Author: jhb Date: Thu Nov 1 22:23:15 2018 New Revision: 340030 URL: https://svnweb.freebsd.org/changeset/base/340030
Log: Restrict setting PTE execute permissions on RISC-V. Previously, RISC-V was enabling execute permissions in PTEs for any readable page. Now, execute permissions are only enabled if they were explicitly specified (e.g. via PROT_EXEC to mmap). The one exception is that the initial kernel mapping in locore still maps all of the kernel RWX. While here, change the fault type passed to vm_fault and pmap_fault_fixup to only include a single VM_PROT_* value representing the faulting access to match other architectures rather than passing a bitmask. Reviewed by: markj Sponsored by: DARPA Differential Revision: https://reviews.freebsd.org/D17783 Modified: head/sys/riscv/include/pte.h head/sys/riscv/riscv/locore.S head/sys/riscv/riscv/pmap.c head/sys/riscv/riscv/trap.c Modified: head/sys/riscv/include/pte.h ============================================================================== --- head/sys/riscv/include/pte.h Thu Nov 1 22:17:51 2018 (r340029) +++ head/sys/riscv/include/pte.h Thu Nov 1 22:23:15 2018 (r340030) @@ -78,7 +78,7 @@ typedef uint64_t pn_t; /* page number */ #define PTE_V (1 << 0) /* Valid */ #define PTE_RWX (PTE_R | PTE_W | PTE_X) #define PTE_RX (PTE_R | PTE_X) -#define PTE_KERN (PTE_V | PTE_RWX | PTE_A | PTE_D) +#define PTE_KERN (PTE_V | PTE_R | PTE_W | PTE_A | PTE_D) #define PTE_PPN0_S 10 #define PTE_PPN1_S 19 Modified: head/sys/riscv/riscv/locore.S ============================================================================== --- head/sys/riscv/riscv/locore.S Thu Nov 1 22:17:51 2018 (r340029) +++ head/sys/riscv/riscv/locore.S Thu Nov 1 22:23:15 2018 (r340030) @@ -94,7 +94,7 @@ _start: add t3, t4, t2 li t5, 0 2: - li t0, (PTE_KERN) + li t0, (PTE_KERN | PTE_X) slli t2, t4, PTE_PPN1_S /* << PTE_PPN1_S */ or t5, t0, t2 sd t5, (s1) /* Store PTE entry to position */ Modified: head/sys/riscv/riscv/pmap.c ============================================================================== --- head/sys/riscv/riscv/pmap.c Thu Nov 1 22:17:51 2018 (r340029) +++ head/sys/riscv/riscv/pmap.c Thu Nov 1 22:23:15 2018 (r340030) @@ -2010,7 +2010,7 @@ pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t } int -pmap_fault_fixup(pmap_t pmap, vm_offset_t va, vm_prot_t prot) +pmap_fault_fixup(pmap_t pmap, vm_offset_t va, vm_prot_t ftype) { pt_entry_t orig_l3; pt_entry_t new_l3; @@ -2027,12 +2027,13 @@ pmap_fault_fixup(pmap_t pmap, vm_offset_t va, vm_prot_ orig_l3 = pmap_load(l3); if ((orig_l3 & PTE_V) == 0 || - ((prot & VM_PROT_WRITE) != 0 && (orig_l3 & PTE_W) == 0) || - ((prot & VM_PROT_READ) != 0 && (orig_l3 & PTE_R) == 0)) + (ftype == VM_PROT_WRITE && (orig_l3 & PTE_W) == 0) || + (ftype == VM_PROT_EXECUTE && (orig_l3 & PTE_X) == 0) || + (ftype == VM_PROT_READ && (orig_l3 & PTE_R) == 0)) goto done; new_l3 = orig_l3 | PTE_A; - if ((prot & VM_PROT_WRITE) != 0) + if (ftype == VM_PROT_WRITE) new_l3 |= PTE_D; if (orig_l3 != new_l3) { @@ -2088,7 +2089,9 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, v pa = VM_PAGE_TO_PHYS(m); pn = (pa / PAGE_SIZE); - new_l3 = PTE_V | PTE_R | PTE_X | PTE_A; + new_l3 = PTE_V | PTE_R | PTE_A; + if (prot & VM_PROT_EXECUTE) + new_l3 |= PTE_X; if (flags & VM_PROT_WRITE) new_l3 |= PTE_D; if (prot & VM_PROT_WRITE) @@ -2464,7 +2467,9 @@ pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, v pa = VM_PAGE_TO_PHYS(m); pn = (pa / PAGE_SIZE); - entry = (PTE_V | PTE_R | PTE_X); + entry = PTE_V | PTE_R; + if (prot & VM_PROT_EXECUTE) + entry |= PTE_X; entry |= (pn << PTE_PPN0_S); /* Modified: head/sys/riscv/riscv/trap.c ============================================================================== --- head/sys/riscv/riscv/trap.c Thu Nov 1 22:17:51 2018 (r340029) +++ head/sys/riscv/riscv/trap.c Thu Nov 1 22:23:15 2018 (r340030) @@ -207,9 +207,11 @@ data_abort(struct trapframe *frame, int lower) if ((frame->tf_scause == EXCP_FAULT_STORE) || (frame->tf_scause == EXCP_STORE_PAGE_FAULT)) { - ftype = (VM_PROT_READ | VM_PROT_WRITE); + ftype = VM_PROT_WRITE; + } else if (frame->tf_scause == EXCP_INST_PAGE_FAULT) { + ftype = VM_PROT_EXECUTE; } else { - ftype = (VM_PROT_READ); + ftype = VM_PROT_READ; } if (pmap_fault_fixup(map->pmap, va, ftype)) _______________________________________________ [email protected] mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "[email protected]"
