[committed] Return to caller when _dl_fixup fails on hppa

[John David Anglin <dave.anglin@bell.net>]

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The attached change modifies _dl_runtime_resolve to return to its caller when _dl_fixup
fails.  This can occur on hppa when the caller attempts to call an undefined weak function.
The old code would fault when _dl_fixup fails.

The most problematic function in this regard is __gmon_start__.  Currently, it is linked into
every shared object.  This breaks the --as-needed ld option.

On Debian, we have an additional patch to treat __gmon_start__ as a true weak symbol.
I don't plan to apply this change as it becomes tricky to rebuild a distribution.  Rebuilding
a shared library removes __gmon_start__ and this may break a package using the library.
This isn't a problem after everything is rebuilt.

Dave
--
John David Anglin	dave.anglin@bell.net



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2017-07-16  John David Anglin  <danglin@gcc.gnu.org>

	* sysdeps/hppa/dl-trampoline.S (_dl_runtime_resolve): Return to caller
	if _dl_fixup fails.

diff --git a/sysdeps/hppa/dl-trampoline.S b/sysdeps/hppa/dl-trampoline.S
index 856339bffe..f1294a931f 100644
--- a/sysdeps/hppa/dl-trampoline.S
+++ b/sysdeps/hppa/dl-trampoline.S
@@ -82,6 +82,11 @@ _dl_runtime_resolve:
 	bl	_dl_fixup,%rp
 	copy	%r21,%r19		/* set fixup func ltp */
 
+	/* Sometimes a final executable may attempt to call an undefined
+	   weak function (e.g., __gmon_start__).  Return if the function
+	   was not resolved by _dl_fixup */
+	comib,=	0,%r28,1f
+
 	/* Load up the returned func descriptor */
 	copy	%r28, %r22
 	copy	%r29, %r19
@@ -107,6 +112,13 @@ _dl_runtime_resolve:
 	/* Jump to new function, but return to previous function */
 	bv	%r0(%r22)
 	ldw	-20(%sp),%rp
+
+1:
+	/* Return to previous function */
+	ldw	-148(%sp),%rp
+	bv	%r0(%rp)
+	ldo	-128(%sp),%sp
+
         .EXIT
         .PROCEND
 	cfi_endproc