1/*
2 * Copyright 2015-2022 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (the "License").  You may not use
5 * this file except in compliance with the License.  You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10#ifndef OSSL_CRYPTO_ASYNC_POSIX_H
11#define OSSL_CRYPTO_ASYNC_POSIX_H
12#include <openssl/e_os2.h>
13
14#if defined(OPENSSL_SYS_UNIX) \
15    && defined(OPENSSL_THREADS) && !defined(OPENSSL_NO_ASYNC) \
16    && !defined(__ANDROID__) && !defined(__OpenBSD__)
17
18# include <unistd.h>
19
20# if _POSIX_VERSION >= 200112L \
21     && (_POSIX_VERSION < 200809L || defined(__GLIBC__))
22
23# include <pthread.h>
24
25#  define ASYNC_POSIX
26#  define ASYNC_ARCH
27
28#  if defined(__CET__) || defined(__ia64__)
29/*
30 * When Intel CET is enabled, makecontext will create a different
31 * shadow stack for each context.  async_fibre_swapcontext cannot
32 * use _longjmp.  It must call swapcontext to swap shadow stack as
33 * well as normal stack.
34 * On IA64 the register stack engine is not saved across setjmp/longjmp. Here
35 * swapcontext() performs correctly.
36 */
37#   define USE_SWAPCONTEXT
38#  endif
39#  if defined(__aarch64__) && defined(__clang__) \
40    && defined(__ARM_FEATURE_BTI_DEFAULT) && __ARM_FEATURE_BTI_DEFAULT == 1
41/*
42 * setjmp/longjmp don't currently work with BTI on all libc implementations
43 * when compiled by clang. This is because clang doesn't put a BTI after the
44 * call to setjmp where it returns the second time. This then fails on libc
45 * implementations - notably glibc - which use an indirect jump to there.
46 * So use the swapcontext implementation, which does work.
47 * See https://github.com/llvm/llvm-project/issues/48888.
48 */
49#   define USE_SWAPCONTEXT
50#  endif
51#  include <ucontext.h>
52#  ifndef USE_SWAPCONTEXT
53#   include <setjmp.h>
54#  endif
55
56typedef struct async_fibre_st {
57    ucontext_t fibre;
58#  ifndef USE_SWAPCONTEXT
59    jmp_buf env;
60    int env_init;
61#  endif
62} async_fibre;
63
64static ossl_inline int async_fibre_swapcontext(async_fibre *o, async_fibre *n, int r)
65{
66#  ifdef USE_SWAPCONTEXT
67    swapcontext(&o->fibre, &n->fibre);
68#  else
69    o->env_init = 1;
70
71    if (!r || !_setjmp(o->env)) {
72        if (n->env_init)
73            _longjmp(n->env, 1);
74        else
75            setcontext(&n->fibre);
76    }
77#  endif
78
79    return 1;
80}
81
82#  define async_fibre_init_dispatcher(d)
83
84int async_fibre_makecontext(async_fibre *fibre);
85void async_fibre_free(async_fibre *fibre);
86
87# endif
88#endif
89#endif /* OSSL_CRYPTO_ASYNC_POSIX_H */
90