From: Helge Deller <deller@gmx.de>
To: John David Anglin <dave.anglin@bell.net>
Cc: linux-parisc@vger.kernel.org,
James Bottomley <James.Bottomley@HansenPartnership.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [PATCH] parisc: Fix syscall restarts
Date: Sun, 20 Dec 2015 20:48:22 +0100 [thread overview]
Message-ID: <56770606.9020005@gmx.de> (raw)
In-Reply-To: <B201D30D-8677-4D06-B3F9-EA4494972EF5@bell.net>
On 20.12.2015 20:39, John David Anglin wrote:
> On 2015-12-18, at 6:30 PM, Helge Deller wrote:
>
>> + /* Usually we don't have to restore %r20 (the system call number)
>> + * because it gets loaded in the delay slot of the branch external
>> + * instruction via the ldi instruction.
>> + * In some cases a register-to-register copy instruction might have
>> + * been used instead, in which case we need to copy the syscall
>> + * number into the source register before returning to userspace.
>> + */
>
> I'm thinking it might be better to fix syscall() in glibc. The copy could be
> moved before ble and a nop placed delay slot.
Yes, I think it should be fixed in glibc which makes it cleaner.
I looked at dietlibc. There a "nop" is being used.
Nevertheless, it may happen anytime if people forget, that we will see a
"copy" there again, so IMHO it's probably safer to include the workaround in
kernel too.
Helge
next prev parent reply other threads:[~2015-12-20 19:48 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-18 23:30 [PATCH] parisc: Fix syscall restarts Helge Deller
2015-12-20 13:59 ` Mathieu Desnoyers
2015-12-20 14:09 ` Mathieu Desnoyers
2015-12-20 15:49 ` Helge Deller
2015-12-20 16:50 ` James Bottomley
2015-12-20 20:35 ` Helge Deller
2015-12-21 8:03 ` James Bottomley
2015-12-21 14:39 ` Mathieu Desnoyers
2015-12-20 18:31 ` John David Anglin
2015-12-20 19:32 ` Helge Deller
2015-12-20 19:46 ` John David Anglin
2015-12-20 20:06 ` Helge Deller
2015-12-20 23:57 ` John David Anglin
2015-12-21 14:42 ` Mathieu Desnoyers
2015-12-21 15:12 ` John David Anglin
2015-12-20 19:39 ` John David Anglin
2015-12-20 19:48 ` Helge Deller [this message]
2015-12-20 20:01 ` John David Anglin
2015-12-20 20:18 ` Helge Deller
2015-12-20 20:45 ` John David Anglin
2015-12-20 20:14 ` John David Anglin
2015-12-20 20:19 ` Helge Deller
2015-12-20 20:21 ` Helge Deller
2015-12-20 20:53 ` John David Anglin
2015-12-21 9:19 ` [PATCH] parisc: Fix syscall restarts (v2) Helge Deller
2015-12-21 13:11 ` John David Anglin
2015-12-21 20:27 ` Mathieu Desnoyers
2015-12-21 20:54 ` Helge Deller
2015-12-24 16:07 ` Mathieu Desnoyers
2015-12-24 16:51 ` John David Anglin
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