x86_64: expand and shrink messages in copy{in, out}msg routines

* i386/i386/copy_user.h: new file to handle 32/64 bit differences
  - add msg_usize() to recontruct the user-space message size
  - add copyin/copyout helpers for addresses and ports
* include/mach/message.h: add msg alignment macros
* ipc/ipc_kmsg.c:
  - copyin/out ports names instead of using pointer magic
* ipc/ipc_mqueue.c: use msg_usize() to check if we can actually
  receive the message
* ipc/mach_msg.c: Likewise for continuations in receive path
* x86_64/Makefrag.am: add x86_64/copy_user.c
* x86_64/copy_user.c: new file to handle message expansion and
  shrinking during copyinmsg/copyoutmsg for 64 bit kernels.
  - port names -> port pointers on all 64-bit builds
  - 32-bit pointer -> 64 bit pointer when using 32-bit userspace
* x86_64/locore.S: remove copyinmsg() and copyoutmsg()
Message-Id: <20230116105857.240210-3-luca@orpolo.org>

1 files changed, 102 insertions, 0 deletions

diff --git a/i386/i386/copy_user.h b/i386/i386/copy_user.h
new file mode 100644
index 00000000..c7e8b4e1
--- /dev/null
+++ b/i386/i386/copy_user.h
@@ -0,0 +1,102 @@
+/*
+ *  Copyright (C) 2023 Free Software Foundation
+ *
+ * This program is free software ; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation ; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY ; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with the program ; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef COPY_USER_H
+#define COPY_USER_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <machine/locore.h>
+#include <mach/message.h>
+
+/*
+ * The copyin_32to64() and copyout_64to32() routines are meant for data types
+ * that have different size in kernel and user space. They should be independent
+ * of endianness and hopefully can be reused in the future on other archs.
+ * These types are e.g.:
+ * - port names vs port pointers, on a 64-bit kernel
+ * - memory addresses, on a 64-bit kernel and 32-bit user
+ */
+
+static inline int copyin_32to64(const uint32_t *uaddr, uint64_t *kaddr)
+{
+  uint32_t rkaddr;
+  int ret;
+  ret = copyin(uaddr, &rkaddr, sizeof(uint32_t));
+  if (ret)
+    return ret;
+  *kaddr = rkaddr;
+  return 0;
+}
+
+static inline int copyout_64to32(const uint64_t *kaddr, uint32_t *uaddr)
+{
+  uint32_t rkaddr=*kaddr;
+  return copyout(&rkaddr, uaddr, sizeof(uint32_t));
+}
+
+static inline int copyin_address(const rpc_vm_offset_t *uaddr, vm_offset_t *kaddr)
+{
+#ifdef USER32
+  return copyin_32to64(uaddr, kaddr);
+#else /* USER32 */
+  return copyin(uaddr, kaddr, sizeof(*uaddr));
+#endif /* USER32 */
+}
+
+static inline int copyout_address(const vm_offset_t *kaddr, rpc_vm_offset_t *uaddr)
+{
+#ifdef USER32
+  return copyout_64to32(kaddr, uaddr);
+#else /* USER32 */
+  return copyout(kaddr, uaddr, sizeof(*kaddr));
+#endif /* USER32 */
+}
+
+static inline int copyin_port(const mach_port_name_t *uaddr, mach_port_t *kaddr)
+{
+#ifdef __x86_64
+  return copyin_32to64(uaddr, kaddr);
+#else /* __x86_64__ */
+  return copyin(uaddr, kaddr, sizeof(*uaddr));
+#endif /* __x86_64__ */
+}
+
+static inline int copyout_port(const mach_port_t *kaddr, mach_port_name_t *uaddr)
+{
+#ifdef __x86_64
+  return copyout_64to32(kaddr, uaddr);
+#else /* __x86_64__ */
+  return copyout(kaddr, uaddr, sizeof(*kaddr));
+#endif /* __x86_64__ */
+}
+
+// XXX we could add another field to kmsg to store the user-side size, but then we
+// should check if we can  obtain it for rpc and notifications originating from
+// the kernel
+#ifndef __x86_64__
+static inline size_t msg_usize(const mach_msg_header_t *kmsg)
+{
+  return kmsg->msgh_size;
+}
+#else /* __x86_64__ */
+size_t msg_usize(const mach_msg_header_t *kmsg);
+#endif /* __x86_64__ */
+
+#endif /* COPY_USER_H */