* Re: [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
[not found] <bebe9cec-5156-4bfc-9b41-6db09af69981@email.android.com>
@ 2017-05-30 16:54 ` Steve Ellcey
2017-05-30 19:22 ` Steve Ellcey
0 siblings, 1 reply; 7+ messages in thread
From: Steve Ellcey @ 2017-05-30 16:54 UTC (permalink / raw)
To: siddhesh; +Cc: libc-alpha, Siddhesh Poyarekar, adhemerval.zanella
On Sat, 2017-05-27 at 07:54 +0530, siddhesh@gotplt.org wrote:
> Your test program should work provided that it is a fresh build since
> an older build will end up picking the old dl-procinfo.h and thus set
> hwcap_mask to 0.
>
> I'm out this weekend, but I'll take a look at it on Monday.
>
> Siddhesh
I will rerun configure and build but I think I am using the correct
(new) sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h header file and
it does have:
#define HWCAP_IMPORTANT HWCAP_CPUID
Steve Ellcey
sellcey@cavium.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
2017-05-30 16:54 ` [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check Steve Ellcey
@ 2017-05-30 19:22 ` Steve Ellcey
2017-05-30 20:23 ` Steve Ellcey
0 siblings, 1 reply; 7+ messages in thread
From: Steve Ellcey @ 2017-05-30 19:22 UTC (permalink / raw)
To: siddhesh; +Cc: libc-alpha, Siddhesh Poyarekar, adhemerval.zanella
Siddhesh,
I think the problem may be in dl-tunables.h.  I could not get either of
your patches that change that file (1 of 4 and 1 of 5) to apply cleanly
to this file. Â 1 of 4 was small, but 1 of 5 is more complex and I may
have messed it up while trying to apply it by hand. Â Could you redo at
least patch 1 of 5 so it applies cleanly to top-of-tree dl-tunables.h.
Or maybe you could just send me a copy of dl-tunables.h so I can drop
it in without the patch command.
Steve Ellcey
sellcey@cavium.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
2017-05-30 19:22 ` Steve Ellcey
@ 2017-05-30 20:23 ` Steve Ellcey
2017-06-01 5:29 ` Siddhesh Poyarekar
0 siblings, 1 reply; 7+ messages in thread
From: Steve Ellcey @ 2017-05-30 20:23 UTC (permalink / raw)
To: siddhesh; +Cc: libc-alpha, Siddhesh Poyarekar, adhemerval.zanella
On Tue, 2017-05-30 at 12:22 -0700, Steve Ellcey wrote:
> Siddhesh,
>
> I think the problem may be in dl-tunables.h.  I could not get either
> of
> your patches that change that file (1 of 4 and 1 of 5) to apply
> cleanly
> to this file. Â 1 of 4 was small, but 1 of 5 is more complex and I may
> have messed it up while trying to apply it by hand. Â Could you redo
> at
> least patch 1 of 5 so it applies cleanly to top-of-tree dl-
> tunables.h.
> Or maybe you could just send me a copy of dl-tunables.h so I can drop
> it in without the patch command.
>
> Steve Ellcey
> sellcey@cavium.com
OK, I made a little progress. Â If I don't set LD_HWCAP_MASK then it
seems to be treating it as 0, even though the default value is supposed
to be HWCAP_IMPORTANT which gets set to HWCAP_CPUID.  If I explicitly
set LD_HWCAP_MASK to 0x800 then I get the correct heaviour and my
program checks for CPUID. Â I am not sure why the default value for
LD_HWCAP_MASK does not seem to be right.
Steve Ellcey
sellcey@cavium.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
2017-05-30 20:23 ` Steve Ellcey
@ 2017-06-01 5:29 ` Siddhesh Poyarekar
2017-06-01 16:22 ` Steve Ellcey
0 siblings, 1 reply; 7+ messages in thread
From: Siddhesh Poyarekar @ 2017-06-01 5:29 UTC (permalink / raw)
To: sellcey; +Cc: libc-alpha, adhemerval.zanella
On Wednesday 31 May 2017 01:53 AM, Steve Ellcey wrote:
> OK, I made a little progress. If I don't set LD_HWCAP_MASK then it
> seems to be treating it as 0, even though the default value is supposed
> to be HWCAP_IMPORTANT which gets set to HWCAP_CPUID. If I explicitly
> set LD_HWCAP_MASK to 0x800 then I get the correct heaviour and my
> program checks for CPUID. I am not sure why the default value for
> LD_HWCAP_MASK does not seem to be right.
I just realized what's going on; it is a bug in tunables. The
__tunables_set_val function returns without setting the value if the
value was not set by glibc.tune.hwcap_mask or LD_HWCAP_MASK, which is
wrong. It should return whatever is set in the tunable list.
I'll fix that and repost.
