crash: let arch decide usable memory range in reserved area

Although the crashkernel area is reserved, on architectures like PowerPC,
it is possible for the crashkernel reserved area to contain comp

crash: let arch decide usable memory range in reserved area

Although the crashkernel area is reserved, on architectures like PowerPC,
it is possible for the crashkernel reserved area to contain components
like RTAS, TCE, OPAL, etc. To avoid placing kexec segments over these
components, PowerPC has its own set of APIs to locate holes in the
crashkernel reserved area.

Add an arch hook in the generic locate mem hole APIs so that architectures
can handle such special regions in the crashkernel area while locating
memory holes for kexec segments using generic APIs. With this, a lot of
redundant arch-specific code can be removed, as it performs the exact same
job as the generic APIs.

To keep the generic and arch-specific changes separate, the changes
related to moving PowerPC to use the generic APIs and the removal of
PowerPC-specific APIs for memory hole allocation are done in a subsequent
patch titled "powerpc/crash: Use generic APIs to locate memory hole for
kdump.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Sourabh Jain <[email protected]>
Acked-by: Baoquan He <[email protected]>
Cc: Hari Bathini <[email protected]>
Cc: Madhavan Srinivasan <[email protected]>
Cc: Mahesh Salgaonkar <[email protected]>
Cc: Michael Ellerman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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crash: Remove KEXEC_CORE_NOTE_NAME

KEXEC_CORE_NOTE_NAME is no longer used.

Signed-off-by: Akihiko Odaki <[email protected]>
Acked-by: Baoquan He <[email protected]>
Reviewed-by: Dave Martin <Da

crash: Remove KEXEC_CORE_NOTE_NAME

KEXEC_CORE_NOTE_NAME is no longer used.

Signed-off-by: Akihiko Odaki <[email protected]>
Acked-by: Baoquan He <[email protected]>
Reviewed-by: Dave Martin <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Kees Cook <[email protected]>

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kexec: fix the unexpected kexec_dprintk() macro

Jiri reported that the current kexec_dprintk() always prints out debugging
message whenever kexec/kdmmp loading is triggered. That is not wanted.
Th

kexec: fix the unexpected kexec_dprintk() macro

Jiri reported that the current kexec_dprintk() always prints out debugging
message whenever kexec/kdmmp loading is triggered. That is not wanted.
The debugging message is supposed to be printed out when 'kexec -s -d' is
specified for kexec/kdump loading.

After investigating, the reason is the current kexec_dprintk() takes
printk(KERN_INFO) or printk(KERN_DEBUG) depending on whether '-d' is
specified. However, distros usually have defaulg log level like below:

[~]# cat /proc/sys/kernel/printk
7 4 1 7

So, even though '-d' is not specified, printk(KERN_DEBUG) also always
prints out. I thought printk(KERN_DEBUG) is equal to pr_debug(), it's
not.

Fix it by changing to use pr_info() instead which are expected to work.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: cbc2fe9d9cb2 ("kexec_file: add kexec_file flag to control debug printing")
Signed-off-by: Baoquan He <[email protected]>
Reported-by: Jiri Slaby <[email protected]>
Closes: https://lore.kernel.org/all/[email protected]
Reviewed-by: Dave Young <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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crash: add a new kexec flag for hotplug support

Commit a72bbec70da2 ("crash: hotplug support for kexec_load()")
introduced a new kexec flag, `KEXEC_UPDATE_ELFCOREHDR`. Kexec tool uses
this flag to i

crash: add a new kexec flag for hotplug support

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 <[email protected]>
Acked-by: Baoquan He <[email protected]>
Acked-by: Hari Bathini <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Link: https://msgid.link/[email protected]

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crash: split crash dumping code out from kexec_core.c

Currently, KEXEC_CORE select CRASH_CORE automatically because crash codes
need be built in to avoid compiling error when building kexec code eve

crash: split crash dumping code out from kexec_core.c

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/[email protected]
Signed-off-by: Baoquan He <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Cc: Hari Bathini <[email protected]>
Cc: Pingfan Liu <[email protected]>
Cc: Klara Modin <[email protected]>
Cc: Michael Kelley <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Yang Li <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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crash: split vmcoreinfo exporting code out from crash_core.c

Now move the relevant codes into separate files:
kernel/crash_reserve.c, include/linux/crash_reserve.h.

