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#include <linux/linkage.h>
2 #include <linux/lguest.h>
3 #include <asm/asm-offsets.h>
4 #include <asm/thread_info.h>
5
6 /* FIXME: Once asm/processor-flags.h goes in, include that */
7 #define X86_EFLAGS_IF 0x00000200
8
9 /*
10 * This is where we begin: we have a magic signature which the launcher looks
11 * for. The plan is that the Linux boot protocol will be extended with a
12* "platform type" field which will guide us here from the normal entry point,
13 * but for the moment this suffices. We pass the virtual address of the boot
14 * info to lguest_init().
15 *
16 * We put it in .init.text will be discarded after boot.
17 */
18 .section .init.text, "ax", @progbits
19 .ascii "GenuineLguest"
20 /* Set up initial stack. */
// #define THREAD_SIZE 8192
/* union thread_union {
* struct thread_info thread_info;
* unsigned long stack[THREAD_SIZE/sizeof(long)];
* };
*/
21 movl $(init_thread_union+THREAD_SIZE),%esp
22 movl %esi, %eax
23 addl $__PAGE_OFFSET, %eax
24 jmp lguest_init
25
26 /* The templates for inline patching. */
27 #define LGUEST_PATCH(name, insns...) \
28 lgstart_##name: insns; lgend_##name:; \
29 .globl lgstart_##name; .globl lgend_##name
30
31 LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled)
32 LGUEST_PATCH(sti, movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled)
33 LGUEST_PATCH(popf, movl %eax, lguest_data+LGUEST_DATA_irq_enabled)
34 LGUEST_PATCH(pushf, movl lguest_data+LGUEST_DATA_irq_enabled, %eax)
35
36 .text
37 /* These demark the EIP range where host should never deliver interrupts. */
38 .global lguest_noirq_start
39 .global lguest_noirq_end
40
41 /*
42 * We move eflags word to lguest_data.irq_enabled to restore interrupt state.
43 * For page faults, gpfs and virtual interrupts, the hypervisor has saved
44 * eflags manually, otherwise it was delivered directly and so eflags reflects
45 * the real machine IF state, ie. interrupts on. Since the kernel always dies
46 * if it takes such a trap with interrupts disabled anyway, turning interrupts
47 * back on unconditionally here is OK.
48 */
/* There are two problems with this: firstly, we need to use a register to do
* the copy and secondly, the whole thing needs to be atomic. The first
* problem is easy to solve: push %eax on the stack so we can use it, and then
* restore it at the end just before the real "iret".
*
* The second is harder: copying eflags to lguest_data.irq_enabled will turn
* interrupts on before we
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