Implement relocator for riscv

Signed-off-by: Huang Qi <[email protected]>

Author: no1wudi

core/iwasm/aot/aot_loader.c

@@ -1034,7 +1034,8 @@ load_object_data_sections(const uint8 **p_buf, const uint8 *buf_end,
     /* Create each data section */
     for (i = 0; i < module->data_section_count; i++) {
         int map_prot = MMAP_PROT_READ | MMAP_PROT_WRITE;
-#if defined(BUILD_TARGET_X86_64) || defined(BUILD_TARGET_AMD_64)
+#if defined(BUILD_TARGET_X86_64) || defined(BUILD_TARGET_AMD_64) \
+     || defined(BUILD_TARGET_RISCV64)
         /* aot code and data in x86_64 must be in range 0 to 2G due to
            relocation for R_X86_64_32/32S/PC32 */
         int map_flags = MMAP_MAP_32BIT;

core/iwasm/aot/arch/aot_reloc_riscv.c

@@ -0,0 +1,86 @@
+/*
+ * Copyright (C) 2021 XiaoMi Corporation. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#include "aot_reloc.h"
+
+#define R_RISCV_CALL 18
+
+static SymbolMap target_sym_map[] = { REG_COMMON_SYMBOLS };
+
+void
+get_current_target(char *target_buf, uint32 target_buf_size)
+{
+    snprintf(target_buf, target_buf_size, "riscv");
+}
+
+uint32
+get_plt_item_size()
+{
+    return 16;
+}
+
+SymbolMap *
+get_target_symbol_map(uint32 *sym_num)
+{
+    *sym_num = sizeof(target_sym_map) / sizeof(SymbolMap);
+    return target_sym_map;
+}
+
+uint32
+get_plt_table_size()
+{
+    return get_plt_item_size() * (sizeof(target_sym_map) / sizeof(SymbolMap));
+}
+
+void
+init_plt_table(uint8 *plt)
+{}
+
+bool
+apply_relocation(AOTModule *module,
+                 uint8 *target_section_addr,
+                 uint32 target_section_size,
+                 uint64 reloc_offset,
+                 uint64 reloc_addend,
+                 uint32 reloc_type,
+                 void *symbol_addr,
+                 int32 symbol_index,
+                 char *error_buf,
+                 uint32 error_buf_size)
+{
+    uint8 *P = target_section_addr + reloc_offset;
+    uint32 hi20, lo12;
+
+    hi20 = (uint32)((unsigned long)symbol_addr & 0xfffff000);
+    lo12 = (uint32)(((unsigned long)symbol_addr & 0xfff) << 20);
+
+    switch (reloc_type) {
+        case R_RISCV_CALL:
+            if ((uint32)(uintptr_t)symbol_addr != (uintptr_t)symbol_addr) {
+                if (error_buf != NULL) {
+                    snprintf(
+                      error_buf, error_buf_size,
+                      "Jump address exceeds 32-bit address space (0-4GB).");
+                }
+                return false;
+            }
+
+            /* lui  t0, hi20 */
+            *(uint32 *)(P + 0) = (uint32)hi20 | 0x2b7;
+            /* jalr ra, lo12(t0) */
+            *(uint32 *)(P + 4) = (uint32)lo12 | 0x280e7;
+            break;
+
+        default:
+            if (error_buf != NULL)
+                snprintf(error_buf, error_buf_size,
+                         "Load relocation section failed: "
+                         "invalid relocation type %ld.",
+                         reloc_type);
+            return false;
+    }
+
+    return true;
+}

core/iwasm/aot/iwasm_aot.cmake

@@ -23,6 +23,8 @@ elseif (WAMR_BUILD_TARGET STREQUAL "MIPS")
   set (arch_source ${IWASM_AOT_DIR}/arch/aot_reloc_mips.c)
 elseif (WAMR_BUILD_TARGET STREQUAL "XTENSA")
   set (arch_source ${IWASM_AOT_DIR}/arch/aot_reloc_xtensa.c)
+elseif (WAMR_BUILD_TARGET MATCHES "RISCV*")
+  set (arch_source ${IWASM_AOT_DIR}/arch/aot_reloc_riscv.c)
 else ()
   message (FATAL_ERROR "Build target isn't set")
 endif ()