diff mbox series

hppa: Wire up cacheflush syscall

Message ID Zos8gVaGUcuaaNaI@carbonx1
State New
Headers
Series hppa: Wire up cacheflush syscall |

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Commit Message

Helge Deller July 8, 2024, 1:10 a.m. UTC 
  The hppa Linux kernel supports the cacheflush() syscall
since version 6.5. This adds the glibc syscall wrapper.

Signed-off-by: Helge Deller <deller@gmx.de>

---

Comments

Florian Weimer July 8, 2024, 8:13 a.m. UTC | #1 
* Helge Deller:

> diff --git a/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
> new file mode 100644
> index 0000000000..16e47d1329
> --- /dev/null
> +++ b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
> @@ -0,0 +1,36 @@

> +#ifndef _SYS_CACHECTL_H
> +#define _SYS_CACHECTL_H 1
> +
> +#include <features.h>
> +
> +/* Get the kernel definition for the op bits.  */
> +#include <asm/cachectl.h>

This makes this header (<sys/cachectl.h>) unusable with older kernel
headers.  I think it also results in a test failure with older headers.
Is this a problem?

In similar cases, we use LINUX_VERSION_CODE checks (for older compilers)
and __has_include to support backports.

Thanks,
Florian
Helge Deller July 8, 2024, 8:58 a.m. UTC | #2 
On 7/8/24 10:13, Florian Weimer wrote:
> * Helge Deller:
>
>> diff --git a/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
>> new file mode 100644
>> index 0000000000..16e47d1329
>> --- /dev/null
>> +++ b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
>> @@ -0,0 +1,36 @@
>
>> +#ifndef _SYS_CACHECTL_H
>> +#define _SYS_CACHECTL_H 1
>> +
>> +#include <features.h>
>> +
>> +/* Get the kernel definition for the op bits.  */
>> +#include <asm/cachectl.h>
>
> This makes this header (<sys/cachectl.h>) unusable with older kernel
> headers.  I think it also results in a test failure with older headers.
> Is this a problem?

hppa lives in debian unstable, so basically you should always use
the latest kernel & kernel headers when upgrading glibc.
So, personally I think it's ok to ask people to upgrade.
Dave, any opinion on this?

> In similar cases, we use LINUX_VERSION_CODE checks (for older compilers)
> and __has_include to support backports.

I'd prefer to not add additional checks.
Another (maybe easier) possibility is to simply backport the kernel asm/cachectl.h
file (just the header, not the implementation, so the syscall will return -ENOSYS on
older kernels):
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c6d96328fecdda16e12f3b3c33f3677f4bcef89f

Helge
Andreas K. Huettel July 8, 2024, 4 p.m. UTC | #3 
Am Montag, 8. Juli 2024, 10:58:35 CEST schrieb Helge Deller:
> On 7/8/24 10:13, Florian Weimer wrote:
> > * Helge Deller:
> >
> >> diff --git a/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
> >> new file mode 100644
> >> index 0000000000..16e47d1329
> >> --- /dev/null
> >> +++ b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
> >> @@ -0,0 +1,36 @@
> >
> >> +#ifndef _SYS_CACHECTL_H
> >> +#define _SYS_CACHECTL_H 1
> >> +
> >> +#include <features.h>
> >> +
> >> +/* Get the kernel definition for the op bits.  */
> >> +#include <asm/cachectl.h>
> >
> > This makes this header (<sys/cachectl.h>) unusable with older kernel
> > headers.  I think it also results in a test failure with older headers.
> > Is this a problem?
> 
> hppa lives in debian unstable, so basically you should always use
> the latest kernel & kernel headers when upgrading glibc.

