Mailing List Archive

XEN_GUEST_HANDLE_PARAM is going to be used to distinguish guest pointers
stored in memory from guest pointers as hypercall parameters.

guest_handle_* macros default to XEN_GUEST_HANDLE_PARAM as return type.
Two new guest_handle_to_param and guest_handle_from_param macros are
introduced to do conversions.

Changes in v2:

- add 2 missing #define _XEN_GUEST_HANDLE_PARAM for the compilation of
the compat code.

Changes in v3:

- move the guest_handle_cast change into this patch;
- add a clear comment on top of guest_handle_cast;
- also s/XEN_GUEST_HANDLE/XEN_GUEST_HANDLE_PARAM in
guest_handle_from_ptr and const_guest_handle_from_ptr;
- introduce guest_handle_from_param and guest_handle_to_param.

Changes in v4:

- make both XEN_GUEST_HANDLE and XEN_GUEST_HANDLE_PARAM unions on ARM;
- simplify set_xen_guest_handle_raw on ARM;
- add type checking in guest_handle_to_param and guest_handle_from_param
trivial.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
xen/include/asm-arm/guest_access.h | 32 ++++++++++++++++++++++++++++----
xen/include/asm-x86/guest_access.h | 29 +++++++++++++++++++++++++----
xen/include/public/arch-arm.h | 26 ++++++++++++++++++++++----
xen/include/public/arch-ia64.h | 9 +++++++++
xen/include/public/arch-x86/xen.h | 9 +++++++++
xen/include/xen/xencomm.h | 22 +++++++++++++++++++++-
6 files changed, 114 insertions(+), 13 deletions(-)

diff --git a/xen/include/asm-arm/guest_access.h b/xen/include/asm-arm/guest_access.h
index 0fceae6..5686217 100644
--- a/xen/include/asm-arm/guest_access.h
+++ b/xen/include/asm-arm/guest_access.h
@@ -27,16 +27,40 @@ unsigned long raw_clear_guest(void *to, unsigned len);
#define guest_handle_add_offset(hnd, nr) ((hnd).p += (nr))
#define guest_handle_subtract_offset(hnd, nr) ((hnd).p -= (nr))

-/* Cast a guest handle to the specified type of handle. */
+/* Cast a guest handle (either XEN_GUEST_HANDLE or XEN_GUEST_HANDLE_PARAM)
+ * to the specified type of XEN_GUEST_HANDLE_PARAM. */
#define guest_handle_cast(hnd, type) ({ \
type *_x = (hnd).p; \
- (XEN_GUEST_HANDLE(type)) { _x }; \
+ (XEN_GUEST_HANDLE_PARAM(type)) { _x }; \
+})
+
+/* Cast a XEN_GUEST_HANDLE to XEN_GUEST_HANDLE_PARAM */
+#define guest_handle_to_param(hnd, type) ({ \
+ typeof((hnd).p) _x = (hnd).p; \
+ XEN_GUEST_HANDLE_PARAM(type) _y = { _x }; \
+ /* type checking: make sure that the pointers inside \
+ * XEN_GUEST_HANDLE and XEN_GUEST_HANDLE_PARAM are of \
+ * the same type, then return hnd */ \
+ (void)(&_x == &_y.p); \
+ _y; \
+})
+
+
+/* Cast a XEN_GUEST_HANDLE_PARAM to XEN_GUEST_HANDLE */
+#define guest_handle_from_param(hnd, type) ({ \
+ typeof((hnd).p) _x = (hnd).p; \
+ XEN_GUEST_HANDLE(type) _y = { _x }; \
+ /* type checking: make sure that the pointers inside \
+ * XEN_GUEST_HANDLE and XEN_GUEST_HANDLE_PARAM are of \
+ * the same type, then return hnd */ \
+ (void)(&_x == &_y.p); \
+ _y; \
})

#define guest_handle_from_ptr(ptr, type) \
- ((XEN_GUEST_HANDLE(type)) { (type *)ptr })
+ ((XEN_GUEST_HANDLE_PARAM(type)) { (type *)ptr })
#define const_guest_handle_from_ptr(ptr, type) \
- ((XEN_GUEST_HANDLE(const_##type)) { (const type *)ptr })
+ ((XEN_GUEST_HANDLE_PARAM(const_##type)) { (const type *)ptr })

/*
* Copy an array of objects to guest context via a guest handle,
diff --git a/xen/include/asm-x86/guest_access.h b/xen/include/asm-x86/guest_access.h
index 2b429c2..e67ed82 100644
--- a/xen/include/asm-x86/guest_access.h
+++ b/xen/include/asm-x86/guest_access.h
@@ -45,16 +45,37 @@
#define guest_handle_add_offset(hnd, nr) ((hnd).p += (nr))
#define guest_handle_subtract_offset(hnd, nr) ((hnd).p -= (nr))