And add config item CRASH_RESERV

crash: split vmcoreinfo exporting code out from crash_core.c

Now move the relevant codes into separate files:
kernel/crash_reserve.c, include/linux/crash_reserve.h.

And add config item CRASH_RESERVE to control its enabling.

And also update the old ifdeffery of CONFIG_CRASH_CORE, including of
<linux/crash_core.h> and config item dependency on CRASH_CORE
accordingly.

And also do renaming as follows:
- arch/xxx/kernel/{crash_core.c => vmcore_info.c}
because they are only related to vmcoreinfo exporting on x86, arm64,
riscv.

And also Remove config item CRASH_CORE, and rely on CONFIG_KEXEC_CORE to
decide if build in crash_core.c.

[[email protected]: remove duplicated include in vmcore_info.c]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Baoquan He <[email protected]>
Signed-off-by: Yang Li <[email protected]>
Acked-by: Hari Bathini <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Cc: Pingfan Liu <[email protected]>
Cc: Klara Modin <[email protected]>
Cc: Michael Kelley <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Yang Li <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

kexec: split crashkernel reservation code out from crash_core.c

Patch series "Split crash out from kexec and clean up related config
items", v3.

Motivation:
=============
Previously, LKP reported a

kexec: split crashkernel reservation code out from crash_core.c

Patch series "Split crash out from kexec and clean up related config
items", v3.

Motivation:
=============
Previously, LKP reported a building error. When investigating, it can't
be resolved reasonablly with the present messy kdump config items.

https://lore.kernel.org/oe-kbuild-all/[email protected]/

The kdump (crash dumping) related config items could causes confusions:

Firstly,

CRASH_CORE enables codes including
- crashkernel reservation;
- elfcorehdr updating;
- vmcoreinfo exporting;
- crash hotplug handling;

Now fadump of powerpc, kcore dynamic debugging and kdump all selects
CRASH_CORE, while fadump
- fadump needs crashkernel parsing, vmcoreinfo exporting, and accessing
global variable 'elfcorehdr_addr';
- kcore only needs vmcoreinfo exporting;
- kdump needs all of the current kernel/crash_core.c.

So only enabling PROC_CORE or FA_DUMP will enable CRASH_CORE, this
mislead people that we enable crash dumping, actual it's not.

Secondly,

It's not reasonable to allow KEXEC_CORE select CRASH_CORE.

Because KEXEC_CORE enables codes which allocate control pages, copy
kexec/kdump segments, and prepare for switching. These codes are
shared by both kexec reboot and kdump. We could want kexec reboot,
but disable kdump. In that case, CRASH_CORE should not be selected.

--------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_KEXEC=y
CONFIG_KEXEC_FILE=y
---------------------

Thirdly,

It's not reasonable to allow CRASH_DUMP select KEXEC_CORE.

That could make KEXEC_CORE, CRASH_DUMP are enabled independently from
KEXEC or KEXEC_FILE. However, w/o KEXEC or KEXEC_FILE, the KEXEC_CORE
code built in doesn't make any sense because no kernel loading or
switching will happen to utilize the KEXEC_CORE code.
---------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
---------------------

In this case, what is worse, on arch sh and arm, KEXEC relies on MMU,
while CRASH_DUMP can still be enabled when !MMU, then compiling error is
seen as the lkp test robot reported in above link.

------arch/sh/Kconfig------
config ARCH_SUPPORTS_KEXEC
def_bool MMU

config ARCH_SUPPORTS_CRASH_DUMP
def_bool BROKEN_ON_SMP
---------------------------

Changes:
===========
1, split out crash_reserve.c from crash_core.c;
2, split out vmcore_infoc. from crash_core.c;
3, move crash related codes in kexec_core.c into crash_core.c;
4, remove dependency of FA_DUMP on CRASH_DUMP;
5, clean up kdump related config items;
6, wrap up crash codes in crash related ifdefs on all 8 arch-es
which support crash dumping, except of ppc;

Achievement:
===========
With above changes, I can rearrange the config item logic as below (the right
item depends on or is selected by the left item):

