Merge branch 'android-2.6.39' into android-tegra-2.6.39

3 files changed, 214 insertions, 18 deletions

diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index bca7e61928c7..37da2cc8f618 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -7,6 +7,7 @@ obj-y				:= dma-mapping.o extable.o fault.o init.o \
 
 obj-$(CONFIG_MMU)		+= fault-armv.o flush.o idmap.o ioremap.o \
 				   mmap.o pgd.o mmu.o vmregion.o
+obj-$(CONFIG_DEBUG_RODATA)	+= rodata.o
 
 ifneq ($(CONFIG_MMU),y)
 obj-y				+= nommu.o
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 6cf76b3b68d1..2190f888e257 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -530,11 +530,25 @@ static void __init *early_alloc(unsigned long sz)
 	return ptr;
 }
 
-static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr, unsigned long prot)
+static pte_t * __init early_pte_alloc(pmd_t *pmd)
+{
+	if (pmd_none(*pmd) || pmd_bad(*pmd))
+		return early_alloc(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE);
+	return pmd_page_vaddr(*pmd);
+}
+
+static void __init early_pte_install(pmd_t *pmd, pte_t *pte, unsigned long prot)
+{
+	__pmd_populate(pmd, __pa(pte), prot);
+	BUG_ON(pmd_bad(*pmd));
+}
+
+static pte_t * __init early_pte_alloc_and_install(pmd_t *pmd,
+	unsigned long addr, unsigned long prot)
 {
 	if (pmd_none(*pmd)) {
-		pte_t *pte = early_alloc(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE);
-		__pmd_populate(pmd, __pa(pte), prot);
+		pte_t *pte = early_pte_alloc(pmd);
+		early_pte_install(pmd, pte, prot);
 	}
 	BUG_ON(pmd_bad(*pmd));
 	return pte_offset_kernel(pmd, addr);
@@ -544,16 +558,23 @@ static void __init alloc_init_pte(pmd_t *pmd, unsigned long addr,
 				  unsigned long end, unsigned long pfn,
 				  const struct mem_type *type)
 {
-	pte_t *pte = early_pte_alloc(pmd, addr, type->prot_l1);
+	pte_t *start_pte = early_pte_alloc(pmd);
+	pte_t *pte = start_pte + pte_index(addr);
+
+	/* If replacing a section mapping, the whole section must be replaced */
+	BUG_ON(pmd_bad(*pmd) && ((addr | end) & ~PMD_MASK));
+
 	do {
 		set_pte_ext(pte, pfn_pte(pfn, __pgprot(type->prot_pte)), 0);
 		pfn++;
 	} while (pte++, addr += PAGE_SIZE, addr != end);
+	early_pte_install(pmd, start_pte, type->prot_l1);
 }
 
 static void __init alloc_init_section(pud_t *pud, unsigned long addr,
 				      unsigned long end, phys_addr_t phys,
-				      const struct mem_type *type)
+				      const struct mem_type *type,
+				      bool force_pages)
 {
 	pmd_t *pmd = pmd_offset(pud, addr);
 
@@ -563,7 +584,7 @@ static void __init alloc_init_section(pud_t *pud, unsigned long addr,
 	 * L1 entries, whereas PGDs refer to a group of L1 entries making
 	 * up one logical pointer to an L2 table.
 	 */
-	if (((addr | end | phys) & ~SECTION_MASK) == 0) {
+	if (((addr | end | phys) & ~SECTION_MASK) == 0 && !force_pages) {
 		pmd_t *p = pmd;
 
 		if (addr & SECTION_SIZE)
@@ -585,14 +606,14 @@ static void __init alloc_init_section(pud_t *pud, unsigned long addr,
 }
 
 static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end,
-	unsigned long phys, const struct mem_type *type)
+	unsigned long phys, const struct mem_type *type, bool force_pages)
 {
 	pud_t *pud = pud_offset(pgd, addr);
 	unsigned long next;
 
 	do {
 		next = pud_addr_end(addr, end);
-		alloc_init_section(pud, addr, next, phys, type);
+		alloc_init_section(pud, addr, next, phys, type, force_pages);
 		phys += next - addr;
 	} while (pud++, addr = next, addr != end);
 }
@@ -664,7 +685,7 @@ static void __init create_36bit_mapping(struct map_desc *md,
  * offsets, and we take full advantage of sections and
  * supersections.
  */
-static void __init create_mapping(struct map_desc *md)
+static void __init create_mapping(struct map_desc *md, bool force_pages)
 {
 	unsigned long addr, length, end;
 	phys_addr_t phys;
@@ -711,7 +732,7 @@ static void __init create_mapping(struct map_desc *md)
 	do {
 		unsigned long next = pgd_addr_end(addr, end);
 
