People reported kernel panic occurs during system boots up with mem boot option.
After checking code, several problems are found about memmap= and mem= in boot
stage
kaslr.
*) In commit f28442497b5c ("x86/boot: Fix KASLR and memmap= collision"), only
one memmap
entry is considered and only the last one if multiple memmap entries are
specified.
*) mem= and memmap=nn[KMG] are not considered yet. They are used to limit max
address
of system. Kernel can't be randomized to be above the limit.
*) kernel-parameters.txt doesn't tell the updated behaviour of memmap=.
This patchset tries to solve above issues, and it sits on top of
tip:x86/boot branch.
Changelog
v4->v5:
1. Change patch log according to Thomas's comment.
2. Put "Fall through" to the right place in parse_memmap() according
to Kees's suggestion.
v3->v4:
1. Code improved patch 1/3 according to Kees's suggestion.
2. Add 'Fall through' in switch case of parse_memmap() which
is suggestd by Kees.
v2->v3:
No functionality change in this round.
1. Use local static variable insted of global variable
mem_avoid_memmap_index in patch 1/3.
2. Fix a typo in patch 3/3.
v1->v2:
1. The original patch 1/4 has been put in tip:x86/boot and no update,
so it's not included in this post.
2. Use patch log Ingo reorganized.
3. lib/ctype.c and lib/cmdline.c are needed for kaslr.c, while those
EXPORT_SYMBOL(x) contained caused failure of build on 32-bit allmodconfig:
......
ld: -r and -shared may not be used together
scripts/Makefile.build:294: recipe for target
'arch/x86/boot/compressed/kaslr.o' failed
......
Disabling the symbol exporting removes the build failure.
4. Use dynamic allocation to allocate memory to contain copied kernel cmdline
buffer, it's implemented in include/linux/decompress/mm.h.
Baoquan He (3):
KASLR: Parse all memmap entries in command line
KASLR: Handle memory limit specified by memmap and mem option
Documentation/kernel-parameters.txt: Update 'memmap=' option
description
Documentation/admin-guide/kernel-parameters.txt | 9 ++
arch/x86/boot/compressed/cmdline.c | 2 +-
arch/x86/boot/compressed/kaslr.c | 190 ++++++++++++++++--------
arch/x86/boot/string.c | 8 +
4 files changed, 143 insertions(+), 66 deletions(-)
--
2.5.5
