0c75ebaad0
If Thumb code is being generated and frame pointers are enabled, the Thumb frame pointer in r7 clashes with any local variable which may need to be assigned to r7 (e.g. the syscall NR when making a raw syscall). With gcc, the double use of r7 results in a build error, e.g. strace-4.22/tests/inject-nf.c:86:1: error: r7 cannot be used in asm here With clang, the double use of r7 can result in the compiler silently generating broken code which crashes at run time due to frame pointer corruption: https://bugs.llvm.org/show_bug.cgi?id=34165 In most cases the problem isn't visible as frame pointers will be disabled automatically due to optimisation level. However to handle cases where frame pointers are enabled (e.g. when CFLAGS etc are set to support a debug build, etc) provide a version of raw_syscall_0 which manually saves and restores the frame pointer value in r7 to a temporary register before setting up the syscall NR in r7 and invoking the syscall. * linux/arm/raw_syscall.h (raw_syscall_0) [__thumb__]: Provide an alternative version. Signed-off-by: Andre McCurdy <armccurdy@gmail.com>
65 lines
2.2 KiB
C
65 lines
2.2 KiB
C
/*
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* Raw syscalls.
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*
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* Copyright (c) 2018 The strace developers.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef STRACE_RAW_SYSCALL_H
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#define STRACE_RAW_SYSCALL_H
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# include "kernel_types.h"
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static inline kernel_ulong_t
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raw_syscall_0(const kernel_ulong_t nr, kernel_ulong_t *err)
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{
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*err = 0;
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#ifdef __thumb__ /* && FRAME_POINTERS_ENABLED */
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register kernel_ulong_t rt;
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register kernel_ulong_t r0 __asm__("r0");
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__asm__ __volatile__("mov %1,r7; mov r7,%2; swi 0x0; mov r7,%1"
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: "=r"(r0), "=&r"(rt)
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: "r"(nr)
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: "memory");
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#else
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register kernel_ulong_t r7 __asm__("r7") = nr;
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register kernel_ulong_t r0 __asm__("r0");
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__asm__ __volatile__("swi 0x0"
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: "=r"(r0)
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: "r"(r7)
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: "memory");
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#endif
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return r0;
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}
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# define raw_syscall_0 raw_syscall_0
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#endif /* !STRACE_RAW_SYSCALL_H */
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