Added memory access type for mmu

src/cpu/rv32cpu.c

@@ -682,7 +682,7 @@ __attribute__((noreturn)) void cpu_loop(rv32_cpu_t* cpu)
 {
 	while(1)
 	{
-		// Aquire CPU and memory mutex
+		// Aquire CPU mutex
 		pthread_mutex_lock(&cpu0_mutex);
 
 		// No simulation ticks left : wakeup people waiting on sim end
@@ -692,8 +692,6 @@ __attribute__((noreturn)) void cpu_loop(rv32_cpu_t* cpu)
 		while(!cpu->sim_ticks_left)
 			pthread_cond_wait(&cpu0->sim_condition, &cpu0_mutex);
 
-		// pthread_mutex_lock(&memory_mutex);
-
 		// Fetch
 		raw_instruction_t raw_instruction;
 		if(cpu->pc > memory_size - 4)
@@ -701,7 +699,7 @@ __attribute__((noreturn)) void cpu_loop(rv32_cpu_t* cpu)
 			fprintf(stderr, "Error: instruction fetch: pc is out of addressable memory\n");
 			exit(EXIT_FAILURE);
 		}
-		raw_instruction.data = mem_read32(cpu->pc);
+		raw_instruction.data = mem_fetch(cpu->pc);
 
 		// Decode
 		instruction_t instruction;
@@ -726,8 +724,7 @@ __attribute__((noreturn)) void cpu_loop(rv32_cpu_t* cpu)
 		if(cpu->sim_ticks_left != (-1))
 			cpu->sim_ticks_left--;
 
-		// Let go of cpu and memory mutex
-		// pthread_mutex_unlock(&memory_mutex);
+		// Let go of cpu mutex
 		pthread_mutex_unlock(&cpu0_mutex);
 	}
 }

src/memory/memory.c

@@ -40,7 +40,7 @@ void mem_register_mmio(uint32_t address, uint32_t reg_size, uint32_t reg_count,
 
 void mem_write8(uint32_t address, uint8_t value)
 {
-	address = mmu_resolve(cpu0, address);
+	address = mmu_resolve(cpu0, WRITE, address);
 
 	// Look wether we are on an MMIO region
 	struct MMIO_ENTRY* io = mmio;
@@ -71,7 +71,7 @@ void mem_write8(uint32_t address, uint8_t value)
 
 void mem_write16(uint32_t address, uint16_t value)
 {
-	address = mmu_resolve(cpu0, address);
+	address = mmu_resolve(cpu0, WRITE, address);
 
 	// Look wether we are on an MMIO region
 	struct MMIO_ENTRY* io = mmio;
@@ -102,7 +102,7 @@ void mem_write16(uint32_t address, uint16_t value)
 
 void mem_write32(uint32_t address, uint32_t value)
 {
-	address = mmu_resolve(cpu0, address);
+	address = mmu_resolve(cpu0, WRITE, address);
 
 	// Look wether we are on an MMIO region
 	struct MMIO_ENTRY* io = mmio;
@@ -133,7 +133,7 @@ void mem_write32(uint32_t address, uint32_t value)
 
 uint8_t mem_read8(uint32_t address)
 {
-	address = mmu_resolve(cpu0, address);
+	address = mmu_resolve(cpu0, READ, address);
 
     // Look wether we are on an MMIO region
 	struct MMIO_ENTRY* io = mmio;
@@ -164,7 +164,7 @@ uint8_t mem_read8(uint32_t address)
 
 uint16_t mem_read16(uint32_t address)
 {
-	address = mmu_resolve(cpu0, address);
+	address = mmu_resolve(cpu0, READ, address);
 
     // Look wether we are on an MMIO region
 	struct MMIO_ENTRY* io = mmio;
@@ -195,7 +195,7 @@ uint16_t mem_read16(uint32_t address)
 
 uint32_t mem_read32(uint32_t address)
 {
-	address = mmu_resolve(cpu0, address);
+	address = mmu_resolve(cpu0, READ, address);
 	
