| /* |
| * 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 <asm/asm-offsets.h> |
| #include <asm/thread_info.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 |
| ENDPROC(xen_adjust_exception_frame) |
| |
| 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) |
| |
| 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(cpu_current_top_of_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) |
| |
| /* |
| * 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 entry_SYSCALL_64_after_swapgs |
| ENDPROC(xen_syscall_target) |
| |
| #ifdef CONFIG_IA32_EMULATION |
| |
| /* 32-bit compat syscall target */ |
| ENTRY(xen_syscall32_target) |
| undo_xen_syscall |
| jmp entry_SYSCALL_compat |
| ENDPROC(xen_syscall32_target) |
| |
| /* 32-bit compat sysenter target */ |
| ENTRY(xen_sysenter_target) |
| undo_xen_syscall |
| jmp entry_SYSENTER_compat |
| 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 */ |