-		alloc_init_pud(pgd, addr, next, phys, type);
+		alloc_init_pud(pgd, addr, next, phys, type, force_pages);
 
 		phys += next - addr;
 		addr = next;
@@ -726,7 +747,7 @@ void __init iotable_init(struct map_desc *io_desc, int nr)
 	int i;
 
 	for (i = 0; i < nr; i++)
-		create_mapping(io_desc + i);
+		create_mapping(io_desc + i, false);
 }
 
 static void * __initdata vmalloc_min = (void *)(VMALLOC_END - SZ_128M);
@@ -969,12 +990,12 @@ static void __init devicemaps_init(struct machine_desc *mdesc)
 	map.virtual = 0xffff0000;
 	map.length = PAGE_SIZE;
 	map.type = MT_HIGH_VECTORS;
-	create_mapping(&map);
+	create_mapping(&map, false);
 
 	if (!vectors_high()) {
 		map.virtual = 0;
 		map.type = MT_LOW_VECTORS;
-		create_mapping(&map);
+		create_mapping(&map, false);
 	}
 
 	/*
@@ -996,20 +1017,23 @@ static void __init devicemaps_init(struct machine_desc *mdesc)
 static void __init kmap_init(void)
 {
 #ifdef CONFIG_HIGHMEM
-	pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
+	pkmap_page_table = early_pte_alloc_and_install(pmd_off_k(PKMAP_BASE),
 		PKMAP_BASE, _PAGE_KERNEL_TABLE);
 #endif
 }
 
+
 static void __init map_lowmem(void)
 {
 	struct memblock_region *reg;
+	phys_addr_t start;
+	phys_addr_t end;
+	struct map_desc map;
 
 	/* Map all the lowmem memory banks. */
 	for_each_memblock(memory, reg) {
-		phys_addr_t start = reg->base;
-		phys_addr_t end = start + reg->size;
-		struct map_desc map;
+		start = reg->base;
+		end = start + reg->size;
 
 		if (end > lowmem_limit)
 			end = lowmem_limit;
@@ -1021,8 +1045,20 @@ static void __init map_lowmem(void)
 		map.length = end - start;
 		map.type = MT_MEMORY;
 
-		create_mapping(&map);
+		create_mapping(&map, false);
 	}
+
+#ifdef CONFIG_DEBUG_RODATA
+	start = __pa(_stext) & PMD_MASK;
+	end = ALIGN(__pa(__end_rodata), PMD_SIZE);
+
+	map.pfn = __phys_to_pfn(start);
+	map.virtual = __phys_to_virt(start);
+	map.length = end - start;
+	map.type = MT_MEMORY;
+
+	create_mapping(&map, true);
+#endif
 }
 
