[RFC] powerpc: restore TOC when static longjmp to shared object
Rogerio Alves
rcardoso@linux.vnet.ibm.com
Tue May 22 18:41:00 GMT 2018
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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