linux-toradex.git/kernel/kexec_file.c, branch v6.9-rc4

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

kexec: exclude elfcorehdr from the segment digest

2023-08-24T23:25:13+00:00

When a crash kernel is loaded via the kexec_file_load() syscall, the
kernel places the various segments (ie crash kernel, crash initrd,
boot_params, elfcorehdr, purgatory, etc) in memory.  For those
architectures that utilize purgatory, a hash digest of the segments is
calculated for integrity checking.  The digest is embedded into the
purgatory image prior to placing in memory.

Updates to the elfcorehdr in response to CPU and memory changes would
cause the purgatory integrity checking to fail (at crash time, and no
vmcore created).  Therefore, the elfcorehdr segment is explicitly excluded
from the purgatory digest, enabling updates to the elfcorehdr while also
avoiding the need to recompute the hash digest and reload purgatory.

Link: https://lkml.kernel.org/r/20230814214446.6659-4-eric.devolder@oracle.com
Signed-off-by: Eric DeVolder 
Suggested-by: Baoquan He 
Reviewed-by: Sourabh Jain 
Acked-by: Hari Bathini 
Acked-by: Baoquan He 
Cc: Akhil Raj 
Cc: Bjorn Helgaas 
Cc: Borislav Petkov (AMD) 
Cc: Boris Ostrovsky 
Cc: Dave Hansen 
Cc: Dave Young 
Cc: David Hildenbrand 
Cc: Eric W. Biederman 
Cc: Greg Kroah-Hartman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Jonathan Corbet 
Cc: Konrad Rzeszutek Wilk 
Cc: Mimi Zohar 
Cc: Naveen N. Rao 
Cc: Oscar Salvador 
Cc: "Rafael J. Wysocki" 
Cc: Sean Christopherson 
Cc: Takashi Iwai 
Cc: Thomas Gleixner 
Cc: Thomas Weißschuh 
Cc: Valentin Schneider 
Cc: Vivek Goyal 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

crash: move a few code bits to setup support of crash hotplug

2023-08-24T23:25:13+00:00

Patch series "crash: Kernel handling of CPU and memory hot un/plug", v28.

Once the kdump service is loaded, if changes to CPUs or memory occur,
either by hot un/plug or off/onlining, the crash elfcorehdr must also be
updated.

The elfcorehdr describes to kdump the CPUs and memory in the system, and
any inaccuracies can result in a vmcore with missing CPU context or memory
regions.

The current solution utilizes udev to initiate an unload-then-reload of
the kdump image (eg.  kernel, initrd, boot_params, purgatory and
elfcorehdr) by the userspace kexec utility.  In the original post I
outlined the significant performance problems related to offloading this
activity to userspace.

This patchset introduces a generic crash handler that registers with the
CPU and memory notifiers.  Upon CPU or memory changes, from either hot
un/plug or off/onlining, this generic handler is invoked and performs
important housekeeping, for example obtaining the appropriate lock, and
then invokes an architecture specific handler to do the appropriate
elfcorehdr update.

Note the description in patch 'crash: change crash_prepare_elf64_headers()
to for_each_possible_cpu()' and 'x86/crash: optimize CPU changes' that
enables further optimizations related to CPU plug/unplug/online/offline
performance of elfcorehdr updates.

In the case of x86_64, the arch specific handler generates a new
elfcorehdr, and overwrites the old one in memory; thus no involvement with
userspace needed.

To realize the benefits/test this patchset, one must make a couple
of minor changes to userspace:

 - Prevent udev from updating kdump crash kernel on hot un/plug changes.
   Add the following as the first lines to the RHEL udev rule file
   /usr/lib/udev/rules.d/98-kexec.rules:

   # The kernel updates the crash elfcorehdr for CPU and memory changes
   SUBSYSTEM=="cpu", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"
   SUBSYSTEM=="memory", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end"

   With this changeset applied, the two rules evaluate to false for
   CPU and memory change events and thus skip the userspace
   unload-then-reload of kdump.

 - Change to the kexec_file_load for loading the kdump kernel:
   Eg. on RHEL: in /usr/bin/kdumpctl, change to:
    standard_kexec_args="-p -d -s"
   which adds the -s to select kexec_file_load() syscall.

This kernel patchset also supports kexec_load() with a modified kexec
userspace utility.  A working changeset to the kexec userspace utility is
posted to the kexec-tools mailing list here:

 http://lists.infradead.org/pipermail/kexec/2023-May/027049.html

To use the kexec-tools patch, apply, build and install kexec-tools, then
change the kdumpctl's standard_kexec_args to replace the -s with
--hotplug.  The removal of -s reverts to the kexec_load syscall and the
addition of --hotplug invokes the changes put forth in the kexec-tools
patch.


This patch (of 8):

The crash hotplug support leans on the work for the kexec_file_load()
syscall.  To also support the kexec_load() syscall, a few bits of code
need to be move outside of CONFIG_KEXEC_FILE.  As such, these bits are
moved out of kexec_file.c and into a common location crash_core.c.

In addition, struct crash_mem and crash_notes were moved to new locales so
that PROC_KCORE, which sets CRASH_CORE alone, builds correctly.

No functionality change intended.

Link: https://lkml.kernel.org/r/20230814214446.6659-1-eric.devolder@oracle.com
Link: https://lkml.kernel.org/r/20230814214446.6659-2-eric.devolder@oracle.com
Signed-off-by: Eric DeVolder 
Reviewed-by: Sourabh Jain 
Acked-by: Hari Bathini 
Acked-by: Baoquan He 
Cc: Akhil Raj 
Cc: Bjorn Helgaas 
Cc: Borislav Petkov (AMD) 
Cc: Boris Ostrovsky 
Cc: Dave Hansen 
Cc: Dave Young 
Cc: David Hildenbrand 
Cc: Eric W. Biederman 
Cc: Greg Kroah-Hartman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Jonathan Corbet 
Cc: Konrad Rzeszutek Wilk 
Cc: Mimi Zohar 
Cc: Naveen N. Rao 
Cc: Oscar Salvador 
Cc: "Rafael J. Wysocki" 
Cc: Sean Christopherson 
Cc: Takashi Iwai 
Cc: Thomas Gleixner 
Cc: Thomas Weißschuh 
Cc: Valentin Schneider 
Cc: Vivek Goyal 
Cc: Vlastimil Babka 
Signed-off-by: Andrew Morton

kexec: rename ARCH_HAS_KEXEC_PURGATORY

2023-08-18T17:18:54+00:00

The Kconfig refactor to consolidate KEXEC and CRASH options utilized
option names of the form ARCH_SUPPORTS_