1 files changed, 41 insertions, 9 deletions

diff --git a/arch/x86/xen/xen-asm.S b/arch/x86/xen/xen-asm.S
index 83189cf5cdce..b518f36d1ca2 100644
--- a/arch/x86/xen/xen-asm.S
+++ b/arch/x86/xen/xen-asm.S
@@ -20,10 +20,33 @@
 
 #include <linux/init.h>
 #include <linux/linkage.h>
+#include <linux/objtool.h>
 #include <../entry/calling.h>
 
 .pushsection .noinstr.text, "ax"
 /*
+ * PV hypercall interface to the hypervisor.
+ *
+ * Called via inline asm(), so better preserve %rcx and %r11.
+ *
+ * Input:
+ *	%eax: hypercall number
+ *	%rdi, %rsi, %rdx, %r10, %r8: args 1..5 for the hypercall
+ * Output: %rax
+ */
+SYM_FUNC_START(xen_hypercall_pv)
+	ANNOTATE_NOENDBR
+	push %rcx
+	push %r11
+	UNWIND_HINT_SAVE
+	syscall
+	UNWIND_HINT_RESTORE
+	pop %r11
+	pop %rcx
+	RET
+SYM_FUNC_END(xen_hypercall_pv)
+
+/*
  * Disabling events is simply a matter of making the event mask
  * non-zero.
  */
@@ -176,7 +199,6 @@ SYM_CODE_START(xen_early_idt_handler_array)
 SYM_CODE_END(xen_early_idt_handler_array)
 	__FINIT
 
-hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
 /*
  * Xen64 iret frame:
  *
@@ -186,17 +208,28 @@ hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
  *	cs
  *	rip		<-- standard iret frame
  *
- *	flags
+ *	flags		<-- xen_iret must push from here on
  *
- *	rcx		}
- *	r11		}<-- pushed by hypercall page
- * rsp->rax		}
+ *	rcx
+ *	r11
+ * rsp->rax
  */
+.macro xen_hypercall_iret
+	pushq $0	/* Flags */
+	push %rcx
+	push %r11
+	push %rax
+	mov  $__HYPERVISOR_iret, %eax
+	syscall		/* Do the IRET. */
+#ifdef CONFIG_MITIGATION_SLS
+	int3
+#endif
+.endm
+
 SYM_CODE_START(xen_iret)
 	UNWIND_HINT_UNDEFINED
 	ANNOTATE_NOENDBR
-	pushq $0
-	jmp hypercall_iret
+	xen_hypercall_iret
 SYM_CODE_END(xen_iret)
 
 /*
@@ -301,8 +334,7 @@ SYM_CODE_START(xen_entry_SYSENTER_compat)
 	ENDBR
 	lea 16(%rsp), %rsp	/* strip %rcx, %r11 */
 	mov $-ENOSYS, %rax
-	pushq $0
-	jmp hypercall_iret
+	xen_hypercall_iret
 SYM_CODE_END(xen_entry_SYSENTER_compat)
 SYM_CODE_END(xen_entry_SYSCALL_compat)