     // Look wether we are on an MMIO region
 	struct MMIO_ENTRY* io = mmio;
@@ -223,3 +223,26 @@ uint32_t mem_read32(uint32_t address)
 	pthread_mutex_unlock(&memory_mutex);
     return tr;
 }
+
+uint32_t mem_fetch(uint32_t address)
+{
+	address = mmu_resolve(cpu0, INSTRUCTION_FETCH, address);
+	
+    // Look wether we are on an MMIO region
+	struct MMIO_ENTRY* io = mmio;
+	while(io)
+	{
+		if(MMIO_INSIDE(io, address))
+		{
+			fprintf(stderr, "MEMORY: Trying to fetch an instruction inside an MMIO region !\n");
+			exit(EXIT_FAILURE);
+		}
+		io = io->next;
+	}
+
+	// Proceed with memory read
+	pthread_mutex_lock(&memory_mutex);
+	uint32_t tr = *((uint32_t*) &memory[address]);
+	pthread_mutex_unlock(&memory_mutex);
+    return tr;
+}

src/memory/memory.h

@@ -14,5 +14,6 @@ void mem_write32(uint32_t address, uint32_t value);
 uint8_t mem_read8(uint32_t address);
 uint16_t mem_read16(uint32_t address);
 uint32_t mem_read32(uint32_t address);
+uint32_t mem_fetch(uint32_t address);
 
 #endif

src/memory/mmu.c

@@ -44,7 +44,24 @@ extern uint8_t* memory;
 #define VADDR_VPN_0 (0x003FF000)
 #define VADDR_PAGE_OFFSET (0x00000FFF)
 
-uint32_t mmu_resolve(rv32_cpu_t* cpu, uint32_t vaddr)
+uint32_t mmu_scause_from_access(memory_access_type_t access_type)
+{
+	switch(access_type)
+	{
+		case READ:
+			return SCAUSE_LOAD_PAGE_FAULT;
+		case WRITE:
+			return SCAUSE_STORE_AMO_PAGE_FAULT;
+		case INSTRUCTION_FETCH:
+			return SCAUSE_INSTRUCTION_PAGE_FAULT;
+		default:
+			fprintf(stderr, "mmu_scause_from_access: invalid parameter\n");
+			exit(EXIT_FAILURE);
+			break;
+	}
+}
+
+uint32_t mmu_resolve(rv32_cpu_t* cpu, memory_access_type_t access_type, uint32_t vaddr)
 {
 	// TODO: Make sure we are in S-mode or U-mode
 
@@ -64,8 +81,7 @@ uint32_t mmu_resolve(rv32_cpu_t* cpu, uint32_t vaddr)
 	if(!(pte & PTE_V))
 	{
 		// Invalid PTE
-		// TODO : Add a MEMORY_ACCESS_TYPE
-		exception_trigger(cpu, SCAUSE_INSTRUCTION_PAGE_FAULT);
+		exception_trigger(cpu, mmu_scause_from_access(access_type));
 	}
 
 	if((pte & PTE_R) || (pte & PTE_W) || (pte & PTE_X))
@@ -93,7 +109,7 @@ uint32_t mmu_resolve(rv32_cpu_t* cpu, uint32_t vaddr)
 	if(!(pte & PTE_V))
 	{
 		// Invalid PTE
-		exception_trigger(cpu, SCAUSE_INSTRUCTION_PAGE_FAULT);
+		exception_trigger(cpu, mmu_scause_from_access(access_type));
 	}
 
 	// This must be a leaf PTE, as Sv32 only supports 2-level mappings

src/memory/mmu.h

@@ -4,6 +4,13 @@
 #include <stdint.h>
 #include "cpu/rv32cpu.h"
 
-uint32_t mmu_resolve(rv32_cpu_t* cpu, uint32_t vaddr);
+typedef enum MEMORY_ACCESS_TYPE
+{
+    READ,
+    WRITE,
+    INSTRUCTION_FETCH
+} memory_access_type_t;
+
+uint32_t mmu_resolve(rv32_cpu_t* cpu, memory_access_type_t access_type, uint32_t vaddr);
 
 #endif