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authorIgor Mammedov <imammedo@redhat.com>2011-09-01 13:46:55 +0200
committerKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2011-09-01 12:54:42 -0400
commitd198d499148a0c64a41b3aba9e7dd43772832b91 (patch)
treeddc0bf46ac10d84db5d06dceb44c21770692f596 /arch
parentd312ae878b6aed3912e1acaaf5d0b2a9d08a4f11 (diff)
downloadop-kernel-dev-d198d499148a0c64a41b3aba9e7dd43772832b91.zip
op-kernel-dev-d198d499148a0c64a41b3aba9e7dd43772832b91.tar.gz
xen: x86_32: do not enable iterrupts when returning from exception in interrupt context
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 CC: stable@kernel.org 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>
Diffstat (limited to 'arch')
-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 22a2093..b040b0e 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
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