Ahem.
https://www.gentoo.org/downloads/#hppa

> So, personally I think it's ok to ask people to upgrade.
> Dave, any opinion on this?
> 
> > In similar cases, we use LINUX_VERSION_CODE checks (for older compilers)
> > and __has_include to support backports.
> 
> I'd prefer to not add additional checks.
> Another (maybe easier) possibility is to simply backport the kernel asm/cachectl.h
> file (just the header, not the implementation, so the syscall will return -ENOSYS on
> older kernels):
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c6d96328fecdda16e12f3b3c33f3677f4bcef89f
> 
> Helge
>
Helge Deller July 8, 2024, 6:26 p.m. UTC | #4 
On 7/8/24 18:00, Andreas K. Huettel wrote:
> Am Montag, 8. Juli 2024, 10:58:35 CEST schrieb Helge Deller:
>> On 7/8/24 10:13, Florian Weimer wrote:
>>> * Helge Deller:
>>>
>>>> diff --git a/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
>>>> new file mode 100644
>>>> index 0000000000..16e47d1329
>>>> --- /dev/null
>>>> +++ b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
>>>> @@ -0,0 +1,36 @@
>>>
>>>> +#ifndef _SYS_CACHECTL_H
>>>> +#define _SYS_CACHECTL_H 1
>>>> +
>>>> +#include <features.h>
>>>> +
>>>> +/* Get the kernel definition for the op bits.  */
>>>> +#include <asm/cachectl.h>
>>>
>>> This makes this header (<sys/cachectl.h>) unusable with older kernel
>>> headers.  I think it also results in a test failure with older headers.
>>> Is this a problem?
>>
>> hppa lives in debian unstable, so basically you should always use
>> the latest kernel & kernel headers when upgrading glibc.
>
> Ahem.
> https://www.gentoo.org/downloads/#hppa

Sure. But I didn't mentioned it, because Gentoo usually uses a
more recent kernel than Debian, right?

Helge
Sam James July 9, 2024, 1:41 p.m. UTC | #5 
Helge Deller <deller@gmx.de> writes:

> On 7/8/24 18:00, Andreas K. Huettel wrote:
>> Am Montag, 8. Juli 2024, 10:58:35 CEST schrieb Helge Deller:
>>> On 7/8/24 10:13, Florian Weimer wrote:
>>>> * Helge Deller:
>>>>
>>>>> diff --git a/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
>>>>> new file mode 100644
>>>>> index 0000000000..16e47d1329
>>>>> --- /dev/null
>>>>> +++ b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
>>>>> @@ -0,0 +1,36 @@
>>>>
>>>>> +#ifndef _SYS_CACHECTL_H
>>>>> +#define _SYS_CACHECTL_H 1
>>>>> +
>>>>> +#include <features.h>
>>>>> +
>>>>> +/* Get the kernel definition for the op bits.  */
>>>>> +#include <asm/cachectl.h>
>>>>
>>>> This makes this header (<sys/cachectl.h>) unusable with older kernel
>>>> headers.  I think it also results in a test failure with older headers.
>>>> Is this a problem?
>>>
>>> hppa lives in debian unstable, so basically you should always use
>>> the latest kernel & kernel headers when upgrading glibc.
>>
>> Ahem.
>> https://www.gentoo.org/downloads/#hppa
>
> Sure. But I didn't mentioned it, because Gentoo usually uses a
> more recent kernel than Debian, right?
>

In this instance, I wonder if we should do the extra checks. The kernel
instability because of the cache / TLB issues means at least one of our
machines runs an older kernel for now. (Dave's latest patches seem to
help a lot there, but you get the point.)

thanks,
sam
John David Anglin Aug. 3, 2024, 8:57 a.m. UTC | #6 
On 2024-07-09 9:41 a.m., Sam James wrote:
> In this instance, I wonder if we should do the extra checks. The kernel
> instability because of the cache / TLB issues means at least one of our
> machines runs an older kernel for now. (Dave's latest patches seem to
> help a lot there, but you get the point.)
Can you be more specific?  Do you still experience instability due to cache / TLB issues
on this machine?

Dave
Sam James Sept. 26, 2024, 7:08 p.m. UTC | #7 
John David Anglin <dave.anglin@bell.net> writes:

> On 2024-07-09 9:41 a.m., Sam James wrote:
>> In this instance, I wonder if we should do the extra checks. The kernel
>> instability because of the cache / TLB issues means at least one of our
>> machines runs an older kernel for now. (Dave's latest patches seem to
>> help a lot there, but you get the point.)
> Can you be more specific?  Do you still experience instability due to cache / TLB issues
> on this machine?

Sorry for the delay. Our main machine, 'muta', has been suffering
instability for a while. It ended up also having bad RAM and failing
disks. We've now replaced them last night.

We had a lot of kernel crashes since then but after upgrading to
6.10.11, everything seems okay so far. Fingers crossed, and then I can
get back to the other bits (like testing the binutils patch).

(The panics were all in pte_offset_map_nolock.)

