1 /** 2 * \file timing.h 3 * 4 * \brief Portable interface to timeouts and to the CPU cycle counter 5 */ 6 /* 7 * Copyright The Mbed TLS Contributors 8 * SPDX-License-Identifier: Apache-2.0 9 * 10 * Licensed under the Apache License, Version 2.0 (the "License"); you may 11 * not use this file except in compliance with the License. 12 * You may obtain a copy of the License at 13 * 14 * http://www.apache.org/licenses/LICENSE-2.0 15 * 16 * Unless required by applicable law or agreed to in writing, software 17 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 18 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 19 * See the License for the specific language governing permissions and 20 * limitations under the License. 21 */ 22 #ifndef MBEDTLS_TIMING_H 23 #define MBEDTLS_TIMING_H 24 25 #if !defined(MBEDTLS_CONFIG_FILE) 26 #include "mbedtls/config.h" 27 #else 28 #include MBEDTLS_CONFIG_FILE 29 #endif 30 31 #include <stdint.h> 32 33 #ifdef __cplusplus 34 extern "C" { 35 #endif 36 37 #if !defined(MBEDTLS_TIMING_ALT) 38 // Regular implementation 39 // 40 41 /** 42 * \brief timer structure 43 */ 44 struct mbedtls_timing_hr_time 45 { 46 unsigned char opaque[32]; 47 }; 48 49 /** 50 * \brief Context for mbedtls_timing_set/get_delay() 51 */ 52 typedef struct mbedtls_timing_delay_context 53 { 54 struct mbedtls_timing_hr_time timer; 55 uint32_t int_ms; 56 uint32_t fin_ms; 57 } mbedtls_timing_delay_context; 58 59 #else /* MBEDTLS_TIMING_ALT */ 60 #include "timing_alt.h" 61 #endif /* MBEDTLS_TIMING_ALT */ 62 63 extern volatile int mbedtls_timing_alarmed; 64 65 /** 66 * \brief Return the CPU cycle counter value 67 * 68 * \warning This is only a best effort! Do not rely on this! 69 * In particular, it is known to be unreliable on virtual 70 * machines. 71 * 72 * \note This value starts at an unspecified origin and 73 * may wrap around. 74 */ 75 unsigned long mbedtls_timing_hardclock( void ); 76 77 /** 78 * \brief Return the elapsed time in milliseconds 79 * 80 * \param val points to a timer structure 81 * \param reset If 0, query the elapsed time. Otherwise (re)start the timer. 82 * 83 * \return Elapsed time since the previous reset in ms. When 84 * restarting, this is always 0. 85 * 86 * \note To initialize a timer, call this function with reset=1. 87 * 88 * Determining the elapsed time and resetting the timer is not 89 * atomic on all platforms, so after the sequence 90 * `{ get_timer(1); ...; time1 = get_timer(1); ...; time2 = 91 * get_timer(0) }` the value time1+time2 is only approximately 92 * the delay since the first reset. 93 */ 94 unsigned long mbedtls_timing_get_timer( struct mbedtls_timing_hr_time *val, int reset ); 95 96 /** 97 * \brief Setup an alarm clock 98 * 99 * \param seconds delay before the "mbedtls_timing_alarmed" flag is set 100 * (must be >=0) 101 * 102 * \warning Only one alarm at a time is supported. In a threaded 103 * context, this means one for the whole process, not one per 104 * thread. 105 */ 106 void mbedtls_set_alarm( int seconds ); 107 108 /** 109 * \brief Set a pair of delays to watch 110 * (See \c mbedtls_timing_get_delay().) 111 * 112 * \param data Pointer to timing data. 113 * Must point to a valid \c mbedtls_timing_delay_context struct. 114 * \param int_ms First (intermediate) delay in milliseconds. 115 * The effect if int_ms > fin_ms is unspecified. 116 * \param fin_ms Second (final) delay in milliseconds. 117 * Pass 0 to cancel the current delay. 118 * 119 * \note To set a single delay, either use \c mbedtls_timing_set_timer 120 * directly or use this function with int_ms == fin_ms. 121 */ 122 void mbedtls_timing_set_delay( void *data, uint32_t int_ms, uint32_t fin_ms ); 123 124 /** 125 * \brief Get the status of delays 126 * (Memory helper: number of delays passed.) 127 * 128 * \param data Pointer to timing data 129 * Must point to a valid \c mbedtls_timing_delay_context struct. 130 * 131 * \return -1 if cancelled (fin_ms = 0), 132 * 0 if none of the delays are passed, 133 * 1 if only the intermediate delay is passed, 134 * 2 if the final delay is passed. 135 */ 136 int mbedtls_timing_get_delay( void *data ); 137 138 #if defined(MBEDTLS_SELF_TEST) 139 /** 140 * \brief Checkup routine 141 * 142 * \return 0 if successful, or 1 if a test failed 143 */ 144 int mbedtls_timing_self_test( int verbose ); 145 #endif 146 147 #ifdef __cplusplus 148 } 149 #endif 150 151 #endif /* timing.h */ 152