diff options
| author | Anton Blanchard <anton@samba.org> | 2014-07-03 15:52:03 +1000 |
|---|---|---|
| committer | Benjamin Herrenschmidt <benh@kernel.crashing.org> | 2014-07-11 16:05:58 +1000 |
| commit | cc1adb5f32557f10f48e8febbef7278a2db9d593 (patch) | |
| tree | f1570219053c85fa3db71e123af26f5776c16dd5 /net/lapb/lapb_in.c | |
| parent | 8fa5d4547eb69b7ed710cb03486d33a3a5dc2ead (diff) | |
powerpc/pseries: Use jump labels for hcall tracepoints
hcall tracepoints add quite a few instructions to our hcall path:
plpar_hcall:
mr r2,r2
mfcr r0
stw r0,8(r1)
b 164 <---- start
ld r12,0(r2)
std r12,32(r1)
cmpdi r12,0
beq 164 <---- end
...
We have an unconditional branch that gets noped out during boot and
a load/compare/branch. We also store the tracepoint value to the
stack for the hcall_exit path to use.
By using jump labels we can simplify this to just a single nop that
gets replaced with a branch when the tracepoint is enabled:
plpar_hcall:
mr r2,r2
mfcr r0
stw r0,8(r1)
nop <----
...
If jump labels are not enabled, we fall back to the old method.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'net/lapb/lapb_in.c')
0 files changed, 0 insertions, 0 deletions