Map .rodata and the KVA range corresponding to the ISA hole as NX on amd64

processors that support NX.

Tested on amd64 machines with and without NX capability.

Additional NX ranges can be added as desired to the table defined by
this diff.

ok deraadt@

1 files changed, 63 insertions, 3 deletions

diff --git a/sys/arch/amd64/amd64/pmap.c b/sys/arch/amd64/amd64/pmap.c
index 6c1a932f0bc..cc726f0fbd2 100644
--- a/sys/arch/amd64/amd64/pmap.c
+++ b/sys/arch/amd64/amd64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.76 2014/10/31 04:33:51 mlarkin Exp $	*/
+/*	$OpenBSD: pmap.c,v 1.77 2014/11/07 03:20:02 mlarkin Exp $	*/
 /*	$NetBSD: pmap.c,v 1.3 2003/05/08 18:13:13 thorpej Exp $	*/
 
 /*
@@ -278,6 +278,47 @@ extern vaddr_t lo32_paddr;
 vaddr_t virtual_avail;
 extern int end;
 
+extern vaddr_t __rodata_start;
+extern int __rodata_size;
+extern vaddr_t erodata;
+
+/*
+ * NX range definitions
+ */
+struct nx_range_description {
+	vaddr_t start;
+	size_t size;
+	vm_prot_t prot;
+	int is_ptr;
+};
+
+static const struct nx_range_description nx_ranges[] = {
+	/*
+	 * List of ranges to map as NX (non-execute) if the processor supports
+	 * NX. Each range consists of a start vaddr and size (in bytes), and a
+	 * protection value (eg, VM_PROT_READ or VM_PROT_READ | VM_PROT_WRITE).
+	 *
+	 * The list also includes an 'is_ptr' field in each element to denote
+	 * if the 'start' value is a constant (is_ptr == 0) or should be
+	 * interpreted as an address containing the real value (is_ptr == 1).
+	 *
+	 * The range includes the page containing [start va] and extends through
+	 * and including the page containing [end va].
+	 */
+	{ /* .rodata range */
+	    (vaddr_t)&__rodata_start,
+	    (size_t)&__rodata_size,
+	    VM_PROT_READ,
+	    0
+	},
+	{ /* ISA hole */
+	    (vaddr_t)&atdevbase,
+	    IOM_SIZE,
+	    VM_PROT_READ | VM_PROT_WRITE,
+	    1
+	}
+};
+
 /*
  * local prototypes
  */
@@ -531,13 +572,13 @@ pmap_kremove(vaddr_t sva, vsize_t len)
 paddr_t
 pmap_bootstrap(paddr_t first_avail, paddr_t max_pa)
 {
-	vaddr_t kva, kva_end, kva_start = VM_MIN_KERNEL_ADDRESS;
+	vaddr_t kva, kva_end, kva_start = VM_MIN_KERNEL_ADDRESS, nx_start;
 	struct pmap *kpm;
 	int i;
 	unsigned long p1i;
 	pt_entry_t pg_nx = (cpu_feature & CPUID_NXE? PG_NX : 0);
 	long ndmpdp;
-	paddr_t dmpd, dmpdp;
+	paddr_t dmpd, dmpdp, nx_paddr;
 
 	/*
 	 * define the boundaries of the managed kernel virtual address
@@ -692,6 +733,25 @@ pmap_bootstrap(paddr_t first_avail, paddr_t max_pa)
 	    &pool_allocator_nointr);
 
 	/*
+	 * Enable NX ranges, resets page permissions on already mapped ranges
+	 */
+	 if (pg_nx) {
+		for (i = 0 ; i < nitems(nx_ranges); i++ ) {
+			if (nx_ranges[i].is_ptr)
+				nx_start = *(vaddr_t *)(nx_ranges[i].start);
+			else
+				nx_start = nx_ranges[i].start;
+
+			for (kva = nx_start; kva < nx_start + nx_ranges[i].size;
+			    kva += PAGE_SIZE) {
+				if(pmap_extract(pmap_kernel(), kva, &nx_paddr))
+					pmap_kenter_pa(kva, nx_paddr,
+					    nx_ranges[i].prot);
+			}
+		}	
+	}
+
+	/*
 	 * ensure the TLB is sync'd with reality by flushing it...
 	 */