diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 1c62046c01..020df615bd 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -212,8 +212,8 @@ long arch_do_domctl(
     case XEN_DOMCTL_shadow_op:
         ret = paging_domctl(d, &domctl->u.shadow_op, u_domctl, 0);
         if ( ret == -ERESTART )
-            return hypercall_create_continuation(__HYPERVISOR_arch_1,
-                                                 "h", u_domctl);
+            return hypercall_create_continuation(
+                       __HYPERVISOR_paging_domctl_cont, "h", u_domctl);
         copyback = true;
         break;
 
diff --git a/xen/arch/x86/hvm/hypercall.c b/xen/arch/x86/hvm/hypercall.c
index 62b5349e7d..3a35543997 100644
--- a/xen/arch/x86/hvm/hypercall.c
+++ b/xen/arch/x86/hvm/hypercall.c
@@ -124,8 +124,6 @@ static long cf_check hvm_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
     [ __HYPERVISOR_ ## x ] = { (hypercall_fn_t *) do_ ## x,  \
                                (hypercall_fn_t *) compat_ ## x }
 
-#define do_arch_1             paging_domctl_continuation
-
 static const struct {
     hypercall_fn_t *native, *compat;
 } hvm_hypercall_table[] = {
@@ -158,11 +156,9 @@ static const struct {
 #ifdef CONFIG_HYPFS
     HYPERCALL(hypfs_op),
 #endif
-    HYPERCALL(arch_1)
+    HYPERCALL(paging_domctl_cont)
 };
 
-#undef do_arch_1
-
 #undef HYPERCALL
 #undef HVM_CALL
 #undef COMPAT_CALL
@@ -300,7 +296,7 @@ int hvm_hypercall(struct cpu_user_regs *regs)
 #endif
 
         curr->hcall_compat = true;
-        regs->rax = hvm_hypercall_table[eax].compat(ebx, ecx, edx, esi, edi);
+        regs->eax = hvm_hypercall_table[eax].compat(ebx, ecx, edx, esi, edi);
         curr->hcall_compat = false;
 
 #ifndef NDEBUG
diff --git a/xen/arch/x86/hypercall.c b/xen/arch/x86/hypercall.c
index 2370d31d3f..07e1a45ef5 100644
--- a/xen/arch/x86/hypercall.c
+++ b/xen/arch/x86/hypercall.c
@@ -75,7 +75,7 @@ const hypercall_args_t hypercall_args_table[NR_hypercalls] =
     ARGS(dm_op, 3),
     ARGS(hypfs_op, 5),
     ARGS(mca, 1),
-    ARGS(arch_1, 1),
+    ARGS(paging_domctl_cont, 1),
 };
 
 #undef COMP
diff --git a/xen/arch/x86/include/asm/hypercall.h b/xen/arch/x86/include/asm/hypercall.h
index 1c57236dc7..81ca25f7b3 100644
--- a/xen/arch/x86/include/asm/hypercall.h
+++ b/xen/arch/x86/include/asm/hypercall.h
@@ -15,6 +15,8 @@
 #include <public/arch-x86/xen-mca.h> /* for do_mca */
 #include <asm/paging.h>
 
+#define __HYPERVISOR_paging_domctl_cont __HYPERVISOR_arch_1
+
 typedef unsigned long hypercall_fn_t(
     unsigned long, unsigned long, unsigned long,
     unsigned long, unsigned long);
@@ -84,7 +86,7 @@ do_set_debugreg(
     int reg,
     unsigned long value);
 
-extern unsigned long cf_check
+extern long cf_check
 do_get_debugreg(
     int reg);
 
@@ -122,7 +124,7 @@ do_mmuext_op(
 extern long cf_check do_callback_op(
     int cmd, XEN_GUEST_HANDLE_PARAM(const_void) arg);
 
-extern unsigned long cf_check
+extern long cf_check
 do_iret(
     void);
 
@@ -137,17 +139,20 @@ do_set_segment_base(
     unsigned int which,
     unsigned long base);
 
+long cf_check do_nmi_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) arg);
+
+long cf_check do_xenpmu_op(unsigned int op,
+                           XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg);
+
+long cf_check do_paging_domctl_cont(
+    XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl);
+
 #ifdef CONFIG_COMPAT
 
 #include <compat/arch-x86/xen.h>
 #include <compat/physdev.h>
 #include <compat/platform.h>
 
