xen: arm: separate guest user regs from internal guest state.

struct cpu_user_regs is currently used as both internal state
(specifically at the base of the stack) and a guest/toolstack
visible API (via struct vcpu_guest_context used by
XEN_DOMCTL_{g,s}etvcpucontext and VCPUOP_initialise).

This causes problems when we want to make the API 64-bit clean since
we don't really want to change the size of the on-stack struct.

So split into vcpu_guest_core_regs which is the API facing struct
and keep cpu_user_regs purely internal, translate between the two.

In the user API arrange for both 64- and 32-bit registers to be
included in a layout which does not differ depending on toolstack
architecture. Also switch to using the more formal banked register
names (e.g. with the _usr suffix) for clarity.

This is an ABI change. Note that the kernel doesn't currently use
this data structure so it affects the tools interface only.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Tim Deegan <tim@xen.org>

4 files changed, 25 insertions, 7 deletions

diff --git a/tools/include/xen-foreign/mkheader.py b/tools/include/xen-foreign/mkheader.py
index c63db31c6e..8a784d342a 100644
--- a/tools/include/xen-foreign/mkheader.py
+++ b/tools/include/xen-foreign/mkheader.py
@@ -25,7 +25,15 @@ inttypes["arm32"] = {
 };
 header["arm32"] = """
 #define __arm___ARM32 1
+#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
+# define __DECL_REG(n64, n32) union { uint64_t n64; uint32_t n32; }
+#else
+# define __DECL_REG(n64, n32) uint64_t n64
+#endif
 """;
+footer["arm32"] = """
+#undef __DECL_REG
+"""
 
 inttypes["arm64"] = {
     "unsigned long" : "__danger_unsigned_long_on_arm64",
@@ -35,7 +43,15 @@ inttypes["arm64"] = {
 };
 header["arm64"] = """
 #define __aarch64___ARM64 1
+#if defined(__GNUC__) && !defined(__STRICT_ANSI__)
+# define __DECL_REG(n64, n32) union { uint64_t n64; uint32_t n32; }
+#else
+# define __DECL_REG(n64, n32) uint64_t n64
+#endif
 """;
+footer["arm64"] = """
+#undef __DECL_REG
+"""
 
 # x86_32
 inttypes["x86_32"] = {
diff --git a/tools/include/xen-foreign/reference.size b/tools/include/xen-foreign/reference.size
index 1d75ff330e..de36455453 100644
--- a/tools/include/xen-foreign/reference.size
+++ b/tools/include/xen-foreign/reference.size
@@ -3,8 +3,9 @@ structs                   |   arm32   arm64  x86_32  x86_64
 
 start_info                |       -       -    1112    1168
 trap_info                 |       -       -       8      16
-cpu_user_regs             |     160     160      68     200
-vcpu_guest_context        |     180     160    2800    5168
+cpu_user_regs             |       -       -      68     200
+vcpu_guest_core_regs      |     304     304       -       -
+vcpu_guest_context        |     336     336    2800    5168
 arch_vcpu_info            |       -       -      24      16
 vcpu_time_info            |       -       -      32      32
 vcpu_info                 |       -       -      64      64
diff --git a/tools/include/xen-foreign/structs.py b/tools/include/xen-foreign/structs.py
index 5aec2c5cc2..0b33a77480 100644
--- a/tools/include/xen-foreign/structs.py
+++ b/tools/include/xen-foreign/structs.py
@@ -6,6 +6,7 @@ unions  = [ "vcpu_cr_regs",
 structs = [ "start_info",
             "trap_info",
             "cpu_user_regs",
+            "vcpu_guest_core_regs",
             "vcpu_guest_context",
             "arch_vcpu_info",
             "vcpu_time_info",
diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
index 7f6d7ce6aa..041832e68e 100644
--- a/tools/libxc/xc_dom_arm.c
+++ b/tools/libxc/xc_dom_arm.c
@@ -107,17 +107,17 @@ static int vcpu_arm(struct xc_dom_image *dom, void *ptr)
     /* clear everything */
     memset(ctxt, 0, sizeof(*ctxt));
 
-    ctxt->user_regs.pc = dom->parms.virt_entry;
+    ctxt->user_regs.pc32 = dom->parms.virt_entry;
 
     /* Linux boot protocol. See linux.Documentation/arm/Booting. */
-    ctxt->user_regs.r0 = 0; /* SBZ */
+    ctxt->user_regs.r0_usr = 0; /* SBZ */
     /* Machine ID: We use DTB therefore no machine id */
-    ctxt->user_regs.r1 = 0xffffffff;
+    ctxt->user_regs.r1_usr = 0xffffffff;
     /* ATAGS/DTB: We currently require that the guest kernel to be
      * using CONFIG_ARM_APPENDED_DTB. Ensure that r2 does not look
      * like a valid pointer to a set of ATAGS or a DTB.
      */
-    ctxt->user_regs.r2 = 0xffffffff;
+    ctxt->user_regs.r2_usr = 0xffffffff;
 
     ctxt->sctlr = /* #define SCTLR_BASE */0x00c50078;
 
@@ -130,7 +130,7 @@ static int vcpu_arm(struct xc_dom_image *dom, void *ptr)
     ctxt->flags = VGCF_online;
 
     DOMPRINTF("Initial state CPSR %#"PRIx32" PC %#"PRIx32,
-           ctxt->user_regs.cpsr, ctxt->user_regs.pc);
+           ctxt->user_regs.cpsr, ctxt->user_regs.pc32);
 
     return 0;
 }