powerpc/32: implement fast entry for syscalls on non BOOKE

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This patch implements a fast entry for syscalls.

Syscalls don't have to preserve non volatile registers except LR.

This patch then implement a fast entry for syscalls, where
volatile registers get clobbered.

As this entry is dedicated to syscall it always sets MSR_EE
and warns in case MSR_EE was previously off

It also assumes that the call is always from user, system calls are
unexpected from kernel.

The overall series improves null_syscall selftest by 12,5% on an 83xx
and by 17% on a 8xx.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

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This commit is contained in:

Christophe Leroy 2019-04-30 12:39:02 +00:00 • committed by Michael Ellerman

parent 40530db7c6

commit b86fb88855

5 changed files with 116 additions and 10 deletions

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32

arch/powerpc/kernel/entry_32.S

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3

arch/powerpc/kernel/head_32.S

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85

arch/powerpc/kernel/head_32.h

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3

arch/powerpc/kernel/head_40x.S

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3

arch/powerpc/kernel/head_8xx.S

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