Revert "ARM: allow the kernel text section to be made read-only"
This reverts commit e5e483d13369ab62d95f1738edce3cd64c7ca2ff.
This change breaks LPAE support. Other patches provide the same
functionality so just revert the patch.
Change-Id: Iea1e88064a1618ca1fc9d717ee5a4ffe77681745
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
diff --git a/arch/arm/Kconfig.debug b/arch/arm/Kconfig.debug
index ed18cae..3a9b770 100644
--- a/arch/arm/Kconfig.debug
+++ b/arch/arm/Kconfig.debug
@@ -63,27 +63,6 @@
8 - SIGSEGV faults
16 - SIGBUS faults
-config DEBUG_RODATA
- bool "Write protect kernel text section"
- default n
- depends on DEBUG_KERNEL && MMU
- ---help---
- Mark the kernel text section as write-protected in the pagetables,
- in order to catch accidental (and incorrect) writes to such const
- data. This will cause the size of the kernel, plus up to 4MB, to
- be mapped as pages instead of sections, which will increase TLB
- pressure.
- If in doubt, say "N".
-
-config DEBUG_RODATA_TEST
- bool "Testcase for the DEBUG_RODATA feature"
- depends on DEBUG_RODATA
- default n
- ---help---
- This option enables a testcase for the DEBUG_RODATA
- feature.
- If in doubt, say "N"
-
# These options are only for real kernel hackers who want to get their hands dirty.
config DEBUG_LL
bool "Kernel low-level debugging functions (read help!)"
diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index d021905..584fe0b 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -16,7 +16,6 @@
#include <asm/shmparam.h>
#include <asm/cachetype.h>
#include <asm/outercache.h>
-#include <asm/rodata.h>
#define CACHE_COLOUR(vaddr) ((vaddr & (SHMLBA - 1)) >> PAGE_SHIFT)
diff --git a/arch/arm/include/asm/rodata.h b/arch/arm/include/asm/rodata.h
deleted file mode 100644
index 8c8add8..0000000
--- a/arch/arm/include/asm/rodata.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/*
- * arch/arm/include/asm/rodata.h
- *
- * Copyright (C) 2011 Google, Inc.
- *
- * Author: Colin Cross <ccross@android.com>
- *
- * 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.
- */
-#ifndef _ASMARM_RODATA_H
-#define _ASMARM_RODATA_H
-
-#ifndef __ASSEMBLY__
-
-#ifdef CONFIG_DEBUG_RODATA
-
-int set_memory_rw(unsigned long virt, int numpages);
-int set_memory_ro(unsigned long virt, int numpages);
-
-void mark_rodata_ro(void);
-void set_kernel_text_rw(void);
-void set_kernel_text_ro(void);
-#else
-static inline void set_kernel_text_rw(void) { }
-static inline void set_kernel_text_ro(void) { }
-#endif
-
-#endif
-
-#endif
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index bf17145..df0bf0c 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -13,7 +13,6 @@
*/
#include <linux/ftrace.h>
-#include <linux/module.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
@@ -64,20 +63,6 @@
}
#endif
-int ftrace_arch_code_modify_prepare(void)
-{
- set_kernel_text_rw();
- set_all_modules_text_rw();
- return 0;
-}
-
-int ftrace_arch_code_modify_post_process(void)
-{
- set_all_modules_text_ro();
- set_kernel_text_ro();
- return 0;
-}
-
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
return arm_gen_branch_link(pc, addr);
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile
index 6314e94..d177b05 100644
--- a/arch/arm/mm/Makefile
+++ b/arch/arm/mm/Makefile
@@ -7,7 +7,6 @@
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 8575f78..25cb67c 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -604,53 +604,30 @@
return early_alloc_aligned(sz, sz);
}
-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));
-}
-
-#ifdef CONFIG_HIGHMEM
-static pte_t * __init early_pte_alloc_and_install(pmd_t *pmd,
- unsigned long addr, unsigned long prot)
+static pte_t * __init early_pte_alloc(pmd_t *pmd, unsigned long addr, unsigned long prot)
{
if (pmd_none(*pmd)) {
- pte_t *pte = early_pte_alloc(pmd);
- early_pte_install(pmd, pte, prot);
+ pte_t *pte = early_alloc(PTE_HWTABLE_OFF + PTE_HWTABLE_SIZE);
+ __pmd_populate(pmd, __pa(pte), prot);
}
BUG_ON(pmd_bad(*pmd));
return pte_offset_kernel(pmd, addr);
}
-#endif
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 *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));
-
+ pte_t *pte = early_pte_alloc(pmd, addr, type->prot_l1);
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,
- bool force_pages)
+ const struct mem_type *type)
{
pmd_t *pmd = pmd_offset(pud, addr);
@@ -660,7 +637,7 @@
* L1 entries, whereas PGDs refer to a group of L1 entries making
* up one logical pointer to an L2 table.
