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authorJeremy Fitzhardinge <jeremy@goop.org>2008-07-09 02:07:14 +0400
committerIngo Molnar <mingo@elte.hu>2008-07-16 13:05:52 +0400
commit6fcac6d305e8238939e169f4c52e8ec8a552a31f (patch)
treeb973a215938121d42bc586925d9712f205badea0 /arch/x86/xen/xen-asm_64.S
parentd6182fbf04164016cb6540db02eef3d6bdc967c3 (diff)
downloadlinux-6fcac6d305e8238939e169f4c52e8ec8a552a31f.tar.xz
xen64: set up syscall and sysenter entrypoints for 64-bit
We set up entrypoints for syscall and sysenter. sysenter is only used for 32-bit compat processes, whereas syscall can be used in by both 32 and 64-bit processes. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/xen/xen-asm_64.S')
-rw-r--r--arch/x86/xen/xen-asm_64.S129
1 files changed, 127 insertions, 2 deletions
diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
index b147b495daef..4038cbfe3331 100644
--- 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 */