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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: Florian Weimer <fweimer at redhat dot com>, Alexander Monakov <amonakov at ispras dot ru>
- Cc: libc-alpha at sourceware dot org
- Date: Thu, 21 Jun 2018 16:14:14 -0300
- Subject: Re: [RFC] powerpc: restore TOC when static longjmp to shared object
- References: <f88767a0-1a38-564d-7bd8-0b5db5bc04df@linux.vnet.ibm.com> <4c67a306-d447-1158-1b92-22ed1cfcfa0a@linux.vnet.ibm.com> <alpine.LNX.2.20.13.1805231219280.27433@monopod.intra.ispras.ru> <8ac334c6-bcf4-7c72-8d28-900fdd3b0bc4@linux.vnet.ibm.com> <alpine.LNX.2.20.13.1805231637590.27433@monopod.intra.ispras.ru> <2b5a4221-f766-0f57-1aa5-94991c4dfa8e@linux.vnet.ibm.com> <4de7760b-04a9-855c-34ac-1565c5532fb9@linux.vnet.ibm.com> <90c62dd8-876c-81d9-c816-ede6882b8e70@redhat.com>
Hi Florian,
I've make the changes you asked for. Thank you for your review. Patch v4
is attached.
Regards
Em 04-06-2018 11:38, Florian Weimer escreveu:
On 06/04/2018 04:34 PM, Rogerio Alves wrote:
diff --git a/setjmp/tst-setjmp-bug21895-static.c
b/setjmp/tst-setjmp-bug21895-static.c
new file mode 100644
index 0000000..6ab5340
--- /dev/null
+++ b/setjmp/tst-setjmp-bug21895-static.c
+ /* Destroy TOC area on caller frame. */
+ asm volatile(
+ "li 14, 0\n\t"
+ "std 14, 24(%0)"
+ :
+ : "r" (jb->__jmpbuf[20])
+ );
Sorry, this test is now very POWER-specific and needs to be moved into a
POWER sysdeps directory (preferably the most generic one where the test
is expected to be valid and pass).
Thanks,
Florian
>From da7c3e786e34390d9c2edda44333209076df995f 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 v4] 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.
*sysdeps/powerpc/powerpc64/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.
*sysdeps/powerpc/powerpc64/setjmp-bug21895.c: New test file.
*sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c: New test file.
---
Changes in v4: Per Florian and Tulio review. The tests now uses inline
asm specific for Power so the tests was moved to
sysdep/powerpc/powerpc64.
Changes in v3: as pointed out by Alexander Monakov we can't rely on
alloca/memset since gcc can optimize this out or it can save the
registers on the stack and the test will no longer make sense. Now I use
a small asm code to deliberately overwrite TOC area on caller frame with
zero. If the TOC is not restored by longjmp the test will fail.
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.
sysdeps/powerpc/powerpc64/Makefile | 12 ++++
sysdeps/powerpc/powerpc64/__longjmp-common.S | 5 +-
sysdeps/powerpc/powerpc64/setjmp-bug21895.c | 52 ++++++++++++++
.../powerpc/powerpc64/tst-setjmp-bug21895-static.c | 81 ++++++++++++++++++++++
5 files changed, 146 insertions(+), 5 deletions(-)
create mode 100644 sysdeps/powerpc/powerpc64/setjmp-bug21895.c
create mode 100644 sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c
diff --git a/sysdeps/powerpc/powerpc64/Makefile b/sysdeps/powerpc/powerpc64/Makefile
index 9d15db0..a0bd0c9 100644
--- a/sysdeps/powerpc/powerpc64/Makefile
+++ b/sysdeps/powerpc/powerpc64/Makefile
@@ -47,3 +47,15 @@ ifeq ($(subdir),gmon)
CFLAGS-mcount.c += $(no-special-regs)
sysdep_routines += ppc-mcount
endif
+
+ifeq ($(subdir),setjmp)
+tests += tst-setjmp-bug21895-static
+tests-static += tst-setjmp-bug21895-static
+modules-names += setjmp-bug21895
+
+$(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
+endif
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)
diff --git a/sysdeps/powerpc/powerpc64/setjmp-bug21895.c b/sysdeps/powerpc/powerpc64/setjmp-bug21895.c
new file mode 100644
index 0000000..9e65f23
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/setjmp-bug21895.c
@@ -0,0 +1,52 @@
+/* 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 <string.h>
+#include <setjmp.h>
+
+/* Copy r1 adress to a local variable. */
+#define GET_STACK_POINTER(sp) \
+ ({ \
+ asm volatile ("mr %0, 1\n\t" \
+ : "=r" (sp) \
+ ); \
+ })
+
+jmp_buf jb;
+void (*bar)(jmp_buf, unsigned long);
+
+void
+lbar (unsigned long sp)
+{
+ bar(jb, sp);
+ for(;;);
+}
+
+void
+foo (void)
+{
+ unsigned long sp;
+ /* Copy r1 (stack pointer) to sp. It will be use later to get
+ TOC area. */
+ GET_STACK_POINTER(sp);
+ setjmp(jb);
+ lbar(sp);
+
+ for(;;);
+}
diff --git a/sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c b/sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c
new file mode 100644
index 0000000..235ba50
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/tst-setjmp-bug21895-static.c
@@ -0,0 +1,81 @@
+/* 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>
+
+/* Set TOC area pointed by sp to zero. */
+#define SET_TOC_TO_ZERO(sp) \
+ ({ \
+ unsigned int zero = 0; \
+ asm volatile( \
+ "std %0, 24(%1)\n\t" \
+ :: "r" (zero), "r" (sp) \
+ ); \
+ })
+
+static void
+bar (jmp_buf jb, unsigned long sp)
+{
+ static int i;
+ if (i++==1)
+ exit(0); /* Success. */
+
+ /* This will set TOC are on caller frame (foo) to zero. __longjmp
+ must restore r2 otherwise a segmentation fault will happens after
+ it jumps back to foo. */
+ SET_TOC_TO_ZERO(sp);
+ 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, unsigned long) = 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>
--
2.7.4