powerpc/32: Always save non volatile GPRs at syscall entry

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In preparation for porting syscall entry/exit to C, inconditionally
save non volatile general purpose registers.

Commit 965dd3ad30 ("powerpc/64/syscall: Remove non-volatile GPR save
optimisation") provides detailed explanation.

This increases the number of cycles by 24 cycles on 8xx with
null_syscall benchmark (280 => 304 cycles)

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/21c08162b83655195fe9ead78ff2cfd28508d023.1612796617.git.christophe.leroy@csgroup.eu

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This commit is contained in:

Christophe Leroy 2021-02-08 15:10:32 +00:00 • committed by Michael Ellerman

parent c01b916658

commit fbcee2ebe8

4 changed files with 8 additions and 62 deletions

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46

arch/powerpc/kernel/entry_32.S

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2

arch/powerpc/kernel/head_32.h

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2

arch/powerpc/kernel/head_booke.h

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20

arch/powerpc/kernel/syscalls/syscall.tbl

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