PROC_KCORE -----------> VMCORE_INFO

|----------> VMCORE_INFO
FA_DUMP----|
|----------> CRASH_RESERVE

---->VMCORE_INFO
/
|---->CRASH_RESERVE
KEXEC --| /|
|--> KEXEC_CORE--> CRASH_DUMP-->/-|---->PROC_VMCORE
KEXEC_FILE --| \ |
\---->CRASH_HOTPLUG


KEXEC --|
|--> KEXEC_CORE (for kexec reboot only)
KEXEC_FILE --|

Test
========
On all 8 architectures, including x86_64, arm64, s390x, sh, arm, mips,
riscv, loongarch, I did below three cases of config item setting and
building all passed. Take configs on x86_64 as exampmle here:

(1) Both CONFIG_KEXEC and KEXEC_FILE is unset, then all kexec/kdump
items are unset automatically:
# Kexec and crash features
# CONFIG_KEXEC is not set
# CONFIG_KEXEC_FILE is not set
# end of Kexec and crash features

(2) set CONFIG_KEXEC_FILE and 'make olddefconfig':
---------------
# Kexec and crash features
CONFIG_CRASH_RESERVE=y
CONFIG_VMCORE_INFO=y
CONFIG_KEXEC_CORE=y
CONFIG_KEXEC_FILE=y
CONFIG_CRASH_DUMP=y
CONFIG_CRASH_HOTPLUG=y
CONFIG_CRASH_MAX_MEMORY_RANGES=8192
# end of Kexec and crash features
---------------

(3) unset CONFIG_CRASH_DUMP in case 2 and execute 'make olddefconfig':
------------------------
# Kexec and crash features
CONFIG_KEXEC_CORE=y
CONFIG_KEXEC_FILE=y
# end of Kexec and crash features
------------------------

Note:
For ppc, it needs investigation to make clear how to split out crash
code in arch folder. Hope Hari and Pingfan can help have a look, see if
it's doable. Now, I make it either have both kexec and crash enabled, or
disable both of them altogether.


This patch (of 14):

Both kdump and fa_dump of ppc rely on crashkernel reservation. Move the
relevant codes into separate files: crash_reserve.c,
include/linux/crash_reserve.h.

And also add config item CRASH_RESERVE to control its enabling of the
codes. And update config items which has relationship with crashkernel
reservation.

And also change ifdeffery from CONFIG_CRASH_CORE to CONFIG_CRASH_RESERVE
when those scopes are only crashkernel reservation related.

And also rename arch/XXX/include/asm/{crash_core.h => crash_reserve.h} on
arm64, x86 and risc-v because those architectures' crash_core.h is only
related to crashkernel reservation.

[[email protected]: s/CRASH_RESEERVE/CRASH_RESERVE/, per Klara Modin]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Baoquan He <[email protected]>
Acked-by: Hari Bathini <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Eric W. Biederman <[email protected]>
Cc: Pingfan Liu <[email protected]>
Cc: Klara Modin <[email protected]>
Cc: Michael Kelley <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Yang Li <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

kexec_file: add kexec_file flag to control debug printing

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

Currently, specifying '-d' on kexec command will print a lot of deb

kexec_file: add kexec_file flag to control debug printing

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/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Baoquan He <[email protected]>
Cc: Conor Dooley <[email protected]>
Cc: Joe Perches <[email protected]>
Cc: Nathan Chancellor <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

crash_core: move crashk_*res definition into crash_core.c

Both crashk_res and crashk_low_res are used to mark the reserved
crashkernel regions in iomem_resource tree. And later the generic
crashker

crash_core: move crashk_*res definition into crash_core.c

Both crashk_res and crashk_low_res are used to mark the reserved
crashkernel regions in iomem_resource tree. And later the generic
crashkernel resrvation will be added into crash_core.c. So move
crashk_res and crashk_low_res definition into crash_core.c to avoid
compiling error if CONFIG_CRASH_CORE=on while CONFIG_KEXEC_CORE is unset.

Meanwhile include <asm/crash_core.h> in <linux/crash_core.h> if generic
reservation is needed. In that case, <asm/crash_core.h> need be added by
ARCH. In asm/crash_core.h, ARCH can provide its own macro definitions to
override macros in <linux/crash_core.h> if needed. Wrap the including
into CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope to
avoid compiling error in other ARCH-es which don't take the generic
reservation way yet.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Baoquan He <[email protected]>
Reviewed-by: Zhen Lei <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Chen Jiahao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

crash: hotplug support for kexec_load()

The hotplug support for kexec_load() requires changes to the userspace
kexec-tools and a little extra help from the kernel.

