From 3d3e4e6c397a58d21dbc3be7fbe0c0173f193644 Mon Sep 17 00:00:00 2001
From: Tony Puccinelli
Date: Tue, 20 Jul 2010 04:04:13 +0000
Subject: coded for more relocations, added check for RELA type relocations,
 added comments

svn-id: r51048
---
 backends/platform/ds/arm9/source/dsloader.cpp | 55 +++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 3 deletions(-)

(limited to 'backends/platform')

diff --git a/backends/platform/ds/arm9/source/dsloader.cpp b/backends/platform/ds/arm9/source/dsloader.cpp
index 2f953cc33b..c0e8b63dbc 100644
--- a/backends/platform/ds/arm9/source/dsloader.cpp
+++ b/backends/platform/ds/arm9/source/dsloader.cpp
@@ -97,16 +97,18 @@ bool DLObject::relocate(Common::SeekableReadStream* DLFile, unsigned long offset
 	int a = 0;
 	unsigned int relocation = 0;
 
+	// Loop over relocation entries
 	for (int i = 0; i < cnt; i++) {
 
+		// Get the symbol this relocation entry is referring to
 		Elf32_Sym *sym = (Elf32_Sym *)(_symtab) + (REL_INDEX(rel[i].r_info));
 
+		// Get the target instruction in the code
 		unsigned int *target = (unsigned int *)((char *)relSegment + rel[i].r_offset);
 
 		unsigned int origTarget = *target;	// Save for debugging
 
-		//DBG("%d, ", REL_TYPE(rel[i].r_info));
-
+		// Act differently based on the type of relocation
 		switch (REL_TYPE(rel[i].r_info)) {
 
 		case R_ARM_ABS32:
@@ -151,6 +153,48 @@ bool DLObject::relocate(Common::SeekableReadStream* DLFile, unsigned long offset
 			}
 			break;
 
+		case R_ARM_CALL:
+			if (sym->st_shndx < SHN_LOPROC) {			// Only shift for plugin section.
+				a = *target & 0x00ffffff;
+				a = (a << 8) >> 6;				// Calculate addend by sign-extending (insn[23:0] << 2)
+				relocation = a + (Elf32_Addr)_segment;  // Shift by main offset
+
+				/*TODO:
+				 * if (SYM_TYPE(sym->st_info) == STT_FUNC && symbol addresses a thumb instruction) {
+				 * 	relocation |= 1;
+				 * }
+				 */
+
+				relocation = relocation - rel[i].r_offset;
+				relocation = relocation >> 2;
+				*target &= 0xff000000;					// Clean lower 26 target bits
+				*target |= (relocation & 0x00ffffff);
+
+				DBG("R_ARM_CALL: i=%d, a=%x, origTarget=%x, target=%x\n", i, a, origTarget, *target);
+			}
+			break;
+
+		case R_ARM_JUMP24:
+			if (sym->st_shndx < SHN_LOPROC) {			// Only shift for plugin section.
+				a = *target & 0x00ffffff;
+				a = (a << 8) >> 6;				// Calculate addend by sign-extending (insn[23:0] << 2)
+				relocation = a + (Elf32_Addr)_segment;  // Shift by main offset
+
+				/*TODO:
+				 * if (SYM_TYPE(sym->st_info) == STT_FUNC && symbol addresses a thumb instruction) {
+				 * 	relocation |= 1;
+				 * }
+				 */
+
+				relocation = relocation - rel[i].r_offset;
+				relocation = relocation >> 2;
+				*target &= 0xff000000;					// Clean lower 26 target bits
+				*target |= (relocation & 0x00ffffff);
+
+				DBG("R_ARM_CALL: i=%d, a=%x, origTarget=%x, target=%x\n", i, a, origTarget, *target);
+			}
+			break;
+
 		case R_ARM_V4BX:
 			DBG("R_ARM_V4BX: No relocation calculation necessary\n");
 			break;
@@ -365,12 +409,17 @@ bool DLObject::relocateRels(Common::SeekableReadStream* DLFile, Elf32_Ehdr *ehdr
 		Elf32_Shdr *curShdr = &(shdr[i]);
 		//Elf32_Shdr *linkShdr = &(shdr[curShdr->sh_info]);
 
-		if (curShdr->sh_type == SHT_REL && 						// Check for a relocation section
+		if ((curShdr->sh_type == SHT_REL || curShdr->sh_type == SHT_RELA) &&		// Check for a relocation section
 		        curShdr->sh_entsize == sizeof(Elf32_Rel) &&		// Check for proper relocation size
 		        (int)curShdr->sh_link == _symtab_sect &&			// Check that the sh_link connects to our symbol table
 		        curShdr->sh_info < ehdr->e_shnum &&					// Check that the relocated section exists
 		        (shdr[curShdr->sh_info].sh_flags & SHF_ALLOC)) {  	// Check if relocated section resides in memory
 
+			if (curShdr->sh_type == SHT_RELA) {
+					seterror("RELA entries not supported for ARM yet!\n");
+					return false;
+			}
+
 			if (!relocate(DLFile, curShdr->sh_offset, curShdr->sh_size, _segment)) {
 				return false;
 			}
-- 
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