[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3 4/9] Clear AC bit in RFLAGS to protect Xen itself by SMAP
> -----Original Message----- > From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > Sent: Monday, April 28, 2014 5:58 PM > To: Wu, Feng > Cc: andrew.cooper3@xxxxxxxxxx; ian.campbell@xxxxxxxxxx; Dong, Eddie; > Nakajima, Jun; Tian, Kevin; xen-devel@xxxxxxxxxxxxx > Subject: RE: [PATCH v3 4/9] Clear AC bit in RFLAGS to protect Xen itself by > SMAP > > >>> On 28.04.14 at 11:43, <feng.wu@xxxxxxxxx> wrote: > > > > >> -----Original Message----- > >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > >> Sent: Monday, April 28, 2014 5:26 PM > >> To: Wu, Feng > >> Cc: andrew.cooper3@xxxxxxxxxx; ian.campbell@xxxxxxxxxx; Dong, Eddie; > >> Nakajima, Jun; Tian, Kevin; xen-devel@xxxxxxxxxxxxx > >> Subject: Re: [PATCH v3 4/9] Clear AC bit in RFLAGS to protect Xen itself by > > SMAP > >> > >> >>> On 28.04.14 at 05:15, <feng.wu@xxxxxxxxx> wrote: > >> > @@ -466,6 +468,7 @@ ENTRY(dom_crash_sync_extable) > >> > jmp asm_domain_crash_synchronous /* Does not return */ > >> > > >> > ENTRY(common_interrupt) > >> > + ASM_CLAC > >> > SAVE_ALL > >> > movq %rsp,%rdi > >> > callq do_IRQ > >> > @@ -485,6 +488,7 @@ ENTRY(page_fault) > >> > movl $TRAP_page_fault,4(%rsp) > >> > /* No special register assumptions. */ > >> > GLOBAL(handle_exception) > >> > + ASM_CLAC > >> > SAVE_ALL > >> > >> Did you check whether the addition wouldn't better go right into > >> SAVE_ALL? > > > > Most of them can be moved into SAVE_ALL obviously, however, there are two > > exceptions: > > > > 1. SAVE_ALL is not executed in the beginning of some exception handlers, > > such as, double_fault, nmi, etc. > > But that's orthogonal - I didn't say that would automatically cover > _all_ cases. So, do you think we can move CLAC into SAVE_ALL in these cases? Thanks! > > > 2. We don't need CLAC in .fixup section where SAVE_ALL is used. > > Do we not? I think the AC bit is clear when running SAVE_ALL in the .fixup section. > > Jan > Thanks, Feng _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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