Given a kdump capture kernel load

crash: hotplug support for kexec_load()

The hotplug support for kexec_load() requires changes to the userspace
kexec-tools and a little extra help from the kernel.

Given a kdump capture kernel loaded via kexec_load(), and a subsequent
hotplug event, the crash hotplug handler finds the elfcorehdr and rewrites
it to reflect the hotplug change. That is the desired outcome, however,
at kernel panic time, the purgatory integrity check fails (because the
elfcorehdr changed), and the capture kernel does not boot and no vmcore is
generated.

Therefore, the userspace kexec-tools/kexec must indicate to the kernel
that the elfcorehdr can be modified (because the kexec excluded the
elfcorehdr from the digest, and sized the elfcorehdr memory buffer
appropriately).

To facilitate hotplug support with kexec_load():
- a new kexec flag KEXEC_UPATE_ELFCOREHDR indicates that it is
safe for the kernel to modify the kexec_load()'d elfcorehdr
- the /sys/kernel/crash_elfcorehdr_size node communicates the
preferred size of the elfcorehdr memory buffer
- The sysfs crash_hotplug nodes (ie.
/sys/devices/system/[cpu|memory]/crash_hotplug) dynamically
take into account kexec_file_load() vs kexec_load() and
KEXEC_UPDATE_ELFCOREHDR.
This is critical so that the udev rule processing of crash_hotplug
is all that is needed to determine if the userspace unload-then-load
of the kdump image is to be skipped, or not. The proposed udev
rule change looks like:
# 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"

The table below indicates the behavior of kexec_load()'d kdump image
updates (with the new udev crash_hotplug rule in place):

Kernel |Kexec
-------+-----+----
Old |Old |New
| a | a
-------+-----+----
New | a | b
-------+-----+----

where kexec 'old' and 'new' delineate kexec-tools has the needed
modifications for the crash hotplug feature, and kernel 'old' and 'new'
delineate the kernel supports this crash hotplug feature.

Behavior 'a' indicates the unload-then-reload of the entire kdump image.
For the kexec 'old' column, the unload-then-reload occurs due to the
missing flag KEXEC_UPDATE_ELFCOREHDR. An 'old' kernel (with 'new' kexec)
does not present the crash_hotplug sysfs node, which leads to the
unload-then-reload of the kdump image.

Behavior 'b' indicates the desired optimized behavior of the kernel
directly modifying the elfcorehdr and avoiding the unload-then-reload of
the kdump image.

If the udev rule is not updated with crash_hotplug node check, then no
matter any combination of kernel or kexec is new or old, the kdump image
continues to be unload-then-reload on hotplug changes.

To fully support crash hotplug feature, there needs to be a rollout of
kernel, kexec-tools and udev rule changes. However, the order of the
rollout of these pieces does not matter; kexec_load()'d kdump images still
function for hotplug as-is.

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

show more ...

crash: memory and CPU hotplug sysfs attributes

Introduce the crash_hotplug attribute for memory and CPUs for use by
userspace. These attributes directly facilitate the udev rule for
managing usersp

crash: memory and CPU hotplug sysfs attributes

Introduce the crash_hotplug attribute for memory and CPUs for use by
userspace. These attributes directly facilitate the udev rule for
managing userspace re-loading of the crash kernel upon hot un/plug
changes.

For memory, expose the crash_hotplug attribute to the
/sys/devices/system/memory directory. For example:

# udevadm info --attribute-walk /sys/devices/system/memory/memory81
looking at device '/devices/system/memory/memory81':
KERNEL=="memory81"
SUBSYSTEM=="memory"
DRIVER==""
ATTR{online}=="1"
ATTR{phys_device}=="0"
ATTR{phys_index}=="00000051"
ATTR{removable}=="1"
ATTR{state}=="online"
ATTR{valid_zones}=="Movable"

looking at parent device '/devices/system/memory':
KERNELS=="memory"
SUBSYSTEMS==""
DRIVERS==""
ATTRS{auto_online_blocks}=="offline"
ATTRS{block_size_bytes}=="8000000"
ATTRS{crash_hotplug}=="1"

