105 lines
3.4 KiB
C
105 lines
3.4 KiB
C
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/*-
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* Copyright (c) 2014 Ian Lepore <ian@freebsd.org>
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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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <machine/elf.h>
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#include <link.h>
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#include <stddef.h>
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/*
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* ARM EABI unwind helper.
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*
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* This finds the exidx section address and size associated with a given code
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* address. There are separate implementations for static and dynamic code.
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*
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* GCC expects this function to exist as __gnu_Unwind_Find_exidx(), clang and
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* BSD tools expect it to be dl_unwind_find_exidx(). Both have the same API, so
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* we set up an alias for GCC.
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*/
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__strong_reference(dl_unwind_find_exidx, __gnu_Unwind_Find_exidx);
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/*
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* Each entry in the exidx section is a pair of 32-bit words. We don't
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* interpret the contents of the entries here; this typedef is just a local
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* convenience for using sizeof() and doing pointer math.
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*/
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typedef struct exidx_entry {
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uint32_t data[2];
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} exidx_entry;
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#ifdef __PIC__
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/*
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* Unwind helper for dynamically linked code.
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*
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* This finds the shared object that contains the given address, and returns the
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* address of the exidx section in that shared object along with the number of
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* entries in that section, or NULL if it wasn't found.
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*/
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void *
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dl_unwind_find_exidx(const void *pc, int *pcount)
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{
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const Elf_Phdr *hdr;
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struct dl_phdr_info info;
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int i;
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if (_rtld_addr_phdr(pc, &info)) {
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hdr = info.dlpi_phdr;
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for (i = 0; i < info.dlpi_phnum; i++, hdr++) {
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if (hdr->p_type == PT_ARM_EXIDX) {
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*pcount = hdr->p_memsz / sizeof(exidx_entry);
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return ((void *)(info.dlpi_addr + hdr->p_vaddr));
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}
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}
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}
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return (NULL);
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}
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#else /* !__PIC__ */
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/*
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* Unwind helper for statically linked code.
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*
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* In a statically linked program, the linker populates a pair of symbols with
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* the addresses of the start and end of the exidx table, so returning the
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* address and count of elements is pretty straighforward.
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*/
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void *
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dl_unwind_find_exidx(const void *pc, int *pcount)
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{
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extern struct exidx_entry __exidx_start;
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extern struct exidx_entry __exidx_end;
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*pcount = (int)(&__exidx_end - &__exidx_start);
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return (&__exidx_start);
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}
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#endif /* __PIC__ */
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