From e2a81baf6604a2e08e10c7405b0349106f77c8af Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Mon, 17 Mar 2008 16:37:17 -0700 Subject: xen: support sysenter/sysexit if hypervisor does 64-bit Xen supports sysenter for 32-bit guests, so support its use. (sysenter is faster than int $0x80 in 32-on-64.) sysexit is still not supported, so we fake it up using iret. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/xen/xen-asm.S | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) (limited to 'arch/x86/xen/xen-asm.S') diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S index 99223cc323be..1ac08082a4b4 100644 --- a/arch/x86/xen/xen-asm.S +++ b/arch/x86/xen/xen-asm.S @@ -280,6 +280,62 @@ ENTRY(xen_iret_crit_fixup) 2: ret +ENTRY(xen_sysexit) + /* Store vcpu_info pointer for easy access. Do it this + way to avoid having to reload %fs */ +#ifdef CONFIG_SMP + GET_THREAD_INFO(%eax) + movl TI_cpu(%eax),%eax + movl __per_cpu_offset(,%eax,4),%eax + mov per_cpu__xen_vcpu(%eax),%eax +#else + movl per_cpu__xen_vcpu, %eax +#endif + + /* We can't actually use sysexit in a pv guest, + so fake it up with iret */ + pushl $__USER_DS /* user stack segment */ + pushl %ecx /* user esp */ + pushl PT_EFLAGS+2*4(%esp) /* user eflags */ + pushl $__USER_CS /* user code segment */ + pushl %edx /* user eip */ + +xen_sysexit_start_crit: + /* Unmask events... */ + movb $0, XEN_vcpu_info_mask(%eax) + /* ...and test for pending. + There's a preempt window here, but it doesn't + matter because we're within the critical section. */ + testb $0xff, XEN_vcpu_info_pending(%eax) + + /* If there's something pending, mask events again so we + can directly inject it back into the kernel. */ + jnz 1f + + movl PT_EAX+5*4(%esp),%eax +2: iret +1: movb $1, XEN_vcpu_info_mask(%eax) +xen_sysexit_end_crit: + addl $5*4, %esp /* remove iret frame */ + /* no need to re-save regs, but need to restore kernel %fs */ + mov $__KERNEL_PERCPU, %eax + mov %eax, %fs + jmp xen_do_upcall +.section __ex_table,"a" + .align 4 + .long 2b,iret_exc +.previous + + .globl xen_sysexit_start_crit, xen_sysexit_end_crit +/* + sysexit fixup is easy, since the old frame is still sitting there + on the stack. We just need to remove the new recursive + interrupt and return. + */ +ENTRY(xen_sysexit_crit_fixup) + addl $PT_OLDESP+5*4, %esp /* remove frame+iret */ + jmp xen_do_upcall + /* Force an event check by making a hypercall, but preserve regs before making the call. -- cgit v1.2.3