diff options
| author | Helge Deller <deller@gmx.de> | 2021-12-23 21:46:35 +0100 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2022-01-07 01:29:21 +0100 |
| commit | 4b9d2a731c3d22a05c1bccdb11b6e00054ff5fda (patch) | |
| tree | 5eef0589eef5ddb7f78c6deb8d12109ae6d14b01 /arch/parisc/mm | |
| parent | 9e9d4b460f23bab61672eae397417d03917d116c (diff) | |
| download | lwn-4b9d2a731c3d22a05c1bccdb11b6e00054ff5fda.tar.gz lwn-4b9d2a731c3d22a05c1bccdb11b6e00054ff5fda.zip | |
parisc: Switch user access functions to signal errors in r29 instead of r8
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>
Diffstat (limited to 'arch/parisc/mm')
| -rw-r--r-- | arch/parisc/mm/fault.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c index 4a6221b869fd..01fd2a32acc6 100644 --- a/arch/parisc/mm/fault.c +++ b/arch/parisc/mm/fault.c @@ -148,11 +148,11 @@ int fixup_exception(struct pt_regs *regs) * Fix up get_user() and put_user(). * ASM_EXCEPTIONTABLE_ENTRY_EFAULT() sets the least-significant * bit in the relative address of the fixup routine to indicate - * that %r8 should be loaded with -EFAULT to report a userspace - * access error. + * that gr[ASM_EXCEPTIONTABLE_REG] should be loaded with + * -EFAULT to report a userspace access error. */ if (fix->fixup & 1) { - regs->gr[8] = -EFAULT; + regs->gr[ASM_EXCEPTIONTABLE_REG] = -EFAULT; /* zero target register for get_user() */ if (parisc_acctyp(0, regs->iir) == VM_READ) { |