From: Laurent Vivier <Laurent.Vivier@bull.net>
Date: Thu, 25 Oct 2007 12:18:53 +0000 (+0200)
Subject: KVM: SVM: Let gcc to choose which registers to save (x86_64)
X-Git-Tag: v2.6.25-rc1~1138^2~186
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=54a08c0449683f763dc69e653d17e8c120e16299;p=pandora-kernel.git

KVM: SVM: Let gcc to choose which registers to save (x86_64)

This patch lets GCC to determine which registers to save when we
switch to/from a VCPU in the case of AMD x86_64.

* Original code saves following registers:

    rbx, rcx, rdx, rsi, rdi, rbp,
    r8, r9, r10, r11, r12, r13, r14, r15

* Patched code:

  - informs GCC that we modify following registers
    using the clobber description:

    rbx, rcx, rdx, rsi, rdi
    r8, r9, r10, r11, r12, r13, r14, r15

  - rbp is saved (pop/push) because GCC seems to ignore its use in the clobber
    description.

Signed-off-by: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Avi Kivity <avi@qumranet.com>
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