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kdumpst-load/config: Add option to use crashkernel as pstore/ram memory

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Currently kdumpst only allows a proper RAM buffer to be used as ramoops
memory area - this is the proper way of doing that, but there are cases
in which it's not trivial to have these buffers available:

(a) In case it's not there by default (due to kernel alignment / device-tree)
for example, there is no easy parameter to reserve such area right now
(using mem= is the way to go, but a bit complex to gather the exact size).

(b) The kernel parameter crashkernel= does something like this: reserve
a piece of memory not to be used by the kernel. It's meant for kdump, but
can be (ab)used for other purposes.

So, we hereby add a way for kdumpst to make use of crash reserved area
if the users wish so; the risks are exposed in the config file text.

Also, since we're changing this code, take the opportunity to improve the
sanitization of addresses from /proc/iomem and fix a corner case of empty
RANGE in the iomem parsing routine.

Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
This commit is contained in:
Guilherme G. Piccoli
2023-12-23 12:03:00 -05:00
parent acd5a64652
commit 63345d21a7
2 changed files with 17 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
00-default.conf
View File

@ -16,9 +16,15 @@
# relies in having an available RAM buffer on /proc/iomem with at least # relies in having an available RAM buffer on /proc/iomem with at least
# PSTORE_MEM_AMOUNT (decimal, in MB) in size. Also, kernel must be able to # PSTORE_MEM_AMOUNT (decimal, in MB) in size. Also, kernel must be able to
# allocate a contiguous memory amount of PSTORE_RECORD_SZ (decimal, MB). # allocate a contiguous memory amount of PSTORE_RECORD_SZ (decimal, MB).
# If there is no such RAM buffer, there is a possibility to make use of
# the crash kernel area for that. There are risks: such memory area could
# have its address mapped differently across kernel updates; also if both
# pstore and the kdump kernel are loaded, that memory region will be for
# sure corrupted by the kexec panic load - so, kind of a last resource.
USE_PSTORE_RAM=1 USE_PSTORE_RAM=1
PSTORE_MEM_AMOUNT=4194304 PSTORE_MEM_AMOUNT=4194304
PSTORE_RECORD_SZ=1048576 PSTORE_RECORD_SZ=1048576
PSTORE_RAM_USE_CRASH_MEM=0
# #
# #
# Mount-related options # Mount-related options

14
kdumpst-load.sh.in
View File

@ -77,10 +77,14 @@ clear_all_initrds() {
# Next routine parses /proc/iomem to obtain the biggest RAM buffer # Next routine parses /proc/iomem to obtain the biggest RAM buffer
# available. Saves the results in 2 global variables: MEM_{SIZE,START}. # available. Saves the results in 2 global variables: MEM_{SIZE,START}.
parse_ram_buffers() { parse_ram_buffers() {
BUFFERS="$(grep "RAM buffer" /proc/iomem)" BUFFERS="$(grep "$1" /proc/iomem)"
while read -r line while read -r line
do do
RANGE=$(echo "$line" | cut -f1 -d\ ) RANGE=$(echo "$line" | sed 's/^[[:space:]]*//g' | cut -f1 -d:)
if [ "${RANGE}" == '' ]; then
continue
fi
MEM_END=$(echo "$RANGE" | cut -f2 -d-) MEM_END=$(echo "$RANGE" | cut -f2 -d-)
MSTART=$(echo "$RANGE" | cut -f1 -d-) MSTART=$(echo "$RANGE" | cut -f1 -d-)
@ -155,7 +159,11 @@ if [ "${USE_PSTORE_RAM}" -eq 1 ]; then
RECORD_SIZE="${PSTORE_RECORD_SZ}" RECORD_SIZE="${PSTORE_RECORD_SZ}"
MEM_SIZE=0 MEM_SIZE=0
parse_ram_buffers parse_ram_buffers "RAM buffer"
if [ "${MEM_SIZE}" -eq 0 ] && [ "${PSTORE_RAM_USE_CRASH_MEM}" -eq 1 ]; then
parse_ram_buffers "Crash kernel"
fi
if [ "${MEM_SIZE}" -gt 0 ]; then if [ "${MEM_SIZE}" -gt 0 ]; then
if modprobe ramoops mem_address=0x"${MEM_START}" mem_size="${MEM_REQUIRED}" record_size="${RECORD_SIZE}"; then if modprobe ramoops mem_address=0x"${MEM_START}" mem_size="${MEM_REQUIRED}" record_size="${RECORD_SIZE}"; then