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Re: [RFC] powerpc: restore TOC when static longjmp to shared object
- From: Rogerio Alves <rcardoso at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Tue, 22 May 2018 15:40:54 -0300
- Subject: Re: [RFC] powerpc: restore TOC when static longjmp to shared object
- References: <f88767a0-1a38-564d-7bd8-0b5db5bc04df@linux.vnet.ibm.com>
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
>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