Patchwork [RFC] powerpc: restore TOC when static longjmp to shared object

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Submitter rcardoso@linux.vnet.ibm.com
Date May 16, 2018, 7:36 p.m.
Message ID <1242a273-48fd-9bde-bbb1-91bc2d107ac8@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/27304/
State Superseded
Headers show

Comments

rcardoso@linux.vnet.ibm.com - May 16, 2018, 7:36 p.m.
Attached to this email I am sending the first version of the patch but I 
have a problem with this patch. I can't make the test work. By some 
reason it can't find the .so needed by the test:

FAIL:
./setjmp-bug21895.so: cannot open shared object file: No such file or 
directory

Notice that if I manually execute the command on make check stdout 
inside the folder it works fine. I'd appreciate any help on that.

Regards

Em 15-05-2018 17:48, Tulio Magno Quites Machado Filho escreveu:
> Florian Weimer <fw@deneb.enyo.de> writes:
> 
>> * Rogerio Alves:
>>
>>> One simple solution would be always restore the TOC pointer by uncomment
>>> the line bellow:
>>>
>>> /*     std r2,FRAME_TOC_SAVE(r1)       Restore the TOC save area.  */
>>>
>>> Or maybe we can check if we have a valid TOC pointer before restore it,
>>> instead #if defined SHARED.
>>
>> Is the register reserved for the TOC pointer in static builds, too?
>> Then I suggest to unconditionally save nad restore it; not doing so
>> looks like a pointless micro-optimization.
>>
>> Another problem with sharing jump buffers across static dlopen is that
>> you might not have identical pointer guard values.
>>
>>> I would like to request for comments on this matter: Should we fix/work
>>> this? Is feasible to change longjmp to always restore TOC pointer?
>>
>> Does setjmp already save it unonditionally?
>>
>> Removal of static dlopen is still some time away; it's likely not
>> going to happen in this cycle, and the fix looks simple enough.
> 
> If static dlopen is still going to be supported for some cycles, I also agree
> it should be saved and restored unconditionally.
>

Patch

From eb9895f1548c8f6e1826095aee3221eaf9ce84c9 Mon Sep 17 00:00:00 2001
From: Rogerio Alves <rcardoso@linux.vnet.ibm.com>
Date: Wed, 16 May 2018 14:20:53 -0500
Subject: [PATCH] [PATCH v1] powerpc: Always restore TOC on longjmp.

This patch change longjmp to always restore the TOC pointer (r2 register)
to the caller frame on powerpc. This is related to bug 21895[1] that reports
a situation where you have a static longjmp to a shared object file.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=21895

2018-05-16 Rogerio A. Cardoso <rcardoso@linux.vnet.ibm.com>

	*sysdeps/powerpc/powerpc64/__longjmp-common.S: Remove condition code for
	restore r2 on longjmp.
	*setjmp/Makefile: Include test build directives.
	*setjmp/setjmp-bug21895.c: new test file.
	*setjmp/tst-setjmp-bug21895.c: new test file.
---
 setjmp/Makefile                              | 18 ++++++--
 setjmp/setjmp-bug21895.c                     | 42 ++++++++++++++++++
 setjmp/tst-setjmp-bug21895.c                 | 65 ++++++++++++++++++++++++++++
 sysdeps/powerpc/powerpc64/__longjmp-common.S |  5 +--
 4 files changed, 123 insertions(+), 7 deletions(-)
 create mode 100644 setjmp/setjmp-bug21895.c
 create mode 100644 setjmp/tst-setjmp-bug21895.c

diff --git a/setjmp/Makefile b/setjmp/Makefile
index dc2fcc6..e715ee6 100644
--- a/setjmp/Makefile
+++ b/setjmp/Makefile
@@ -22,16 +22,28 @@  subdir	:= setjmp
 
 include ../Makeconfig
 
-headers	:= setjmp.h bits/setjmp.h bits/setjmp2.h
+headers	:= setjmp.h bits/setjmp.h bits/setjmp2.h bits/dlfcn.h dlfcn/dlfcn.h
 
 routines	:= setjmp sigjmp bsd-setjmp bsd-_setjmp \
 		   longjmp __longjmp jmp-unwind
 
 tests		:= tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \
-		   tst-sigsetjmp tst-setjmp-static
+		   tst-sigsetjmp tst-setjmp-static tst-setjmp-bug21895
+
 tests-static	:= tst-setjmp-static
 
+modules-names = setjmp-bug21895
 
 include ../Rules
 
-$(objpfx)tst-setjmp-fp: $(libm)
+test-modules = $(addprefix $(objpfx),$(addsuffix .so,$(modules-names)))
+
+ifeq ($(build-shared),yes)
+tests: $(test-modules)
+endif
+
+$(objpfx)setjmp-bug21895.so: $(libdl)
+$(objpfx)tst-setjmp-bug21895: $(libdl)
+$(objpfx)tst-setjmp-bug21895.out: $(objpfx)setjmp-bug21895.so
+
+$(objpfx)ts-tsetjmp-fp: $(libm)
diff --git a/setjmp/setjmp-bug21895.c b/setjmp/setjmp-bug21895.c
new file mode 100644
index 0000000..d6f5516
--- /dev/null
+++ b/setjmp/setjmp-bug21895.c
@@ -0,0 +1,42 @@ 
+/* Copyright (C) 2013-2018 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/>.  */
+
+/* Test that setjmp/longjmp interoperability with static dlopen.
+   Bugzila #21895.  */
+#include <alloca.h>
+#include <string.h>
+#include <setjmp.h>
+
+jmp_buf jb;
+void (*bar)(jmp_buf);
+
+void
+lbar (int i, ...)
+{
+  bar(jb);
+  for(;;);
+}
+
+void
+foo (void)
+{
+  int i = setjmp(jb);
+  char *c = alloca(256);
+  memset(c, 0, 256);
+  lbar(i);
+  for(;;);
+}
diff --git a/setjmp/tst-setjmp-bug21895.c b/setjmp/tst-setjmp-bug21895.c
new file mode 100644
index 0000000..5333494
--- /dev/null
+++ b/setjmp/tst-setjmp-bug21895.c
@@ -0,0 +1,65 @@ 
+/* Copyright (C) 2013-2018 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/>.  */
+
+/* Test that setjmp/longjmp interoperability with static dlopen.
+   Bugzila #21895.  */
+
+#include <setjmp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <dlfcn.h>
+
+static void
+bar (jmp_buf jb)
+{
+  static int i;
+  if (i++==1) exit(0);
+  longjmp(jb, i);
+}
+
+static int
+do_test (void)
+{
+  void *h = dlopen("./setjmp-bug21895.so", RTLD_NOW);
+  if (!h) {
+    puts ("FAIL: ");
+    puts (dlerror());
+    return 1;
+  }
+
+  void (*pfoo)(void) = dlsym(h, "foo");
+  if (!pfoo) {
+    puts ("FAIL: ");
+    puts (dlerror());
+    return 1;
+  }
+
+  void (**ppbar)(jmp_buf) = dlsym(h, "bar");
+  if (!ppbar) {
+    puts ("FAIL: ");
+    puts (dlerror());
+    return 1;
+  }
+
+  *ppbar = bar;
+  pfoo();
+
+  for(;;);
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"
diff --git a/sysdeps/powerpc/powerpc64/__longjmp-common.S b/sysdeps/powerpc/powerpc64/__longjmp-common.S
index 0e10b8d..a5973c9 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)
-- 
2.7.4