Bernd Schmidt writes: abstract away addresses so we can support FDPIC ELFs

4 files changed, 75 insertions, 6 deletions

diff --git a/ldso/include/dl-defs.h b/ldso/include/dl-defs.h
index 878ebc3b8..dc6531d19 100644
--- a/ldso/include/dl-defs.h
+++ b/ldso/include/dl-defs.h
@@ -66,4 +66,70 @@ typedef struct {
 
 #endif
 
+/* Machines in which different sections may be relocated by different
+   amounts should define this and LD_RELOC_ADDR.  If you change this,
+   make sure you change struct link_map in include/link.h accordingly
+   such that it matches a prefix of struct elf_resolve.  */
+#ifndef DL_LOADADDR_TYPE
+# define DL_LOADADDR_TYPE ElfW(Addr)
+#endif
+
+/* When DL_LOADADDR_TYPE is not a scalar value, or some different
+   computation is needed to relocate an address, define this.  */
+#ifndef DL_RELOC_ADDR
+# define DL_RELOC_ADDR(ADDR, LOADADDR) \
+  ((void*)((intptr_t)(ADDR) + (intptr_t)(LOADADDR)))
+#endif
+
+/* Define if any declarations/definitions of local variables are
+   needed in a function that calls DT_INIT_LOADADDR or
+   DL_INIT_LOADADDR_HDR.  Declarations must be properly terminated
+   with a semicolon, and non-declaration statements are forbidden.  */
+#ifndef DL_INIT_LOADADDR_EXTRA_DECLS
+# define DL_INIT_LOADADDR_EXTRA_DECLS /* int i; */
+#endif
+
+/* Prepare a DL_LOADADDR_TYPE data structure for incremental
+   initialization with DL_INIT_LOADADDR_HDR, given pointers to a base
+   load address and to program headers.  */
+#ifndef DL_INIT_LOADADDR
+# define DL_INIT_LOADADDR(LOADADDR, BASEADDR, PHDR, PHDRCNT) \
+  ((LOADADDR) = (BASEADDR))
+#endif
+
+/* Convert a DL_LOADADDR_TYPE to an identifying pointer.  Used mostly
+   for debugging.  */
+#ifndef DL_LOADADDR_BASE
+# define DL_LOADADDR_BASE(LOADADDR) (LOADADDR)
+#endif
+
+/* Initialize a LOADADDR representing the loader itself.  It's only
+   called from DL_BOOT, so additional arguments passed to it may be
+   referenced.  */
+#ifndef DL_INIT_LOADADDR_BOOT
+# define DL_INIT_LOADADDR_BOOT(LOADADDR, BASEADDR) \
+  ((LOADADDR) = (BASEADDR))
+#endif
+
+/* Initialize a LOADADDR representing the program.  It's called from
+   DL_BOOT only.  */
+#ifndef DL_INIT_LOADADDR_PROG
+# define DL_INIT_LOADADDR_PROG(LOADADDR, BASEADDR) \
+  ((LOADADDR) = (BASEADDR))
+#endif
+
+/* Test whether a given ADDR is more likely to be within the memory
+   region mapped to TPNT (a struct elf_resolve *) than to TFROM.
+   Everywhere that this is used, TFROM is initially NULL, and whenever
+   a potential match is found, it's updated.  One might want to walk
+   the chain of elf_resolve to locate the best match and return false
+   whenever TFROM is non-NULL, or use an exact-matching algorithm
+   using additional information encoded in DL_LOADADDR_TYPE to test
+   for exact containment.  */
+#ifndef DL_ADDR_IN_LOADADDR
+# define DL_ADDR_IN_LOADADDR(ADDR, TPNT, TFROM) \
+  ((void*)(TPNT)->loadaddr < (void*)(ADDR)			\
+   && (! (TFROM) || (TFROM)->loadaddr < (TPNT)->loadaddr))
+#endif
+
 #endif	/* _LD_DEFS_H */
diff --git a/ldso/include/dl-elf.h b/ldso/include/dl-elf.h
index de404aec1..9e364d680 100644
--- a/ldso/include/dl-elf.h
+++ b/ldso/include/dl-elf.h
@@ -94,10 +94,12 @@ extern void _dl_protect_relro (struct elf_resolve *l);
 
 #define DYNAMIC_SIZE (DT_NUM+OS_NUM+ARCH_NUM)
 
-extern void _dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[], void *debug_addr, ElfW(Addr) load_off);
+extern void _dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[], void *debug_addr,
+				   DL_LOADADDR_TYPE load_off);
 
 static __always_inline
-void __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[], void *debug_addr, ElfW(Addr) load_off)
+void __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[], void *debug_addr,
+			     DL_LOADADDR_TYPE load_off)
 {
 	for (; dpnt->d_tag; dpnt++) {
 		if (dpnt->d_tag < DT_NUM) {
@@ -139,7 +141,8 @@ void __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[], void
 #define ADJUST_DYN_INFO(tag, load_off) \
 	do { \
 		if (dynamic_info[tag]) \
-			dynamic_info[tag] += load_off; \
+			dynamic_info[tag] = (unsigned long)DL_RELOC_ADDR (dynamic_info[tag], \
+									  load_off); \
 	} while(0)
 	ADJUST_DYN_INFO(DT_HASH, load_off);
 	ADJUST_DYN_INFO(DT_PLTGOT, load_off);
diff --git a/ldso/include/dl-hash.h b/ldso/include/dl-hash.h
index b12b36f3b..26fb334fe 100644
--- a/ldso/include/dl-hash.h
+++ b/ldso/include/dl-hash.h
@@ -28,7 +28,7 @@ struct dyn_elf{
 struct elf_resolve{
   /* These entries must be in this order to be compatible with the interface used
      by gdb to obtain the list of symbols. */
-  ElfW(Addr) loadaddr;		/* Base address shared object is loaded at.  */
+  DL_LOADADDR_TYPE loadaddr;	/* Base address shared object is loaded at.  */
   char *libname;		/* Absolute file name object was found in.  */
   ElfW(Dyn) *dynamic_addr;	/* Dynamic section of the shared object.  */
   struct elf_resolve * next;
@@ -77,7 +77,7 @@ extern struct elf_resolve * _dl_loaded_modules;
 extern struct dyn_elf 	  * _dl_handles;
 
 extern struct elf_resolve * _dl_add_elf_hash_table(const char * libname, 
-	char * loadaddr, unsigned long * dynamic_info, 
+	DL_LOADADDR_TYPE loadaddr, unsigned long * dynamic_info, 
 	unsigned long dynamic_addr, unsigned long dynamic_size);
 
 extern char * _dl_find_hash(const char * name, struct dyn_elf * rpnt1, 
diff --git a/ldso/include/ldso.h b/ldso/include/ldso.h
index 0a3f70691..573652e61 100644
--- a/ldso/include/ldso.h
+++ b/ldso/include/ldso.h
@@ -88,7 +88,7 @@ extern void _dl_unsetenv(const char *symbol, char **envp);
 extern char *_dl_strdup(const char *string);
 extern void _dl_dprintf(int, const char *, ...);
 
-extern void _dl_get_ready_to_run(struct elf_resolve *tpnt, unsigned long load_addr,
+extern void _dl_get_ready_to_run(struct elf_resolve *tpnt, DL_LOADADDR_TYPE load_addr,
 		ElfW(auxv_t) auxvt[AT_EGID + 1], char **envp, char **argv);
 
 #endif /* _LDSO_H_ */