bf98bae3d8
as latter clobbers flags which interferes with fastop emulation in
KVM, leading to guests freezing during boot
- A fix for the DIV(0) quotient data leak on Zen1 to clear the divider
buffers at the right time
- Disable the SRSO mitigation on unaffected configurations as it got
enabled there unnecessarily
- Change .text section name to fix CONFIG_LTO_CLANG builds
- Improve the optprobe indirect jmp check so that certain configurations
can still be able to use optprobes at all
- A serious and good scrubbing of the untraining routines by PeterZ:
- Add proper speculation stopping traps so that objtool is happy
- Adjust objtool to handle the new thunks
- Make the thunk pointer assignable to the different untraining
sequences at runtime, thus avoiding the alternative at the return
thunk. It simplifies the code a bit too.
- Add a entry_untrain_ret() main entry point which selects the
respective untraining sequence
- Rename things so that they're more clear
- Fix stack validation with FRAME_POINTER=y builds
- Fix static call patching to handle when a JMP to the return thunk is
the last insn on the very last module memory page
- Add more documentation about what each untraining routine does and
why
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Merge tag 'x86_urgent_for_v6.5_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Borislav Petkov:
"Extraordinary embargoed times call for extraordinary measures. That's
why this week's x86/urgent branch is larger than usual, containing all
the known fallout fixes after the SRSO mitigation got merged.
I know, it is a bit late in the game but everyone who has reported a
bug stemming from the SRSO pile, has tested that branch and has
confirmed that it fixes their bug.
Also, I've run it on every possible hardware I have and it is looking
good. It is running on this very machine while I'm typing, for 2 days
now without an issue. Famous last words...
- Use LEA ...%rsp instead of ADD %rsp in the Zen1/2 SRSO return
sequence as latter clobbers flags which interferes with fastop
emulation in KVM, leading to guests freezing during boot
- A fix for the DIV(0) quotient data leak on Zen1 to clear the
divider buffers at the right time
- Disable the SRSO mitigation on unaffected configurations as it got
enabled there unnecessarily
- Change .text section name to fix CONFIG_LTO_CLANG builds
- Improve the optprobe indirect jmp check so that certain
configurations can still be able to use optprobes at all
- A serious and good scrubbing of the untraining routines by PeterZ:
- Add proper speculation stopping traps so that objtool is happy
- Adjust objtool to handle the new thunks
- Make the thunk pointer assignable to the different untraining
sequences at runtime, thus avoiding the alternative at the
return thunk. It simplifies the code a bit too.
- Add a entry_untrain_ret() main entry point which selects the
respective untraining sequence
- Rename things so that they're more clear
- Fix stack validation with FRAME_POINTER=y builds
- Fix static call patching to handle when a JMP to the return thunk
is the last insn on the very last module memory page
- Add more documentation about what each untraining routine does and
why"
* tag 'x86_urgent_for_v6.5_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/srso: Correct the mitigation status when SMT is disabled
x86/static_call: Fix __static_call_fixup()
objtool/x86: Fixup frame-pointer vs rethunk
x86/srso: Explain the untraining sequences a bit more
x86/cpu/kvm: Provide UNTRAIN_RET_VM
x86/cpu: Cleanup the untrain mess
x86/cpu: Rename srso_(.*)_alias to srso_alias_\1
x86/cpu: Rename original retbleed methods
x86/cpu: Clean up SRSO return thunk mess
x86/alternative: Make custom return thunk unconditional
objtool/x86: Fix SRSO mess
x86/cpu: Fix up srso_safe_ret() and __x86_return_thunk()
x86/cpu: Fix __x86_return_thunk symbol type
x86/retpoline,kprobes: Skip optprobe check for indirect jumps with retpolines and IBT
x86/retpoline,kprobes: Fix position of thunk sections with CONFIG_LTO_CLANG
x86/srso: Disable the mitigation on unaffected configurations
x86/CPU/AMD: Fix the DIV(0) initial fix attempt
x86/retpoline: Don't clobber RFLAGS during srso_safe_ret()
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.