[RFC] powerpc: restore TOC when static longjmp to shared object
Commit Message
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.
>
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
@@ -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)
new file mode 100644
@@ -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(;;);
+}
new file mode 100644
@@ -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"
@@ -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