This patch allows to load modules with bad pc-relative relocation info
produced by "objcopy -I pe-i386 -O elf32-i386"
(See also thread "Building GRUB on platforms without ELF support")
Christian
2007-11-19 Christian Franke <[EMAIL PROTECTED]>
* kern/i386/dl.c [__CYGWIN__] (fix_pc_rel_relocation): New function
to fix bad PC relative relocation produced by objcopy.
[__CYGWIN__] (grub_arch_dl_relocate_symbols): Add fix of PC relative
relocation.
(grub_arch_dl_relocate_symbols): Abort on unknown relocation type.
--- grub2.orig/kern/i386/dl.c 2007-07-22 01:32:26.000000000 +0200
+++ grub2/kern/i386/dl.c 2007-11-19 20:50:52.609375000 +0100
@@ -37,6 +37,28 @@ grub_arch_dl_check_header (void *ehdr)
return GRUB_ERR_NONE;
}
+#ifdef __CYGWIN__
+/* Fix PC relative relocation. Objcopy does not adjust
+the addent when converting from pe-i386 to elf32-i386. */
+static int
+fix_pc_rel_relocation (Elf32_Word *addr)
+{
+ /* To be safe, check instruction first. */
+ const unsigned char * pc = (const unsigned char *)addr - 1;
+ if (!(*pc == 0xe8/*call*/ || *pc == 0xe9/*jmp*/))
+ return grub_error (GRUB_ERR_BAD_MODULE, "unknown pc-relative instruction %02x", *pc);
+ /* Check and adjust offset. */
+ if (*addr != (Elf32_Word)-4)
+ {
+ if (*addr != 0)
+ return grub_error (GRUB_ERR_BAD_MODULE, "invalid pc-relative relocation base %lx",
+ (long)(*addr));
+ *addr = (Elf32_Word)-4;
+ }
+ return GRUB_ERR_NONE;
+}
+#endif
+
/* Relocate symbols. */
grub_err_t
grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr)
@@ -99,9 +121,17 @@ grub_arch_dl_relocate_symbols (grub_dl_t
break;
case R_386_PC32:
+#ifdef __CYGWIN__
+ if (fix_pc_rel_relocation (addr))
+ return grub_errno;
+#endif
*addr += (sym->st_value - (Elf32_Word) seg->addr
- rel->r_offset);
break;
+
+ default:
+ return grub_error (GRUB_ERR_BAD_MODULE, "unknown relocation type %x.",
+ ELF32_R_TYPE (rel->r_info));
}
}
}
_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
http://lists.gnu.org/mailman/listinfo/grub-devel
