[MIPS] Implementation of sel_ldr for MIPS architecture.

src/trusted/service_runtime/arch/mips/sel_rt.h

+/*
+ * Copyright 2012 The Native Client Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can
+ * be found in the LICENSE file.
+ */
+
+/*
+ * NaCl Secure Runtime
+ */
+
+#ifndef __NATIVE_CLIENT_SERVICE_RUNTIME_ARCH_MIPS_SEL_RT_H__
+#define __NATIVE_CLIENT_SERVICE_RUNTIME_ARCH_MIPS_SEL_RT_H__ 1
+
+#if !defined(__ASSEMBLER__)
+
+#include <stddef.h>
+
+#include "native_client/src/include/nacl_macros.h"
+#include "native_client/src/include/portability.h"
+#include "native_client/src/shared/platform/nacl_check.h"
+
+uint32_t NaClGetStackPtr(void);
+uint32_t NaClGetGlobalPtr(void);
+
+typedef uint32_t nacl_reg_t;
+
+#define NACL_PRIdNACL_REG NACL_PRId32
+#define NACL_PRIiNACL_REG NACL_PRIi32
+#define NACL_PRIoNACL_REG NACL_PRIo32
+#define NACL_PRIuNACL_REG NACL_PRIu32
+#define NACL_PRIxNACL_REG NACL_PRIx32
+#define NACL_PRIXNACL_REG NACL_PRIX32
+
+/*
+ * NOTE: This struct needs to be synchronized with NACL_CALLEE_SAVE_LIST
+ */
+
+struct NaClThreadContext {
+  nacl_reg_t  t6, t7, s0, s1, s2, s3, s4, s5, s6, s7, t8;

[Mark Seaborn, 2012/09/18 03:24:34]

Can you put some comments here to indicate the registers whose contents are
trusted?  i.e. t6 and t7 contain masks.

And t8 is used to store the untrusted TLS value (thread pointer), right?

[petarj, 2012/09/19 17:27:51]

Removed the registers variables for t6 and t7 from the structure.

+  /*           0   4   8   c  10  14  18  1c  20  24  28 */
+
+  nacl_reg_t  global_ptr, stack_ptr, frame_ptr, prog_ctr;
+  /*                  2c         30         34        38 */
+
+  /*
+   * sys_ret and new_prog_ctr are not a part of the thread's register set,
+   * but are needed by NaClSwitch. By including them here, the two
+   * use the same interface.
+   */
+  uint32_t  sysret;
+  /*            3c */
+  uint32_t  new_prog_ctr;
+  /*            40 */
+  uint32_t  trusted_stack_ptr;
+  /*            44 */
+  uint32_t  tls_idx;
+  /*            48 */
+};
+
+#endif /* !defined(__ASSEMBLER__) */
+
+#define NACL_THREAD_CONTEXT_OFFSET_T6                  0x00
+#define NACL_THREAD_CONTEXT_OFFSET_T7                  0x04
+#define NACL_THREAD_CONTEXT_OFFSET_S0                  0x08
+#define NACL_THREAD_CONTEXT_OFFSET_S1                  0x0c
+#define NACL_THREAD_CONTEXT_OFFSET_S2                  0x10
+#define NACL_THREAD_CONTEXT_OFFSET_S3                  0x14
+#define NACL_THREAD_CONTEXT_OFFSET_S4                  0x18
+#define NACL_THREAD_CONTEXT_OFFSET_S5                  0x1c
+#define NACL_THREAD_CONTEXT_OFFSET_S6                  0x20
+#define NACL_THREAD_CONTEXT_OFFSET_S7                  0x24
+#define NACL_THREAD_CONTEXT_OFFSET_T8                  0x28
+#define NACL_THREAD_CONTEXT_OFFSET_GLOBAL_PTR          0x2c
+#define NACL_THREAD_CONTEXT_OFFSET_STACK_PTR           0x30
+#define NACL_THREAD_CONTEXT_OFFSET_FRAME_PTR           0x34
+
+#if !defined(__ASSEMBLER__)
+
+/*
+ * This function exists as a function only because compile-time
+ * assertions need to be inside a function.  This function does not
+ * need to be called for the assertions to be checked.
+ */
+static INLINE void NaClThreadContextOffsetCheck(void) {
+

[Mark Seaborn, 2012/09/18 03:24:34]

Nit: don't start the function with an empty line

[petarj, 2012/09/19 17:27:51]

Done.

[petarj, 2012/09/19 17:27:51]

Done.

+  int offset = 0;
+
+#define NACL_CHECK_FIELD(offset_name, field) \
+    NACL_COMPILE_TIME_ASSERT(offset_name == \
+                             offsetof(struct NaClThreadContext, field)); \
+    CHECK(offset == offset_name); \
+    offset += sizeof(((struct NaClThreadContext *) NULL)->field);
+
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_T6, t6);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_T7, t7);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_S0, s0);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_S1, s1);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_S2, s2);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_S3, s3);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_S4, s4);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_S5, s5);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_S6, s6);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_S7, s7);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_T8, t8);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_GLOBAL_PTR, global_ptr);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_STACK_PTR, stack_ptr);
+  NACL_CHECK_FIELD(NACL_THREAD_CONTEXT_OFFSET_FRAME_PTR, frame_ptr);

[Mark Seaborn, 2012/09/18 03:24:34]

I'd suggest also doing:

  CHECK(offset == sizeof(struct NaClThreadContext));

at the end to ensure no fields are missed.

Plus:
#undef NACL_CHECK_FIELD
for neatness.

[petarj, 2012/09/19 17:27:51]

Done.

[petarj, 2012/09/19 17:27:51]

Done.

+}
+
+#endif /* !defined(__ASSEMBLER__) */
+
+#endif /* __NATIVE_CLIENT_SERVICE_RUNTIME_ARCH_MIPS_SEL_RT_H___ */