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[PARISC] only make executable areas executable 

Currently parisc has the whole kernel marked as RWX, meaning any
kernel page at all is eligible to be executed.  This can cause a
theoretical problem on systems with combined I/D TLB because the act
of referencing a page causes a TLB insertion with an executable bit.
This TLB entry may be used by the CPU as the basis for speculating the
page into the I-Cache.  If this speculated page is subsequently used
for a user process, there is the possibility we will get a stale
I-cache line picked up as the binary executes.

As a point of good practise, only mark actual kernel text pages as
executable.  The same has to be done for init_text pages, but they're
converted to data pages (and the I-Cache flushed) when the init memory
is released.

Signed-off-by: James Bottomley <James.Bottomley@suse.de>
This commit is contained in:
James Bottomley 2011-04-14 18:25:21 -05:00 committed by James Bottomley
parent e38f5b7450
commit d7dd2ff11b
6 changed files with 166 additions and 122 deletions
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9
arch/parisc/include/asm/pgtable.h
View File

@ -177,7 +177,10 @@ struct vm_area_struct;
#define _PAGE_TABLE (_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE | _PAGE_DIRTY | _PAGE_ACCESSED)
#define _PAGE_CHG_MASK (PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
#define _PAGE_KERNEL (_PAGE_PRESENT | _PAGE_EXEC | _PAGE_READ | _PAGE_WRITE | _PAGE_DIRTY | _PAGE_ACCESSED)
#define _PAGE_KERNEL_RO (_PAGE_PRESENT | _PAGE_READ | _PAGE_DIRTY | _PAGE_ACCESSED)
#define _PAGE_KERNEL_EXEC (_PAGE_KERNEL_RO | _PAGE_EXEC)
#define _PAGE_KERNEL_RWX (_PAGE_KERNEL_EXEC | _PAGE_WRITE)
#define _PAGE_KERNEL (_PAGE_KERNEL_RO | _PAGE_WRITE)
/* The pgd/pmd contains a ptr (in phys addr space); since all pgds/pmds
* are page-aligned, we don't care about the PAGE_OFFSET bits, except
@ -208,7 +211,9 @@ struct vm_area_struct;
#define PAGE_COPY PAGE_EXECREAD
#define PAGE_RWX __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_READ | _PAGE_WRITE | _PAGE_EXEC |_PAGE_ACCESSED)
#define PAGE_KERNEL __pgprot(_PAGE_KERNEL)
#define PAGE_KERNEL_RO __pgprot(_PAGE_KERNEL & ~_PAGE_WRITE)
#define PAGE_KERNEL_EXEC __pgprot(_PAGE_KERNEL_EXEC)
#define PAGE_KERNEL_RWX __pgprot(_PAGE_KERNEL_RWX)
#define PAGE_KERNEL_RO __pgprot(_PAGE_KERNEL_RO)
#define PAGE_KERNEL_UNC __pgprot(_PAGE_KERNEL | _PAGE_NO_CACHE)
#define PAGE_GATEWAY __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_GATEWAY| _PAGE_READ)

3
arch/parisc/kernel/entry.S
View File

@ -692,6 +692,9 @@ ENTRY(fault_vector_11)
END(fault_vector_11)
#endif
/* Fault vector is separately protected and *must* be on its own page */
.align PAGE_SIZE
ENTRY(end_fault_vector)
.import handle_interruption,code
.import do_cpu_irq_mask,code

5
arch/parisc/kernel/head.S
View File

@ -106,8 +106,9 @@ $bss_loop:
#endif
/* Now initialize the PTEs themselves */
ldo 0+_PAGE_KERNEL(%r0),%r3 /* Hardwired 0 phys addr start */
/* Now initialize the PTEs themselves. We use RWX for
* everything ... it will get remapped correctly later */
ldo 0+_PAGE_KERNEL_RWX(%r0),%r3 /* Hardwired 0 phys addr start */
ldi (1<<(KERNEL_INITIAL_ORDER-PAGE_SHIFT)),%r11 /* PFN count */
load32 PA(pg0),%r1

10
arch/parisc/kernel/module.c
View File

@ -61,8 +61,10 @@
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/bug.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <asm/pgtable.h>
#include <asm/unwind.h>
#if 0
@ -214,7 +216,13 @@ void *module_alloc(unsigned long size)
{
if (size == 0)
return NULL;
return vmalloc(size);
/* using RWX means less protection for modules, but it's
* easier than trying to map the text, data, init_text and
* init_data correctly */
return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
GFP_KERNEL | __GFP_HIGHMEM,
PAGE_KERNEL_RWX, -1,
__builtin_return_address(0));
}
#ifndef CONFIG_64BIT

1
arch/parisc/kernel/vmlinux.lds.S
View File

@ -134,6 +134,7 @@ SECTIONS
. = ALIGN(16384);
__init_begin = .;
INIT_TEXT_SECTION(16384)
. = ALIGN(PAGE_SIZE);
INIT_DATA_SECTION(16)
/* we have to discard exit text and such at runtime, not link time */
.exit.text :

