parisc: Switch user access functions to signal errors in r29 instead of r8

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Use register r29 instead of register r8 to signal faults when accessing
user memory. In case of faults, the fixup routine will store -EFAULT in
this register.

This change saves up to 752 bytes on a 32bit kernel, partly because the
compiler doesn't need to save and restore the old r8 value on the stack.

bloat-o-meter results for usage with r29 register:
add/remove: 0/0 grow/shrink: 23/86 up/down: 228/-980 (-752)

bloat-o-meter results for usage with r28 register:
add/remove: 0/0 grow/shrink: 28/83 up/down: 296/-956 (-660)

Signed-off-by: Helge Deller <deller@gmx.de>

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This commit is contained in:

Helge Deller 2021-12-23 21:46:35 +01:00

parent 9e9d4b460f

commit 4b9d2a731c

2 changed files with 11 additions and 7 deletions

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12

arch/parisc/include/asm/uaccess.h

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6

arch/parisc/mm/fault.c

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