For CPUs, expose the crash_hotplug attribute to the
/sys/devices/system/cpu directory. For example:

# udevadm info --attribute-walk /sys/devices/system/cpu/cpu0
looking at device '/devices/system/cpu/cpu0':
KERNEL=="cpu0"
SUBSYSTEM=="cpu"
DRIVER=="processor"
ATTR{crash_notes}=="277c38600"
ATTR{crash_notes_size}=="368"
ATTR{online}=="1"

looking at parent device '/devices/system/cpu':
KERNELS=="cpu"
SUBSYSTEMS==""
DRIVERS==""
ATTRS{crash_hotplug}=="1"
ATTRS{isolated}==""
ATTRS{kernel_max}=="8191"
ATTRS{nohz_full}==" (null)"
ATTRS{offline}=="4-7"
ATTRS{online}=="0-3"
ATTRS{possible}=="0-7"
ATTRS{present}=="0-3"

With these sysfs attributes in place, it is possible to efficiently
instruct the udev rule to skip crash kernel reloading for kernels
configured with crash hotplug support.

For example, the following is the proposed udev rule change for RHEL
system 98-kexec.rules (as the first lines of the rule file):

# 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"

When examined in the context of 98-kexec.rules, the above rules test if
crash_hotplug is set, and if so, the userspace initiated
unload-then-reload of the crash kernel is skipped.

CPU and memory checks are separated in accordance with CONFIG_HOTPLUG_CPU
and CONFIG_MEMORY_HOTPLUG kernel config options. If an architecture
supports, for example, memory hotplug but not CPU hotplug, then the
/sys/devices/system/memory/crash_hotplug attribute file is present, but
the /sys/devices/system/cpu/crash_hotplug attribute file will NOT be
present. Thus the udev rule skips userspace processing of memory hot
un/plug events, but the udev rule will evaluate false for CPU events, thus
allowing userspace to process CPU hot un/plug events (ie the
unload-then-reload of the kdump capture kernel).

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

show more ...

crash: add generic infrastructure for crash hotplug support

To support crash hotplug, a mechanism is needed to update the crash
elfcorehdr upon CPU or memory changes (eg. hot un/plug or off/ onlini

crash: add generic infrastructure for crash hotplug support

To support crash hotplug, a mechanism is needed to update the crash
elfcorehdr upon CPU or memory changes (eg. hot un/plug or off/ onlining).
The crash elfcorehdr describes the CPUs and memory to be written into the
vmcore.

To track CPU changes, callbacks are registered with the cpuhp mechanism
via cpuhp_setup_state_nocalls(CPUHP_BP_PREPARE_DYN). The crash hotplug
elfcorehdr update has no explicit ordering requirement (relative to other
cpuhp states), so meets the criteria for utilizing CPUHP_BP_PREPARE_DYN.
CPUHP_BP_PREPARE_DYN is a dynamic state and avoids the need to introduce a
new state for crash hotplug. Also, CPUHP_BP_PREPARE_DYN is the last state
in the PREPARE group, just prior to the STARTING group, which is very
close to the CPU starting up in a plug/online situation, or stopping in a
unplug/ offline situation. This minimizes the window of time during an
actual plug/online or unplug/offline situation in which the elfcorehdr
would be inaccurate. Note that for a CPU being unplugged or offlined, the
CPU will still be present in the list of CPUs generated by
crash_prepare_elf64_headers(). However, there is no need to explicitly
omit the CPU, see justification in 'crash: change
crash_prepare_elf64_headers() to for_each_possible_cpu()'.

To track memory changes, a notifier is registered to capture the memblock
MEM_ONLINE and MEM_OFFLINE events via register_memory_notifier().

The CPU callbacks and memory notifiers invoke crash_handle_hotplug_event()
which performs needed tasks and then dispatches the event to the
architecture specific arch_crash_handle_hotplug_event() to update the
elfcorehdr with the current state of CPUs and memory. During the process,
the kexec_lock is held.

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

show more ...

