When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200209105901.1620958-1-gregkh@linuxfoundation.org
Add a sys interface to allow querying the memory reserved by FADump for
saving the crash dump.
Also added Documentation/ABI for the new sysfs file.
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191211160910.21656-7-sourabhjain@linux.ibm.com
As the number of FADump sysfs files increases it is hard to manage all
of them inside /sys/kernel directory. It's better to have all the
FADump related sysfs files in a dedicated directory
/sys/kernel/fadump. But in order to maintain backward compatibility a
symlink has been added for every sysfs that has moved to new location.
As the FADump sysfs files are now part of a dedicated directory there
is no need to prefix their name with fadump_, hence sysfs file names
are also updated. For example fadump_enabled sysfs file is now
referred as enabled.
Also consolidate ABI documentation for all the FADump sysfs files in a
single file Documentation/ABI/testing/sysfs-kernel-fadump.
Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com>
Tested-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191211160910.21656-4-sourabhjain@linux.ibm.com
Currently it is not possible to distinguish the case when fadump is
supported by firmware and disabled in kernel and completely unsupported
using the kernel sysfs interface. User can investigate the devicetree
but it is more reasonable to provide sysfs files in case we get some
fadumpv2 in the future.
With this patch sysfs files are available whenever fadump is supported
by firmware.
There is duplicate message about lack of support by firmware in
fadump_reserve_mem and setup_fadump. Remove the duplicate message in
setup_fadump.
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Reviewed-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191107164757.15140-1-msuchanek@suse.de
With support to copy multiple kernel boot memory regions owing to copy
size limitation, also handle holes in the memory area to be preserved.
Support as many as 128 kernel boot memory regions. This allows having
an adequate FADump capture kernel size for different scenarios.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821385448.5656.6124791213910877759.stgit@hbathini.in.ibm.com
RMA_START is defined as '0' and there is even a BUILD_BUG_ON() to
make sure it is never anything else. Remove this macro and use '0'
instead as code change is needed anyway when it has to be something
else. Also, remove unused RMA_END macro.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821384096.5656.15026984053970204652.stgit@hbathini.in.ibm.com
OPAL loads kernel & initrd at 512MB offset (256MB size), also exported
as ibm,opal/dump/fw-load-area. So, if boot memory size of FADump is
less than 768MB, kernel memory to be exported as '/proc/vmcore' would
be overwritten by f/w while loading kernel & initrd. To avoid such a
scenario, enforce a minimum boot memory size of 768MB on OPAL platform
and skip using FADump if a newer F/W version loads kernel & initrd
above 768MB.
Also, irrespective of RMA size, set the minimum boot memory size
expected on pseries platform at 320MB. This is to avoid inflating the
minimum memory requirements on systems with 512M/1024M RMA size.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821381414.5656.1592867278535469652.stgit@hbathini.in.ibm.com
Add a new kernel config option, CONFIG_PRESERVE_FA_DUMP that ensures
that crash data, from previously crash'ed kernel, is preserved. This
helps in cases where FADump is not enabled but the subsequent memory
preserving kernel boot is likely to process this crash data. One
typical usecase for this config option is petitboot kernel.
As OPAL allows registering address with it in the first kernel and
retrieving it after MPIPL, use it to store the top of boot memory.
A kernel that intends to preserve crash data retrieves it and avoids
using memory beyond this address.
Move arch_reserved_kernel_pages() function as it is needed for both
FA_DUMP and PRESERVE_FA_DUMP configurations.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821375751.5656.11459483669542541602.stgit@hbathini.in.ibm.com
The size parameter to fadump_reserve_crash_area() function is not needed
as all the memory above boot memory size must be preserved anyway. Update
the function by dropping this redundant parameter.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821374440.5656.2945512543806951766.stgit@hbathini.in.ibm.com
Commit 0962e8004e ("powerpc/prom: Scan reserved-ranges node for
memory reservations") enabled support to parse 'reserved-ranges' DT
node to reserve kernel memory falling in these ranges for firmware
purposes. Along with the preserved area memory, ensure memory in
reserved ranges is not overlapped with memory released by capture
kernel aftering saving vmcore. Also, fix the off-by-one error in
fadump_release_reserved_area function while releasing memory.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821371358.5656.6061214942558818661.stgit@hbathini.in.ibm.com
Make allocate_crash_memory_ranges() and free_crash_memory_ranges()
functions generic to reuse them for memory management of all types of
dynamic memory range arrays. This change helps in memory management
of reserved ranges array to be added later.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821369863.5656.4375667005352155892.stgit@hbathini.in.ibm.com
Earlier, memblock_find_in_range() was not used to find the memory to
be reserved for FADump as bottom up allocation mode was not supported.
