diff options
Diffstat (limited to 'drivers/lguest/lguest_asm.S')
| -rw-r--r-- | drivers/lguest/lguest_asm.S | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/drivers/lguest/lguest_asm.S b/drivers/lguest/lguest_asm.S new file mode 100644 index 00000000000..5ac3d20bb18 --- /dev/null +++ b/drivers/lguest/lguest_asm.S @@ -0,0 +1,53 @@ +#include <linux/linkage.h> +#include <linux/lguest.h> +#include <asm/asm-offsets.h> +#include <asm/thread_info.h> + +/* FIXME: Once asm/processor-flags.h goes in, include that */ +#define X86_EFLAGS_IF 0x00000200 + +/* + * This is where we begin: we have a magic signature which the launcher looks + * for. The plan is that the Linux boot protocol will be extended with a + * "platform type" field which will guide us here from the normal entry point, + * but for the moment this suffices. + * + * We put it in .init.text will be discarded after boot. + */ +.section .init.text, "ax", @progbits +.ascii "GenuineLguest" + /* Set up initial stack. */ + movl $(init_thread_union+THREAD_SIZE),%esp + jmp lguest_init + +/* The templates for inline patching. */ +#define LGUEST_PATCH(name, insns...) \ + lgstart_##name: insns; lgend_##name:; \ + .globl lgstart_##name; .globl lgend_##name + +LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled) +LGUEST_PATCH(sti, movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled) +LGUEST_PATCH(popf, movl %eax, lguest_data+LGUEST_DATA_irq_enabled) +LGUEST_PATCH(pushf, movl lguest_data+LGUEST_DATA_irq_enabled, %eax) + +.text +/* These demark the EIP range where host should never deliver interrupts. */ +.global lguest_noirq_start +.global lguest_noirq_end + +/* + * We move eflags word to lguest_data.irq_enabled to restore interrupt state. + * For page faults, gpfs and virtual interrupts, the hypervisor has saved + * eflags manually, otherwise it was delivered directly and so eflags reflects + * the real machine IF state, ie. interrupts on. Since the kernel always dies + * if it takes such a trap with interrupts disabled anyway, turning interrupts + * back on unconditionally here is OK. + */ +ENTRY(lguest_iret) + pushl %eax + movl 12(%esp), %eax +lguest_noirq_start: + movl %eax,%ss:lguest_data+LGUEST_DATA_irq_enabled + popl %eax + iret +lguest_noirq_end: |