diff options
Diffstat (limited to 'ANDROID_3.4.5/arch/x86/xen/xen-asm_32.S')
| -rw-r--r-- | ANDROID_3.4.5/arch/x86/xen/xen-asm_32.S | 230 |
1 files changed, 0 insertions, 230 deletions
diff --git a/ANDROID_3.4.5/arch/x86/xen/xen-asm_32.S b/ANDROID_3.4.5/arch/x86/xen/xen-asm_32.S deleted file mode 100644 index b040b0e5..00000000 --- a/ANDROID_3.4.5/arch/x86/xen/xen-asm_32.S +++ /dev/null @@ -1,230 +0,0 @@ -/* - * Asm versions of Xen pv-ops, suitable for either direct use or - * inlining. The inline versions are the same as the direct-use - * versions, with the pre- and post-amble chopped off. - * - * This code is encoded for size rather than absolute efficiency, with - * a view to being able to inline as much as possible. - * - * We only bother with direct forms (ie, vcpu in pda) of the - * operations here; the indirect forms are better handled in C, since - * they're generally too large to inline anyway. - */ - -#include <asm/thread_info.h> -#include <asm/processor-flags.h> -#include <asm/segment.h> - -#include <xen/interface/xen.h> - -#include "xen-asm.h" - -/* - * Force an event check by making a hypercall, but preserve regs - * before making the call. - */ -check_events: - push %eax - push %ecx - push %edx - call xen_force_evtchn_callback - pop %edx - pop %ecx - pop %eax - ret - -/* - * We can't use sysexit directly, because we're not running in ring0. - * But we can easily fake it up using iret. Assuming xen_sysexit is - * jumped to with a standard stack frame, we can just strip it back to - * a standard iret frame and use iret. - */ -ENTRY(xen_sysexit) - movl PT_EAX(%esp), %eax /* Shouldn't be necessary? */ - orl $X86_EFLAGS_IF, PT_EFLAGS(%esp) - lea PT_EIP(%esp), %esp - - jmp xen_iret -ENDPROC(xen_sysexit) - -/* - * This is run where a normal iret would be run, with the same stack setup: - * 8: eflags - * 4: cs - * esp-> 0: eip - * - * This attempts to make sure that any pending events are dealt with - * on return to usermode, but there is a small window in which an - * event can happen just before entering usermode. If the nested - * interrupt ends up setting one of the TIF_WORK_MASK pending work - * flags, they will not be tested again before returning to - * usermode. This means that a process can end up with pending work, - * which will be unprocessed until the process enters and leaves the - * kernel again, which could be an unbounded amount of time. This - * means that a pending signal or reschedule event could be - * indefinitely delayed. - * - * The fix is to notice a nested interrupt in the critical window, and - * if one occurs, then fold the nested interrupt into the current - * interrupt stack frame, and re-process it iteratively rather than - * recursively. This means that it will exit via the normal path, and - * all pending work will be dealt with appropriately. - * - * Because the nested interrupt handler needs to deal with the current - * stack state in whatever form its in, we keep things simple by only - * using a single register which is pushed/popped on the stack. - */ -ENTRY(xen_iret) - /* test eflags for special cases */ - testl $(X86_EFLAGS_VM | XEN_EFLAGS_NMI), 8(%esp) - jnz hyper_iret - - push %eax - ESP_OFFSET=4 # bytes pushed onto stack - - /* - * 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 xen_vcpu(%eax), %eax -#else - movl xen_vcpu, %eax -#endif - - /* check IF state we're restoring */ - testb $X86_EFLAGS_IF>>8, 8+1+ESP_OFFSET(%esp) - - /* - * Maybe enable events. Once this happens we could get a - * recursive event, so the critical region starts immediately - * afterwards. However, if that happens we don't end up - * resuming the code, so we don't have to be worried about - * being preempted to another CPU. - */ - setz XEN_vcpu_info_mask(%eax) -xen_iret_start_crit: - - /* check for unmasked and pending */ - cmpw $0x0001, XEN_vcpu_info_pending(%eax) - - /* - * If there's something pending, mask events again so we can - * jump back into xen_hypervisor_callback. Otherwise do not - * touch XEN_vcpu_info_mask. - */ - jne 1f - movb $1, XEN_vcpu_info_mask(%eax) - -1: popl %eax - - /* - * From this point on the registers are restored and the stack - * updated, so we don't need to worry about it if we're - * preempted - */ -iret_restore_end: - - /* - * Jump to hypervisor_callback after fixing up the stack. - * Events are masked, so jumping out of the critical region is - * OK. - */ - je xen_hypervisor_callback - -1: iret -xen_iret_end_crit: -.section __ex_table, "a" - .align 4 - .long 1b, iret_exc -.previous - -hyper_iret: - /* put this out of line since its very rarely used */ - jmp hypercall_page + __HYPERVISOR_iret * 32 - - .globl xen_iret_start_crit, xen_iret_end_crit - -/* - * This is called by xen_hypervisor_callback in entry.S when it sees - * that the EIP at the time of interrupt was between - * xen_iret_start_crit and xen_iret_end_crit. We're passed the EIP in - * %eax so we can do a more refined determination of what to do. - * - * The stack format at this point is: - * ---------------- - * ss : (ss/esp may be present if we came from usermode) - * esp : - * eflags } outer exception info - * cs } - * eip } - * ---------------- <- edi (copy dest) - * eax : outer eax if it hasn't been restored - * ---------------- - * eflags } nested exception info - * cs } (no ss/esp because we're nested - * eip } from the same ring) - * orig_eax }<- esi (copy src) - * - - - - - - - - - * fs } - * es } - * ds } SAVE_ALL state - * eax } - * : : - * ebx }<- esp - * ---------------- - * - * In order to deliver the nested exception properly, we need to shift - * everything from the return addr up to the error code so it sits - * just under the outer exception info. This means that when we - * handle the exception, we do it in the context of the outer - * exception rather than starting a new one. - * - * The only caveat is that if the outer eax hasn't been restored yet - * (ie, it's still on stack), we need to insert its value into the - * SAVE_ALL state before going on, since it's usermode state which we - * eventually need to restore. - */ -ENTRY(xen_iret_crit_fixup) - /* - * Paranoia: Make sure we're really coming from kernel space. - * One could imagine a case where userspace jumps into the - * critical range address, but just before the CPU delivers a - * GP, it decides to deliver an interrupt instead. Unlikely? - * Definitely. Easy to avoid? Yes. The Intel documents - * explicitly say that the reported EIP for a bad jump is the - * jump instruction itself, not the destination, but some - * virtual environments get this wrong. - */ - movl PT_CS(%esp), %ecx - andl $SEGMENT_RPL_MASK, %ecx - cmpl $USER_RPL, %ecx - je 2f - - lea PT_ORIG_EAX(%esp), %esi - lea PT_EFLAGS(%esp), %edi - - /* - * If eip is before iret_restore_end then stack - * hasn't been restored yet. - */ - cmp $iret_restore_end, %eax - jae 1f - - movl 0+4(%edi), %eax /* copy EAX (just above top of frame) */ - movl %eax, PT_EAX(%esp) - - lea ESP_OFFSET(%edi), %edi /* move dest up over saved regs */ - - /* set up the copy */ -1: std - mov $PT_EIP / 4, %ecx /* saved regs up to orig_eax */ - rep movsl - cld - - lea 4(%edi), %esp /* point esp to new frame */ -2: jmp xen_do_upcall - |