Messages in this thread Patch in this message | | | From | Igor Mammedov <> | Subject | [PATCH] xen: x86_32: do not enable iterrupts when returning from exception in interrupt context | Date | Thu, 1 Sep 2011 01:47:18 +0200 |
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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.
Signed-off-by: Igor Mammedov <imammedo@redhat.com> --- arch/x86/xen/xen-asm_32.S | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/arch/x86/xen/xen-asm_32.S b/arch/x86/xen/xen-asm_32.S index 22a2093..313dca7 100644 --- a/arch/x86/xen/xen-asm_32.S +++ b/arch/x86/xen/xen-asm_32.S @@ -113,10 +113,14 @@ 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. */ + jne ignore_vcpu_info_mask sete XEN_vcpu_info_mask(%eax) +ignore_vcpu_info_mask: + popl %eax /* -- 1.7.1
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