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

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

Once the kdump service is loaded, if changes to CPUs or memor

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

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

show more ...

kexec: remove unnecessary arch_kexec_kernel_image_load()

arch_kexec_kernel_image_load() only calls kexec_image_load_default(), and
there are no arch-specific implementations.

Remove the unnecessary

kexec: remove unnecessary arch_kexec_kernel_image_load()

arch_kexec_kernel_image_load() only calls kexec_image_load_default(), and
there are no arch-specific implementations.

Remove the unnecessary arch_kexec_kernel_image_load() and make
kexec_image_load_default() static.

No functional change intended.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Acked-by: Baoquan He <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Eric Biederman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

x86/kexec: remove unnecessary arch_kexec_kernel_image_load()

Patch series "kexec: Remove unnecessary arch hook", v2.

There are no arch-specific things in arch_kexec_kernel_image_load(), so
remove i

x86/kexec: remove unnecessary arch_kexec_kernel_image_load()

Patch series "kexec: Remove unnecessary arch hook", v2.

There are no arch-specific things in arch_kexec_kernel_image_load(), so
remove it and just use the generic version.


This patch (of 2):

The x86 implementation of arch_kexec_kernel_image_load() is functionally
identical to the generic arch_kexec_kernel_image_load():

arch_kexec_kernel_image_load # x86
if (!image->fops || !image->fops->load)
return ERR_PTR(-ENOEXEC);
return image->fops->load(image, image->kernel_buf, ...)

arch_kexec_kernel_image_load # generic
kexec_image_load_default
if (!image->fops || !image->fops->load)
return ERR_PTR(-ENOEXEC);
return image->fops->load(image, image->kernel_buf, ...)

Remove the x86-specific version and use the generic
arch_kexec_kernel_image_load(). No functional change intended.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Acked-by: Baoquan He <[email protected]>
Cc: Borislav Petkov (AMD) <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Eric Biederman <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

kexec: introduce sysctl parameters kexec_load_limit_*

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

kexec: introduce sysctl parameters kexec_load_limit_*

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/[email protected]
Signed-off-by: Ricardo Ribalda <[email protected]>
Reviewed-by: Steven Rostedt (Google) <[email protected]>
Acked-by: Baoquan He <[email protected]>
Cc: Bagas Sanjaya <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Guilherme G. Piccoli <[email protected]> # Steam Deck
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Philipp Rudo <[email protected]>
Cc: Ross Zwisler <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

kexec: factor out kexec_load_permitted

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@ch

kexec: factor out kexec_load_permitted

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

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ricardo Ribalda <[email protected]>
Reviewed-by: Steven Rostedt (Google) <[email protected]>
Acked-by: Baoquan He <[email protected]>
Cc: Bagas Sanjaya <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Guilherme G. Piccoli <[email protected]>
Cc: Joel Fernandes (Google) <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Philipp Rudo <[email protected]>
Cc: Ross Zwisler <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

kexec: replace crash_mem_range with range

We already have struct range, so just use it.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Li Chen <lchen@ambarella

kexec: replace crash_mem_range with range

We already have struct range, so just use it.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Li Chen <[email protected]>
Signed-off-by: Baoquan He <[email protected]>
Acked-by: Baoquan He <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Chen Lifu <[email protected]>
Cc: "Eric W . Biederman" <[email protected]>
Cc: Jianglei Nie <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Russell King <[email protected]>
Cc: ye xingchen <[email protected]>
Cc: Zeal Robot <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

kexec: turn all kexec_mutex acquisitions into trylocks

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


This patch (of 2):

Most acquistions of kexec_mutex are done via mutex_tryloc

kexec: turn all kexec_mutex acquisitions into trylocks

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/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Valentin Schneider <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "Eric W . Biederman" <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Luis Claudio R. Goncalves <[email protected]>
Cc: Miaohe Lin <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Sebastian Andrzej Siewior <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Baoquan He <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

kexec, KEYS: make the code in bzImage64_verify_sig generic

commit 278311e417be ("kexec, KEYS: Make use of platform keyring for
signature verify") adds platform keyring support on x86 kexec but not
a

kexec, KEYS: make the code in bzImage64_verify_sig generic

commit 278311e417be ("kexec, KEYS: Make use of platform keyring for
signature verify") adds platform keyring support on x86 kexec but not
arm64.

