Community source repository for glibc add-on ports branch, master, updated. glibc-2.11-87-g2dcd7ed

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Thu Apr 8 16:47:00 GMT 2010


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- Log -----------------------------------------------------------------
http://sources.redhat.com/git/gitweb.cgi?p=glibc-ports.git;a=commitdiff;h=2dcd7ed8fd149a5aefc8c7a7ff041ff389348b4f

commit 2dcd7ed8fd149a5aefc8c7a7ff041ff389348b4f
Author: Daniel Jacobowitz <dan@codesourcery.com>
Date:   Thu Apr 8 12:43:55 2010 -0400

    Fix unwinding through Thumb-2 system calls.

diff --git a/ChangeLog.arm b/ChangeLog.arm
index d13f4a3..363b865 100644
--- a/ChangeLog.arm
+++ b/ChangeLog.arm
@@ -1,3 +1,12 @@
+2010-04-08  Daniel Jacobowitz  <dan@codesourcery.com>
+
+	* sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S: New file.
+	* sysdeps/unix/sysv/linux/arm/eabi/sysdep.h [__thumb__]
+	(INTERNAL_SYSCALL_RAW): Rewrite to use __libc_do_syscall.
+	* sysdeps/unix/sysv/linux/arm/eabi/Makefile: Add libc-do-syscall
+	to libraries and tests that require it.
+	* sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h: Delete.
+
 2010-03-30  Joseph Myers  <joseph@codesourcery.com>
 
 	* sysdeps/arm/dl-machine.h (VALID_ELF_ABIVERSION, VALID_ELF_OSABI,
diff --git a/sysdeps/unix/sysv/linux/arm/eabi/Makefile b/sysdeps/unix/sysv/linux/arm/eabi/Makefile
index 9f2b0fe..761c964 100644
--- a/sysdeps/unix/sysv/linux/arm/eabi/Makefile
+++ b/sysdeps/unix/sysv/linux/arm/eabi/Makefile
@@ -7,3 +7,34 @@ ifeq ($(subdir),csu)
 # unwind tables for __libc_start_main.
 CFLAGS-libc-start.c += -fexceptions
 endif
+
+# Add a syscall function to each library that needs one.
+
+ifeq ($(subdir),rt)
+librt-sysdep_routines += libc-do-syscall
+librt-shared-only-routines += libc-do-syscall
+endif
+
+ifeq ($(subdir),nptl)
+libpthread-sysdep_routines += libc-do-syscall
+libpthread-shared-only-routines += libc-do-syscall
+endif
+
+ifeq ($(subdir),resolv)
+libanl-sysdep_routines += libc-do-syscall
+libanl-shared-only-routines += libc-do-syscall
+endif
+
+ifeq ($(subdir),csu)
+sysdep_routines += libc-do-syscall
+endif
+
+ifeq ($(subdir),nscd)
+nscd-modules += libc-do-syscall
+endif
+
+ifeq ($(subdir),posix)
+LDFLAGS-tst-rfc3484 += $(common-objpfx)csu/libc-do-syscall.o
+LDFLAGS-tst-rfc3484-2 += $(common-objpfx)csu/libc-do-syscall.o
+LDFLAGS-tst-rfc3484-3 += $(common-objpfx)csu/libc-do-syscall.o
+endif
diff --git a/sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S b/sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S
new file mode 100644
index 0000000..d461712
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S
@@ -0,0 +1,43 @@
+/* Copyright (C) 2010 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <sysdep.h>
+
+/* Out-of-line syscall stub.  We expect the system call number in ip
+   and return the raw result in r0.  No registers are clobbered.
+   We could avoid using the stack for this, but the goal is accurate
+   unwind information - and while there is a reserved prefix in the
+   ARM unwind tables for register to register moves, the actual opcodes
+   are not defined.  */
+
+	.thumb
+	.syntax unified
+	.hidden __libc_do_syscall
+
+ENTRY (__libc_do_syscall)
+	.fnstart
+	push	{r7, lr}
+	.save	{r7, lr}
+	cfi_adjust_cfa_offset (8)
+	cfi_rel_offset (r7, 0)
+	cfi_rel_offset (lr, 4)
+	mov	r7, ip
+	swi	0x0
+	pop	{r7, pc}
+	.fnend
+END (__libc_do_syscall)
diff --git a/sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h b/sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h
deleted file mode 100644
index 3fb1ec9..0000000
--- a/sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h
+++ /dev/null
@@ -1,52 +0,0 @@
-/* Copyright (C) 2008 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, write to the Free
-   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
-   02111-1307 USA.  */
-
-#include_next <aio_misc.h>
-
-#ifdef __thumb2__
-
-#include <errno.h>
-
-/* The Thumb-2 definition of INTERNAL_SYSCALL_RAW has to hide the use
-   of r7 from the compiler because it cannot handle asm clobbering the
-   hard frame pointer.  In aio_suspend, GCC does not eliminate the
-   hard frame pointer because the function uses variable-length
-   arrays, so it generates unwind information using r7 as virtual
-   stack pointer.  During system calls, when r7 has been saved on the
-   stack, this means the unwind information is invalid.  Without extra
-   unwind directives, which would need to cause unwind information for
-   the asm to be generated separately from that for the parts of the
-   function before and after the asm (with three index table entries),
-   it is not possible to represent any temporary change to the virtual
-   stack pointer.  Instead, we move the problematic system calls out
-   of line into a function that does not require a frame pointer.  */
-
-static __attribute_noinline__ void
-aio_misc_wait (int *resultp,
-	       volatile int *futexp,
-	       const struct timespec *timeout,
-	       int cancel)
-{
-  AIO_MISC_WAIT (*resultp, *futexp, timeout, cancel);
-}
-
-#undef AIO_MISC_WAIT
-#define AIO_MISC_WAIT(result, futex, timeout, cancel)	\
-  aio_misc_wait (&result, &futex, timeout, cancel)
-
-#endif
diff --git a/sysdeps/unix/sysv/linux/arm/eabi/sysdep.h b/sysdeps/unix/sysv/linux/arm/eabi/sysdep.h
index 9d90f3e..b7815ba 100644
--- a/sysdeps/unix/sysv/linux/arm/eabi/sysdep.h
+++ b/sysdeps/unix/sysv/linux/arm/eabi/sysdep.h
@@ -44,30 +44,34 @@
    argument; otherwise the (optional) compatibility code for APCS binaries
    may be invoked.  */
 
