linux.git/arch/powerpc/kernel/vdso32, branch v3.17

powerpc/booke64: Use SPRG7 for VDSO

2014-03-20T00:57:14+00:00

Previously SPRG3 was marked for use by both VDSO and critical
interrupts (though critical interrupts were not fully implemented).

In commit 8b64a9dfb091f1eca8b7e58da82f1e7d1d5fe0ad ("powerpc/booke64:
Use SPRG0/3 scratch for bolted TLB miss & crit int"), Mihai Caraman
made an attempt to resolve this conflict by restoring the VDSO value
early in the critical interrupt, but this has some issues:

 - It's incompatible with EXCEPTION_COMMON which restores r13 from the
   by-then-overwritten scratch (this cost me some debugging time).
 - It forces critical exceptions to be a special case handled
   differently from even machine check and debug level exceptions.
 - It didn't occur to me that it was possible to make this work at all
   (by doing a final "ld r13, PACA_EXCRIT+EX_R13(r13)") until after
   I made (most of) this patch. :-)

It might be worth investigating using a load rather than SPRG on return
from all exceptions (except TLB misses where the scratch never leaves
the SPRG) -- it could save a few cycles.  Until then, let's stick with
SPRG for all exceptions.

Since we cannot use SPRG4-7 for scratch without corrupting the state of
a KVM guest, move VDSO to SPRG7 on book3e.  Since neither SPRG4-7 nor
critical interrupts exist on book3s, SPRG3 is still used for VDSO
there.

Signed-off-by: Scott Wood 
Cc: Mihai Caraman 
Cc: Anton Blanchard 
Cc: Paul Mackerras 
Cc: kvm-ppc@vger.kernel.org

powerpc: Use unstripped VDSO image for more accurate profiling data

2014-02-17T00:19:37+00:00

We are seeing a lot of hits in the VDSO that are not resolved by perf.
A while(1) gettimeofday() loop shows the issue:

27.64%  [vdso]  [.] 0x000000000000060c
22.57%  [vdso]  [.] 0x0000000000000628
16.88%  [vdso]  [.] 0x0000000000000610
12.39%  [vdso]  [.] __kernel_gettimeofday
 6.09%  [vdso]  [.] 0x00000000000005f8
 3.58%  test    [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18
 2.94%  [vdso]  [.] __kernel_datapage_offset
 2.90%  test    [.] main

We are using a stripped VDSO image which means only symbols with
relocation info can be resolved. There isn't a lot of point to
stripping the VDSO, the debug info is only about 1kB:

4680 arch/powerpc/kernel/vdso64/vdso64.so
5815 arch/powerpc/kernel/vdso64/vdso64.so.dbg

By using the unstripped image, we can resolve all the symbols in the
VDSO and the perf profile data looks much better:

76.53%  [vdso]  [.] __do_get_tspec
12.20%  [vdso]  [.] __kernel_gettimeofday
 5.05%  [vdso]  [.] __get_datapage
 3.20%  test    [.] main
 2.92%  test    [.] 00000037.plt_call.gettimeofday@@GLIBC_2.18

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Delete non-required instances of include

2014-01-15T02:46:44+00:00

None of these files are actually using any __init type directives
and hence don't need to include .  Most are just a
left over from __devinit and __cpuinit removal, or simply due to
code getting copied from one driver to the next.

The one instance where we add an include for init.h covers off
a case where that file was implicitly getting it from another
header which itself didn't need it.

Signed-off-by: Paul Gortmaker 
Signed-off-by: Benjamin Herrenschmidt

powerpc/8xx: mfspr SPRN_TBRx in lieu of mftb/mftbu is not supported

2013-11-22T22:56:48+00:00

Commit beb2dc0a7a84be003ce54e98b95d65cc66e6e536 breaks the MPC8xx which
seems to not support using mfspr SPRN_TBRx instead of mftb/mftbu
despite what is written in the reference manual.

This patch reverts to the use of mftb/mftbu when CONFIG_8xx is
selected.

Signed-off-by: Christophe Leroy 
Signed-off-by: Scott Wood

powerpc: Add ability to build little endian kernels

2013-10-11T05:48:56+00:00

This patch allows the kbuild system to successfully compile a kernel
for the little endian PowerPC64 architecture. A subsequent patch
will add the CONFIG_CPU_LITTLE_ENDIAN kernel config option which
must be set to build such a kernel.

If cross compiling, CROSS_COMPILE must point to a suitable toolchain
(compiled for the powerpc64le-linux and powerpcle-linux targets).

Signed-off-by: Ian Munsie 
Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Convert some mftb/mftbu into mfspr

2013-08-21T00:33:12+00:00

Some CPUs (such as e500v1/v2) don't implement mftb and will take a
trap.  mfspr should work on everything that has a timebase, and is the
preferred instruction according to ISA v2.06.

Currently we get away with mftb on 85xx because the assembler converts
it to mfspr due to -Wa,-me500.  However, that flag has other effects
that are undesireable for certain targets (e.g.  lwsync is converted to
sync), and is hostile to multiplatform kernels.  Thus we would like to
stop setting it for all e500-family builds.

mftb/mftbu instances which are in 85xx code or common code are
converted.  Instances which will never run on 85xx are left alone.

Signed-off-by: Scott Wood

powerpc: Add VDSO version of time

2013-04-23T06:05:05+00:00

On 04/18/2013 07:38 PM, Anton Blanchard wrote:
> Since you are only reading one long you shouldn't need to check the
> update count and loop, you will always see a consistent value. The
> system call version of time() just does an unprotected load for example.

Fixed.

> With the above change and with Michael's comments covered (decent
> changelog entry and Signed-off-by):
>
> Acked-by: Anton Blanchard 

Thanks for the review, below the updated patch:

From: Adhemerval Zanella 

This patch implement the time syscall as vDSO. The performance speedups
are:

Baseline PPC32: 380 nsec
Baseline PPC64: 350 nsec
vdso PPC32:      20 nsec
vsdo PPC64:      20 nsec

Tested on 64 bit build with both 32 bit and 64 bit userland.

Acked-by: Anton Blanchard 
Signed-off-by: Adhemerval Zanella 
Signed-off-by: Benjamin Herrenschmidt

powerpc: Add VDSO version of getcpu

2012-07-11T04:18:40+00:00

We have a request for a fast method of getting CPU and NUMA node IDs
from userspace. This patch implements a getcpu VDSO function,
similar to x86.

Ben suggested we use SPRG3 which is userspace readable. SPRG3 can be
modified by a KVM guest, so we save the SPRG3 value in the paca and
restore it when transitioning from the guest to the host.

I have a glibc patch that implements sched_getcpu on top of this.
Testing on a POWER7:

baseline: 538 cycles
vdso:      30 cycles

Signed-off-by: Anton Blanchard 
Signed-off-by: Benjamin Herrenschmidt

Fix common misspellings

2011-03-31T14:26:23+00:00

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi

powerpc/Makefiles: Change to new flag variables

2010-10-13T05:19:22+00:00

Replace EXTRA_CFLAGS with ccflags-y and EXTRA_AFLAGS with asflags-y.

Signed-off-by: matt mooney 
Signed-off-by: Benjamin Herrenschmidt