Siddhesh
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
2017-06-01 5:29 ` Siddhesh Poyarekar
@ 2017-06-01 16:22 ` Steve Ellcey
0 siblings, 0 replies; 7+ messages in thread
From: Steve Ellcey @ 2017-06-01 16:22 UTC (permalink / raw)
To: siddhesh; +Cc: libc-alpha, adhemerval.zanella
On Thu, 2017-06-01 at 10:59 +0530, Siddhesh Poyarekar wrote:
>Â
> I just realized what's going on; it is a bug in tunables.  The
> __tunables_set_val function returns without setting the value if the
> value was not set by glibc.tune.hwcap_mask or LD_HWCAP_MASK, which is
> wrong.  It should return whatever is set in the tunable list.
>
> I'll fix that and repost.
>
> Siddhesh
Excellent, I find this functionality very useful so I look forward to
having it in glibc.
Steve Ellcey
sellcey@cavium.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
2017-05-25 20:27 Siddhesh Poyarekar
@ 2017-05-26 20:13 ` Steve Ellcey
0 siblings, 0 replies; 7+ messages in thread
From: Steve Ellcey @ 2017-05-26 20:13 UTC (permalink / raw)
To: Siddhesh Poyarekar, libc-alpha; +Cc: adhemerval.zanella
On Fri, 2017-05-26 at 01:55 +0530, Siddhesh Poyarekar wrote:
>Â
> I have not reposted the earlier 1/5, 2/5 and 4/5 since they have been acked.
> I'll push them in together with all these patches since it did not make sense to
> put them in isolation.
>
> Tested on x86_64 and aarch64.
Siddhesh, does this mean that if I apply these four patches plus
patches 1, 2, and 4 from the earlier set (https://sourceware.org/ml/lib
c-alpha/2017-05/msg00570.html) then I should get the override
functionality?
I have applied those patches, the earlier patch 1 of 5 did not apply
cleanly but I think I fixed that by hand correctly and I had to fix up
the documentation problem that was mentioned in the email but the
override is not working correctly for me (or I am misunderstanding
things).
I wrote a small program to call __libc_ifunc_impl_list and see what
memcpy versions were available on thunderx. Â I see both versions but
the usable flag is 0 for the thunderx version on my thunderx machine
even if I do not set HWCAP_MASK to anything.  When I build the library
with out --enable-tunable, then I get a usable flag of 1 for both
versions of memcpy which is what I would expect. Â Are there any other
patches I need?
Steve Ellcey
sellcey@cavium.com
^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check
@ 2017-05-25 20:27 Siddhesh Poyarekar
2017-05-26 20:13 ` Steve Ellcey
0 siblings, 1 reply; 7+ messages in thread
From: Siddhesh Poyarekar @ 2017-05-25 20:27 UTC (permalink / raw)
To: libc-alpha; +Cc: adhemerval.zanella
Hi,
Here is another take at the remaining patches to allow overriding HWCAP_CPUID
feature check. Changes from the previous version:
- Added convenience macro to get dl_hwcap_mask
- Disable reading LD_HWCAP_MASK in static binaries when tunables are disabled
- Enable reading LD_HWCAP_MASK in static binaries when tunables are enabled
- Fix x86 exponential behaviour with ld_hwcap_mask set to a high value on
static binaries
- Add patch to write hwcap strings to LD_SHOW_AUXV and for ldconfig
I have not reposted the earlier 1/5, 2/5 and 4/5 since they have been acked.
I'll push them in together with all these patches since it did not make sense to
put them in isolation.
Tested on x86_64 and aarch64.
Siddhesh Poyarekar (4):
tunables: Use glibc.tune.hwcap_mask tunable instead of _dl_hwcap_mask
aarch64: Allow overriding HWCAP_CPUID feature check using HWCAP_MASK
Make LD_HWCAP_MASK usable for static binaries
aarch64: Add hwcap string routines
elf/dl-cache.c | 5 +-
elf/dl-hwcaps.c | 11 +++-
elf/dl-hwcaps.h | 30 +++++++++
elf/dl-support.c | 2 +
elf/dl-tunables.h | 2 +
elf/rtld.c | 4 ++
sysdeps/generic/ldsodefs.h | 2 +
sysdeps/sparc/sparc32/dl-machine.h | 6 +-
sysdeps/unix/sysv/linux/aarch64/cpu-features.c | 10 +--
sysdeps/unix/sysv/linux/aarch64/dl-procinfo.c | 15 +++++
sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h | 86 ++++++++++++++++++++++++++
sysdeps/x86/cpu-features.c | 10 +--
12 files changed, 170 insertions(+), 13 deletions(-)
create mode 100644 elf/dl-hwcaps.h
create mode 100644 sysdeps/unix/sysv/linux/aarch64/dl-procinfo.h
--
2.7.4
^ permalink raw reply [flat|nested] 7+ messages in thread
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[not found] <bebe9cec-5156-4bfc-9b41-6db09af69981@email.android.com>
2017-05-30 16:54 ` [PATCH v3 0/4] aarch64: Allow overriding HWCAP_CPUID feature check Steve Ellcey
2017-05-30 19:22 ` Steve Ellcey
2017-05-30 20:23 ` Steve Ellcey
2017-06-01 5:29 ` Siddhesh Poyarekar
2017-06-01 16:22 ` Steve Ellcey
2017-05-25 20:27 Siddhesh Poyarekar
2017-05-26 20:13 ` Steve Ellcey
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