Add __elfN(relocation_offset). It holds the offset between the virtual

(link) address and the physical (load) address. Ideally, the mapping
between link and load addresses should be abstracted by the copyin(),
copyout() and readin() functions, so that we don't have to add kluges
in __elfN(loadimage)(). Then, we could also have paged virtual memory
for the kernel. This can be important under EFI, where you need to
allocate physical memory form the firmware if you want to work in all
scenarios.

2 files changed, 30 insertions, 2 deletions

diff --git a/sys/boot/common/bootstrap.h b/sys/boot/common/bootstrap.h
index 6ecd235..57982d1 100644
--- a/sys/boot/common/bootstrap.h
+++ b/sys/boot/common/bootstrap.h
@@ -233,13 +233,15 @@ void file_addmetadata(struct preloaded_file *fp, int type, size_t size, void *p)
 int  file_addmodule(struct preloaded_file *fp, char *modname, int version,
 	struct kernel_module **newmp);
 
-
 /* MI module loaders */
 #ifdef __elfN
 /* Relocation types. */
 #define ELF_RELOC_REL	1
 #define ELF_RELOC_RELA	2
 
+/* Relocation offset for some architectures */
+extern u_int64_t __elfN(relocation_offset);
+
 struct elf_file;
 typedef Elf_Addr (symaddr_fn)(struct elf_file *ef, Elf_Size symidx);
 
diff --git a/sys/boot/common/load_elf.c b/sys/boot/common/load_elf.c
index bb070fd..eabc426 100644
--- a/sys/boot/common/load_elf.c
+++ b/sys/boot/common/load_elf.c
@@ -83,6 +83,8 @@ static char	*fake_modname(const char *name);
 const char	*__elfN(kerneltype) = "elf kernel";
 const char	*__elfN(moduletype) = "elf module";
 
+u_int64_t	__elfN(relocation_offset) = 0;
+
 /*
  * Attempt to load the file (file) as an ELF module.  It will be stored at
  * (dest), and a pointer to a module structure describing the loaded object
@@ -100,7 +102,7 @@ __elfN(loadfile)(char *filename, u_int64_t dest, struct preloaded_file **result)
 
     fp = NULL;
     bzero(&ef, sizeof(struct elf_file));
-    
+
     /*
      * Open the image, read and validate the ELF header 
      */
@@ -266,9 +268,33 @@ __elfN(loadimage)(struct preloaded_file *fp, elf_file_t ef, u_int64_t off)
 #else
 	off = - (off & 0xff000000u);	/* i386 relocates after locore */
 #endif
+#elif defined(__powerpc__)
+	/*
+	 * On the purely virtual memory machines like e500, the kernel is
+	 * linked against its final VA range, which is most often not
+	 * available at the loader stage, but only after kernel initializes
+	 * and completes its VM settings. In such cases we cannot use p_vaddr
+	 * field directly to load ELF segments, but put them at some
+	 * 'load-time' locations.
+	 */
+	if (off & 0xf0000000u) {
+	    off = -(off & 0xf0000000u);
+	    /*
+	     * XXX the physical load address should not be hardcoded. Note
+	     * that the Book-E kernel assumes that it's loaded at a 16MB
+	     * boundary for now...
+	     */
+	    off += 0x01000000;
+	    ehdr->e_entry += off;
+#ifdef ELF_VERBOSE
+	    printf("Converted entry 0x%08x\n", ehdr->e_entry);
+#endif
+	} else 
+	    off = 0;
 #else
 	off = 0;		/* other archs use direct mapped kernels */
 #endif
+	__elfN(relocation_offset) = off;
     }
     ef->off = off;