But since commit 79442ed189 ("mm/memblock.c: introduce bottom-up
allocation mode") bottom up allocation mode is supported for memblock.
So, use it to find the memory to be reserved for FADump.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821364211.5656.14336025460336135194.stgit@hbathini.in.ibm.com
Make OPAL call to indicate that the dump is processed and the metadata
area in OPAL can be cleared/released. Also, setup/initialize FADump
for re-registration.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821356046.5656.12270927048195494911.stgit@hbathini.in.ibm.com
During kexec boot, metadata address needs to be reset to avoid running
into errors interpreting stale metadata address, in case the kexec'ed
kernel crashes before metadata address could be setup again.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821346629.5656.10783321582005237813.stgit@hbathini.in.ibm.com
OPAL allows registering address with it in the first kernel and
retrieving it after MPIPL. Setup kernel metadata and register its
address with OPAL to use it for processing the crash dump.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821345011.5656.13567765019032928471.stgit@hbathini.in.ibm.com
Except for Reserved dump area (see Documentation/powerpc/firmware-
assisted-dump.rst) which is permanent reserved, all memory above boot
memory size, where boot memory size is the memory required for the
kernel to boot successfully when booted with restricted memory (memory
for capture kernel), is released when the dump is invalidated. Make
this a bit more explicit in the code.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821336092.5656.1079046285366041687.stgit@hbathini.in.ibm.com
Move platform specific register/un-register code, the RTAS calls, to
register/un-register callback functions. This would also mean moving
code that initializes and prints the platform specific FADump data.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821332856.5656.16380417702046411631.stgit@hbathini.in.ibm.com
Introduce callback functions for platform specific operations like
register, unregister, invalidate & such. Also, define place-holders
for the same on pSeries platform.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821330286.5656.15538934400074110770.stgit@hbathini.in.ibm.com
Currently, FADump is only supported on pSeries but that is going to
change soon with FADump support being added on PowerNV platform. So,
move rtas specific definitions to platform code to allow FADump
to have multiple platforms support.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821328494.5656.16219929140866195511.stgit@hbathini.in.ibm.com
Add helper functions to setup & free CPU notes buffer and to find if a
given memory area is contiguous. Also, use boolean as return type for
the function that finds if boot memory area is contiguous. While at
it, save the virtual address of CPU notes buffer instead of physical
address as virtual address is used often.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821318971.5656.9281936950510635858.stgit@hbathini.in.ibm.com
Though asm/fadump.h is meant to be used by other components dealing
with FADump, it also has macros/definitions internal to FADump code.
Move them to a new header file used within FADump code. This also
makes way for refactoring platform specific FADump code.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/156821313134.5656.6597770626574392140.stgit@hbathini.in.ibm.com
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 1334 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
No need to have this in asm/page.h, move it into asm/hugetlb.h
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
For fadump to work successfully there should not be any holes in reserved
memory ranges where kernel has asked firmware to move the content of old
kernel memory in event of crash. Now that fadump uses CMA for reserved
area, this memory area is now not protected from hot-remove operations
unless it is cma allocated. Hence, fadump service can fail to re-register
after the hot-remove operation, if hot-removed memory belongs to fadump
reserved region. To avoid this make sure that memory from fadump reserved
area is not hot-removable if fadump is registered.
However, if user still wants to remove that memory, he can do so by
manually stopping fadump service before hot-remove operation.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
fadump fails to register when there are holes in reserved memory area.
This can happen if user has hot-removed a memory that falls in the
fadump reserved memory area. Throw a meaningful error message to the
user in such case.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
[mpe: is_reserved_memory_area_contiguous() returns bool, unsplit string]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
One of the primary issues with Firmware Assisted Dump (fadump) on Power
is that it needs a large amount of memory to be reserved. On large
systems with TeraBytes of memory, this reservation can be quite
significant.
