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authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2009-11-25 22:15:38 +0100
committerJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2009-12-03 20:14:54 +0100
commit6aaf5d633bb6cead81b396d861d7bae4b9a0ba7e (patch)
tree3bd503d3e7b9aa84c1ab618c53c1b1eadad87c83
parentxen: don't call dpm_resume_noirq() with interrupts disabled. (diff)
downloadlinux-6aaf5d633bb6cead81b396d861d7bae4b9a0ba7e.tar.xz
linux-6aaf5d633bb6cead81b396d861d7bae4b9a0ba7e.zip
xen: use iret for return from 64b kernel to 32b usermode
If Xen wants to return to a 32b usermode with sysret it must use the right form. When using VCGF_in_syscall to trigger this, it looks at the code segment and does a 32b sysret if it is FLAT_USER_CS32. However, this is different from __USER32_CS, so it fails to return properly if we use the normal Linux segment. So avoid the whole mess by dropping VCGF_in_syscall and simply use plain iret to return to usermode. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Jan Beulich <jbeulich@novell.com> Cc: Stable Kernel <stable@kernel.org>
-rw-r--r--arch/x86/xen/xen-asm_64.S4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index 02f496a8dbaa..53adefda4275 100644
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -96,7 +96,7 @@ ENTRY(xen_sysret32)
pushq $__USER32_CS
pushq %rcx
- pushq $VGCF_in_syscall
+ pushq $0
1: jmp hypercall_iret
ENDPATCH(xen_sysret32)
RELOC(xen_sysret32, 1b+1)
@@ -151,7 +151,7 @@ ENTRY(xen_syscall32_target)
ENTRY(xen_sysenter_target)
lea 16(%rsp), %rsp /* strip %rcx, %r11 */
mov $-ENOSYS, %rax
- pushq $VGCF_in_syscall
+ pushq $0
jmp hypercall_iret
ENDPROC(xen_syscall32_target)
ENDPROC(xen_sysenter_target)