-extern int cf_check
-compat_physdev_op(
-    int cmd,
-    XEN_GUEST_HANDLE_PARAM(void) arg);
-
 extern int
 compat_common_vcpu_op(
     int cmd, struct vcpu *v, XEN_GUEST_HANDLE_PARAM(void) arg);
@@ -158,12 +163,8 @@ extern int cf_check compat_mmuext_op(
     XEN_GUEST_HANDLE_PARAM(uint) pdone,
     unsigned int foreigndom);
 
-DEFINE_XEN_GUEST_HANDLE(compat_platform_op_t);
-extern int cf_check compat_platform_op(
-    XEN_GUEST_HANDLE_PARAM(compat_platform_op_t) u_xenpf_op);
-
-extern long cf_check compat_callback_op(
-    int cmd, XEN_GUEST_HANDLE(void) arg);
+extern int cf_check compat_callback_op(
+    int cmd, XEN_GUEST_HANDLE(const_void) arg);
 
 extern int cf_check compat_update_va_mapping(
     unsigned int va, uint32_t lo, uint32_t hi, unsigned int flags);
@@ -181,12 +182,12 @@ extern int cf_check compat_set_gdt(
 extern int cf_check compat_update_descriptor(
     uint32_t pa_lo, uint32_t pa_hi, uint32_t desc_lo, uint32_t desc_hi);
 
-extern unsigned int cf_check compat_iret(void);
+extern int cf_check compat_iret(void);
 
 extern int cf_check compat_nmi_op(
     unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) arg);
 
-extern long cf_check compat_set_callbacks(
+extern int cf_check compat_set_callbacks(
     unsigned long event_selector, unsigned long event_address,
     unsigned long failsafe_selector, unsigned long failsafe_address);
 
diff --git a/xen/arch/x86/include/asm/paging.h b/xen/arch/x86/include/asm/paging.h
index b7ecfd4721..b2b243a4ff 100644
--- a/xen/arch/x86/include/asm/paging.h
+++ b/xen/arch/x86/include/asm/paging.h
@@ -231,9 +231,6 @@ int paging_domctl(struct domain *d, struct xen_domctl_shadow_op *sc,
                   XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl,
                   bool_t resuming);
 
-/* Helper hypercall for dealing with continuations. */
-long cf_check paging_domctl_continuation(XEN_GUEST_HANDLE_PARAM(xen_domctl_t));
-
 /* Call when destroying a vcpu/domain */
 void paging_vcpu_teardown(struct vcpu *v);
 int paging_teardown(struct domain *d);
diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
index b7e2750817..eb9155f81c 100644
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -21,6 +21,7 @@
 
 #include <xen/init.h>
 #include <xen/guest_access.h>
+#include <xen/hypercall.h>
 #include <asm/paging.h>
 #include <asm/shadow.h>
 #include <asm/p2m.h>
@@ -759,7 +760,7 @@ int paging_domctl(struct domain *d, struct xen_domctl_shadow_op *sc,
         return shadow_domctl(d, sc, u_domctl);
 }
 
-long cf_check paging_domctl_continuation(
+long cf_check do_paging_domctl_cont(
     XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
 {
     struct xen_domctl op;
diff --git a/xen/arch/x86/pv/callback.c b/xen/arch/x86/pv/callback.c
index 55148c7f9e..1be9d3f731 100644
--- a/xen/arch/x86/pv/callback.c
+++ b/xen/arch/x86/pv/callback.c
@@ -207,9 +207,9 @@ long cf_check do_set_callbacks(
 #include <compat/callback.h>
 #include <compat/nmi.h>
 
-static long compat_register_guest_callback(struct compat_callback_register *reg)
+static int compat_register_guest_callback(struct compat_callback_register *reg)
 {
-    long ret = 0;
+    int ret = 0;
     struct vcpu *curr = current;
 
     fixup_guest_code_selector(curr->domain, reg->address.cs);
@@ -256,10 +256,10 @@ static long compat_register_guest_callback(struct compat_callback_register *reg)
     return ret;
 }
 
-static long compat_unregister_guest_callback(
+static int compat_unregister_guest_callback(
     struct compat_callback_unregister *unreg)
 {
-    long ret;
+    int ret;
 
     switch ( unreg->type )
     {
@@ -283,9 +283,9 @@ static long compat_unregister_guest_callback(
     return ret;
 }
 
