diff options
| author | Igor Mammedov <imammedo@redhat.com> | 2011-09-01 13:46:55 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-10-03 11:40:12 -0700 |
| commit | 1f51b5d99ced3fc83ab8367e619320c08eee8a7f (patch) | |
| tree | 4dd196fe6207dc917a2e54c84476094f13b0fa23 /arch/x86 | |
| parent | 1c72a517f74eec97133923b5f87a9afbc044423d (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.S | 8 |
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 |