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xen-devel
[Xen-devel] [PATCH 1/2] x86/paravirt: don't restore second return reg
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To: |
"H. Peter Anvin" <hpa@xxxxxxxxxx> |
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Subject: |
[Xen-devel] [PATCH 1/2] x86/paravirt: don't restore second return reg |
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From: |
Jeremy Fitzhardinge <jeremy@xxxxxxxx> |
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Date: |
Fri, 30 Jan 2009 23:17:23 -0800 |
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Cc: |
Zachary Amsden <zach@xxxxxxxxxx>, Rusty Russell <rusty@xxxxxxxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Ian Campbell <ian.campbell@xxxxxxxxxx>, the arch/x86 maintainers <x86@xxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, Ravikiran Thirumalai <kiran@xxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx> |
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Delivery-date: |
Fri, 30 Jan 2009 23:18:07 -0800 |
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References: |
<patchbomb.1233182100@xxxxxxxxxxxxxxxxx> <49815764.6040809@xxxxxxxxxx> <49817C26.2020503@xxxxxxxx> <4983DBC9.5080701@xxxxxxxxxx> |
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Thunderbird 2.0.0.19 (X11/20090105) |
Impact: bugfix
In the 32-bit calling convention, %eax:%edx is used to return 64-bit
values. Don't save and restore %edx around wrapped functions, or they
can't return a full 64-bit result.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
---
arch/x86/include/asm/paravirt.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
===================================================================
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -1522,8 +1522,8 @@
#define PV_RESTORE_REGS "popl %edx; popl %ecx;"
/* save and restore all caller-save registers, except return value */
-#define PV_SAVE_ALL_CALLER_REGS PV_SAVE_REGS
-#define PV_RESTORE_ALL_CALLER_REGS PV_RESTORE_REGS
+#define PV_SAVE_ALL_CALLER_REGS "pushl %ecx;"
+#define PV_RESTORE_ALL_CALLER_REGS "popl %ecx;"
#define PV_FLAGS_ARG "0"
#define PV_EXTRA_CLOBBERS
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