diff options
Diffstat (limited to 'kernel/arch/x86/xen/xen-asm_64.S')
| -rw-r--r-- | kernel/arch/x86/xen/xen-asm_64.S | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/kernel/arch/x86/xen/xen-asm_64.S b/kernel/arch/x86/xen/xen-asm_64.S new file mode 100644 index 000000000..985fc3ee0 --- /dev/null +++ b/kernel/arch/x86/xen/xen-asm_64.S @@ -0,0 +1,159 @@ +/* + * 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/errno.h> +#include <asm/percpu.h> +#include <asm/processor-flags.h> +#include <asm/segment.h> + +#include <xen/interface/xen.h> + +#include "xen-asm.h" + +ENTRY(xen_adjust_exception_frame) + mov 8+0(%rsp), %rcx + mov 8+8(%rsp), %r11 + ret $16 + +hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32 +/* + * Xen64 iret frame: + * + * ss + * rsp + * rflags + * cs + * rip <-- standard iret frame + * + * flags + * + * rcx } + * r11 }<-- pushed by hypercall page + * rsp->rax } + */ +ENTRY(xen_iret) + pushq $0 +1: jmp hypercall_iret +ENDPATCH(xen_iret) +RELOC(xen_iret, 1b+1) + +/* + * sysexit is not used for 64-bit processes, so it's only ever used to + * return to 32-bit compat userspace. + */ +ENTRY(xen_sysexit) + pushq $__USER32_DS + pushq %rcx + pushq $X86_EFLAGS_IF + pushq $__USER32_CS + pushq %rdx + + pushq $0 +1: jmp hypercall_iret +ENDPATCH(xen_sysexit) +RELOC(xen_sysexit, 1b+1) + +ENTRY(xen_sysret64) + /* + * We're already on the usermode stack at this point, but + * still with the kernel gs, so we can easily switch back + */ + movq %rsp, PER_CPU_VAR(rsp_scratch) + movq PER_CPU_VAR(kernel_stack), %rsp + + pushq $__USER_DS + pushq PER_CPU_VAR(rsp_scratch) + pushq %r11 + pushq $__USER_CS + pushq %rcx + + pushq $VGCF_in_syscall +1: jmp hypercall_iret +ENDPATCH(xen_sysret64) +RELOC(xen_sysret64, 1b+1) + +ENTRY(xen_sysret32) + /* + * We're already on the usermode stack at this point, but + * still with the kernel gs, so we can easily switch back + */ + movq %rsp, PER_CPU_VAR(rsp_scratch) + movq PER_CPU_VAR(kernel_stack), %rsp + + pushq $__USER32_DS + pushq PER_CPU_VAR(rsp_scratch) + pushq %r11 + pushq $__USER32_CS + pushq %rcx + + pushq $0 +1: jmp hypercall_iret +ENDPATCH(xen_sysret32) +RELOC(xen_sysret32, 1b+1) + +/* + * Xen handles syscall callbacks much like ordinary exceptions, which + * means we have: + * - kernel gs + * - kernel rsp + * - an iret-like stack frame on the stack (including rcx and r11): + * ss + * rsp + * rflags + * cs + * rip + * r11 + * rsp->rcx + * + * In all the entrypoints, we undo all that to make it look like a + * CPU-generated syscall/sysenter and jump to the normal entrypoint. + */ + +.macro undo_xen_syscall + mov 0*8(%rsp), %rcx + mov 1*8(%rsp), %r11 + mov 5*8(%rsp), %rsp +.endm + +/* Normal 64-bit system call target */ +ENTRY(xen_syscall_target) + undo_xen_syscall + jmp system_call_after_swapgs +ENDPROC(xen_syscall_target) + +#ifdef CONFIG_IA32_EMULATION + +/* 32-bit compat syscall target */ +ENTRY(xen_syscall32_target) + undo_xen_syscall + jmp ia32_cstar_target +ENDPROC(xen_syscall32_target) + +/* 32-bit compat sysenter target */ +ENTRY(xen_sysenter_target) + undo_xen_syscall + jmp ia32_sysenter_target +ENDPROC(xen_sysenter_target) + +#else /* !CONFIG_IA32_EMULATION */ + +ENTRY(xen_syscall32_target) +ENTRY(xen_sysenter_target) + lea 16(%rsp), %rsp /* strip %rcx, %r11 */ + mov $-ENOSYS, %rax + pushq $0 + jmp hypercall_iret +ENDPROC(xen_syscall32_target) +ENDPROC(xen_sysenter_target) + +#endif /* CONFIG_IA32_EMULATION */ |