Fix unwinding through Thumb-2 system calls.
This commit is contained in:
Daniel Jacobowitz
parent
1dbb4edc73
commit
2dcd7ed8fd
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@ -1,3 +1,12 @@
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2010-04-08 Daniel Jacobowitz <dan@codesourcery.com>
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* sysdeps/unix/sysv/linux/arm/eabi/libc-do-syscall.S: New file.
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* sysdeps/unix/sysv/linux/arm/eabi/sysdep.h [__thumb__]
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(INTERNAL_SYSCALL_RAW): Rewrite to use __libc_do_syscall.
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* sysdeps/unix/sysv/linux/arm/eabi/Makefile: Add libc-do-syscall
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to libraries and tests that require it.
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* sysdeps/unix/sysv/linux/arm/eabi/nptl/aio_misc.h: Delete.
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2010-03-30 Joseph Myers <joseph@codesourcery.com>
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* sysdeps/arm/dl-machine.h (VALID_ELF_ABIVERSION, VALID_ELF_OSABI,
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@ -7,3 +7,34 @@ ifeq ($(subdir),csu)
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# unwind tables for __libc_start_main.
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CFLAGS-libc-start.c += -fexceptions
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endif
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# Add a syscall function to each library that needs one.
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ifeq ($(subdir),rt)
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librt-sysdep_routines += libc-do-syscall
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librt-shared-only-routines += libc-do-syscall
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endif
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ifeq ($(subdir),nptl)
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libpthread-sysdep_routines += libc-do-syscall
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libpthread-shared-only-routines += libc-do-syscall
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endif
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ifeq ($(subdir),resolv)
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libanl-sysdep_routines += libc-do-syscall
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libanl-shared-only-routines += libc-do-syscall
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endif
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ifeq ($(subdir),csu)
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sysdep_routines += libc-do-syscall
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endif
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ifeq ($(subdir),nscd)
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nscd-modules += libc-do-syscall
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endif
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ifeq ($(subdir),posix)
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LDFLAGS-tst-rfc3484 += $(common-objpfx)csu/libc-do-syscall.o
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LDFLAGS-tst-rfc3484-2 += $(common-objpfx)csu/libc-do-syscall.o
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LDFLAGS-tst-rfc3484-3 += $(common-objpfx)csu/libc-do-syscall.o
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endif
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@ -0,0 +1,43 @@
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/* Copyright (C) 2010 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <sysdep.h>
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/* Out-of-line syscall stub. We expect the system call number in ip
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and return the raw result in r0. No registers are clobbered.
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We could avoid using the stack for this, but the goal is accurate
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unwind information - and while there is a reserved prefix in the
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ARM unwind tables for register to register moves, the actual opcodes
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are not defined. */
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.thumb
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.syntax unified
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.hidden __libc_do_syscall
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ENTRY (__libc_do_syscall)
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.fnstart
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push {r7, lr}
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.save {r7, lr}
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cfi_adjust_cfa_offset (8)
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cfi_rel_offset (r7, 0)
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cfi_rel_offset (lr, 4)
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mov r7, ip
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swi 0x0
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pop {r7, pc}
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.fnend
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END (__libc_do_syscall)
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@ -1,52 +0,0 @@
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/* Copyright (C) 2008 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include_next <aio_misc.h>
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#ifdef __thumb2__
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#include <errno.h>
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/* The Thumb-2 definition of INTERNAL_SYSCALL_RAW has to hide the use
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of r7 from the compiler because it cannot handle asm clobbering the
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hard frame pointer. In aio_suspend, GCC does not eliminate the
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hard frame pointer because the function uses variable-length
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arrays, so it generates unwind information using r7 as virtual
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stack pointer. During system calls, when r7 has been saved on the
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stack, this means the unwind information is invalid. Without extra
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unwind directives, which would need to cause unwind information for
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the asm to be generated separately from that for the parts of the
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function before and after the asm (with three index table entries),
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it is not possible to represent any temporary change to the virtual
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stack pointer. Instead, we move the problematic system calls out
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of line into a function that does not require a frame pointer. */
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static __attribute_noinline__ void
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aio_misc_wait (int *resultp,
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volatile int *futexp,
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const struct timespec *timeout,
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int cancel)
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{
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AIO_MISC_WAIT (*resultp, *futexp, timeout, cancel);
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}
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#undef AIO_MISC_WAIT
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#define AIO_MISC_WAIT(result, futex, timeout, cancel) \
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aio_misc_wait (&result, &futex, timeout, cancel)
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#endif
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@ -44,30 +44,34 @@
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argument; otherwise the (optional) compatibility code for APCS binaries
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may be invoked. */
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#ifdef __thumb__
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/* Hide the use of r7 from the compiler, this would be a lot
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easier but for the fact that the syscalls can exceed 255.
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For the moment the LOAD_ARGS_7 is sacrificed.
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#if defined(__thumb__)
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/* We can not expose the use of r7 to the compiler. GCC (as
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of 4.5) uses r7 as the hard frame pointer for Thumb - although
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for Thumb-2 it isn't obviously a better choice than r11.
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And GCC does not support asms that conflict with the frame
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pointer.
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This would be easier if syscall numbers never exceeded 255,
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but they do. For the moment the LOAD_ARGS_7 is sacrificed.
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We can't use push/pop inside the asm because that breaks
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unwinding (ie. thread cancellation). */
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/* FIXME: the str / ldr of r7 are not covered by CFI information. */
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unwinding (i.e. thread cancellation) for this frame. We can't
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locally save and restore r7, because we do not know if this
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function uses r7 or if it is our caller's r7; if it is our caller's,
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then unwinding will fail higher up the stack. So we move the
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syscall out of line and provide its own unwind information. */
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#undef LOAD_ARGS_7
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#undef INTERNAL_SYSCALL_RAW
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#define INTERNAL_SYSCALL_RAW(name, err, nr, args...) \
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({ \
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int _sys_buf[2]; \
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register int _a1 asm ("a1"); \
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register int *_r6 asm ("r6") = _sys_buf; \
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*_r6 = name; \
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int _nametmp = name; \
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LOAD_ARGS_##nr (args) \
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asm volatile ("str r7, [r6, #4]\n\t" \
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"ldr r7, [r6]\n\t" \
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"swi 0 @ syscall " #name "\n\t" \
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"ldr r7, [r6, #4]" \
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: "=r" (_a1) \
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: "r" (_r6) ASM_ARGS_##nr \
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: "memory"); \
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_a1; })
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register int _name asm ("ip") = _nametmp; \
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asm volatile ("bl __libc_do_syscall" \
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: "=r" (_a1) \
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: "r" (_name) ASM_ARGS_##nr \
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: "memory", "lr"); \
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_a1; })
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#else /* ARM */
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#undef INTERNAL_SYSCALL_RAW
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#define INTERNAL_SYSCALL_RAW(name, err, nr, args...) \
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