8c86f29bfb
The ZERO_CALL_USED_REGS feature may zero out caller-saved registers
before returning.
In spurious_kernel_fault(), the "pte_offset_kernel()" call results in
this assembly code:
.Ltmp151:
#APP
# ALT: oldnstr
.Ltmp152:
.Ltmp153:
.Ltmp154:
.section .discard.retpoline_safe,"",@progbits
.quad .Ltmp154
.text
callq *pv_ops+536(%rip)
.Ltmp155:
.section .parainstructions,"a",@progbits
.p2align 3, 0x0
.quad .Ltmp153
.byte 67
.byte .Ltmp155-.Ltmp153
.short 1
.text
.Ltmp156:
# ALT: padding
.zero (-(((.Ltmp157-.Ltmp158)-(.Ltmp156-.Ltmp152))>0))*((.Ltmp157-.Ltmp158)-(.Ltmp156-.Ltmp152)),144
.Ltmp159:
.section .altinstructions,"a",@progbits
.Ltmp160:
.long .Ltmp152-.Ltmp160
.Ltmp161:
.long .Ltmp158-.Ltmp161
.short 33040
.byte .Ltmp159-.Ltmp152
.byte .Ltmp157-.Ltmp158
.text
.section .altinstr_replacement,"ax",@progbits
# ALT: replacement 1
.Ltmp158:
movq %rdi, %rax
.Ltmp157:
.text
#NO_APP
.Ltmp162:
testb $-128, %dil
The "testb" here is using %dil, but the %rdi register was cleared before
returning from "callq *pv_ops+536(%rip)". Adding the proper constraints
results in the use of a different register:
movq %r11, %rdi
# Similar to above.
testb $-128, %r11b
Link: https://github.com/KSPP/linux/issues/192
Signed-off-by: Bill Wendling <morbo@google.com>
Reported-and-tested-by: Nathan Chancellor <nathan@kernel.org>
Fixes:
|
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| 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.