-/* Cast a guest handle to the specified type of handle. */
+/* Cast a guest handle (either XEN_GUEST_HANDLE or XEN_GUEST_HANDLE_PARAM)
+ * to the specified type of XEN_GUEST_HANDLE_PARAM. */
#define guest_handle_cast(hnd, type) ({ \
type *_x = (hnd).p; \
- (XEN_GUEST_HANDLE(type)) { _x }; \
+ (XEN_GUEST_HANDLE_PARAM(type)) { _x }; \
+})
+
+/* Cast a XEN_GUEST_HANDLE to XEN_GUEST_HANDLE_PARAM */
+#define guest_handle_to_param(hnd, type) ({ \
+ /* type checking: make sure that the pointers inside \
+ * XEN_GUEST_HANDLE and XEN_GUEST_HANDLE_PARAM are of \
+ * the same type, then return hnd */ \
+ (void)((typeof(&(hnd).p)) 0 == \
+ (typeof(&((XEN_GUEST_HANDLE_PARAM(type)) {}).p)) 0); \
+ (hnd); \
+})
+
+/* Cast a XEN_GUEST_HANDLE_PARAM to XEN_GUEST_HANDLE */
+#define guest_handle_from_param(hnd, type) ({ \
+ /* type checking: make sure that the pointers inside \
+ * XEN_GUEST_HANDLE and XEN_GUEST_HANDLE_PARAM are of \
+ * the same type, then return hnd */ \
+ (void)((typeof(&(hnd).p)) 0 == \
+ (typeof(&((XEN_GUEST_HANDLE_PARAM(type)) {}).p)) 0); \
+ (hnd); \
})

#define guest_handle_from_ptr(ptr, type) \
- ((XEN_GUEST_HANDLE(type)) { (type *)ptr })
+ ((XEN_GUEST_HANDLE_PARAM(type)) { (type *)ptr })
#define const_guest_handle_from_ptr(ptr, type) \
- ((XEN_GUEST_HANDLE(const_##type)) { (const type *)ptr })
+ ((XEN_GUEST_HANDLE_PARAM(const_##type)) { (const type *)ptr })

/*
* Copy an array of objects to guest context via a guest handle,
diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
index 2ae6548..4c6d607 100644
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -51,18 +51,36 @@

#define XEN_HYPERCALL_TAG 0XEA1

+#define uint64_aligned_t uint64_t __attribute__((aligned(8)))

#ifndef __ASSEMBLY__
-#define ___DEFINE_XEN_GUEST_HANDLE(name, type) \
- typedef struct { type *p; } __guest_handle_ ## name
+#define ___DEFINE_XEN_GUEST_HANDLE(name, type) \
+ typedef union { type *p; unsigned long q; } \
+ __guest_handle_ ## name; \
+ typedef union { type *p; uint64_aligned_t q; } \
+ __guest_handle_64_ ## name;

+/*
+ * XEN_GUEST_HANDLE represents a guest pointer, when passed as a field
+ * in a struct in memory. On ARM is always 8 bytes sizes and 8 bytes
+ * aligned.
+ * XEN_GUEST_HANDLE_PARAM represent a guest pointer, when passed as an
+ * hypercall argument. It is 4 bytes on aarch and 8 bytes on aarch64.
+ */
#define __DEFINE_XEN_GUEST_HANDLE(name, type) \
___DEFINE_XEN_GUEST_HANDLE(name, type); \
___DEFINE_XEN_GUEST_HANDLE(const_##name, const type)
#define DEFINE_XEN_GUEST_HANDLE(name) __DEFINE_XEN_GUEST_HANDLE(name, name)
-#define __XEN_GUEST_HANDLE(name) __guest_handle_ ## name
+#define __XEN_GUEST_HANDLE(name) __guest_handle_64_ ## name
#define XEN_GUEST_HANDLE(name) __XEN_GUEST_HANDLE(name)
-#define set_xen_guest_handle_raw(hnd, val) do { (hnd).p = val; } while (0)
+/* this is going to be changes on 64 bit */
+#define XEN_GUEST_HANDLE_PARAM(name) __guest_handle_ ## name
+#define set_xen_guest_handle_raw(hnd, val) \
+ do { \
+ typeof(&(hnd)) t = &(hnd); \
+ _t->q = 0; \
+ _t->p = val; \
+ } while ( 0 )
#ifdef __XEN_TOOLS__
#define get_xen_guest_handle(val, hnd) do { val = (hnd).p; } while (0)
#endif
diff --git a/xen/include/public/arch-ia64.h b/xen/include/public/arch-ia64.h
index c9da5d4..e4e9688 100644
--- a/xen/include/public/arch-ia64.h
+++ b/xen/include/public/arch-ia64.h
@@ -45,8 +45,17 @@
___DEFINE_XEN_GUEST_HANDLE(name, type); \
___DEFINE_XEN_GUEST_HANDLE(const_##name, const type)