In some cases, fadump fails if the memory reserved is insufficient, or
if the reserved memory was DLPAR hot-removed.
In the normal case, post reboot, the preserved memory is filtered to
extract only relevant areas of interest using the makedumpfile tool.
While the tool provides flexibility to determine what needs to be part
of the dump and what memory to filter out, all supported distributions
default this to "Capture only kernel data and nothing else".
We take advantage of this default and the Linux kernel's Contiguous
Memory Allocator (CMA) to fundamentally change the memory reservation
model for fadump.
Instead of setting aside a significant chunk of memory nobody can use,
this patch uses CMA instead, to reserve a significant chunk of memory
that the kernel is prevented from using (due to MIGRATE_CMA), but
applications are free to use it. With this fadump will still be able
to capture all of the kernel memory and most of the user space memory
except the user pages that were present in CMA region.
Essentially, on a P9 LPAR with 2 cores, 8GB RAM and current upstream:
[root@zzxx-yy10 ~]# free -m
total used free shared buff/cache available
Mem: 7557 193 6822 12 541 6725
Swap: 4095 0 4095
With this patch:
[root@zzxx-yy10 ~]# free -m
total used free shared buff/cache available
Mem: 8133 194 7464 12 475 7338
Swap: 4095 0 4095
Changes made here are completely transparent to how fadump has
traditionally worked.
Thanks to Aneesh Kumar and Anshuman Khandual for helping us understand
CMA and its usage.
TODO:
- Handle case where CMA reservation spans nodes.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Use DEFINE_SHOW_ATTRIBUTE macro to simplify the code.
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Firmware-Assisted Dump (FADump) needs to be registered again after any
memory hot add/remove operation to update the crash memory ranges. But
currently, the kernel returns '-EEXIST' if we try to register without
uregistering it first. This could expose the system to racing issues
while unregistering and registering FADump from userspace during udev
events. Spare the userspace of this and let it be taken care of in the
kernel space for a simpler interface.
Since this change, running 'echo 1 > /sys/kernel/fadump_registered'
would result in re-regisering (unregistering and registering) FADump,
if it was already registered.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Acked-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Commit 1bd6a1c4b8 ("powerpc/fadump: handle crash memory ranges array
index overflow") changed crash memory ranges to a dynamic array that
is reallocated on-demand with krealloc(). The relevant header for this
call was not included. The kernel compiles though. But be cautious and
add the header anyway.
Also, memory allocation logic in fadump_add_crash_memory() takes care
of memory allocation for crash memory ranges in all scenarios. Drop
unnecessary memory allocation in fadump_setup_crash_memory_ranges().
Fixes: 1bd6a1c4b8 ("powerpc/fadump: handle crash memory ranges array index overflow")
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
With dynamic memory allocation support for crash memory ranges array,
there is no hard limit on the no. of crash memory ranges kernel could
export, but program headers count could overflow in the /proc/vmcore
ELF file while exporting each memory range as PT_LOAD segment. Reduce
the likelihood of a such scenario, by folding adjacent crash memory
ranges which minimizes the total number of PT_LOAD segments.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Crash memory ranges is an array of memory ranges of the crashing kernel
to be exported as a dump via /proc/vmcore file. The size of the array
is set based on INIT_MEMBLOCK_REGIONS, which works alright in most cases
where memblock memory regions count is less than INIT_MEMBLOCK_REGIONS
value. But this count can grow beyond INIT_MEMBLOCK_REGIONS value since
commit 142b45a72e ("memblock: Add array resizing support").
On large memory systems with a few DLPAR operations, the memblock memory
regions count could be larger than INIT_MEMBLOCK_REGIONS value. On such
systems, registering fadump results in crash or other system failures
like below:
task: c00007f39a290010 ti: c00000000b738000 task.ti: c00000000b738000
NIP: c000000000047df4 LR: c0000000000f9e58 CTR: c00000000010f180
REGS: c00000000b73b570 TRAP: 0300 Tainted: G L X (4.4.140+)
MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 22004484 XER: 20000000
CFAR: c000000000008500 DAR: 000007a450000000 DSISR: 40000000 SOFTE: 0
...
