xen64: set up syscall and sysenter entrypoints for 64-bit

[linux-2.6-omap-h63xx.git] / arch / x86 / xen / xen-asm_64.S

diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index b147b495daef5ee5d2ec1da7071f4295abaf17f6..4038cbfe33319ac954b83437d45b9c189af052da 100644 (file)
--- a/arch/x86/xen/xen-asm_64.S
+++ b/arch/x86/xen/xen-asm_64.S
@@ -15,6 +15,8 @@
 
 #include <asm/asm-offsets.h>
 #include <asm/processor-flags.h>
+#include <asm/errno.h>
+#include <asm/segment.h>
 
 #include <xen/interface/xen.h>
 
@@ -138,9 +140,132 @@ ENTRY(xen_adjust_exception_frame)
        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
-       jmp hypercall_page + __HYPERVISOR_iret * 32
+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)
-       ud2a
+       pushq $__USER32_DS
+       pushq %rcx
+       pushq $X86_EFLAGS_IF
+       pushq $__USER32_CS
+       pushq %rdx
+
+       pushq $VGCF_in_syscall
+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, %gs:pda_oldrsp
+       movq %gs:pda_kernelstack,%rsp
+
+       pushq $__USER_DS
+       pushq %gs:pda_oldrsp
+       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, %gs:pda_oldrsp
+       movq %gs:pda_kernelstack, %rsp
+
+       pushq $__USER32_DS
+       pushq %gs:pda_oldrsp
+       pushq %r11
+       pushq $__USER32_CS
+       pushq %rcx
+
+       pushq $VGCF_in_syscall
+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 $VGCF_in_syscall
+       jmp hypercall_iret
+ENDPROC(xen_syscall32_target)
+ENDPROC(xen_sysenter_target)
+
+#endif /* CONFIG_IA32_EMULATION */