mirror of https://gitee.com/openkylin/linux.git
e16c2983fb
The last change to this Makefile caused relocation errors when loading
a kdump kernel. Restore -mcmodel=large (not -mcmodel=kernel),
-ffreestanding, and -fno-zero-initialized-bsss, without reverting to
the former practice of resetting KBUILD_CFLAGS.
Purgatory.ro is a standalone binary that is not linked against the
rest of the kernel. Its image is copied into an array that is linked
to the kernel, and from there kexec relocates it wherever it desires.
With the previous change to compiler flags, the error "kexec: Overflow
in relocation type 11 value 0x11fffd000" was encountered when trying
to load the crash kernel. This is from kexec code trying to relocate
the purgatory.ro object.
From the error message, relocation type 11 is R_X86_64_32S. The
x86_64 ABI says:
"The R_X86_64_32 and R_X86_64_32S relocations truncate the
computed value to 32-bits. The linker must verify that the
generated value for the R_X86_64_32 (R_X86_64_32S) relocation
zero-extends (sign-extends) to the original 64-bit value."
This type of relocation doesn't work when kexec chooses to place the
purgatory binary in memory that is not reachable with 32 bit
addresses.
The compiler flag -mcmodel=kernel allows those type of relocations to
be emitted, so revert to using -mcmodel=large as was done before.
Also restore the -ffreestanding and -fno-zero-initialized-bss flags
because they are appropriate for a stand alone piece of object code
which doesn't explicitly zero the bss, and one other report has said
undefined symbols are encountered without -ffreestanding.
These identical compiler flag changes need to happen for every object
that becomes part of the purgatory.ro object, so gather them together
first into PURGATORY_CFLAGS_REMOVE and PURGATORY_CFLAGS, and then
apply them to each of the objects that have C source. Do not apply
any of these flags to kexec-purgatory.o, which is not part of the
standalone object but part of the kernel proper.
Tested-by: Vaibhav Rustagi <vaibhavrustagi@google.com>
Tested-by: Andreas Smas <andreas@lonelycoder.com>
Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: None
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: clang-built-linux@googlegroups.com
Cc: dimitri.sivanich@hpe.com
Cc: mike.travis@hpe.com
Cc: russ.anderson@hpe.com
Fixes:
|
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
README
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.