NIP [c000000000047df4] smp_send_reschedule+0x24/0x80
LR [c0000000000f9e58] resched_curr+0x138/0x160
Call Trace:
resched_curr+0x138/0x160 (unreliable)
check_preempt_curr+0xc8/0xf0
ttwu_do_wakeup+0x38/0x150
try_to_wake_up+0x224/0x4d0
__wake_up_common+0x94/0x100
ep_poll_callback+0xac/0x1c0
__wake_up_common+0x94/0x100
__wake_up_sync_key+0x70/0xa0
sock_def_readable+0x58/0xa0
unix_stream_sendmsg+0x2dc/0x4c0
sock_sendmsg+0x68/0xa0
___sys_sendmsg+0x2cc/0x2e0
__sys_sendmsg+0x5c/0xc0
SyS_socketcall+0x36c/0x3f0
system_call+0x3c/0x100
as array index overflow is not checked for while setting up crash memory
ranges causing memory corruption. To resolve this issue, dynamically
allocate memory for crash memory ranges and resize it incrementally,
in units of pagesize, on hitting array size limit.
Fixes: 2df173d9e8 ("fadump: Initialize elfcore header and add PT_LOAD program headers.")
Cc: stable@vger.kernel.org # v3.4+
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
[mpe: Just use PAGE_SIZE directly, fixup variable placement]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Unregister fadump on kexec down path otherwise the fadump registration
in new kexec-ed kernel complains that fadump is already registered.
This makes new kernel to continue using fadump registered by previous
kernel which may lead to invalid vmcore generation. Hence this patch
fixes this issue by un-registering fadump in fadump_cleanup() which is
called during kexec path so that new kernel can register fadump with
new valid values.
Fixes: b500afff11 ("fadump: Invalidate registration and release reserved memory for general use.")
Cc: stable@vger.kernel.org # v3.4+
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
FADump capture kernel boots in restricted memory environment preserving
the context of previous kernel to save vmcore. Supporting hugepages in
such environment makes things unnecessarily complicated, as hugepages
need memory set aside for them. This means most of the capture kernel's
memory is used in supporting hugepages. In most cases, this results in
out-of-memory issues while booting FADump capture kernel. But hugepages
are not of much use in capture kernel whose only job is to save vmcore.
So, disabling hugepages support, when fadump is active, is a reliable
solution for the out of memory issues. Introducing a flag variable to
disable HugeTLB support when fadump is active.
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The second kernel, during early boot after the crash, reserves rest of
the memory above boot memory size to make sure it does not touch any of the
dump memory area. It uses memblock_reserve() that reserves the specified
memory region irrespective of memory holes present within that region.
There are chances where previous kernel would have hot removed some of
its memory leaving memory holes behind. In such cases fadump kernel reports
incorrect number of reserved pages through arch_reserved_kernel_pages()
hook causing kernel to hang or panic.
Fix this by excluding memory holes while reserving rest of the memory
above boot memory size during second kernel boot after crash.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This reverts commit a3b2cb30f2.
That commit tried to fix problems with panic on powerpc in certain
circumstances, where some output from the generic panic code was being
dropped.
Unfortunately, it breaks things worse in other circumstances. In
particular when running a PAPR guest, it will now attempt to reboot
instead of informing the hypervisor (KVM or PowerVM) that the guest
has crashed. The crash notification is important to some
virtualization management layers.
Revert it for now until we can come up with a better solution.
Fixes: a3b2cb30f2 ("powerpc: Do not call ppc_md.panic in fadump panic notifier")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
[mpe: Tweak change log a bit]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Currently sysfs store handlers in fadump use if buf[0] == 'char'.
This means input "100foo" is interpreted as '1' and "01" as '0'.
Change to kstrtoint so leading zeroes and the like is handled in
expected way.
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Acked-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Michal Suchanek <a class="moz-txt-link-rfc2396E" href="mailto:msuchanek@suse.de"><msuchanek@suse.de></a></pre>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There are quite a few machine check exceptions that can be caused by
kernel bugs. To make debugging easier, use the kernel crash path in
cases of synchronous machine checks that occur in kernel mode, if that
would not result in the machine going straight to panic or crash dump.
There is a downside here that die()ing the process in kernel mode can
still leave the system unstable. panic_on_oops will always force the
system to fail-stop, so systems where that behaviour is important will
still do the right thing.
