linux-stable.git/arch/powerpc/kernel/vdso64, branch linux-3.16.y Linux kernel stable tree powerpc: Fix vDSO clock_getres() 2020-02-11T20:03:55+00:00 Vincenzo Frascino vincenzo.frascino@arm.com 2019-12-02T07:57:29+00:00 9b3c5a65b7eaf8b6da97e4ddf74fa44be1064248 commit 552263456215ada7ee8700ce022d12b0cffe4802 upstream. clock_getres in the vDSO library has to preserve the same behaviour of posix_get_hrtimer_res(). In particular, posix_get_hrtimer_res() does: sec = 0; ns = hrtimer_resolution; and hrtimer_resolution depends on the enablement of the high resolution timers that can happen either at compile or at run time. Fix the powerpc vdso implementation of clock_getres keeping a copy of hrtimer_resolution in vdso data and using that directly. Fixes: a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel") Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Shuah Khan <skhan@linuxfoundation.org> [chleroy: changed CLOCK_REALTIME_RES to CLOCK_HRTIMER_RES] Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/a55eca3a5e85233838c2349783bcb5164dae1d09.1575273217.git.christophe.leroy@c-s.fr [bwh: Backported to 3.16: - In asm-offsets.c, use DEFINE() instead of OFFSET() - Adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 552263456215ada7ee8700ce022d12b0cffe4802 upstream.

clock_getres in the vDSO library has to preserve the same behaviour
of posix_get_hrtimer_res().

In particular, posix_get_hrtimer_res() does:
    sec = 0;
    ns = hrtimer_resolution;
and hrtimer_resolution depends on the enablement of the high
resolution timers that can happen either at compile or at run time.

Fix the powerpc vdso implementation of clock_getres keeping a copy of
hrtimer_resolution in vdso data and using that directly.

Fixes: a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel")
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Acked-by: Shuah Khan <skhan@linuxfoundation.org>
[chleroy: changed CLOCK_REALTIME_RES to CLOCK_HRTIMER_RES]
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a55eca3a5e85233838c2349783bcb5164dae1d09.1575273217.git.christophe.leroy@c-s.fr
[bwh: Backported to 3.16:
 - In asm-offsets.c, use DEFINE() instead of OFFSET()
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc: Allow 64bit VDSO __kernel_sync_dicache to work across ranges >4GB 2020-02-11T20:03:34+00:00 Alastair D'Silva alastair@d-silva.org 2019-11-04T02:32:54+00:00 c24394f71b4a52b34862b3437eb0380575dea0c5 commit f9ec11165301982585e5e5f606739b5bae5331f3 upstream. When calling __kernel_sync_dicache with a size >4GB, we were masking off the upper 32 bits, so we would incorrectly flush a range smaller than intended. This patch replaces the 32 bit shifts with 64 bit ones, so that the full size is accounted for. Signed-off-by: Alastair D'Silva <alastair@d-silva.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20191104023305.9581-3-alastair@au1.ibm.com Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit f9ec11165301982585e5e5f606739b5bae5331f3 upstream.

When calling __kernel_sync_dicache with a size >4GB, we were masking
off the upper 32 bits, so we would incorrectly flush a range smaller
than intended.

This patch replaces the 32 bit shifts with 64 bit ones, so that
the full size is accounted for.