260
arch/parisc/mm/init.c
View File

@ -369,24 +369,158 @@ static void __init setup_bootmem(void)
request_resource(&sysram_resources[0], &pdcdata_resource);
}
static void __init map_pages(unsigned long start_vaddr,
unsigned long start_paddr, unsigned long size,
pgprot_t pgprot, int force)
{
pgd_t *pg_dir;
pmd_t *pmd;
pte_t *pg_table;
unsigned long end_paddr;
unsigned long start_pmd;
unsigned long start_pte;
unsigned long tmp1;
unsigned long tmp2;
unsigned long address;
unsigned long vaddr;
unsigned long ro_start;
unsigned long ro_end;
unsigned long fv_addr;
unsigned long gw_addr;
extern const unsigned long fault_vector_20;
extern void * const linux_gateway_page;
ro_start = __pa((unsigned long)_text);
ro_end = __pa((unsigned long)&data_start);
fv_addr = __pa((unsigned long)&fault_vector_20) & PAGE_MASK;
gw_addr = __pa((unsigned long)&linux_gateway_page) & PAGE_MASK;
end_paddr = start_paddr + size;
pg_dir = pgd_offset_k(start_vaddr);
#if PTRS_PER_PMD == 1
start_pmd = 0;
#else
start_pmd = ((start_vaddr >> PMD_SHIFT) & (PTRS_PER_PMD - 1));
#endif
start_pte = ((start_vaddr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1));
address = start_paddr;
vaddr = start_vaddr;
while (address < end_paddr) {
#if PTRS_PER_PMD == 1
pmd = (pmd_t *)__pa(pg_dir);
#else
pmd = (pmd_t *)pgd_address(*pg_dir);
/*
* pmd is physical at this point
*/
if (!pmd) {
pmd = (pmd_t *) alloc_bootmem_low_pages_node(NODE_DATA(0), PAGE_SIZE << PMD_ORDER);
pmd = (pmd_t *) __pa(pmd);
}
pgd_populate(NULL, pg_dir, __va(pmd));
#endif
pg_dir++;
/* now change pmd to kernel virtual addresses */
pmd = (pmd_t *)__va(pmd) + start_pmd;
for (tmp1 = start_pmd; tmp1 < PTRS_PER_PMD; tmp1++, pmd++) {
/*
* pg_table is physical at this point
*/
pg_table = (pte_t *)pmd_address(*pmd);
if (!pg_table) {
pg_table = (pte_t *)
alloc_bootmem_low_pages_node(NODE_DATA(0), PAGE_SIZE);
pg_table = (pte_t *) __pa(pg_table);
}
pmd_populate_kernel(NULL, pmd, __va(pg_table));
/* now change pg_table to kernel virtual addresses */
pg_table = (pte_t *) __va(pg_table) + start_pte;
for (tmp2 = start_pte; tmp2 < PTRS_PER_PTE; tmp2++, pg_table++) {
pte_t pte;
/*
* Map the fault vector writable so we can
* write the HPMC checksum.
*/
if (force)
pte = __mk_pte(address, pgprot);
else if (core_kernel_text(vaddr) &&
address != fv_addr)
pte = __mk_pte(address, PAGE_KERNEL_EXEC);
else
#if defined(CONFIG_PARISC_PAGE_SIZE_4KB)
if (address >= ro_start && address < ro_end
&& address != fv_addr
&& address != gw_addr)
pte = __mk_pte(address, PAGE_KERNEL_RO);
else
#endif
pte = __mk_pte(address, pgprot);
if (address >= end_paddr) {
if (force)
break;
else
pte_val(pte) = 0;
}
set_pte(pg_table, pte);
address += PAGE_SIZE;
vaddr += PAGE_SIZE;
}
start_pte = 0;
if (address >= end_paddr)
break;
}
start_pmd = 0;
}
}
void free_initmem(void)
{
unsigned long addr;
unsigned long init_begin = (unsigned long)__init_begin;
unsigned long init_end = (unsigned long)__init_end;
#ifdef CONFIG_DEBUG_KERNEL
/* The init text pages are marked R-X. We have to
* flush the icache and mark them RW-
*
* This is tricky, because map_pages is in the init section.
* Do a dummy remap of the data section first (the data
* section is already PAGE_KERNEL) to pull in the TLB entries
* for map_kernel */
map_pages(init_begin, __pa(init_begin), init_end - init_begin,
PAGE_KERNEL_RWX, 1);
/* now remap at PAGE_KERNEL since the TLB is pre-primed to execute
* map_pages */
map_pages(init_begin, __pa(init_begin), init_end - init_begin,
PAGE_KERNEL, 1);
/* force the kernel to see the new TLB entries */
__flush_tlb_range(0, init_begin, init_end);
/* Attempt to catch anyone trying to execute code here
* by filling the page with BRK insns.
*/
