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Annotation of Gnu-Mach/i386/xen/xen_locore.S, revision 1.1

1.1     ! root        1: /*
        !             2:  *  Copyright (C) 2006-2009 Free Software Foundation
        !             3:  *
        !             4:  * This program is free software ; you can redistribute it and/or modify
        !             5:  * it under the terms of the GNU General Public License as published by
        !             6:  * the Free Software Foundation ; either version 2 of the License, or
        !             7:  * (at your option) any later version.
        !             8:  *
        !             9:  * This program is distributed in the hope that it will be useful,
        !            10:  * but WITHOUT ANY WARRANTY ; without even the implied warranty of
        !            11:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
        !            12:  * GNU General Public License for more details.
        !            13:  *
        !            14:  * You should have received a copy of the GNU General Public License
        !            15:  * along with the program ; if not, write to the Free Software
        !            16:  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
        !            17:  */
        !            18: 
        !            19: #include <mach/machine/asm.h>
        !            20: 
        !            21: #include <i386/i386asm.h>
        !            22: #include <i386/cpu_number.h>
        !            23: #include <i386/xen.h>
        !            24: 
        !            25:        .data   2
        !            26: int_active:
        !            27:        .long   0
        !            28:        
        !            29: 
        !            30:        .text
        !            31:        .globl  hyp_callback, hyp_failsafe_callback
        !            32:        P2ALIGN(TEXT_ALIGN)
        !            33: hyp_callback:
        !            34:        pushl   %eax
        !            35:        jmp     EXT(all_intrs)
        !            36: 
        !            37: ENTRY(interrupt)
        !            38:        incl    int_active              /* currently handling interrupts */
        !            39:        call    EXT(hyp_c_callback)     /* call generic interrupt routine */
        !            40:        decl    int_active              /* stopped handling interrupts */
        !            41:        sti
        !            42:        ret
        !            43: 
        !            44: /* FIXME: if we're _very_ unlucky, we may be re-interrupted, filling stack
        !            45:  *
        !            46:  * Far from trivial, see mini-os. That said, maybe we could just, before poping
        !            47:  * everything (which is _not_ destructive), save sp into a known place and use
        !            48:  * it+jmp back?
        !            49:  *
        !            50:  * Mmm, there seems to be an iret hypcall that does exactly what we want:
        !            51:  * perform iret, and if IF is set, clear the interrupt mask.
        !            52:  */
        !            53: 
        !            54: /* Pfff, we have to check pending interrupts ourselves. Some other DomUs just make an hypercall for retriggering the irq. Not sure it's really easier/faster */
        !            55: ENTRY(hyp_sti)
        !            56:        pushl   %ebp
        !            57:        movl    %esp, %ebp
        !            58: _hyp_sti:
        !            59:        movb    $0,hyp_shared_info+CPU_CLI /* Enable interrupts */
        !            60:        cmpl    $0,int_active           /* Check whether we were already checking pending interrupts */
        !            61:        jz      0f
        !            62:        popl    %ebp
        !            63:        ret                             /* Already active, just return */
        !            64: 0:
        !            65:        /* Not active, check pending interrupts by hand */
        !            66:        /* no memory barrier needed on x86 */
        !            67:        cmpb    $0,hyp_shared_info+CPU_PENDING
        !            68:        jne     0f
        !            69:        popl    %ebp
        !            70:        ret
        !            71: 0:
        !            72:        movb    $0xff,hyp_shared_info+CPU_CLI
        !            73: 1:
        !            74:        pushl   %eax
        !            75:        pushl   %ecx
        !            76:        pushl   %edx
        !            77:        incl    int_active              /* currently handling interrupts */
        !            78: 
        !            79:        pushl   $0
        !            80:        pushl   $0
        !            81:        call    EXT(hyp_c_callback)
        !            82:        popl    %edx
        !            83:        popl    %edx
        !            84: 
        !            85:        popl    %edx
        !            86:        popl    %ecx
        !            87:        popl    %eax
        !            88:        decl    int_active              /* stopped handling interrupts */
        !            89:        cmpb    $0,hyp_shared_info+CPU_PENDING
        !            90:        jne     1b
        !            91:        jmp     _hyp_sti
        !            92: 
        !            93: /* Hypervisor failed to reload segments. Dump them.  */
        !            94: hyp_failsafe_callback:
        !            95: #if 1
        !            96:        /* load sane segments */
        !            97:        mov     %ss, %ax
        !            98:        mov     %ax, %ds
        !            99:        mov     %ax, %es
        !           100:        mov     %ax, %fs
        !           101:        mov     %ax, %gs
        !           102:        push    %esp
        !           103:        call    EXT(hyp_failsafe_c_callback)
        !           104: #else
        !           105:        popl    %ds
        !           106:        popl    %es
        !           107:        popl    %fs
        !           108:        popl    %gs
        !           109:        iret
        !           110: #endif

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