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191104023305.9581-3-alastair@au1.ibm.com
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/vdso64: Fix CLOCK_MONOTONIC inconsistencies across Y2038 2019-08-13T11:38:43+00:00 Michael Ellerman mpe@ellerman.id.au 2019-03-13T13:14:38+00:00 bb693bc07a915f22f93f4a67c09764bfbe356cd0 commit b5b4453e7912f056da1ca7572574cada32ecb60c upstream. Jakub Drnec reported: Setting the realtime clock can sometimes make the monotonic clock go back by over a hundred years. Decreasing the realtime clock across the y2k38 threshold is one reliable way to reproduce. Allegedly this can also happen just by running ntpd, I have not managed to reproduce that other than booting with rtc at >2038 and then running ntp. When this happens, anything with timers (e.g. openjdk) breaks rather badly. And included a test case (slightly edited for brevity): #define _POSIX_C_SOURCE 199309L #include <stdio.h> #include <time.h> #include <stdlib.h> #include <unistd.h> long get_time(void) { struct timespec tp; clock_gettime(CLOCK_MONOTONIC, &tp); return tp.tv_sec + tp.tv_nsec / 1000000000; } int main(void) { long last = get_time(); while(1) { long now = get_time(); if (now < last) { printf("clock went backwards by %ld seconds!\n", last - now); } last = now; sleep(1); } return 0; } Which when run concurrently with: # date -s 2040-1-1 # date -s 2037-1-1 Will detect the clock going backward. The root cause is that wtom_clock_sec in struct vdso_data is only a 32-bit signed value, even though we set its value to be equal to tk->wall_to_monotonic.tv_sec which is 64-bits. Because the monotonic clock starts at zero when the system boots the wall_to_montonic.tv_sec offset is negative for current and future dates. Currently on a freshly booted system the offset will be in the vicinity of negative 1.5 billion seconds. However if the wall clock is set past the Y2038 boundary, the offset from wall to monotonic becomes less than negative 2^31, and no longer fits in 32-bits. When that value is assigned to wtom_clock_sec it is truncated and becomes positive, causing the VDSO assembly code to calculate CLOCK_MONOTONIC incorrectly. That causes CLOCK_MONOTONIC to jump ahead by ~4 billion seconds which it is not meant to do. Worse, if the time is then set back before the Y2038 boundary CLOCK_MONOTONIC will jump backward. We can fix it simply by storing the full 64-bit offset in the vdso_data, and using that in the VDSO assembly code. We also shuffle some of the fields in vdso_data to avoid creating a hole. The original commit that added the CLOCK_MONOTONIC support to the VDSO did actually use a 64-bit value for wtom_clock_sec, see commit a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel") (Nov 2005). However just 3 days later it was converted to 32-bits in commit 0c37ec2aa88b ("[PATCH] powerpc: vdso fixes (take #2)"), and the bug has existed since then AFAICS. Fixes: 0c37ec2aa88b ("[PATCH] powerpc: vdso fixes (take #2)") Link: http://lkml.kernel.org/r/HaC.ZfES.62bwlnvAvMP.1STMMj@seznam.cz Reported-by: Jakub Drnec <jaydee@email.cz> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> [bwh: Backported to 3.16: CLOCK_MONOTONIC_COARSE is not handled by this vDSO] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit b5b4453e7912f056da1ca7572574cada32ecb60c upstream.

Jakub Drnec reported:
  Setting the realtime clock can sometimes make the monotonic clock go
  back by over a hundred years. Decreasing the realtime clock across
  the y2k38 threshold is one reliable way to reproduce. Allegedly this
  can also happen just by running ntpd, I have not managed to
  reproduce that other than booting with rtc at >2038 and then running
  ntp. When this happens, anything with timers (e.g. openjdk) breaks
  rather badly.

And included a test case (slightly edited for brevity):
  #define _POSIX_C_SOURCE 199309L
  #include <stdio.h>
  #include <time.h>
  #include <stdlib.h>
  #include <unistd.h>

  long get_time(void) {
    struct timespec tp;
    clock_gettime(CLOCK_MONOTONIC, &tp);
    return tp.tv_sec + tp.tv_nsec / 1000000000;
  }

  int main(void) {
    long last = get_time();
    while(1) {
      long now = get_time();
      if (now < last) {
        printf("clock went backwards by %ld seconds!\n", last - now);
      }
      last = now;
      sleep(1);
    }
    return 0;
  }

Which when run concurrently with:
 # date -s 2040-1-1
 # date -s 2037-1-1

Will detect the clock going backward.

The root cause is that wtom_clock_sec in struct vdso_data is only a
32-bit signed value, even though we set its value to be equal to
tk->wall_to_monotonic.tv_sec which is 64-bits.

Because the monotonic clock starts at zero when the system boots the
wall_to_montonic.tv_sec offset is negative for current and future
dates. Currently on a freshly booted system the offset will be in the
vicinity of negative 1.5 billion seconds.