memset((void *)init_begin, 0x00, init_end - init_begin);
/* finally dump all the instructions which were cached, since the
* pages are no-longer executable */
flush_icache_range(init_begin, init_end);
#endif
/* align __init_begin and __init_end to page size,
ignoring linker script where we might have tried to save RAM */
init_begin = PAGE_ALIGN(init_begin);
init_end = PAGE_ALIGN(init_end);
for (addr = init_begin; addr < init_end; addr += PAGE_SIZE) {
ClearPageReserved(virt_to_page(addr));
init_page_count(virt_to_page(addr));
@ -616,114 +750,6 @@ void show_mem(unsigned int filter)
#endif
}
static void __init map_pages(unsigned long start_vaddr, unsigned long start_paddr, unsigned long size, pgprot_t pgprot)
{
pgd_t *pg_dir;
pmd_t *pmd;
pte_t *pg_table;
unsigned long end_paddr;
unsigned long start_pmd;
unsigned long start_pte;
unsigned long tmp1;
unsigned long tmp2;
unsigned long address;
unsigned long ro_start;
unsigned long ro_end;
unsigned long fv_addr;
unsigned long gw_addr;
extern const unsigned long fault_vector_20;
extern void * const linux_gateway_page;
ro_start = __pa((unsigned long)_text);
ro_end = __pa((unsigned long)&data_start);
fv_addr = __pa((unsigned long)&fault_vector_20) & PAGE_MASK;
gw_addr = __pa((unsigned long)&linux_gateway_page) & PAGE_MASK;
end_paddr = start_paddr + size;
pg_dir = pgd_offset_k(start_vaddr);
#if PTRS_PER_PMD == 1
start_pmd = 0;
#else
start_pmd = ((start_vaddr >> PMD_SHIFT) & (PTRS_PER_PMD - 1));
#endif
start_pte = ((start_vaddr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1));
address = start_paddr;
while (address < end_paddr) {
#if PTRS_PER_PMD == 1
pmd = (pmd_t *)__pa(pg_dir);
#else
pmd = (pmd_t *)pgd_address(*pg_dir);
/*
* pmd is physical at this point
*/
if (!pmd) {
pmd = (pmd_t *) alloc_bootmem_low_pages_node(NODE_DATA(0),PAGE_SIZE << PMD_ORDER);
pmd = (pmd_t *) __pa(pmd);
}
pgd_populate(NULL, pg_dir, __va(pmd));
#endif
pg_dir++;
/* now change pmd to kernel virtual addresses */
pmd = (pmd_t *)__va(pmd) + start_pmd;
for (tmp1 = start_pmd; tmp1 < PTRS_PER_PMD; tmp1++,pmd++) {
/*
* pg_table is physical at this point
*/
pg_table = (pte_t *)pmd_address(*pmd);
if (!pg_table) {
pg_table = (pte_t *)
alloc_bootmem_low_pages_node(NODE_DATA(0),PAGE_SIZE);
pg_table = (pte_t *) __pa(pg_table);
}
pmd_populate_kernel(NULL, pmd, __va(pg_table));
/* now change pg_table to kernel virtual addresses */
pg_table = (pte_t *) __va(pg_table) + start_pte;
for (tmp2 = start_pte; tmp2 < PTRS_PER_PTE; tmp2++,pg_table++) {
pte_t pte;
/*
* Map the fault vector writable so we can
* write the HPMC checksum.
*/
#if defined(CONFIG_PARISC_PAGE_SIZE_4KB)
if (address >= ro_start && address < ro_end
&& address != fv_addr
&& address != gw_addr)
pte = __mk_pte(address, PAGE_KERNEL_RO);
else
#endif
pte = __mk_pte(address, pgprot);
if (address >= end_paddr)
pte_val(pte) = 0;
set_pte(pg_table, pte);
address += PAGE_SIZE;
}
start_pte = 0;
if (address >= end_paddr)
break;
}
start_pmd = 0;
}
}
/*
* pagetable_init() sets up the page tables
*
@ -748,14 +774,14 @@ static void __init pagetable_init(void)
size = pmem_ranges[range].pages << PAGE_SHIFT;
map_pages((unsigned long)__va(start_paddr), start_paddr,
size, PAGE_KERNEL);
size, PAGE_KERNEL, 0);
}
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_end && initrd_end > mem_limit) {
printk(KERN_INFO "initrd: mapping %08lx-%08lx\n", initrd_start, initrd_end);
map_pages(initrd_start, __pa(initrd_start),
initrd_end - initrd_start, PAGE_KERNEL);
initrd_end - initrd_start, PAGE_KERNEL, 0);
}
#endif
@ -780,7 +806,7 @@ static void __init gateway_init(void)
*/
map_pages(linux_gateway_page_addr, __pa(&linux_gateway_page),
PAGE_SIZE, PAGE_GATEWAY);
PAGE_SIZE, PAGE_GATEWAY, 1);
}
#ifdef CONFIG_HPUX