-#ifdef __thumb__
-/* Hide the use of r7 from the compiler, this would be a lot
-   easier but for the fact that the syscalls can exceed 255.
-   For the moment the LOAD_ARGS_7 is sacrificed.
+#if defined(__thumb__)
+/* We can not expose the use of r7 to the compiler.  GCC (as
+   of 4.5) uses r7 as the hard frame pointer for Thumb - although
+   for Thumb-2 it isn't obviously a better choice than r11.
+   And GCC does not support asms that conflict with the frame
+   pointer.
+
+   This would be easier if syscall numbers never exceeded 255,
+   but they do.  For the moment the LOAD_ARGS_7 is sacrificed.
    We can't use push/pop inside the asm because that breaks
-   unwinding (ie. thread cancellation).  */
-/* FIXME: the str / ldr of r7 are not covered by CFI information.  */
+   unwinding (i.e. thread cancellation) for this frame.  We can't
+   locally save and restore r7, because we do not know if this
+   function uses r7 or if it is our caller's r7; if it is our caller's,
+   then unwinding will fail higher up the stack.  So we move the
+   syscall out of line and provide its own unwind information.  */
 #undef LOAD_ARGS_7
 #undef INTERNAL_SYSCALL_RAW
 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)		\
   ({								\
-      int _sys_buf[2];						\
       register int _a1 asm ("a1");				\
-      register int *_r6 asm ("r6") = _sys_buf;			\
-      *_r6 = name;						\
+      int _nametmp = name;					\
       LOAD_ARGS_##nr (args)					\
-      asm volatile ("str        r7, [r6, #4]\n\t"		\
-                    "ldr      r7, [r6]\n\t"			\
-                    "swi      0       @ syscall " #name "\n\t"	\
-                    "ldr      r7, [r6, #4]"			\
-                   : "=r" (_a1)					\
-                    : "r" (_r6) ASM_ARGS_##nr			\
-                    : "memory");				\
-       _a1; })
+      register int _name asm ("ip") = _nametmp;			\
+      asm volatile ("bl      __libc_do_syscall"			\
+                    : "=r" (_a1)				\
+                    : "r" (_name) ASM_ARGS_##nr			\
+                    : "memory", "lr");				\
+      _a1; })
 #else /* ARM */
 #undef INTERNAL_SYSCALL_RAW
 #define INTERNAL_SYSCALL_RAW(name, err, nr, args...)		\

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog.arm                                      |    9 +++
 sysdeps/unix/sysv/linux/arm/eabi/Makefile          |   31 ++++++++++++
 .../nptl/fork.c => arm/eabi/libc-do-syscall.S}     |   31 ++++++++---
 sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h   |   52 --------------------
 sysdeps/unix/sysv/linux/arm/eabi/sysdep.h          |   38 ++++++++------
 5 files changed, 83 insertions(+), 78 deletions(-)
 copy sysdeps/unix/sysv/linux/{m68k/nptl/fork.c => arm/eabi/libc-do-syscall.S} (58%)
 delete mode 100644 sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h


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