+/*
+ * XEN_GUEST_HANDLE represents a guest pointer, when passed as a field
+ * in a struct in memory.
+ * XEN_GUEST_HANDLE_PARAM represent a guest pointer, when passed as an
+ * hypercall argument.
+ * XEN_GUEST_HANDLE_PARAM and XEN_GUEST_HANDLE are the same on ia64 but
+ * they might not be on other architectures.
+ */
#define DEFINE_XEN_GUEST_HANDLE(name) __DEFINE_XEN_GUEST_HANDLE(name, name)
#define XEN_GUEST_HANDLE(name) __guest_handle_ ## name
+#define XEN_GUEST_HANDLE_PARAM(name) XEN_GUEST_HANDLE(name)
#define XEN_GUEST_HANDLE_64(name) XEN_GUEST_HANDLE(name)
#define uint64_aligned_t uint64_t
#define set_xen_guest_handle_raw(hnd, val) do { (hnd).p = val; } while (0)
diff --git a/xen/include/public/arch-x86/xen.h b/xen/include/public/arch-x86/xen.h
index 1c186d7..0e10260 100644
--- a/xen/include/public/arch-x86/xen.h
+++ b/xen/include/public/arch-x86/xen.h
@@ -38,12 +38,21 @@
typedef type * __guest_handle_ ## name
#endif

+/*
+ * XEN_GUEST_HANDLE represents a guest pointer, when passed as a field
+ * in a struct in memory.
+ * XEN_GUEST_HANDLE_PARAM represent a guest pointer, when passed as an
+ * hypercall argument.
+ * XEN_GUEST_HANDLE_PARAM and XEN_GUEST_HANDLE are the same on X86 but
+ * they might not be on other architectures.
+ */
#define __DEFINE_XEN_GUEST_HANDLE(name, type) \
___DEFINE_XEN_GUEST_HANDLE(name, type); \
___DEFINE_XEN_GUEST_HANDLE(const_##name, const type)
#define DEFINE_XEN_GUEST_HANDLE(name) __DEFINE_XEN_GUEST_HANDLE(name, name)
#define __XEN_GUEST_HANDLE(name) __guest_handle_ ## name
#define XEN_GUEST_HANDLE(name) __XEN_GUEST_HANDLE(name)
+#define XEN_GUEST_HANDLE_PARAM(name) XEN_GUEST_HANDLE(name)
#define set_xen_guest_handle_raw(hnd, val) do { (hnd).p = val; } while (0)
#ifdef __XEN_TOOLS__
#define get_xen_guest_handle(val, hnd) do { val = (hnd).p; } while (0)
diff --git a/xen/include/xen/xencomm.h b/xen/include/xen/xencomm.h
index 730da7c..3426b8a 100644
--- a/xen/include/xen/xencomm.h
+++ b/xen/include/xen/xencomm.h
@@ -66,11 +66,31 @@ static inline unsigned long xencomm_inline_addr(const void *handle)
/* Cast a guest handle to the specified type of handle. */
#define guest_handle_cast(hnd, type) ({ \
type *_x = (hnd).p; \
- XEN_GUEST_HANDLE(type) _y; \
+ XEN_GUEST_HANDLE_PARAM(type) _y; \
set_xen_guest_handle(_y, _x); \
_y; \
})

+/* Cast a XEN_GUEST_HANDLE to XEN_GUEST_HANDLE_PARAM */
+#define guest_handle_to_param(hnd, type) ({ \
+ /* type checking: make sure that the pointers inside \
+ * XEN_GUEST_HANDLE and XEN_GUEST_HANDLE_PARAM are of \
+ * the same type, then return hnd */ \
+ (void)((typeof(&(hnd).p)) 0 == \
+ (typeof(&((XEN_GUEST_HANDLE_PARAM(type)) {}).p)) 0); \
+ (hnd); \
+})
+
+/* Cast a XEN_GUEST_HANDLE_PARAM to XEN_GUEST_HANDLE */
+#define guest_handle_from_param(hnd, type) ({ \
+ /* type checking: make sure that the pointers inside \
+ * XEN_GUEST_HANDLE and XEN_GUEST_HANDLE_PARAM are of \
+ * the same type, then return hnd */ \
+ (void)((typeof(&(hnd).p)) 0 == \
+ (typeof(&((XEN_GUEST_HANDLE_PARAM(type)) {}).p)) 0); \
+ (hnd); \
+})
+
/* Since we run in real mode, we can safely access all addresses. That also
* means our __routines are identical to our "normal" routines. */
#define guest_handle_okay(hnd, nr) 1
--
1.7.2.5


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