required

2023-12-11T01:21:44+00:00

Patch series "kexec_file: Load kernel at top of system RAM if required".

Justification:
==============

Kexec_load interface has been doing top down searching and loading
kernel/initrd/purgtory etc to prepare for kexec reboot.  In that way, the
benefits are that it avoids to consume and fragment limited low memory
which satisfy DMA buffer allocation and big chunk of continuous memory
during system init; and avoids to stir with BIOS/FW reserved or occupied
areas, or corner case handling/work around/quirk occupied areas when doing
system init.  By the way, the top-down searching and loading of kexec-ed
kernel is done in user space utility code.

For kexec_file loading, even if kexec_buf.top_down is 'true', it's simply
ignored.  It calls walk_system_ram_res() directly to go through all
resources of System RAM bottom up, to find an available memory region,
then call locate_mem_hole_callback() to allocate memory in that found
memory region from top to down.  This is not expected and inconsistent
with kexec_load.

Implementation
===============

In patch 1, introduce a new function walk_system_ram_res_rev() which is a
variant of walk_system_ram_res(), it walks through a list of all the
resources of System RAM in reversed order, i.e., from higher to lower.

In patch 2, check if kexec_buf.top_down is 'true' in
kexec_walk_resources(), if yes, call walk_system_ram_res_rev() to find
memory region of system RAM from top to down to load kernel/initrd etc.

Background information: ======================= And I ever tried this in
the past in a different way, please see below link.  In the post, I tried
to adjust struct sibling linking code, replace the the singly linked list
with list_head so that walk_system_ram_res_rev() can be implemented in a
much easier way.  Finally I failed. 
https://lore.kernel.org/all/20180718024944.577-4-bhe@redhat.com/

This time, I picked up the patch from AKASHI Takahiro's old post and made
some change to take as the current patch 1:
https://lists.infradead.org/pipermail/linux-arm-kernel/2017-September/531456.html


This patch (of 2):

Kexec_load interface has been doing top down searching and loading
kernel/initrd/purgtory etc to prepare for kexec reboot.  In that way, the
benefits are that it avoids to consume and fragment limited low memory
which satisfy DMA buffer allocation and big chunk of continuous memory
during system init; and avoids to stir with BIOS/FW reserved or occupied
areas, or corner case handling/work around/quirk occupied areas when doing
system init.  By the way, the top-down searching and loading of kexec-ed
kernel is done in user space utility code.

For kexec_file loading, even if kexec_buf.top_down is 'true', it's simply
ignored.  It calls walk_system_ram_res() directly to go through all
resources of System RAM bottom up, to find an available memory region,
then call locate_mem_hole_callback() to allocate memory in that found
memory region from top to down.  This is not expected and inconsistent
with kexec_load.

Here check if kexec_buf.top_down is 'true' in kexec_walk_resources(), if
yes, call the newly added walk_system_ram_res_rev() to find memory region
of system RAM from top to down to load kernel/initrd etc.

Link: https://lkml.kernel.org/r/20231114091658.228030-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20231114091658.228030-3-bhe@redhat.com
Signed-off-by: Baoquan He 
Cc: AKASHI Takahiro 
Cc: Baoquan He 
Cc: Eric Biederman 
Signed-off-by: Andrew Morton

Merge tag 'integrity-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

2023-08-30T16:16:56+00:00

Pull integrity subsystem updates from Mimi Zohar:

 - With commit 099f26f22f58 ("integrity: machine keyring CA
   configuration") certificates may be loaded onto the IMA keyring,
   directly or indirectly signed by keys on either the "builtin" or the
   "machine" keyrings.

   With the ability for the system/machine owner to sign the IMA policy
   itself without needing to recompile the kernel, update the IMA
   architecture specific policy rules to require the IMA policy itself
   be signed.

   [ As commit 099f26f22f58 was upstreamed in linux-6.4, updating the
     IMA architecture specific policy now to require signed IMA policies
     may break userspace expectations. ]

 - IMA only checked the file data hash was not on the system blacklist
   keyring for files with an appended signature (e.g. kernel modules,
   Power kernel image).

   Check all file data hashes regardless of how it was signed

 - Code cleanup, and a kernel-doc update

* tag 'integrity-v6.6' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  kexec_lock: Replace kexec_mutex() by kexec_lock() in two comments
  ima: require signed IMA policy when UEFI secure boot is enabled
  integrity: Always reference the blacklist keyring with appraisal
  ima: Remove deprecated IMA_TRUSTED_KEYRING Kconfig