1*677a88ceSIan Lepore /*-
2*677a88ceSIan Lepore * Copyright (c) 2014 Ian Lepore <ian@freebsd.org>
3*677a88ceSIan Lepore * All rights reserved.
4*677a88ceSIan Lepore *
5*677a88ceSIan Lepore * Redistribution and use in source and binary forms, with or without
6*677a88ceSIan Lepore * modification, are permitted provided that the following conditions
7*677a88ceSIan Lepore * are met:
8*677a88ceSIan Lepore * 1. Redistributions of source code must retain the above copyright
9*677a88ceSIan Lepore * notice, this list of conditions and the following disclaimer.
10*677a88ceSIan Lepore * 2. Redistributions in binary form must reproduce the above copyright
11*677a88ceSIan Lepore * notice, this list of conditions and the following disclaimer in the
12*677a88ceSIan Lepore * documentation and/or other materials provided with the distribution.
13*677a88ceSIan Lepore *
14*677a88ceSIan Lepore * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15*677a88ceSIan Lepore * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16*677a88ceSIan Lepore * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17*677a88ceSIan Lepore * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18*677a88ceSIan Lepore * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19*677a88ceSIan Lepore * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20*677a88ceSIan Lepore * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21*677a88ceSIan Lepore * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22*677a88ceSIan Lepore * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23*677a88ceSIan Lepore * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24*677a88ceSIan Lepore * SUCH DAMAGE.
25*677a88ceSIan Lepore */
26*677a88ceSIan Lepore
27*677a88ceSIan Lepore #include <sys/types.h>
28*677a88ceSIan Lepore #include <machine/elf.h>
29*677a88ceSIan Lepore #include <link.h>
30*677a88ceSIan Lepore #include <stddef.h>
31*677a88ceSIan Lepore
32*677a88ceSIan Lepore /*
33*677a88ceSIan Lepore * ARM EABI unwind helper.
34*677a88ceSIan Lepore *
35*677a88ceSIan Lepore * This finds the exidx section address and size associated with a given code
36*677a88ceSIan Lepore * address. There are separate implementations for static and dynamic code.
37*677a88ceSIan Lepore *
38*677a88ceSIan Lepore * GCC expects this function to exist as __gnu_Unwind_Find_exidx(), clang and
39*677a88ceSIan Lepore * BSD tools expect it to be dl_unwind_find_exidx(). Both have the same API, so
40*677a88ceSIan Lepore * we set up an alias for GCC.
41*677a88ceSIan Lepore */
42*677a88ceSIan Lepore __strong_reference(dl_unwind_find_exidx, __gnu_Unwind_Find_exidx);
43*677a88ceSIan Lepore
44*677a88ceSIan Lepore /*
45*677a88ceSIan Lepore * Each entry in the exidx section is a pair of 32-bit words. We don't
46*677a88ceSIan Lepore * interpret the contents of the entries here; this typedef is just a local
47*677a88ceSIan Lepore * convenience for using sizeof() and doing pointer math.
48*677a88ceSIan Lepore */
49*677a88ceSIan Lepore typedef struct exidx_entry {
50*677a88ceSIan Lepore uint32_t data[2];
51*677a88ceSIan Lepore } exidx_entry;
52*677a88ceSIan Lepore
53*677a88ceSIan Lepore #ifdef __PIC__
54*677a88ceSIan Lepore
55*677a88ceSIan Lepore /*
56*677a88ceSIan Lepore * Unwind helper for dynamically linked code.
57*677a88ceSIan Lepore *
58*677a88ceSIan Lepore * This finds the shared object that contains the given address, and returns the
59*677a88ceSIan Lepore * address of the exidx section in that shared object along with the number of
60*677a88ceSIan Lepore * entries in that section, or NULL if it wasn't found.
61*677a88ceSIan Lepore */
62*677a88ceSIan Lepore void *
dl_unwind_find_exidx(const void * pc,int * pcount)63*677a88ceSIan Lepore dl_unwind_find_exidx(const void *pc, int *pcount)
64*677a88ceSIan Lepore {
65*677a88ceSIan Lepore const Elf_Phdr *hdr;
66*677a88ceSIan Lepore struct dl_phdr_info info;
67*677a88ceSIan Lepore int i;
68*677a88ceSIan Lepore
69*677a88ceSIan Lepore if (_rtld_addr_phdr(pc, &info)) {
70*677a88ceSIan Lepore hdr = info.dlpi_phdr;
71*677a88ceSIan Lepore for (i = 0; i < info.dlpi_phnum; i++, hdr++) {
72*677a88ceSIan Lepore if (hdr->p_type == PT_ARM_EXIDX) {
73*677a88ceSIan Lepore *pcount = hdr->p_memsz / sizeof(exidx_entry);
74*677a88ceSIan Lepore return ((void *)(info.dlpi_addr + hdr->p_vaddr));
75*677a88ceSIan Lepore }
76*677a88ceSIan Lepore }
77*677a88ceSIan Lepore }
78*677a88ceSIan Lepore return (NULL);
79*677a88ceSIan Lepore }
80*677a88ceSIan Lepore
81*677a88ceSIan Lepore #else /* !__PIC__ */
82*677a88ceSIan Lepore
83*677a88ceSIan Lepore /*
84*677a88ceSIan Lepore * Unwind helper for statically linked code.
85*677a88ceSIan Lepore *
86*677a88ceSIan Lepore * In a statically linked program, the linker populates a pair of symbols with
87*677a88ceSIan Lepore * the addresses of the start and end of the exidx table, so returning the
88*677a88ceSIan Lepore * address and count of elements is pretty straighforward.
89*677a88ceSIan Lepore */
90*677a88ceSIan Lepore void *
dl_unwind_find_exidx(const void * pc,int * pcount)91*677a88ceSIan Lepore dl_unwind_find_exidx(const void *pc, int *pcount)
92*677a88ceSIan Lepore {
93*677a88ceSIan Lepore extern struct exidx_entry __exidx_start;
94*677a88ceSIan Lepore extern struct exidx_entry __exidx_end;
95*677a88ceSIan Lepore
96*677a88ceSIan Lepore *pcount = (int)(&__exidx_end - &__exidx_start);
97*677a88ceSIan Lepore return (&__exidx_start);
98*677a88ceSIan Lepore }
99*677a88ceSIan Lepore
100*677a88ceSIan Lepore #endif /* __PIC__ */
101*677a88ceSIan Lepore
102