The code in bzImage64_verify_sig uses the keys on the
.builtin_trusted_keys, .machine, if configured and enabled,
.secondary_trusted_keys, also if configured, and .platform keyrings
to verify the signed kernel image as PE file.

Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Michal Suchanek <[email protected]>
Signed-off-by: Coiby Xu <[email protected]>
Signed-off-by: Mimi Zohar <[email protected]>

show more ...

kexec: clean up arch_kexec_kernel_verify_sig

Before commit 105e10e2cf1c ("kexec_file: drop weak attribute from
functions"), there was already no arch-specific implementation
of arch_kexec_kernel_ver

kexec: clean up arch_kexec_kernel_verify_sig

Before commit 105e10e2cf1c ("kexec_file: drop weak attribute from
functions"), there was already no arch-specific implementation
of arch_kexec_kernel_verify_sig. With weak attribute dropped by that
commit, arch_kexec_kernel_verify_sig is completely useless. So clean it
up.

Note later patches are dependent on this patch so it should be backported
to the stable tree as well.

Cc: [email protected]
Suggested-by: Eric W. Biederman <[email protected]>
Reviewed-by: Michal Suchanek <[email protected]>
Acked-by: Baoquan He <[email protected]>
Signed-off-by: Coiby Xu <[email protected]>
[[email protected]: reworded patch description "Note"]
Link: https://lore.kernel.org/linux-integrity/[email protected]/
Signed-off-by: Mimi Zohar <[email protected]>

show more ...

kexec: drop weak attribute from functions

Drop __weak attribute from functions in kexec_core.c:
- machine_kexec_post_load()
- arch_kexec_protect_crashkres()
- arch_kexec_unprotect_crashkres()
- cras

kexec: drop weak attribute from functions

Drop __weak attribute from functions in kexec_core.c:
- machine_kexec_post_load()
- arch_kexec_protect_crashkres()
- arch_kexec_unprotect_crashkres()
- crash_free_reserved_phys_range()

Link: https://lkml.kernel.org/r/c0f6219e03cb399d166d518ab505095218a902dd.1656659357.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Naveen N. Rao <[email protected]>
Suggested-by: Eric Biederman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Mimi Zohar <[email protected]>

show more ...

kexec_file: drop weak attribute from functions

As requested
(http://lkml.kernel.org/r/[email protected]),
this series converts weak functions in kexec to use the #ifdef a

kexec_file: drop weak attribute from functions

As requested
(http://lkml.kernel.org/r/[email protected]),
this series converts weak functions in kexec to use the #ifdef approach.

Quoting the 3e35142ef99fe ("kexec_file: drop weak attribute from
arch_kexec_apply_relocations[_add]") changelog:

: 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.

This patch (of 2);

Drop __weak attribute from functions in kexec_file.c:
- arch_kexec_kernel_image_probe()
- arch_kimage_file_post_load_cleanup()
- arch_kexec_kernel_image_load()
- arch_kexec_locate_mem_hole()
- arch_kexec_kernel_verify_sig()

arch_kexec_kernel_image_load() calls into kexec_image_load_default(), so
drop the static attribute for the latter.

arch_kexec_kernel_verify_sig() is not overridden by any architecture, so
drop the __weak attribute.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/2cd7ca1fe4d6bb6ca38e3283c717878388ed6788.1656659357.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Naveen N. Rao <[email protected]>
Suggested-by: Eric Biederman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Mimi Zohar <[email protected]>

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ima: force signature verification when CONFIG_KEXEC_SIG is configured

Currently, an unsigned kernel could be kexec'ed when IMA arch specific
policy is configured unless lockdown is enabled. Enforce

ima: force signature verification when CONFIG_KEXEC_SIG is configured

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 <[email protected]>
Signed-off-by: Coiby Xu <[email protected]>
Signed-off-by: Mimi Zohar <[email protected]>

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kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add]

Since commit d1bcae833b32f1 ("ELF: Don't generate unused section
symbols") [1], binutils (v2.36+) started dropping section sym

kexec_file: drop weak attribute from arch_kexec_apply_relocations[_add]

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

[[email protected]: arch/s390/include/asm/kexec.h needs linux/module.h]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Michael Ellerman <[email protected]>
Signed-off-by: Naveen N. Rao <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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