1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include "private/bionic_call_ifunc_resolver.h"
30 #include <sys/auxv.h>
31 #include <sys/hwprobe.h>
32 #include <sys/ifunc.h>
33
34 #include "bionic/macros.h"
35 #include "private/bionic_auxv.h"
36
37 // This code is called in the linker before it has been relocated, so minimize calls into other
38 // parts of Bionic. In particular, we won't ever have two ifunc resolvers called concurrently, so
39 // initializing the ifunc resolver argument doesn't need to be thread-safe.
40
__bionic_call_ifunc_resolver(ElfW (Addr)resolver_addr)41 ElfW(Addr) __bionic_call_ifunc_resolver(ElfW(Addr) resolver_addr) {
42 #if defined(__aarch64__)
43 typedef ElfW(Addr) (*ifunc_resolver_t)(uint64_t, __ifunc_arg_t*);
44 BIONIC_USED_BEFORE_LINKER_RELOCATES static __ifunc_arg_t arg;
45 BIONIC_USED_BEFORE_LINKER_RELOCATES static bool initialized = false;
46 if (!initialized) {
47 initialized = true;
48 arg._size = sizeof(__ifunc_arg_t);
49 arg._hwcap = getauxval(AT_HWCAP);
50 arg._hwcap2 = getauxval(AT_HWCAP2);
51 }
52 return reinterpret_cast<ifunc_resolver_t>(resolver_addr)(arg._hwcap | _IFUNC_ARG_HWCAP, &arg);
53 #elif defined(__arm__)
54 typedef ElfW(Addr) (*ifunc_resolver_t)(unsigned long);
55 static unsigned long hwcap = getauxval(AT_HWCAP);
56 return reinterpret_cast<ifunc_resolver_t>(resolver_addr)(hwcap);
57 #elif defined(__riscv)
58 // The third argument is currently unused, but reserved for future
59 // expansion. If we pass nullptr from the beginning, it'll be easier
60 // to recognize if/when we pass actual data (and matches glibc).
61 typedef ElfW(Addr) (*ifunc_resolver_t)(uint64_t, __riscv_hwprobe_t, void*);
62 static uint64_t hwcap = getauxval(AT_HWCAP);
63 return reinterpret_cast<ifunc_resolver_t>(resolver_addr)(hwcap, __riscv_hwprobe, nullptr);
64 #else
65 typedef ElfW(Addr) (*ifunc_resolver_t)(void);
66 return reinterpret_cast<ifunc_resolver_t>(resolver_addr)();
67 #endif
68 }
69