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

[Rogerio Alves <rcardoso@linux.vnet.ibm.com>]

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I've attached patch v2 to this email with the fixes suggested by Adhemerval.

One last issue is regard to the copyright on the tests. I put a 
copyright there but, the test is based on a test the user reported in 
bugzilla. I've adapted to libsupport and changed some of the code. What 
should I do in that case? I have to get the permission from the author 
first since the test is a derivative work? Some of the tests doesn't 
have copyright, and some of them mention the person who reports the test 
like stdio-common/tstscanf.c but I can't find a standard.


Em 16-05-2018 21:42, libc-alpha-digest-help@sourceware.org escreveu:
> 
> On 16/05/2018 16:36, Rogerio Alves wrote:
>> 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.
>>>
>> 0001-PATCH-v1-powerpc-Always-restore-TOC-on-longjmp.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
> Please indicate where you actually tested this patch (since the make check
> is broken).
> 

I've fixed the test thanks to your suggestion.

>> 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.
> You need to add each rules you might add, the ones you are changing, and
> removing (check other ChangeLog for example).
> 

Done.
>> 	*setjmp/setjmp-bug21895.c: new test file.
>> 	*setjmp/tst-setjmp-bug21895.c: new test file.
> Capitalize the new.
> 

Done.

>> ---
>>   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
> Why does it require adding more headers here? This is meant be installed afaik
> and I am not following the requirement here.
> 
>>   
>>   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
>> +
> Since the idea is test for static build I would recommend to follow the other
> static naming, i.e, tst-setjmp-bug21895-static.
> 

Done. Added static suffix.

>>   tests-static	:= tst-setjmp-static
>>   
>> +modules-names = setjmp-bug21895
>>   
>>   include ../Rules
>>   
>> -$(objpfx)tst-setjmp-fp: $(libm)
> I do not think you meant to remove this rule.
> 

It was not removed I've write the new rules before this rule. Anyway 
I've fixed it on v2.

>> +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)
> I think the idea is to build the test even if build-shared is set to no (since
> you are testing static linking).  I think what you want is:
> 
> ---
> 
> diff --git a/setjmp/Makefile b/setjmp/Makefile
> index dc2fcc6..231474b 100644
> --- a/setjmp/Makefile
> +++ b/setjmp/Makefile
> @@ -28,10 +28,17 @@ 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
> -tests-static   := tst-setjmp-static
> +                  tst-sigsetjmp tst-setjmp-static tst-setjmp-bug21895-static
> 
> +tests-static   := tst-setjmp-static tst-setjmp-bug21895-static
> +
> +modules-names = setjmp-bug21895
> 
>   include ../Rules
> 
>   $(objpfx)tst-setjmp-fp: $(libm)
> +$(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
> 
> ---
> 
> At least with qemu-static it seems to work with your patch.
> 
> 

Thanks to your help it's working now. That's exactly what I wanted.

>> 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.
> Wrong Copyright date span and missing one line description.
> 
Fixed.
>> +   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.
> Wrong Copyright date span and missing one line description.
> 
Fixed.
>> +   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);
> Better to just use name, since on test environment variable in Makefile
> change I proposed the path to build setjmp folder is already on the
> LD_LIBRARY_PATH list.
> 
>> +  if (!h) {
>> +    puts ("FAIL: ");
>> +    puts (dlerror());
>> +    return 1;
>> +  }
> Wrong indentation and please use libsupport macros.
> 

Fixed. Using libsupport now.
>> +
>> +  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"
> We do not use test-skeleton.c inclusion any longer, use libsupport
> (support/test-driver.c).
> 

Done.

>> 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.  */
> Space before tab in indent.
>

Done.

>>   	ld r21,((JB_GPRS+7)*8)(r3)
>>   	lfd fp21,((JB_FPRS+7)*8)(r3)
>>   	ld r22,((JB_GPRS+8)*8)(r3)
>> -- 2.7.4
>>


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From 989f90132a77d8f1199881d88f51384f25d452fb 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 v2] 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: 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.
	*setjmp/setjmp-bug21895.c: New test file.
	*setjmp/tst-setjmp-bug21895-static.c: New test file.
---
 Changes in v2: Per Adhemerval Zanella. Fix test fail using the suggestions
given. Fix changelog. Fix copyright and indentation for new tests. Change
tests to use libsupport instead old test-skeleton. Fix a extra space
in  __longjmp-common.

 setjmp/Makefile                              | 16 ++++++-
 setjmp/setjmp-bug21895.c                     | 44 ++++++++++++++++++
 setjmp/tst-setjmp-bug21895-static.c          | 67 ++++++++++++++++++++++++++++
 sysdeps/powerpc/powerpc64/__longjmp-common.S |  5 +--
 4 files changed, 127 insertions(+), 5 deletions(-)
 create mode 100644 setjmp/setjmp-bug21895.c
 create mode 100644 setjmp/tst-setjmp-bug21895-static.c

diff --git a/setjmp/Makefile b/setjmp/Makefile
index dc2fcc6..d70daa2 100644
--- a/setjmp/Makefile
+++ b/setjmp/Makefile
@@ -29,9 +29,23 @@ routines	:= setjmp sigjmp bsd-setjmp bsd-_setjmp \
 
 tests		:= tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \
 		   tst-sigsetjmp tst-setjmp-static
-tests-static	:= tst-setjmp-static
 
+tests-static	:= tst-setjmp-static tst-setjmp-bug21895-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)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
diff --git a/setjmp/setjmp-bug21895.c b/setjmp/setjmp-bug21895.c
new file mode 100644
index 0000000..f8f3016
--- /dev/null
+++ b/setjmp/setjmp-bug21895.c
@@ -0,0 +1,44 @@
+/* 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 <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-static.c b/setjmp/tst-setjmp-bug21895-static.c
new file mode 100644
index 0000000..5338499
--- /dev/null
+++ b/setjmp/tst-setjmp-bug21895-static.c
@@ -0,0 +1,67 @@
+/* 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>
+
+static void
+bar (jmp_buf jb)
+{
+  static int i;
+  if (i++==1)
+    exit(0);	/* Success.  */
+
+  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) = dlsym(h, "bar");
+  if (!ppbar)
+    {
+      puts(dlerror());
+      return 1;
+    }
+
+  *ppbar = bar;
+  pfoo();
+
+  for(;;);
+}
+
+/* Make sure the test will not stuck if jmp fails and fall into one of
+   for(;;).  */
+#define TIMEOUT 100
+#include <support/test-driver.c>
diff --git a/sysdeps/powerpc/powerpc64/__longjmp-common.S b/sysdeps/powerpc/powerpc64/__longjmp-common.S
index 0e10b8d..99c17c5 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