 /*
diff --git a/arch/arm/mm/rodata.c b/arch/arm/mm/rodata.c
new file mode 100644
index 000000000000..9a8eb841c428
--- /dev/null
+++ b/arch/arm/mm/rodata.c
@@ -0,0 +1,159 @@
+/*
+ *  linux/arch/arm/mm/rodata.c
+ *
+ *  Copyright (C) 2011 Google, Inc.
+ *
+ *  Author: Colin Cross <ccross@android.com>
+ *
+ *  Based on x86 implementation in arch/x86/mm/init_32.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+
+#include <asm/cache.h>
+#include <asm/pgtable.h>
+#include <asm/rodata.h>
+#include <asm/sections.h>
+#include <asm/tlbflush.h>
+
+#include "mm.h"
+
+static int kernel_set_to_readonly __read_mostly;
+
+#ifdef CONFIG_DEBUG_RODATA_TEST
+static const int rodata_test_data = 0xC3;
+
+static noinline void rodata_test(void)
+{
+	int result;
+
+	pr_info("%s: attempting to write to read-only section:\n", __func__);
+
+	if (*(volatile int *)&rodata_test_data != 0xC3) {
+		pr_err("read only data changed before test\n");
+		return;
+	}
+
+	/*
+	 * Attempt to to write to rodata_test_data, trapping the expected
+	 * data abort.  If the trap executed, result will be 1.  If it didn't,
+	 * result will be 0xFF.
+	 */
+	asm volatile(
+		"0:	str	%[zero], [%[rodata_test_data]]\n"
+		"	mov	%[result], #0xFF\n"
+		"	b	2f\n"
+		"1:	mov	%[result], #1\n"
+		"2:\n"
+
+		/* Exception fixup - if store at label 0 faults, jumps to 1 */
+		".pushsection __ex_table, \"a\"\n"
+		"	.long	0b, 1b\n"
+		".popsection\n"
+
+		: [result] "=r" (result)
+		: [rodata_test_data] "r" (&rodata_test_data), [zero] "r" (0)
+		: "memory"
+	);
+
+	if (result == 1)
+		pr_info("write to read-only section trapped, success\n");
+	else
+		pr_err("write to read-only section NOT trapped, test failed\n");
+
+	if (*(volatile int *)&rodata_test_data != 0xC3)
+		pr_err("read only data changed during write\n");
+}
+#else
+static inline void rodata_test(void) { }
+#endif
+
+static int set_page_attributes(unsigned long virt, int numpages,
+	pte_t (*f)(pte_t))
+{
+	pmd_t *pmd;
+	pte_t *pte;
+	unsigned long start = virt;
+	unsigned long end = virt + (numpages << PAGE_SHIFT);
+	unsigned long pmd_end;
+
+	while (virt < end) {
+		pmd = pmd_off_k(virt);
+		pmd_end = min(ALIGN(virt + 1, PMD_SIZE), end);
+
+		if ((pmd_val(*pmd) & PMD_TYPE_MASK) != PMD_TYPE_TABLE) {
+			pr_err("%s: pmd %p=%08lx for %08lx not page table\n",
+				__func__, pmd, pmd_val(*pmd), virt);
+			virt = pmd_end;
+			continue;
+		}
+
+		while (virt < pmd_end) {
+			pte = pte_offset_kernel(pmd, virt);
+			set_pte_ext(pte, f(*pte), 0);
+			virt += PAGE_SIZE;
+		}
+	}
+
+	flush_tlb_kernel_range(start, end);
+
+	return 0;
+}
+
+int set_memory_ro(unsigned long virt, int numpages)
+{
+	return set_page_attributes(virt, numpages, pte_wrprotect);
+}
+EXPORT_SYMBOL(set_memory_ro);
+
+int set_memory_rw(unsigned long virt, int numpages)
+{
+	return set_page_attributes(virt, numpages, pte_mkwrite);
+}
+EXPORT_SYMBOL(set_memory_rw);
+
+void set_kernel_text_rw(void)
+{
+	unsigned long start = PAGE_ALIGN((unsigned long)_text);
+	unsigned long size = PAGE_ALIGN((unsigned long)__end_rodata) - start;
+
+	if (!kernel_set_to_readonly)
+		return;
+
+	pr_debug("Set kernel text: %lx - %lx to read-write\n",
+		 start, start + size);
+
+	set_memory_rw(start, size >> PAGE_SHIFT);
+}
+
+void set_kernel_text_ro(void)
+{
+	unsigned long start = PAGE_ALIGN((unsigned long)_text);
+	unsigned long size = PAGE_ALIGN((unsigned long)__end_rodata) - start;
+
+	if (!kernel_set_to_readonly)
+		return;
+
+	pr_info_once("Write protecting the kernel text section %lx - %lx\n",
+		start, start + size);
+
+	pr_debug("Set kernel text: %lx - %lx to read only\n",
+		 start, start + size);
+
+	set_memory_ro(start, size >> PAGE_SHIFT);
+}
+
+void mark_rodata_ro(void)
+{
+	kernel_set_to_readonly = 1;
+
+	set_kernel_text_ro();
+
+	rodata_test();
+}