[MIPS] Implementation of sel_ldr for MIPS architecture.

src/trusted/service_runtime/arch/mips/sel_ldr_mips.c

+/*
+ * 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.
+ */
+
+#include <string.h>
+
+#include "native_client/src/include/nacl_assert.h"
+#include "native_client/src/shared/platform/nacl_check.h"
+#include "native_client/src/trusted/service_runtime/nacl_globals.h"
+#include "native_client/src/trusted/service_runtime/sel_ldr.h"
+#include "native_client/src/trusted/service_runtime/arch/mips/sel_ldr_mips.h"
+#include "native_client/src/trusted/service_runtime/arch/mips/tramp_mips.h"
+
+
+/*
+ * NOTE: the trampoline organization for MIPS is currenly assuming
+ * NACL_TRAMPOLINE_SIZE == 32. This is contrary to the bundle size
+ * which is 16.
+ */
+
+/*
+ * Install a syscall trampoline at target_addr.  NB: Thread-safe.
+ * The code being patched is from tramp.S
+ */
+void  NaClPatchOneTrampoline(struct NaClApp *nap,
+                             uintptr_t      target_addr) {
+  struct NaClPatchInfo  patch_info;
+  uint16_t upper, lower;
+  char *tramp_ptr = (char *)&NaCl_trampoline_seg_code;
+  void (*funcptr)(void) = NaClSyscallSeg;
+  uint32_t func_addr = (uint32_t)funcptr;
+  unsigned long tramp_buffer[8];
+  size_t tramp_size = ((uintptr_t) &NaCl_trampoline_seg_end
+                       - (uintptr_t) &NaCl_trampoline_seg_code);
+
+  UNREFERENCED_PARAMETER(nap);
+
+  /*
+   * We copy trampoline code to buffer so that we can patch it with address
+   * of NaClSyscallSeg.
+   */
+
+  ASSERT_MSG(tramp_size <= 8 * sizeof(unsigned long),
+     "Trampoline size is bigger than tramp_buffer size");
+
+  memcpy(tramp_buffer, tramp_ptr, tramp_size);
+
+  /*
+   * For MIPS we do not need to patch ds, cs segments.
+   */
+
+  NaClPatchInfoCtor(&patch_info);
+
+  /*
+   * We break address of NaClSyscallSeg into upper and lower 16 bits, so that
+   * we can patch first and second instruction of trampoline respectively.
+   */
+
+  upper = (uint16_t)(func_addr >>16);

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

Nit: put spaces around '>>'.  Also a space after '(uint16_t)'

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

Done.

+  lower = (uint16_t)(func_addr & 0xffff);
+
+  tramp_buffer[0] = (tramp_buffer[0] & (0xFFFF0000)) | upper;
+  tramp_buffer[1] = (tramp_buffer[1] & (0xFFFF0000)) | lower;
+
+  patch_info.dst = target_addr;
+  patch_info.src = (uintptr_t) tramp_buffer;
+  patch_info.nbytes = ((uintptr_t) &NaCl_trampoline_seg_end
+                       - (uintptr_t) &NaCl_trampoline_seg_code);
+
+  NaClApplyPatchToMemory(&patch_info);
+}
+
+void NaClFillMemoryRegionWithHalt(void *start, size_t size) {
+  uint32_t *inst = (uint32_t *) start;
+  uint32_t i;
+
+  CHECK(sizeof *inst == NACL_HALT_LEN);
+  CHECK(0 == size % NACL_HALT_LEN);
+  /*
+   * Check that the region start is 4 bytes aligned.
+   */
+  CHECK(0 == (uint32_t)start % NACL_HALT_LEN);
+
+  for (i = 0; i < (size / NACL_HALT_LEN); i++)
+    inst[i] = NACL_HALT_OPCODE;
+}
+
+
+void NaClFillTrampolineRegion(struct NaClApp *nap) {
+  NaClFillMemoryRegionWithHalt((void *)(nap->mem_start + NACL_TRAMPOLINE_START),
+                               NACL_TRAMPOLINE_SIZE);
+}
+
+void  NaClLoadSpringboard(struct NaClApp  *nap) {
+  UNREFERENCED_PARAMETER(nap);
+}
+