x86/entry/64: Remove the SYSCALL64 fast path

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commit 21d375b6b3

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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This commit is contained in:

Andy Lutomirski 2018-01-28 10:38:49 -08:00 • committed by Greg Kroah-Hartman

parent 74ae346691

commit 8459ebcbd6

2 changed files with 2 additions and 122 deletions

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117

arch/x86/entry/entry_64.S

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7

arch/x86/entry/syscall_64.c

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