Author: dim
Date: Sat Sep 3 11:41:00 2011
New Revision: 225366
URL: http://svn.freebsd.org/changeset/base/225366
Log:
When libexec/rtld-elf/rtld.c is compiled with clang, the r_debug_state()
function (a hook necessary for gdb support), is inlined, but since the
function contains no code, no calls to it are generated. When gdb is
debugging a dynamically linked program, this causes backtraces to be
corrupted.
Fix it by marking the function __noinline, and inserting an empty asm
statement, that pretends to clobber memory. This forces the compiler to
emit calls to r_debug_state() throughout rtld.c.
Approved by: re (kib)
Modified:
head/libexec/rtld-elf/rtld.c
Modified: head/libexec/rtld-elf/rtld.c
==============================================================================
--- head/libexec/rtld-elf/rtld.c Sat Sep 3 08:31:59 2011
(r225365)
+++ head/libexec/rtld-elf/rtld.c Sat Sep 3 11:41:00 2011
(r225366)
@@ -144,7 +144,7 @@ static void ld_utrace_log(int, void *, v
static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
struct dl_phdr_info *phdr_info);
-void r_debug_state(struct r_debug *, struct link_map *);
+void r_debug_state(struct r_debug *, struct link_map *) __noinline;
/*
* Data declarations.
@@ -2782,6 +2782,14 @@ linkmap_delete(Obj_Entry *obj)
void
r_debug_state(struct r_debug* rd, struct link_map *m)
{
+ /*
+ * The following is a hack to force the compiler to emit calls to
+ * this function, even when optimizing. If the function is empty,
+ * the compiler is not obliged to emit any code for calls to it,
+ * even when marked __noinline. However, gdb depends on those
+ * calls being made.
+ */
+ __asm __volatile("" : : : "memory");
}
/*
_______________________________________________
svn-src-all@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
