rvemu

commit feb123c9c5c8b0cdcee6cb11bcf14344a44adf98
parent 2960ee19a669a70430c0ccdb7b21ec3b2f4f5729
Author: Michail Konstantinos Dimopoulos <mk@mcdim.xyz>
Date:   Sat,  5 Sep 2026 23:09:56 +0300

Added store/load checks and traps

Diffstat:
M
exec.c
 | 
63
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
M
exec.h
 | 
2
+-
M
main.c
 | 
12
++++++++++++
M
trap.h
 | 
2
--

4 files changed, 72 insertions(+), 7 deletions(-)
diff --git a/exec.c b/exec.c
@@ -216,13 +216,38 @@ static void exec_itype_loads(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	uint32_t x;
 	switch(i.funct3) {
 	case 0x0:
+		if (addr > MEMSIZE - 1) {
+			raise_trap(cpu, TRAP_LOAD_ACCESS_FAULT, inst);
+			return;
+		}
+
 		x = (uint32_t)(int32_t)(int8_t)mem[addr];
 		break;
 	case 0x1:
+		if ((addr & UINT32_C(0x1)) != 0) {
+			raise_trap(cpu, TRAP_LOAD_MISALIGNED, inst);
+			return;
+		}
+
+		if (addr + 1 > MEMSIZE - 1) {
+			raise_trap(cpu, TRAP_LOAD_ACCESS_FAULT, inst);
+			return;
+		}
+
 		uint16_t half = (uint16_t)mem[addr] | ((uint16_t)mem[addr+1] << 8);
 		x = (uint32_t)(int32_t)(int16_t)half;
 		break;
 	case 0x2:
+		if ((addr & UINT32_C(0x3)) != 0) {
+			raise_trap(cpu, TRAP_LOAD_MISALIGNED, inst);
+			return;
+		}
+
+		if (addr + 3 > MEMSIZE - 1) {
+			raise_trap(cpu, TRAP_LOAD_ACCESS_FAULT, inst);
+			return;
+		}
+
 		/* TODO: clean up */
 		x = (uint32_t)(int32_t)(
 				((uint16_t)mem[addr] | ((uint16_t)mem[addr+1] << 8))
@@ -232,9 +257,24 @@ static void exec_itype_loads(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 		    );
 		break;
 	case 0x4:
+		if (addr > MEMSIZE - 1) {
+			raise_trap(cpu, TRAP_LOAD_ACCESS_FAULT, inst);
+			return;
+		}
+
 		x = (uint32_t)(uint8_t)mem[addr];
 		break;
 	case 0x5:
+		if ((addr & UINT32_C(0x1)) != 0) {
+			raise_trap(cpu, TRAP_LOAD_MISALIGNED, inst);
+			return;
+		}
+
+		if (addr + 1 > MEMSIZE - 1) {
+			raise_trap(cpu, TRAP_LOAD_ACCESS_FAULT, inst);
+			return;
+		}
+
 		uint16_t uhalf = (uint16_t)mem[addr] | ((uint16_t)mem[addr+1] << 8);
 		x = (uint32_t)uhalf;
 		break;
@@ -258,11 +298,21 @@ static void exec_stype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 	/* TODO: helpers, better checks */
 	switch(s.funct3) {
 	case 0x0:
+		if (addr > MEMSIZE - 1) {
+			raise_trap(cpu, TRAP_STORE_ACCESS_FAULT, inst);
+			return;
+		}
+
 		mem[addr] = cpu->x[s.rs2] & 255;
 		break;
 	case 0x1:
-		if (addr+1 > MEMSIZE-1) {
-			fprintf(stderr, "Illegal addr\n");
+		if ((addr & UINT32_C(0x1)) != 0) {
+			raise_trap(cpu, TRAP_STORE_MISALIGNED, inst);
+			return;
+		}
+
+		if (addr + 1 > MEMSIZE - 1) {
+			raise_trap(cpu, TRAP_STORE_ACCESS_FAULT, inst);
 			return;
 		}
 
@@ -272,8 +322,13 @@ static void exec_stype(cpu_state_t *cpu, uint32_t inst, uint8_t *mem) {
 		}
 		break;
 	case 0x2:
-		if (addr+3 > MEMSIZE-1) {
-			fprintf(stderr, "Illegal addr\n");
+		if ((addr & UINT32_C(0x3)) != 0) {
+			raise_trap(cpu, TRAP_STORE_MISALIGNED, inst);
+			return;
+		}
+
+		if (addr + 3 > MEMSIZE - 1) {
+			raise_trap(cpu, TRAP_STORE_ACCESS_FAULT, inst);
 			return;
 		}
 		if (addr % 4 == 0) {
diff --git a/exec.h b/exec.h
@@ -3,7 +3,7 @@
 
 #include "trap.h"
 
-#define MEMSIZE 4128
+#define MEMSIZE 4096
 
 typedef enum {
 	CPU_RUNNING = 0,
diff --git a/main.c b/main.c
@@ -75,6 +75,18 @@ trap_handler(cpu_state_t *cpu)
 		case TRAP_INSTRUCTION_ACCESS_FAULT: 
 			printf("Instruction access fault\n");
 			break;
+		case TRAP_LOAD_MISALIGNED:
+			printf("Load misaligned\n");
+			break;
+		case TRAP_LOAD_ACCESS_FAULT:
+			printf("Load access fault\n");
+			break;
+		case TRAP_STORE_MISALIGNED:
+			printf("Store misaligned\n");
+			break;
+		case TRAP_STORE_ACCESS_FAULT:
+			printf("Store access fault\n");
+			break;
 		case TRAP_NONE:
 			printf("No trap cause\n");
 			break;
diff --git a/trap.h b/trap.h
@@ -8,12 +8,10 @@ typedef enum {
 	TRAP_ILLEGAL_INSTRUCTION,
 	TRAP_INSTRUCTION_MISALIGNED,
 	TRAP_INSTRUCTION_ACCESS_FAULT,
-/*
 	TRAP_LOAD_MISALIGNED,
 	TRAP_LOAD_ACCESS_FAULT,
 	TRAP_STORE_MISALIGNED,
 	TRAP_STORE_ACCESS_FAULT
-*/
 } trap_cause_t;
 
 typedef struct {