However if the wall clock is set past the Y2038 boundary, the offset
from wall to monotonic becomes less than negative 2^31, and no longer
fits in 32-bits. When that value is assigned to wtom_clock_sec it is
truncated and becomes positive, causing the VDSO assembly code to
calculate CLOCK_MONOTONIC incorrectly.

That causes CLOCK_MONOTONIC to jump ahead by ~4 billion seconds which
it is not meant to do. Worse, if the time is then set back before the
Y2038 boundary CLOCK_MONOTONIC will jump backward.

We can fix it simply by storing the full 64-bit offset in the
vdso_data, and using that in the VDSO assembly code. We also shuffle
some of the fields in vdso_data to avoid creating a hole.

The original commit that added the CLOCK_MONOTONIC support to the VDSO
did actually use a 64-bit value for wtom_clock_sec, see commit
a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support to
32 bits kernel") (Nov 2005). However just 3 days later it was
converted to 32-bits in commit 0c37ec2aa88b ("[PATCH] powerpc: vdso
fixes (take #2)"), and the bug has existed since then AFAICS.

Fixes: 0c37ec2aa88b ("[PATCH] powerpc: vdso fixes (take #2)")
Link: http://lkml.kernel.org/r/HaC.ZfES.62bwlnvAvMP.1STMMj@seznam.cz
Reported-by: Jakub Drnec <jaydee@email.cz>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
[bwh: Backported to 3.16: CLOCK_MONOTONIC_COARSE is not handled by
 this vDSO]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/vdso64: Use double word compare on pointers 2017-02-23T03:54:06+00:00 Anton Blanchard anton@samba.org 2016-09-25T07:16:53+00:00 a35222e8ca8ee8603281008692a4cc2d6eab1624 commit 5045ea37377ce8cca6890d32b127ad6770e6dce5 upstream. __kernel_get_syscall_map() and __kernel_clock_getres() use cmpli to check if the passed in pointer is non zero. cmpli maps to a 32 bit compare on binutils, so we ignore the top 32 bits. A simple test case can be created by passing in a bogus pointer with the bottom 32 bits clear. Using a clk_id that is handled by the VDSO, then one that is handled by the kernel shows the problem: printf("%d\n", clock_getres(CLOCK_REALTIME, (void *)0x100000000)); printf("%d\n", clock_getres(CLOCK_BOOTTIME, (void *)0x100000000)); And we get: 0 -1 The bigger issue is if we pass a valid pointer with the bottom 32 bits clear, in this case we will return success but won't write any data to the pointer. I stumbled across this issue because the LLVM integrated assembler doesn't accept cmpli with 3 arguments. Fix this by converting them to cmpldi. Fixes: a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel") Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 5045ea37377ce8cca6890d32b127ad6770e6dce5 upstream.

__kernel_get_syscall_map() and __kernel_clock_getres() use cmpli to
check if the passed in pointer is non zero. cmpli maps to a 32 bit
compare on binutils, so we ignore the top 32 bits.

A simple test case can be created by passing in a bogus pointer with
the bottom 32 bits clear. Using a clk_id that is handled by the VDSO,
then one that is handled by the kernel shows the problem:

  printf("%d\n", clock_getres(CLOCK_REALTIME, (void *)0x100000000));
  printf("%d\n", clock_getres(CLOCK_BOOTTIME, (void *)0x100000000));

And we get:

  0
  -1

The bigger issue is if we pass a valid pointer with the bottom 32 bits
clear, in this case we will return success but won't write any data
to the pointer.

I stumbled across this issue because the LLVM integrated assembler
doesn't accept cmpli with 3 arguments. Fix this by converting them to
cmpldi.