>
> Dave

thanks,
sam
Helge Deller Sept. 27, 2024, 7:16 a.m. UTC | #8 
On 9/26/24 21:08, Sam James wrote:
> John David Anglin <dave.anglin@bell.net> writes:
>
>> On 2024-07-09 9:41 a.m., Sam James wrote:
>>> In this instance, I wonder if we should do the extra checks. The kernel
>>> instability because of the cache / TLB issues means at least one of our
>>> machines runs an older kernel for now. (Dave's latest patches seem to
>>> help a lot there, but you get the point.)
>> Can you be more specific?  Do you still experience instability due to cache / TLB issues
>> on this machine?
>
> Sorry for the delay. Our main machine, 'muta', has been suffering
> instability for a while. It ended up also having bad RAM and failing
> disks. We've now replaced them last night.
>
> We had a lot of kernel crashes since then but after upgrading to
> 6.10.11, everything seems okay so far.

FYI, Dave's commit 72d95924ee35 ("parisc: Try to fix random segmentation faults in package builds") [1]
was a game-changer for the parisc kernel. It went into kernel 6.10 and since then
our 64-bit debian builds run absolutely stable.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=72d95924ee35c8cd16ef52f912483ee938a34d49
diff mbox series

Patch

diff --git a/sysdeps/unix/sysv/linux/hppa/Makefile b/sysdeps/unix/sysv/linux/hppa/Makefile
index 2e031e2f8a..9eebe8e0e7 100644
--- a/sysdeps/unix/sysv/linux/hppa/Makefile
+++ b/sysdeps/unix/sysv/linux/hppa/Makefile
@@ -15,6 +15,11 @@  test-xfail-check-wx-segment = *
 
 endif # $(subdir) == elf
 
+ifeq ($(subdir),misc)
+sysdep_routines += cacheflush
+sysdep_headers += sys/cachectl.h
+endif
+
 ifeq ($(subdir),debug)
 test-xfail-tst-ssp-1 = $(have-ssp)
 endif # $(subdir) == debug
diff --git a/sysdeps/unix/sysv/linux/hppa/Versions b/sysdeps/unix/sysv/linux/hppa/Versions
index 78528e5fa2..f7ac20ab7e 100644
--- a/sysdeps/unix/sysv/linux/hppa/Versions
+++ b/sysdeps/unix/sysv/linux/hppa/Versions
@@ -23,4 +23,7 @@  libc {
   GLIBC_2.19 {
     fanotify_mark;
   }
+  GLIBC_2.40 {
+    cacheflush;
+  }
 }
diff --git a/sysdeps/unix/sysv/linux/hppa/libc.abilist b/sysdeps/unix/sysv/linux/hppa/libc.abilist
index fbcd60c2b3..965b946ab0 100644
--- a/sysdeps/unix/sysv/linux/hppa/libc.abilist
+++ b/sysdeps/unix/sysv/linux/hppa/libc.abilist
@@ -2821,6 +2821,7 @@  GLIBC_2.4 sys_errlist D 0x400
 GLIBC_2.4 sys_nerr D 0x4
 GLIBC_2.4 unlinkat F
 GLIBC_2.4 unshare F
+GLIBC_2.40 cacheflush F
 GLIBC_2.5 __readlinkat_chk F
 GLIBC_2.5 inet6_opt_append F
 GLIBC_2.5 inet6_opt_find F
diff --git a/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
new file mode 100644
index 0000000000..16e47d1329
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/hppa/sys/cachectl.h
@@ -0,0 +1,36 @@ 
+/* HPPA cache flushing interface.
+   Copyright (C) 2018-2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _SYS_CACHECTL_H
+#define _SYS_CACHECTL_H 1
+
+#include <features.h>
+
+/* Get the kernel definition for the op bits.  */
+#include <asm/cachectl.h>
+
+__BEGIN_DECLS
+
+#ifdef __USE_MISC
+extern int cacheflush (void *__addr, const int __nbytes,
+		       const int __op) __THROW;
+#endif
+
+__END_DECLS
+
+#endif /* sys/cachectl.h */
diff --git a/sysdeps/unix/sysv/linux/hppa/syscalls.list b/sysdeps/unix/sysv/linux/hppa/syscalls.list
index 12e4adeccc..b3020114d6 100644
--- a/sysdeps/unix/sysv/linux/hppa/syscalls.list
+++ b/sysdeps/unix/sysv/linux/hppa/syscalls.list
@@ -8,5 +8,6 @@  listen		-	listen		i:ii	__listen	listen
 shutdown	-	shutdown	i:ii	__shutdown	shutdown
 socket		-	socket		i:iii	__socket	socket
 socketpair	-	socketpair	i:iiif	__socketpair	socketpair
+cacheflush	-	cacheflush	i:pii	_flush_cache	cacheflush
 
 personality	EXTRA	personality	Ei:i	__personality	personality