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SubjectRe: [PATCH v3] x86/bugs: Only harden syscalls when needed
On Tue, Apr 16, 2024 at 04:02:21PM -0700, Josh Poimboeuf wrote:
> Syscall hardening (i.e., converting the syscall indirect branch to a
> series of direct branches) may cause performance regressions in certain
> scenarios. Only use the syscall hardening when indirect branches are
> considered unsafe.
>
> Fixes: 1e3ad78334a6 ("x86/syscall: Don't force use of indirect calls for system calls")
> Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
> v3:
> - fix X86_FEATURE_INDIRECT_SAFE value
>
> arch/x86/entry/common.c | 15 ++++++++++++---
> arch/x86/entry/syscall_32.c | 11 +----------
> arch/x86/entry/syscall_64.c | 6 ------
> arch/x86/entry/syscall_x32.c | 7 ++++++-
> arch/x86/include/asm/cpufeatures.h | 1 +
> arch/x86/include/asm/syscall.h | 8 +++++++-
> arch/x86/kernel/cpu/bugs.c | 31 +++++++++++++++++++++++++++++-
> 7 files changed, 57 insertions(+), 22 deletions(-)

I poked at this a bit and can't find anything that I can complain about
so

Acked-by: Borislav Petkov (AMD) <bp@alien8.de>

I'll pick it up into urgent if no one complains soon.

Thx.

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

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