Fixes: a7f290dad32e ("[PATCH] powerpc: Merge vdso's and add vdso support to 32 bits kernel")
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/booke64: Use SPRG7 for VDSO 2014-03-20T00:57:14+00:00 Scott Wood scottwood@freescale.com 2014-03-10T22:29:38+00:00 9d378dfac885f72b8b369d08fc61bef36e2f2dd1 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 <scottwood@freescale.com> Cc: Mihai Caraman <mihai.caraman@freescale.com> Cc: Anton Blanchard <anton@samba.org> Cc: Paul Mackerras <paulus@samba.org> Cc: kvm-ppc@vger.kernel.org 
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 <scottwood@freescale.com>
Cc: Mihai Caraman <mihai.caraman@freescale.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: kvm-ppc@vger.kernel.org
powerpc: Use unstripped VDSO image for more accurate profiling data 2014-02-17T00:19:37+00:00 Anton Blanchard anton@au1.ibm.com 2014-02-12T06:18:50+00:00 24b659a13866b935eca72748ce725279bd3c4466 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 <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
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 <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Delete non-required instances of include <linux/init.h> 2014-01-15T02:46:44+00:00 Paul Gortmaker paul.gortmaker@windriver.com 2014-01-09T05:44:29+00:00 c141611fb1ee2cfc374cf9be5327e97f361c4bed None of these files are actually using any __init type directives and hence don't need to include <linux/init.h>. 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 <paul.gortmaker@windriver.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
None of these files are actually using any __init type directives
and hence don't need to include <linux/init.h>.  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 <paul.gortmaker@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Wrong DWARF CFI in the kernel vdso for little-endian / ELFv2 2013-11-20T22:19:23+00:00 Ulrich Weigand Ulrich.Weigand@de.ibm.com 2013-11-20T20:38:05+00:00 280270828f108be56f0c486def58acabb070244f I've finally tracked down why my CR signal-unwind test case still fails on little-endian. The problem turned to be that the kernel installs a signal trampoline in the vDSO, and provides a DWARF CFI record for that trampoline. This CFI describes the save location for CR: rsave (70, 38*RSIZE + (RSIZE - CRSIZE)) which is correct for big-endian, but points to the wrong word on little-endian. This is wrong no matter which ABI. In addition, for the ELFv2 ABI, we should not only provide a CFI record for register 70 (cr2), but for all CR fields separately. Strictly speaking, I guess this would mean providing two separate vDSO images, one for ELFv1 processes and one for ELFv2 processes (or maybe playing some tricks with conditional DWARF expressions). However, having CFI records for the other CR fields in ELFv1 is not actually wrong, they just will be ignored. So it seems the simplest fix would be just to always provide CFI for all the fields. Signed-off-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com> Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
I've finally tracked down why my CR signal-unwind test case still
fails on little-endian.  The problem turned to be that the kernel
installs a signal trampoline in the vDSO, and provides a DWARF CFI
record for that trampoline.  This CFI describes the save location
for CR:

  rsave (70, 38*RSIZE + (RSIZE - CRSIZE))

which is correct for big-endian, but points to the wrong word on
little-endian.   This is wrong no matter which ABI.

In addition, for the ELFv2 ABI, we should not only provide a CFI
record for register 70 (cr2), but for all CR fields separately.
Strictly speaking, I guess this would mean providing two separate
vDSO images, one for ELFv1 processes and one for ELFv2 processes (or
maybe playing some tricks with conditional DWARF expressions).
However, having CFI records for the other CR fields in ELFv1 is not
actually wrong, they just will be ignored.   So it seems the simplest
fix would be just to always provide CFI for all the fields.

Signed-off-by: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Add ability to build little endian kernels 2013-10-11T05:48:56+00:00 Ian Munsie imunsie@au1.ibm.com 2013-09-23T02:05:11+00:00 d72b08017161ab385d4ae080ea415c9eb7ceef83 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 <imunsie@au1.ibm.com> Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
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 <imunsie@au1.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Add VDSO version of time 2013-04-23T06:05:05+00:00 Adhemerval Zanella azanella@linux.vnet.ibm.com 2013-04-22T09:29:33+00:00 fcb41a2030abe0eb716ef0798035ef9562097f42 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 <anton@samba.org> Thanks for the review, below the updated patch: From: Adhemerval Zanella <azanella@linux.vnet.ibm.com> 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 <anton@samba.org> Signed-off-by: Adhemerval Zanella <azanella@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
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 <anton@samba.org>

Thanks for the review, below the updated patch:

From: Adhemerval Zanella <azanella@linux.vnet.ibm.com>

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 <anton@samba.org>
Signed-off-by: Adhemerval Zanella <azanella@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>