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Hardened MMU permission checks

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This commit is contained in:
Valentin Haudiquet 2023-10-23 17:52:21 +02:00
parent 07f683dc41
commit b57739fe38
1 changed files with 24 additions and 0 deletions
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24
src/memory/mmu.c
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@ -89,6 +89,18 @@ uint32_t mmu_resolve(rv32_cpu_t* cpu, memory_access_type_t access_type, uint32_t
// Leaf PTE, we are ready to resolve the mapping // Leaf PTE, we are ready to resolve the mapping
// This is a 4 MiB megapage // This is a 4 MiB megapage
// For an execute, check if we are allowed to execute
if(access_type == INSTRUCTION_FETCH && !(pte & PTE_X))
exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
// For a write, check if we are allowed to write
if(access_type == WRITE && !(pte & PTE_W))
exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
// For a read, check if we are allowed to read
if(access_type == READ && !(pte & PTE_R))
exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
// Physical Address: [PPN[1] = pte.PPN[1], PPN[0] = vaddr.VPN[0], offset] // Physical Address: [PPN[1] = pte.PPN[1], PPN[0] = vaddr.VPN[0], offset]
uint32_t paddr = 0; uint32_t paddr = 0;
paddr |= (PTE_PPN_1(pte) << 22); paddr |= (PTE_PPN_1(pte) << 22);
@ -120,6 +132,18 @@ uint32_t mmu_resolve(rv32_cpu_t* cpu, memory_access_type_t access_type, uint32_t
exit(EXIT_FAILURE); exit(EXIT_FAILURE);
} }
// For an execute, check if we are allowed to execute
if(access_type == INSTRUCTION_FETCH && !(pte & PTE_X))
exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
// For a write, check if we are allowed to write
if(access_type == WRITE && !(pte & PTE_W))
exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
// For a read, check if we are allowed to read
if(access_type == READ && !(pte & PTE_R))
exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
// Physical Address: [PPN[1] = pte.PPN[1], PPN[0] = pte.PPN[0], offset] // Physical Address: [PPN[1] = pte.PPN[1], PPN[0] = pte.PPN[0], offset]
uint32_t paddr = 0; uint32_t paddr = 0;
paddr |= (PTE_PPN_1(pte) << 22); paddr |= (PTE_PPN_1(pte) << 22);