[PATCH 09/13] ARM32: module: handle more relocations

[Ahmad Fatoum <a.fatoum@barebox.org>]

Compiling with arm-linux-gnueabihf-gcc (Debian 14.2.0-19) 14.2.0
generates a few more relocation types than the module loader currently
supports.

Import support for them from Linux, so we can start automatically
testing this feature.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
 arch/arm/include/asm/elf.h |  2 ++
 arch/arm/lib32/module.c    | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/arch/arm/include/asm/elf.h b/arch/arm/include/asm/elf.h
index 0b4704a4a561..f3b6e0dd37c3 100644
--- a/arch/arm/include/asm/elf.h
+++ b/arch/arm/include/asm/elf.h
@@ -29,9 +29,11 @@ typedef struct user_fp elf_fpregset_t;
 
 #define R_ARM_NONE	0
 #define R_ARM_PC24	1
+#define R_ARM_REL32	3
 #define R_ARM_ABS32	2
 #define R_ARM_CALL	28
 #define R_ARM_JUMP24	29
+#define R_ARM_PREL31	42
 
 #define R_ARM_THM_CALL		10
 #define R_ARM_THM_JUMP24	30
diff --git a/arch/arm/lib32/module.c b/arch/arm/lib32/module.c
index 7214e3c73c3d..0cf04ea9faba 100644
--- a/arch/arm/lib32/module.c
+++ b/arch/arm/lib32/module.c
@@ -49,6 +49,9 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 		loc = dstsec->sh_addr + rel->r_offset;
 
 		switch (ELF32_R_TYPE(rel->r_info)) {
+		case R_ARM_NONE:
+			/* ignore */
+			break;
 		case R_ARM_ABS32:
 			*(u32 *)loc += sym->st_value;
 			break;
@@ -90,6 +93,23 @@ apply_relocate(Elf32_Shdr *sechdrs, const char *strtab, unsigned int symindex,
 			*(u32 *)loc |= offset & 0x00ffffff;
 			break;
 
+		case R_ARM_PREL31:
+			offset = (*(s32 *)loc << 1) >> 1; /* sign extend */
+			offset += sym->st_value - loc;
+			if (offset >= 0x40000000 || offset < -0x40000000) {
+				pr_err("%s: section %u reloc %u sym '%s': relocation %u out of range (%#lx -> %#x)\n",
+				       module->name, relindex, i, strtab + sym->st_name,
+				       ELF32_R_TYPE(rel->r_info), loc,
+				       sym->st_value);
+				return -ENOEXEC;
+			}
+			*(u32 *)loc &= 0x80000000;
+			*(u32 *)loc |= offset & 0x7fffffff;
+			break;
+
+		case R_ARM_REL32:
+			*(u32 *)loc += sym->st_value - loc;
+			break;
 		default:
 			printf("%s: unknown relocation: %u\n",
 			       module->name, ELF32_R_TYPE(rel->r_info));
-- 
2.47.3