As a test, when triggering an i-side 0111b error (ifetch from foreign
address) in kernel mode process context on POWER9, the kernel currently
dies quickly like this:
Severe Machine check interrupt [Not recovered]
NIP [ffff000000000000]: 0xffff000000000000
Initiator: CPU
Error type: Real address [Instruction fetch (foreign)]
[ 127.426651616,0] OPAL: Reboot requested due to Platform error.
Effective[ 127.426693712,3] OPAL: Reboot requested due to Platform error. address: ffff000000000000
opal: Reboot type 1 not supported
Kernel panic - not syncing: PowerNV Unrecovered Machine Check
CPU: 56 PID: 4425 Comm: syscall Tainted: G M 4.12.0-rc1-13857-ga4700a261072-dirty #35
Call Trace:
[ 128.017988928,4] IPMI: BUG: Dropping ESEL on the floor due to
buggy/mising code in OPAL for this BMC
Rebooting in 10 seconds..
Trying to free IRQ 496 from IRQ context!
After this patch, the process is killed and the kernel continues with
this message, which gives enough information to identify the offending
branch (i.e., with CFAR):
Severe Machine check interrupt [Not recovered]
NIP [ffff000000000000]: 0xffff000000000000
Initiator: CPU
Error type: Real address [Instruction fetch (foreign)]
Effective address: ffff000000000000
Oops: Machine check, sig: 7 [#1]
SMP NR_CPUS=2048
NUMA
PowerNV
Modules linked in: iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 ...
CPU: 22 PID: 4436 Comm: syscall Tainted: G M 4.12.0-rc1-13857-ga4700a261072-dirty #36
task: c000000932300000 task.stack: c000000932380000
NIP: ffff000000000000 LR: 00000000217706a4 CTR: ffff000000000000
REGS: c00000000fc8fd80 TRAP: 0200 Tainted: G M (4.12.0-rc1-13857-ga4700a261072-dirty)
MSR: 90000000001c1003 <SF,HV,ME,RI,LE>
CR: 24000484 XER: 20000000
CFAR: c000000000004c80 DAR: 0000000021770a90 DSISR: 0a000000 SOFTE: 1
GPR00: 0000000000001ebe 00007fffce4818b0 0000000021797f00 0000000000000000
GPR04: 00007fff8007ac24 0000000044000484 0000000000004000 00007fff801405e8
GPR08: 900000000280f033 0000000024000484 0000000000000000 0000000000000030
GPR12: 9000000000001003 00007fff801bc370 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR24: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR28: 00007fff801b0000 0000000000000000 00000000217707a0 00007fffce481918
NIP [ffff000000000000] 0xffff000000000000
LR [00000000217706a4] 0x217706a4
Call Trace:
Instruction dump:
XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
If fadump is not registered, and no other crash or debug handlers are
registered, the powerpc panic handler stops the guest before the
generic panic code can push out debug information to the console.
Currently, system reset injection causes the guest to silently stop.
Stop calling ppc_md.panic in the panic notifier. crash_fadump already
does rtas_os_term() to terminate the guest if fadump is registered.
Remove ppc_md.panic. Move fadump panic notifier into fadump code.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
vmcoreinfo_max_size stands for the vmcoreinfo_data, the correct one we
should use is vmcoreinfo_note whose total size is VMCOREINFO_NOTE_SIZE.
Like explained in commit 77019967f0 ("kdump: fix exported size of
vmcoreinfo note"), it should not affect the actual function, but we
better fix it, also this change should be safe and backward compatible.
After this, we can get rid of variable vmcoreinfo_max_size, let's use
the corresponding macros directly, fewer variables means more safety for
vmcoreinfo operation.
[xlpang@redhat.com: fix build warning]
Link: http://lkml.kernel.org/r/1494830606-27736-1-git-send-email-xlpang@redhat.com
Link: http://lkml.kernel.org/r/1493281021-20737-2-git-send-email-xlpang@redhat.com
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Reviewed-by: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Around 95% of memory is reserved by fadump/capture kernel. All this
memory is freed, one page at a time, on writing '1' to the node
/sys/kernel/fadump_release_mem. On systems with large memory, this
can take a long time to complete, leading to soft lockup warning
messages. To avoid this, add reschedule points at regular intervals.
