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| 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 /arch/powerpc/include/asm/jump_label.h | |
| parent | powerpc/powernv: Add a page size parameter to pnv_pci_setup_iommu_table() (diff) | |
| download | linux-dev-cc1adb5f32557f10f48e8febbef7278a2db9d593.tar.xz linux-dev-cc1adb5f32557f10f48e8febbef7278a2db9d593.zip | |
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 'arch/powerpc/include/asm/jump_label.h')
| -rw-r--r-- | arch/powerpc/include/asm/jump_label.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h index f016bb699b5f..efbf9a322a23 100644 --- a/arch/powerpc/include/asm/jump_label.h +++ b/arch/powerpc/include/asm/jump_label.h @@ -10,6 +10,7 @@ * 2 of the License, or (at your option) any later version. */ +#ifndef __ASSEMBLY__ #include <linux/types.h> #include <asm/feature-fixups.h> @@ -42,4 +43,12 @@ struct jump_entry { jump_label_t key; }; +#else +#define ARCH_STATIC_BRANCH(LABEL, KEY) \ +1098: nop; \ + .pushsection __jump_table, "aw"; \ + FTR_ENTRY_LONG 1098b, LABEL, KEY; \ + .popsection +#endif + #endif /* _ASM_POWERPC_JUMP_LABEL_H */ |