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authorIgor Mammedov <imammedo@redhat.com>2011-09-01 13:46:55 +0200
committerGreg Kroah-Hartman <gregkh@suse.de>2011-10-03 11:40:12 -0700
commit1f51b5d99ced3fc83ab8367e619320c08eee8a7f (patch)
tree4dd196fe6207dc917a2e54c84476094f13b0fa23 /arch/x86
parent1c72a517f74eec97133923b5f87a9afbc044423d (diff)
xen: x86_32: do not enable iterrupts when returning from exception in interrupt context
commit d198d499148a0c64a41b3aba9e7dd43772832b91 upstream. If vmalloc page_fault happens inside of interrupt handler with interrupts disabled then on exit path from exception handler when there is no pending interrupts, the following code (arch/x86/xen/xen-asm_32.S:112): cmpw $0x0001, XEN_vcpu_info_pending(%eax) sete XEN_vcpu_info_mask(%eax) will enable interrupts even if they has been previously disabled according to eflags from the bounce frame (arch/x86/xen/xen-asm_32.S:99) testb $X86_EFLAGS_IF>>8, 8+1+ESP_OFFSET(%esp) setz XEN_vcpu_info_mask(%eax) Solution is in setting XEN_vcpu_info_mask only when it should be set according to cmpw $0x0001, XEN_vcpu_info_pending(%eax) but not clearing it if there isn't any pending events. Reproducer for bug is attached to RHBZ 707552 Signed-off-by: Igor Mammedov <imammedo@redhat.com> Acked-by: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/xen/xen-asm_32.S8
1 files changed, 5 insertions, 3 deletions
diff --git a/arch/x86/xen/xen-asm_32.S b/arch/x86/xen/xen-asm_32.S
index 22a2093b5862..b040b0e518ca 100644
--- a/arch/x86/xen/xen-asm_32.S
+++ b/arch/x86/xen/xen-asm_32.S
@@ -113,11 +113,13 @@ xen_iret_start_crit:
/*
* If there's something pending, mask events again so we can
- * jump back into xen_hypervisor_callback
+ * jump back into xen_hypervisor_callback. Otherwise do not
+ * touch XEN_vcpu_info_mask.
*/
- sete XEN_vcpu_info_mask(%eax)
+ jne 1f
+ movb $1, XEN_vcpu_info_mask(%eax)
- popl %eax
+1: popl %eax
/*
* From this point on the registers are restored and the stack