[GitHub] [incubator-nuttx] yamt commented on a change in pull request #447: ESP32 module support

[GitBox <gi...@apache.org>]

yamt commented on a change in pull request #447: ESP32 module support
URL: https://github.com/apache/incubator-nuttx/pull/447#discussion_r388825966
 
 

 ##########
 File path: libs/libc/machine/xtensa/arch_elf.c
 ##########
 @@ -0,0 +1,217 @@
+/****************************************************************************
+ * libs/libc/machine/xtensa/arch_elf.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <assert.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <arch/elf.h>
+#include <nuttx/elf.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+static bool is_l32r(const unsigned char *p)
+{
+  return (p[0] & 0xf) == 1;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_checkarch
+ *
+ * Description:
+ *   Given the ELF header in 'hdr', verify that the ELF file is appropriate
+ *   for the current, configured architecture.  Every architecture that uses
+ *   the ELF loader must provide this function.
+ *
+ * Input Parameters:
+ *   hdr - The ELF header read from the ELF file.
+ *
+ * Returned Value:
+ *   True if the architecture supports this ELF file.
+ *
+ ****************************************************************************/
+
+bool up_checkarch(FAR const Elf32_Ehdr *ehdr)
+{
+  /* Make sure it's an Xtensa executable */
+
+  if (ehdr->e_machine != EM_XTENSA)
+    {
+      berr("ERROR: Not for ARM: e_machine=%04x\n", ehdr->e_machine);
+      return false;
+    }
+
+  /* Make sure that 32-bit objects are supported */
+
+  if (ehdr->e_ident[EI_CLASS] != ELFCLASS32)
+    {
+      berr("ERROR: Need 32-bit objects: e_ident[EI_CLASS]=%02x\n", ehdr->e_ident[EI_CLASS]);
+      return false;
+    }
+
+  /* Verify endian-ness */
+
+#ifdef CONFIG_ENDIAN_BIG
+#error not implemented
+  if (ehdr->e_ident[EI_DATA] != ELFDATA2MSB)
+#else
+  if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB)
+#endif
+    {
+      berr("ERROR: Wrong endian-ness: e_ident[EI_DATA]=%02x\n", ehdr->e_ident[EI_DATA]);
+      return false;
+    }
+
+  return true;
+}
+
+/****************************************************************************
+ * Name: up_relocate and up_relocateadd
+ *
+ * Description:
+ *   Perform on architecture-specific ELF relocation.  Every architecture
+ *   that uses the ELF loader must provide this function.
+ *
+ * Input Parameters:
+ *   rel - The relocation type
+ *   sym - The ELF symbol structure containing the fully resolved value.
+ *         There are a few relocation types for a few architectures that do
+ *         not require symbol information.  For those, this value will be
+ *         NULL.  Implementations of these functions must be able to handle
+ *         that case.
+ *   addr - The address that requires the relocation.
+ *
+ * Returned Value:
+ *   Zero (OK) if the relocation was successful.  Otherwise, a negated errno
+ *   value indicating the cause of the relocation failure.
+ *
+ ****************************************************************************/
+
+int up_relocate(FAR const Elf32_Rel *rel, FAR const Elf32_Sym *sym,
+                uintptr_t addr)
+{
+  unsigned int relotype;
+
+  /* All relocations except R_ARM_V4BX depend upon having valid symbol
 
 Review comment:
   @masayuki2009 
   i'm looking at https://github.com/eerimoq/hardware-reference/blob/master/esp32/xtensa%20Instruction%20Set%20Architecture%20(ISA)%20Reference%20Manual.pdf
   for instruction encoding.
   wrt relocation, i have no documentation. this code is based on some reading of espressif's llvm fork + wild guesses.
   https://github.com/espressif/llvm-project
   

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