From: Shivaprasad G Bhat <sbhat@linux.vnet.ibm.com>
To: Richard Henderson <richard.henderson@linaro.org>,
dgibson@redhat.com, riku.voipio@iki.fi, laurent@vivier.eu
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] linux-user: ppc64: don't use volatile register during safe_syscall
Date: Fri, 27 Jul 2018 12:12:14 +0530 [thread overview]
Message-ID: <a40f756f-7bdd-755b-2086-810a2b7f711b@linux.vnet.ibm.com> (raw)
In-Reply-To: <b707ccc3-47bb-569f-3df0-aeb91e90b820@linaro.org>
On 07/26/2018 10:56 PM, Richard Henderson wrote:
> On 07/25/2018 11:48 PM, Shivaprasad G Bhat wrote:
>> Reference:
>> https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#REG
> This document is for _CALL_ELF < 2. For ppc64le, the document is at
>
> https://openpowerfoundation.org/wp-content/uploads/2016/03/ABI64BitOpenPOWERv1.1_16July2015_pub4.pdf
>
> In both cases, it appears that we can (ab)use SP+16 to save
> the value of r14 across the syscall. This slot would normally
> be used for saving our own return address (LR), but we have no
> need to save that value because it *is* preserved across the syscall.
I will send updated patch as suggested.
Thanks,
Shivaprasad
>
>
> r~
>
prev parent reply other threads:[~2018-07-27 6:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-26 6:48 [Qemu-devel] [PATCH] linux-user: ppc64: don't use volatile register during safe_syscall Shivaprasad G Bhat
2018-07-26 7:48 ` Laurent Vivier
2018-07-26 17:15 ` Richard Henderson
2018-07-26 17:39 ` Laurent Vivier
2018-07-27 4:47 ` Richard Henderson
2018-07-27 8:01 ` Laurent Vivier
2018-07-26 17:26 ` Richard Henderson
2018-07-27 6:42 ` Shivaprasad G Bhat [this message]
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