[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] xen/x86: Adjust stack pointer in xen_sysexit
On 11/13/2015 06:26 PM, Andy Lutomirski wrote: On Fri, Nov 13, 2015 at 3:18 PM, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:After 32-bit syscall rewrite, and specifically after commit 5f310f739b4c ("x86/entry/32: Re-implement SYSENTER using the new C path"), the stack frame that is passed to xen_sysexit is no longer a "standard" one (i.e. it's not pt_regs). We need to adjust it so that subsequent xen_iret can use it.I'm wondering if this should be more straightforward: movq %rsp, %rdi call do_fast_syscall_32 testl %eax, %eax jz .Lsyscall_32_done /* Opportunistic SYSRET */ sysret32_from_system_call: XEN_DO_SYSRET32 where XEN_DO_SYSRET32 is a simple pv op that, on Xen, jumps to a variant of Xen's iret path that knows that the fast path is okay. This patch is for 32-bit kernel. I actually haven't looked at compat code (probably because our tests don't try that), I need to do that too. As for XEN_DO_SYSRET32 --- we'd presumably need to have a nop for baremetal otherwise current paravirt op will use native_usergs_sysret32 (for compat code). Which means a new pv_op, I think. -boris _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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