2 * Asm versions of Xen pv-ops, suitable for either direct use or
3 * inlining. The inline versions are the same as the direct-use
4 * versions, with the pre- and post-amble chopped off.
6 * This code is encoded for size rather than absolute efficiency, with
7 * a view to being able to inline as much as possible.
9 * We only bother with direct forms (ie, vcpu in pda) of the
10 * operations here; the indirect forms are better handled in C, since
11 * they're generally too large to inline anyway.
14 #include <asm/errno.h>
15 #include <asm/percpu.h>
16 #include <asm/processor-flags.h>
17 #include <asm/segment.h>
18 #include <asm/asm-offsets.h>
20 #include <xen/interface/xen.h>
24 ENTRY(xen_adjust_exception_frame)
29 hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
37 * rip <-- standard iret frame
42 * r11 }<-- pushed by hypercall page
53 * We're already on the usermode stack at this point, but
54 * still with the kernel gs, so we can easily switch back
56 movq %rsp, PER_CPU_VAR(rsp_scratch)
57 movq PER_CPU_VAR(cpu_tss + TSS_sp0), %rsp
60 pushq PER_CPU_VAR(rsp_scratch)
65 pushq $VGCF_in_syscall
67 ENDPATCH(xen_sysret64)
68 RELOC(xen_sysret64, 1b+1)
72 * We're already on the usermode stack at this point, but
73 * still with the kernel gs, so we can easily switch back
75 movq %rsp, PER_CPU_VAR(rsp_scratch)
76 movq PER_CPU_VAR(cpu_tss + TSS_sp0), %rsp
79 pushq PER_CPU_VAR(rsp_scratch)
86 ENDPATCH(xen_sysret32)
87 RELOC(xen_sysret32, 1b+1)
90 * Xen handles syscall callbacks much like ordinary exceptions, which
94 * - an iret-like stack frame on the stack (including rcx and r11):
103 * In all the entrypoints, we undo all that to make it look like a
104 * CPU-generated syscall/sysenter and jump to the normal entrypoint.
107 .macro undo_xen_syscall
113 /* Normal 64-bit system call target */
114 ENTRY(xen_syscall_target)
116 jmp system_call_after_swapgs
117 ENDPROC(xen_syscall_target)
119 #ifdef CONFIG_IA32_EMULATION
121 /* 32-bit compat syscall target */
122 ENTRY(xen_syscall32_target)
124 jmp ia32_cstar_target
125 ENDPROC(xen_syscall32_target)
127 /* 32-bit compat sysenter target */
128 ENTRY(xen_sysenter_target)
130 jmp ia32_sysenter_target
131 ENDPROC(xen_sysenter_target)
133 #else /* !CONFIG_IA32_EMULATION */
135 ENTRY(xen_syscall32_target)
136 ENTRY(xen_sysenter_target)
137 lea 16(%rsp), %rsp /* strip %rcx, %r11 */
141 ENDPROC(xen_syscall32_target)
142 ENDPROC(xen_sysenter_target)
144 #endif /* CONFIG_IA32_EMULATION */