[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [Patch 1/3 v2] x86/irq: local_irq_restore() should not blindly popf
On 21/10/2013 17:33, "Andrew Cooper" <andrew.cooper3@xxxxxxxxxx> wrote: > local_irq_restore() should only be concerned with possibly changing the > interrupt flag. A blind popf could corrupt other system flags. > > While playing in this area, fixup an opencoded use of X86_EFLAGS_IF. > > Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > CC: Keir Fraser <keir@xxxxxxx> > CC: Jan Beulich <JBeulich@xxxxxxxx> > > --- > > This is rather more RFC. It boots and runs VMs, so I am fairly sure it is > functionally correct, but I cant help feeling there might be a neater way to > do the inline assembly. Suggestions welcome. > --- > xen/include/asm-x86/system.h | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/xen/include/asm-x86/system.h b/xen/include/asm-x86/system.h > index 6ab7d56..ff52671 100644 > --- a/xen/include/asm-x86/system.h > +++ b/xen/include/asm-x86/system.h > @@ -3,6 +3,7 @@ > > #include <xen/lib.h> > #include <xen/bitops.h> > +#include <asm/processor.h> > > #define read_segment_register(name) \ > ({ u16 __sel; \ > @@ -159,15 +160,19 @@ static always_inline unsigned long __cmpxchg( > #define local_irq_restore(x) \ > ({ \ > BUILD_BUG_ON(sizeof(x) != sizeof(long)); \ > - asm volatile ( "push" __OS " %0 ; popf" __OS \ > - : : "g" (x) : "memory", "cc" ); \ > + asm volatile ( \ > + "pushf" __OS "\n\t" \ > + "and" __OS " %0, (%%" __OP "sp)\n\t" \ > + "orw %1, (%%" __OP "sp)\n\t" \ > + "popf" __OS "\n\t" : : "g" ( ~X86_EFLAGS_IF ), \ Would this be better as a constant constraint ("i")? > + "g" ( x & X86_EFLAGS_IF ) ); \ > }) > > static inline int local_irq_is_enabled(void) > { > unsigned long flags; > local_save_flags(flags); > - return !!(flags & (1<<9)); /* EFLAGS_IF */ > + return !!(flags & X86_EFLAGS_IF); > } > > #define BROKEN_ACPI_Sx 0x0001 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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