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Commit d7dd2ff1 authored by James Bottomley's avatar James Bottomley Committed by James Bottomley
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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: default avatarJames Bottomley <James.Bottomley@suse.de>
parent e38f5b74

arch/parisc/include/asm/pgtable.h

+7 −2
Original line number Original line Diff line number Diff line
@@ -177,7 +177,10 @@ struct vm_area_struct; 




#define _PAGE_TABLE	(_PAGE_PRESENT | _PAGE_READ | _PAGE_WRITE |  _PAGE_DIRTY | _PAGE_ACCESSED)

#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_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

/* 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

 * 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_COPY       PAGE_EXECREAD

#define PAGE_RWX        __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_READ | _PAGE_WRITE | _PAGE_EXEC |_PAGE_ACCESSED)

#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	__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_KERNEL_UNC	__pgprot(_PAGE_KERNEL | _PAGE_NO_CACHE)

#define PAGE_GATEWAY    __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_GATEWAY| _PAGE_READ)

#define PAGE_GATEWAY    __pgprot(_PAGE_PRESENT | _PAGE_USER | _PAGE_ACCESSED | _PAGE_GATEWAY| _PAGE_READ)

arch/parisc/kernel/entry.S

+3 −0
Original line number Original line Diff line number Diff line
@@ -692,6 +692,9 @@ ENTRY(fault_vector_11) 
END(fault_vector_11)

END(fault_vector_11)





#endif

#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		handle_interruption,code

	.import		do_cpu_irq_mask,code

	.import		do_cpu_irq_mask,code

arch/parisc/kernel/head.S

+3 −2
Original line number Original line Diff line number Diff line
@@ -106,8 +106,9 @@ $bss_loop: 
#endif

#endif









	/* Now initialize the PTEs themselves */

	/* Now initialize the PTEs themselves.  We use RWX for

	ldo		0+_PAGE_KERNEL(%r0),%r3 /* Hardwired 0 phys addr start */

	 * 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 */

	ldi		(1<<(KERNEL_INITIAL_ORDER-PAGE_SHIFT)),%r11 /* PFN count */

	load32		PA(pg0),%r1

	load32		PA(pg0),%r1

arch/parisc/kernel/module.c

+9 −1
Original line number Original line Diff line number Diff line
@@ -61,8 +61,10 @@ 
#include <linux/string.h>

#include <linux/string.h>

#include <linux/kernel.h>

#include <linux/kernel.h>

#include <linux/bug.h>

#include <linux/bug.h>

#include <linux/mm.h>

#include <linux/slab.h>

#include <linux/slab.h>





#include <asm/pgtable.h>

#include <asm/unwind.h>

#include <asm/unwind.h>





#if 0

#if 0
@@ -214,7 +216,13 @@ void *module_alloc(unsigned long size) 
{

{

	if (size == 0)

	if (size == 0)

		return NULL;

		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

#ifndef CONFIG_64BIT

arch/parisc/kernel/vmlinux.lds.S

+1 −0
Original line number Original line Diff line number Diff line
@@ -134,6 +134,7 @@ SECTIONS 
	. = ALIGN(16384);

	. = ALIGN(16384);

	__init_begin = .;

	__init_begin = .;

	INIT_TEXT_SECTION(16384)

	INIT_TEXT_SECTION(16384)

	. = ALIGN(PAGE_SIZE);

	INIT_DATA_SECTION(16)

	INIT_DATA_SECTION(16)

	/* we have to discard exit text and such at runtime, not link time */

	/* we have to discard exit text and such at runtime, not link time */

	.exit.text :

	.exit.text :