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			100 lines
		
	
	
		
			4.0 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			100 lines
		
	
	
		
			4.0 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| // Copyright 2020 Espressif Systems (Shanghai) PTE LTD
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| //
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| // Licensed under the Apache License, Version 2.0 (the "License");
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| // you may not use this file except in compliance with the License.
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| // You may obtain a copy of the License at
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| 
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| //     http://www.apache.org/licenses/LICENSE-2.0
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| //
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| // Unless required by applicable law or agreed to in writing, software
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| // distributed under the License is distributed on an "AS IS" BASIS,
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| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| // See the License for the specific language governing permissions and
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| // limitations under the License.
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| #include "sdkconfig.h"
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| #include "soc/rtc_cntl_reg.h"
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| #include "esp_rom_sys.h"
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| 
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| #pragma once
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| 
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| #ifdef __cplusplus
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| extern "C" {
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| #endif
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| 
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| /**
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|  * @brief Assert a condition is true, in a way that should be resistant to fault injection for
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|  * single fault attacks.
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|  *
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|  * - Expands CONDITION multiple times (condition must have no side effects)
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|  * - Compiler is told all registers are invalid before evaluating CONDITION each time, to avoid a fault
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|  *   causing a misread of a register used in all three evaluations of CONDITION.
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|  * - If CONDITION is ever false, a system reset is triggered.
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|  *
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|  * @note Place this macro after a "normal" check of CONDITION that will fail with a normal error
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|  * message. This is the fallback in case a fault injection attack skips or corrupts the result of
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|  * that check. (Although ensure that an attacker can't use fault injection to skip past the "normal"
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|  * error message, to avoid this check entirely.)
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|  *
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|  * @note This macro increases binary size and is slow and should be used sparingly.
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|  *
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|  * @note This macro does not guarantee fault injection resistance. In particular CONDITION must be
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|  * chosen carefully - a fault injection attack which sets CONDITION to true will not be detected by
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|  * this macro. Care must also be taken that an attacker can't use a fault to completely bypass calling
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|  * whatever function tests ESP_FAULT_ASSERT.
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|  *
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|  * @note This is difficult to debug as a failure triggers an instant software reset, and UART output
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|  * is often truncated (as FIFO is not flushed). Define the ESP_FAULT_ASSERT_DEBUG macro to debug any
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|  * failures of this macro due to software bugs.
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|  *
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|  * @param CONDITION A condition which will evaluate true unless an attacker used fault injection to skip or corrupt some other critical system calculation.
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|  *
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|  */
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| #define ESP_FAULT_ASSERT(CONDITION) do {                \
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|         asm volatile ("" ::: "memory");                 \
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|         if(!(CONDITION)) _ESP_FAULT_RESET();            \
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|         asm volatile ("" ::: "memory");                 \
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|         if(!(CONDITION)) _ESP_FAULT_RESET();            \
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|         asm volatile ("" ::: "memory");                 \
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|         if(!(CONDITION)) _ESP_FAULT_RESET();            \
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| } while(0)
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| 
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| #ifndef CONFIG_IDF_TARGET_ARCH_RISCV
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| #define _ESP_FAULT_ILLEGAL_INSTRUCTION asm volatile("ill.n; ill.n; ill.n; ill.n; ill.n; ill.n; ill.n;")
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| #else
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| #define _ESP_FAULT_ILLEGAL_INSTRUCTION asm volatile("unimp; unimp; unimp; unimp; unimp;")
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| #endif
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| 
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| // Uncomment this macro to get debug output if ESP_FAULT_ASSERT() fails
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| //
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| // Note that uncommenting this macro reduces the anti-FI effectiveness
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| //
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| //#define ESP_FAULT_ASSERT_DEBUG
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| 
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| /* Internal macro, purpose is to trigger a system reset if an inconsistency due to fault injection
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|    is detected.
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| 
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|    Illegal instruction opcodes are there as a fallback to crash the CPU in case it doesn't
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|    reset as expected.
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| */
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| #ifndef ESP_FAULT_ASSERT_DEBUG
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| 
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| #define _ESP_FAULT_RESET()  do {                                \
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|         REG_WRITE(RTC_CNTL_OPTIONS0_REG, RTC_CNTL_SW_SYS_RST);  \
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|         _ESP_FAULT_ILLEGAL_INSTRUCTION;                         \
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|     } while(0)
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| 
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| #else // ESP_FAULT_ASSERT_DEBUG
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| 
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| #warning "Enabling ESP_FAULT_ASSERT_DEBUG makes ESP_FAULT_ASSERT() less effective"
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| 
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| #define _ESP_FAULT_RESET()  do {                                        \
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|         esp_rom_printf("ESP_FAULT_ASSERT %s:%d\n", __FILE__, __LINE__); \
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|         _ESP_FAULT_ILLEGAL_INSTRUCTION;                                 \
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|     } while(0)
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| 
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| #endif // ESP_FAULT_ASSERT_DEBUG
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| 
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| #ifdef __cplusplus
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| }
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| #endif
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