-long cf_check compat_callback_op(int cmd, XEN_GUEST_HANDLE(void) arg)
+int cf_check compat_callback_op(int cmd, XEN_GUEST_HANDLE(const_void) arg)
 {
-    long ret;
+    int ret;
 
     switch ( cmd )
     {
@@ -321,7 +321,7 @@ long cf_check compat_callback_op(int cmd, XEN_GUEST_HANDLE(void) arg)
     return ret;
 }
 
-long cf_check compat_set_callbacks(
+int cf_check compat_set_callbacks(
     unsigned long event_selector, unsigned long event_address,
     unsigned long failsafe_selector, unsigned long failsafe_address)
 {
diff --git a/xen/arch/x86/pv/hypercall.c b/xen/arch/x86/pv/hypercall.c
index e8fbee7bbb..fe8dfe9e8f 100644
--- a/xen/arch/x86/pv/hypercall.c
+++ b/xen/arch/x86/pv/hypercall.c
@@ -47,8 +47,6 @@ typedef struct {
 #define COMPAT_CALL(x) HYPERCALL(x)
 #endif
 
-#define do_arch_1             paging_domctl_continuation
-
 static const pv_hypercall_table_t pv_hypercall_table[] = {
     COMPAT_CALL(set_trap_table),
     HYPERCALL(mmu_update),
@@ -109,11 +107,10 @@ static const pv_hypercall_table_t pv_hypercall_table[] = {
 #endif
     HYPERCALL(mca),
 #ifndef CONFIG_PV_SHIM_EXCLUSIVE
-    HYPERCALL(arch_1),
+    HYPERCALL(paging_domctl_cont),
 #endif
 };
 
-#undef do_arch_1
 #undef COMPAT_CALL
 #undef HYPERCALL
 
diff --git a/xen/arch/x86/pv/iret.c b/xen/arch/x86/pv/iret.c
index 797a427ffa..58de9f7922 100644
--- a/xen/arch/x86/pv/iret.c
+++ b/xen/arch/x86/pv/iret.c
@@ -49,7 +49,7 @@ static void async_exception_cleanup(struct vcpu *curr)
         curr->arch.async_exception_state(trap).old_mask;
 }
 
-unsigned long cf_check do_iret(void)
+long cf_check do_iret(void)
 {
     struct cpu_user_regs *regs = guest_cpu_user_regs();
     struct iret_context iret_saved;
@@ -106,7 +106,7 @@ unsigned long cf_check do_iret(void)
 }
 
 #ifdef CONFIG_PV32
-unsigned int cf_check compat_iret(void)
+int cf_check compat_iret(void)
 {
     struct cpu_user_regs *regs = guest_cpu_user_regs();
     struct vcpu *v = current;
diff --git a/xen/arch/x86/pv/misc-hypercalls.c b/xen/arch/x86/pv/misc-hypercalls.c
index 5649aaab44..635f5a644a 100644
--- a/xen/arch/x86/pv/misc-hypercalls.c
+++ b/xen/arch/x86/pv/misc-hypercalls.c
@@ -28,12 +28,16 @@ long cf_check do_set_debugreg(int reg, unsigned long value)
     return set_debugreg(current, reg, value);
 }
 
-unsigned long cf_check do_get_debugreg(int reg)
+long cf_check do_get_debugreg(int reg)
 {
-    unsigned long val;
-    int res = x86emul_read_dr(reg, &val, NULL);
+    /* Avoid implementation defined behavior casting unsigned long to long. */
+    union {
+        unsigned long val;
+        long ret;
+    } u;
+    int res = x86emul_read_dr(reg, &u.val, NULL);
 
-    return res == X86EMUL_OKAY ? val : -ENODEV;
+    return res == X86EMUL_OKAY ? u.ret : -ENODEV;
 }
 
 long cf_check do_fpu_taskswitch(int set)
diff --git a/xen/common/argo.c b/xen/common/argo.c
index 297f6d11f0..26a01c2188 100644
--- a/xen/common/argo.c
+++ b/xen/common/argo.c
@@ -2207,13 +2207,13 @@ do_argo_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) arg1,
 }
 