Also, while memblock_reserve() implicitly takes care of holes in the
given memory range while reserving memory, those holes need to be
taken care of while releasing memory as memory is freed one page at
a time. Add support to skip holes while releasing memory.
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
fadump fails to register when there are holes in boot memory area.
Provide a helpful error message to the user in such case.
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
To register fadump, boot memory area - the size of low memory chunk that
is required for a kernel to boot successfully when booted with restricted
memory, is assumed to have no holes. But this memory area is currently
not protected from hot-remove operations. So, fadump could fail to
re-register after a memory hot-remove operation, if memory is removed
from boot memory area. To avoid this, ensure that memory from boot
memory area is not hot-removed when fadump is registered.
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
fadump sets up crash memory ranges to be used for creating PT_LOAD
program headers in elfcore header. Memory chunk RMA_START through
boot memory area size is added as the first memory range because
firmware, at the time of crash, moves this memory chunk to different
location specified during fadump registration making it necessary to
create a separate program header for it with the correct offset.
This memory chunk is skipped while setting up the remaining memory
ranges. But currently, there is possibility that some of this memory
may have duplicate entries like when it is hot-removed and added
again. Ensure that no two memory ranges represent the same memory.
When 5 lmbs are hot-removed and then hot-plugged before registering
fadump, here is how the program headers in /proc/vmcore exported by
fadump look like
without this change:
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
NOTE 0x0000000000010000 0x0000000000000000 0x0000000000000000
0x0000000000001894 0x0000000000001894 0
LOAD 0x0000000000021020 0xc000000000000000 0x0000000000000000
0x0000000040000000 0x0000000040000000 RWE 0
LOAD 0x0000000040031020 0xc000000000000000 0x0000000000000000
0x0000000010000000 0x0000000010000000 RWE 0
LOAD 0x0000000050040000 0xc000000010000000 0x0000000010000000
0x0000000050000000 0x0000000050000000 RWE 0
LOAD 0x00000000a0040000 0xc000000060000000 0x0000000060000000
0x000000019ffe0000 0x000000019ffe0000 RWE 0
and with this change:
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
NOTE 0x0000000000010000 0x0000000000000000 0x0000000000000000
0x0000000000001894 0x0000000000001894 0
LOAD 0x0000000000021020 0xc000000000000000 0x0000000000000000
0x0000000040000000 0x0000000040000000 RWE 0
LOAD 0x0000000040030000 0xc000000040000000 0x0000000040000000
0x0000000020000000 0x0000000020000000 RWE 0
LOAD 0x0000000060030000 0xc000000060000000 0x0000000060000000
0x000000019ffe0000 0x000000019ffe0000 RWE 0
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Mahesh J Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
By default, 5% of system RAM is reserved for preserving boot memory.
Alternatively, a user can specify the amount of memory to reserve.
See Documentation/powerpc/firmware-assisted-dump.txt for details. In
addition to the memory reserved for preserving boot memory, some more
memory is reserved, to save HPTE region, CPU state data and ELF core
headers.
Memory Reservation during first kernel looks like below:
Low memory Top of memory
0 boot memory size |
| | |<--Reserved dump area -->|
V V | Permanent Reservation V
+-----------+----------/ /----------+---+----+-----------+----+
| | |CPU|HPTE| DUMP |ELF |
+-----------+----------/ /----------+---+----+-----------+----+
| ^
| |
\ /
-------------------------------------------
Boot memory content gets transferred to
reserved area by firmware at the time of
crash
This implicitly means that the sum of the sizes of boot memory, CPU
state data, HPTE region, DUMP preserving area and ELF core headers
can't be greater than the total memory size. But currently, a user is
allowed to specify any value as boot memory size. So, the above rule
is violated when a boot memory size around 50% of the total available
memory is specified. As the kernel is not handling this currently, it
may lead to undefined behavior. Fix it by setting an upper limit for
boot memory size to 25% of the total available memory. Also, instead
of using memblock_end_of_DRAM(), which doesn't take the holes, if any,
in the memory layout into account, use memblock_phys_mem_size() to
calculate the percentage of total available memory.
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
With commit f6e6bedb77 ("powerpc/fadump: Reserve memory at an offset
closer to bottom of RAM"), memory for fadump is no longer reserved at
the top of RAM. But there are still a few places which say so. Change
them appropriately.
Signed-off-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
