x86/entry/64: Remove the SYSCALL64 fast path

Browse source

The SYCALLL64 fast path was a nice, if small, optimization back in the good
old days when syscalls were actually reasonably fast.  Now there is PTI to
slow everything down, and indirect branches are verboten, making everything
messier.  The retpoline code in the fast path is particularly nasty.

Just get rid of the fast path. The slow path is barely slower.

[ tglx: Split out the 'push all extra regs' part ]

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>
Link: https://lkml.kernel.org/r/462dff8d4d64dfbfc851fbf3130641809d980ecd.1517164461.git.luto@kernel.org

...

This commit is contained in:

Andy Lutomirski 2018-01-28 10:38:49 -08:00 • committed by Thomas Gleixner

parent 9471eee918

commit 21d375b6b3

2 changed files with 2 additions and 122 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

117

arch/x86/entry/entry_64.S

View file

7

arch/x86/entry/syscall_64.c

View file