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.
James
---
diff --git a/arch/parisc/include/asm/pgtable.h b/arch/parisc/include/asm/pgtable.h
index 5d7b8ce..22dadeb 100644
--- a/arch/parisc/include/asm/pgtable.h
+++ b/arch/parisc/include/asm/pgtable.h
@@ -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)
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index ead8d2a..6f05944 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -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
diff --git a/arch/parisc/kernel/head.S b/arch/parisc/kernel/head.S
index 145c5e4..37aabd7 100644
--- a/arch/parisc/kernel/head.S
+++ b/arch/parisc/kernel/head.S
@@ -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
diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index 6e81bb5..cedbbb8 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -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
diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
index 8f1e4ef..bf6a43a 100644
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -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 :
diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c
index b7ed8d7..c555175 100644
--- a/arch/parisc/mm/init.c
+++ b/arch/parisc/mm/init.c
@@ -369,24 +369,159 @@ 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 &&
+ address != gw_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 +751,6 @@ 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 +775,14 @@ 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 +807,7 @@ 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
--
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