*/
- if (type->prot_sect && ((addr | end | phys) & ~SECTION_MASK) == 0 && !force_pages) {
+ if (type->prot_sect && ((addr | end | phys) & ~SECTION_MASK) == 0) {
pmd_t *p = pmd;
#ifndef CONFIG_ARM_LPAE
@@ -684,15 +661,14 @@
}
static void __init alloc_init_pud(pgd_t *pgd, unsigned long addr,
- unsigned long end, unsigned long phys, const struct mem_type *type,
- bool force_pages)
+ unsigned long end, unsigned long phys, const struct mem_type *type)
{
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, force_pages);
+ alloc_init_section(pud, addr, next, phys, type);
phys += next - addr;
} while (pud++, addr = next, addr != end);
}
@@ -766,7 +742,7 @@
* offsets, and we take full advantage of sections and
* supersections.
*/
-static void __init create_mapping(struct map_desc *md, bool force_pages)
+static void __init create_mapping(struct map_desc *md)
{
unsigned long addr, length, end;
phys_addr_t phys;
@@ -818,7 +794,7 @@
do {
unsigned long next = pgd_addr_end(addr, end);
- alloc_init_pud(pgd, addr, next, phys, type, force_pages);
+ alloc_init_pud(pgd, addr, next, phys, type);
phys += next - addr;
addr = next;
@@ -839,7 +815,7 @@
vm = early_alloc_aligned(sizeof(*vm) * nr, __alignof__(*vm));
for (md = io_desc; nr; md++, nr--) {
- create_mapping(md, false);
+ create_mapping(md);
vm->addr = (void *)(md->virtual & PAGE_MASK);
vm->size = PAGE_ALIGN(md->length + (md->virtual & ~PAGE_MASK));
vm->phys_addr = __pfn_to_phys(md->pfn);
@@ -1199,12 +1175,12 @@
map.virtual = 0xffff0000;
map.length = PAGE_SIZE;
map.type = MT_HIGH_VECTORS;
- create_mapping(&map, false);
+ create_mapping(&map);
if (!vectors_high()) {
map.virtual = 0;
map.type = MT_LOW_VECTORS;
- create_mapping(&map, false);
+ create_mapping(&map);
}
/*
@@ -1224,7 +1200,7 @@
map.virtual = CONFIG_ARM_USER_ACCESSIBLE_TIMER_BASE;
map.length = PAGE_SIZE;
map.type = MT_DEVICE_USER_ACCESSIBLE;
- create_mapping(&map, false);
+ create_mapping(&map);
}
}
@@ -1241,7 +1217,7 @@
static void __init kmap_init(void)
{
#ifdef CONFIG_HIGHMEM
- pkmap_page_table = early_pte_alloc_and_install(pmd_off_k(PKMAP_BASE),
+ pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE),
PKMAP_BASE, _PAGE_KERNEL_TABLE);
#endif
}
@@ -1349,14 +1325,12 @@
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) {
- start = reg->base;
- end = start + reg->size;
+ phys_addr_t start = reg->base;
+ phys_addr_t end = start + reg->size;
+ struct map_desc map;
if (end > arm_lowmem_limit)
end = arm_lowmem_limit;
@@ -1370,28 +1344,28 @@
map.length = SECTION_SIZE;
map.type = MT_MEMORY;
- create_mapping(&map, false);
+ create_mapping(&map);
map.pfn = __phys_to_pfn(start + SECTION_SIZE);
map.virtual = __phys_to_virt(start + SECTION_SIZE);
map.length = (unsigned long)RX_AREA_END - map.virtual;
map.type = MT_MEMORY_RX;
- create_mapping(&map, false);
+ create_mapping(&map);
map.pfn = __phys_to_pfn(__pa(__start_rodata));
map.virtual = (unsigned long)__start_rodata;
map.length = __init_begin - __start_rodata;
map.type = MT_MEMORY_R;
- create_mapping(&map, false);
+ create_mapping(&map);
map.pfn = __phys_to_pfn(__pa(__init_begin));
map.virtual = (unsigned long)__init_begin;
map.length = __init_data - __init_begin;
map.type = MT_MEMORY;
- create_mapping(&map, false);
+ create_mapping(&map);
map.pfn = __phys_to_pfn(__pa(__init_data));
map.virtual = (unsigned long)__init_data;
@@ -1406,20 +1380,8 @@
map.type = MT_MEMORY;
#endif
- create_mapping(&map, false);
+ create_mapping(&map);
}
-
-#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
deleted file mode 100644
index 9a8eb84..0000000
--- a/arch/arm/mm/rodata.c
+++ /dev/null
@@ -1,159 +0,0 @@
-/*
- * 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();
-}