Prefer the processor-specific _DYNAMIC[] tags value to find out the boundaries

of the .plt whenever possible, and fallback to the old behaviour of searching
for special symbols pointing to its boundaries. No functional change.

2 files changed, 44 insertions, 20 deletions

diff --git a/libexec/ld.so/m88k/rtld_machine.c b/libexec/ld.so/m88k/rtld_machine.c
index a867c3f10d1..f8e70e790f8 100644
--- a/libexec/ld.so/m88k/rtld_machine.c
+++ b/libexec/ld.so/m88k/rtld_machine.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: rtld_machine.c,v 1.4 2013/01/26 20:41:39 miod Exp $	*/
+/*	$OpenBSD: rtld_machine.c,v 1.5 2013/04/20 18:40:42 miod Exp $	*/
 
 /*
  * Copyright (c) 2013 Miodrag Vallat.
@@ -235,7 +235,7 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 	int	fails = 0;
 	Elf_Addr *pltgot = (Elf_Addr *)object->Dyn.info[DT_PLTGOT];
 	Elf_Addr ooff;
-	Elf_Addr plt_addr;
+	Elf_Addr plt_start, plt_end;
 	const Elf_Sym *this;
 
 	if (pltgot == NULL)
@@ -269,26 +269,42 @@ _dl_md_reloc_got(elf_object_t *object, int lazy)
 		object->got_size = ELF_ROUND(object->got_size, _dl_pagesz);
 	}
 
-	plt_addr = 0;
-	object->plt_size = 0;
-	this = NULL;
-	ooff = _dl_find_symbol("__plt_start", &this,
-	    SYM_SEARCH_OBJ | SYM_NOWARNNOTFOUND | SYM_PLT, NULL, object, NULL);
-	if (this != NULL)
-		plt_addr = ooff + this->st_value;
+	/*
+	 * Post-5.3 binaries use dynamic tags to provide the .plt boundaries.
+	 * If the tags are missing, fall back to the special symbol search.
+	 */
+	plt_start = object->Dyn.info[DT_88K_PLTSTART - DT_LOPROC + DT_NUM];
+	plt_end = object->Dyn.info[DT_88K_PLTEND - DT_LOPROC + DT_NUM];
+	if (plt_start == 0 || plt_end == 0) {
+		this = NULL;
+		ooff = _dl_find_symbol("__plt_start", &this,
+		    SYM_SEARCH_OBJ | SYM_NOWARNNOTFOUND | SYM_PLT, NULL,
+		    object, NULL);
+		if (this != NULL)
+			plt_start = ooff + this->st_value;
+		else
+			plt_start = 0;
 
-	this = NULL;
-	ooff = _dl_find_symbol("__plt_end", &this,
-	    SYM_SEARCH_OBJ | SYM_NOWARNNOTFOUND | SYM_PLT, NULL, object, NULL);
-	if (this != NULL)
-		object->plt_size = ooff + this->st_value  - plt_addr;
+		this = NULL;
+		ooff = _dl_find_symbol("__plt_end", &this,
+		    SYM_SEARCH_OBJ | SYM_NOWARNNOTFOUND | SYM_PLT, NULL,
+		    object, NULL);
+		if (this != NULL)
+			plt_end = ooff + this->st_value;
+		else
+			plt_end = 0;
+	} else {
+		plt_start += object->obj_base;
+		plt_end += object->obj_base;
+	}
 
-	if (plt_addr == 0)
+	if (plt_start == 0) {
 		object->plt_start = 0;
-	else {
-		object->plt_start = ELF_TRUNC(plt_addr, _dl_pagesz);
-		object->plt_size += plt_addr - object->plt_start;
-		object->plt_size = ELF_ROUND(object->plt_size, _dl_pagesz);
+		object->plt_size = 0;
+	} else {
+		object->plt_start = ELF_TRUNC(plt_start, _dl_pagesz);
+		object->plt_size =
+		    ELF_ROUND(plt_end, _dl_pagesz) - object->plt_start;
 
 		/*
 		 * GOT relocation will require PLT to be writeable.
diff --git a/sys/arch/m88k/include/exec.h b/sys/arch/m88k/include/exec.h
index f67b9b7372d..a7c6155d68c 100644
--- a/sys/arch/m88k/include/exec.h
+++ b/sys/arch/m88k/include/exec.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: exec.h,v 1.3 2013/02/09 19:21:29 miod Exp $ */
+/*	$OpenBSD: exec.h,v 1.4 2013/04/20 18:40:42 miod Exp $ */
 #ifndef _M88K_EXEC_H_
 #define _M88K_EXEC_H_
 
@@ -16,4 +16,12 @@
 #define _KERN_DO_AOUT
 #define _KERN_DO_ELF
 
+/* Processor specific dynamic tag values.  */
+#define	DT_88K_ADDRBASE	0x70000001
+#define	DT_88K_PLTSTART	0x70000002
+#define	DT_88K_PLTEND	0x70000003
+#define	DT_88K_TDESC	0x70000004
+
+#define	DT_PROCNUM	(DT_88K_TDESC + 1 - DT_LOPROC)
+
 #endif /* _M88K_EXEC_H_ */