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Re: [RFC] powerpc: restore TOC when static longjmp to shared object
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).
>
> 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).
> *setjmp/setjmp-bug21895.c: new test file.
> *setjmp/tst-setjmp-bug21895.c: new test file.
Capitalize the new.
> ---
> 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.
> 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.
> +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.
> 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.
> + 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.
> + 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.
> +
> + 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).
> 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.
> ld r21,((JB_GPRS+7)*8)(r3)
> lfd fp21,((JB_FPRS+7)*8)(r3)
> ld r22,((JB_GPRS+8)*8)(r3)
> -- 2.7.4
>