Support for building and running external apps (#112)

Libraries/elf_loader/include/private/elf_platform.h

@@ -0,0 +1,101 @@
+/*
+ * SPDX-FileCopyrightText: 2023 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include "private/elf_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef ELF_ALIGN_SIZE
+#define ELF_ALIGN_SIZE 4
+#endif
+
+#define ELF_ALIGN(_a)   (((_a) + (ELF_ALIGN_SIZE - 1)) & \
+                         (~(ELF_ALIGN_SIZE - 1)))
+
+/**
+ * @brief Allocate block of memory.
+ *
+ * @param n - Memory size in byte
+ * @param exec - True: memory can run executable code; False: memory can R/W data
+ * 
+ * @return Memory pointer if success or NULL if failed.
+ */
+void *esp_elf_malloc(uint32_t n, bool exec);
+
+/**
+ * @brief Free block of memory.
+ *
+ * @param ptr - memory block pointer allocated by "esp_elf_malloc"
+ * 
+ * @return None
+ */
+void esp_elf_free(void *ptr);
+
+/**
+ * @brief Relocates target architecture symbol of ELF
+ *
+ * @param elf  - ELF object pointer
+ * @param rela - Relocated symbol data
+ * @param sym  - ELF symbol table
+ * @param addr - Jumping target address
+ * 
+ * @return ESP_OK if sucess or other if failed.
+ */
+int esp_elf_arch_relocate(esp_elf_t *elf, const elf32_rela_t *rela,
+                          const elf32_sym_t *sym, uint32_t addr);
+
+/**
+ * @brief Remap symbol from ".data" to ".text" section. 
+ *
+ * @param elf  - ELF object pointer
+ * @param sym  - ELF symbol table
+ * 
+ * @return Remapped symbol value
+ */
+#ifdef CONFIG_ELF_LOADER_CACHE_OFFSET
+uintptr_t elf_remap_text(esp_elf_t *elf, uintptr_t sym);
+#endif
+
+/**
+ * @brief Flush data from cache to external RAM.
+ *
+ * @param None
+ * 
+ * @return None
+ */
+#ifdef CONFIG_ELF_LOADER_LOAD_PSRAM
+void esp_elf_arch_flush(void);
+#endif
+
+/**
+ * @brief Initialize MMU hardware remapping function.
+ *
+ * @param elf - ELF object pointer
+ *
+ * @return 0 if success or a negative value if failed.
+ */
+#ifdef CONFIG_ELF_LOADER_SET_MMU
+int esp_elf_arch_init_mmu(esp_elf_t *elf);
+#endif
+
+/**
+ * @brief De-initialize MMU hardware remapping function.
+ *
+ * @param elf - ELF object pointer
+ *
+ * @return None
+ */
+#ifdef CONFIG_ELF_LOADER_SET_MMU
+void esp_elf_arch_deinit_mmu(esp_elf_t *elf);
+#endif
+
+#ifdef __cplusplus
+}
+#endif