 #ifdef CONFIG_COMPAT
-long cf_check
+int cf_check
 compat_argo_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) arg1,
                XEN_GUEST_HANDLE_PARAM(void) arg2, unsigned long arg3,
                unsigned long arg4)
 {
     struct domain *currd = current->domain;
-    long rc;
+    int rc;
     xen_argo_send_addr_t send_addr;
     xen_argo_iov_t iovs[XEN_ARGO_MAXIOV];
     compat_argo_iov_t compat_iovs[XEN_ARGO_MAXIOV];
@@ -2267,7 +2267,7 @@ compat_argo_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) arg1,
 
     rc = sendv(currd, &send_addr.src, &send_addr.dst, iovs, niov, arg4);
  out:
-    argo_dprintk("<-compat_argo_op(%u)=%ld\n", cmd, rc);
+    argo_dprintk("<-compat_argo_op(%u)=%d\n", cmd, rc);
 
     return rc;
 }
diff --git a/xen/common/kexec.c b/xen/common/kexec.c
index a2ffb6530c..41669964d2 100644
--- a/xen/common/kexec.c
+++ b/xen/common/kexec.c
@@ -1213,7 +1213,7 @@ static int kexec_status(XEN_GUEST_HANDLE_PARAM(void) uarg)
     return !!test_bit(bit, &kexec_flags);
 }
 
-static int do_kexec_op_internal(unsigned long op,
+static int do_kexec_op_internal(unsigned int op,
                                 XEN_GUEST_HANDLE_PARAM(void) uarg,
                                 bool_t compat)
 {
@@ -1265,13 +1265,13 @@ static int do_kexec_op_internal(unsigned long op,
     return ret;
 }
 
-long cf_check do_kexec_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) uarg)
+long cf_check do_kexec_op(unsigned int op, XEN_GUEST_HANDLE_PARAM(void) uarg)
 {
     return do_kexec_op_internal(op, uarg, 0);
 }
 
 #ifdef CONFIG_COMPAT
-int cf_check compat_kexec_op(unsigned long op, XEN_GUEST_HANDLE_PARAM(void) uarg)
+int cf_check compat_kexec_op(unsigned int op, XEN_GUEST_HANDLE_PARAM(void) uarg)
 {
     return do_kexec_op_internal(op, uarg, 1);
 }
diff --git a/xen/include/xen/hypercall.h b/xen/include/xen/hypercall.h
index 81aae7a662..a032ba2b4a 100644
--- a/xen/include/xen/hypercall.h
+++ b/xen/include/xen/hypercall.h
@@ -114,11 +114,6 @@ common_vcpu_op(int cmd,
     struct vcpu *v,
     XEN_GUEST_HANDLE_PARAM(void) arg);
 
-extern long cf_check
-do_nmi_op(
-    unsigned int cmd,
-    XEN_GUEST_HANDLE_PARAM(void) arg);
-
 extern long cf_check
 do_hvm_op(
     unsigned long op,
@@ -126,7 +121,7 @@ do_hvm_op(
 
 extern long cf_check
 do_kexec_op(
-    unsigned long op,
+    unsigned int op,
     XEN_GUEST_HANDLE_PARAM(void) uarg);
 
 extern long cf_check
@@ -145,9 +140,6 @@ extern long cf_check do_argo_op(
 extern long cf_check
 do_xenoprof_op(int op, XEN_GUEST_HANDLE_PARAM(void) arg);
 
-extern long cf_check
-do_xenpmu_op(unsigned int op, XEN_GUEST_HANDLE_PARAM(xen_pmu_params_t) arg);
-
 extern long cf_check
 do_dm_op(
     domid_t domid,
@@ -205,15 +197,21 @@ extern int cf_check compat_xsm_op(
     XEN_GUEST_HANDLE_PARAM(void) op);
 
 extern int cf_check compat_kexec_op(
-    unsigned long op, XEN_GUEST_HANDLE_PARAM(void) uarg);
+    unsigned int op, XEN_GUEST_HANDLE_PARAM(void) uarg);
 
 DEFINE_XEN_GUEST_HANDLE(multicall_entry_compat_t);
 extern int cf_check compat_multicall(
     XEN_GUEST_HANDLE_PARAM(multicall_entry_compat_t) call_list,
     uint32_t nr_calls);
 
+int compat_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg);
+
+typedef struct compat_platform_op compat_platform_op_t;
+DEFINE_XEN_GUEST_HANDLE(compat_platform_op_t);
+int compat_platform_op(XEN_GUEST_HANDLE_PARAM(compat_platform_op_t) u_xenpf_op);
+
 #ifdef CONFIG_ARGO
-extern long cf_check compat_argo_op(
+extern int cf_check compat_argo_op(
     unsigned int cmd,
     XEN_GUEST_HANDLE_PARAM(void) arg1,
     XEN_GUEST_HANDLE_PARAM(void) arg2,