powerpc64: Always restore TOC on longjmp [BZ #21895]

This patch changes longjmp to always restore the TOC pointer (r2 register)
to the caller frame on powerpc64 and powerpc64le.  This is related to bug
21895 that reports a situation where you have a static longjmp to a
shared object file.

	[BZ #21895]
	* sysdeps/powerpc/powerpc64/__longjmp-common.S: Remove condition code for
	restoring r2 in longjmp.
	* sysdeps/powerpc/powerpc64/Makefile: Added tst-setjmp-bug21895-static to
	test list.
	Added rules to build test tst-setjmp-bug21895-static.
	Added module setjmp-bug21895 and rules to build a shared object from it.
	* sysdeps/powerpc/powerpc64/setjmp-bug21895.c: New test file.
	* sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c: New test file.

Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>

4 files changed, 139 insertions, 4 deletions

diff --git a/sysdeps/powerpc/powerpc64/Makefile b/sysdeps/powerpc/powerpc64/Makefile
index 9d15db0328..a0bd0c9504 100644
--- a/sysdeps/powerpc/powerpc64/Makefile
+++ b/sysdeps/powerpc/powerpc64/Makefile
@@ -47,3 +47,15 @@ ifeq ($(subdir),gmon)
 CFLAGS-mcount.c += $(no-special-regs)
 sysdep_routines += ppc-mcount
 endif
+
+ifeq ($(subdir),setjmp)
+tests += tst-setjmp-bug21895-static
+tests-static += tst-setjmp-bug21895-static
+modules-names += setjmp-bug21895
+
+$(objpfx)tst-setjmp-bug21895-static: $(common-objpfx)dlfcn/libdl.a
+$(objpfx)tst-setjmp-bug21895-static.out: $(objpfx)setjmp-bug21895.so
+
+tst-setjmp-bug21895-static-ENV = \
+	LD_LIBRARY_PATH=$(objpfx):$(common-objpfx):$(common-objpfx)setjmp:$(common-objpfx)elf
+endif
diff --git a/sysdeps/powerpc/powerpc64/__longjmp-common.S b/sysdeps/powerpc/powerpc64/__longjmp-common.S
index 0e10b8de19..99c17c5797 100644
--- a/sysdeps/powerpc/powerpc64/__longjmp-common.S
+++ b/sysdeps/powerpc/powerpc64/__longjmp-common.S
@@ -130,9 +130,6 @@ L(no_vmx):
 	ld r0,(JB_LR*8)(r3)
 	ld r14,((JB_GPRS+0)*8)(r3)
 	lfd fp14,((JB_FPRS+0)*8)(r3)
-#if defined SHARED && !IS_IN (rtld)
-	std r2,FRAME_TOC_SAVE(r1)	/* Restore the callers TOC save area.  */
-#endif
 	ld r15,((JB_GPRS+1)*8)(r3)
 	lfd fp15,((JB_FPRS+1)*8)(r3)
 	ld r16,((JB_GPRS+2)*8)(r3)
@@ -152,7 +149,7 @@ L(no_vmx):
 	second argument (-4@4), and target address (8@0), respectively.  */
 	LIBC_PROBE (longjmp, 3, 8@3, -4@4, 8@0)
 	mtlr r0
-/* 	std r2,FRAME_TOC_SAVE(r1)	Restore the TOC save area.  */
+	std r2,FRAME_TOC_SAVE(r1)	/* Restore the TOC save area.  */
 	ld r21,((JB_GPRS+7)*8)(r3)
 	lfd fp21,((JB_FPRS+7)*8)(r3)
 	ld r22,((JB_GPRS+8)*8)(r3)
diff --git a/sysdeps/powerpc/powerpc64/setjmp-bug21895.c b/sysdeps/powerpc/powerpc64/setjmp-bug21895.c
new file mode 100644
index 0000000000..945a251d95
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/setjmp-bug21895.c
@@ -0,0 +1,51 @@
+/* Shared object part of test for setjmp interoperability with static
+   dlopen BZ #21895.
+   Copyright (C) 2017-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <setjmp.h>
+
+/* Copy r1 adress to a local variable.  */
+#define GET_STACK_POINTER(sp)	  \
+  ({				  \
+    asm volatile ("mr %0, 1\n\t"  \
+		  : "=r" (sp));	  \
+  })
+
+jmp_buf jb;
+void (*bar)(jmp_buf, unsigned long);
+
+void
+lbar (unsigned long sp)
+{
+  bar(jb, sp);
+  for(;;);
+}
+
+void
+foo (void)
+{
+  unsigned long sp;
+  /* Copy r1 (stack pointer) to sp. It will be use later to get
+     TOC area.  */
+  GET_STACK_POINTER(sp);
+  setjmp(jb);
+  lbar(sp);
+
+  for(;;);
+}
diff --git a/sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c b/sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c
new file mode 100644
index 0000000000..31ee88cd62
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c
@@ -0,0 +1,75 @@
+/* Test setjmp interoperability with static dlopen BZ #21895.
+   Copyright (C) 2017-2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <setjmp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <dlfcn.h>
+
+/* Set TOC area pointed by sp to zero.  */
+#define SET_TOC_TO_ZERO(sp)					 \
+  ({								 \
+    unsigned int zero = 0;					 \
+    asm volatile ("std %0, 24(%1)\n\t" :: "r" (zero), "r" (sp)); \
+  })
+
+static void
+bar (jmp_buf jb, unsigned long sp)
+{
+  static int i;
+  if (i++==1)
+    exit(0);	/* Success.  */
+
+  /* This will set TOC are on caller frame (foo) to zero. __longjmp
+     must restore r2 otherwise a segmentation fault will happens after
+     it jumps back to foo.  */
+  SET_TOC_TO_ZERO(sp);
+  longjmp(jb, i);
+}
+
+static int
+do_test (void)
+{
+  void *h = dlopen("setjmp-bug21895.so", RTLD_NOW);
+  if (!h)
+    {
+      puts(dlerror());
+      return 1;
+    }
+
+  void (*pfoo)(void) = dlsym(h, "foo");
+  if (!pfoo)
+    {
+      puts(dlerror());
+      return 1;
+    }
+
+  void (**ppbar)(jmp_buf, unsigned long) = dlsym(h, "bar");
+  if (!ppbar)
+    {
+      puts(dlerror());
+      return 1;
+    }
+
+  *ppbar = bar;
+  pfoo();
+
+  for(;;);
+}
+
+#include <support/test-driver.c>