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Commit 1091458d authored by David Daney's avatar David Daney Committed by Ralf Baechle
Browse files

MIPS: Randomize mmap if randomize_va_space is set 



Fairly straight forward: For 32-bit address spaces randomize within a
16MB space, for 64-bit within a 256MB space.

Signed-off-by: default avatarDavid Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1480/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent b3b3c176

arch/mips/include/asm/processor.h

+11 −0
Original line number Diff line number Diff line
@@ -33,6 +33,11 @@ extern void (*cpu_wait)(void); 


extern unsigned int vced_count, vcei_count;



/*

 * MIPS does have an arch_pick_mmap_layout()

 */

#define HAVE_ARCH_PICK_MMAP_LAYOUT 1



/*

 * A special page (the vdso) is mapped into all processes at the very

 * top of the virtual memory space.
@@ -52,6 +57,9 @@ extern unsigned int vced_count, vcei_count; 
 * space during mmap's.

 */

#define TASK_UNMAPPED_BASE	((TASK_SIZE / 3) & ~(PAGE_SIZE))



#define TASK_IS_32BIT_ADDR 1



#endif



#ifdef CONFIG_64BIT
@@ -77,6 +85,9 @@ extern unsigned int vced_count, vcei_count; 
		PAGE_ALIGN(TASK_SIZE32 / 3) : PAGE_ALIGN(TASK_SIZE / 3))

#define TASK_SIZE_OF(tsk)						\

	(test_tsk_thread_flag(tsk, TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE)



#define TASK_IS_32BIT_ADDR test_thread_flag(TIF_32BIT_ADDR)



#endif



#ifdef __KERNEL__

arch/mips/kernel/syscall.c

+20 −1
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/ipc.h>

#include <linux/uaccess.h>

#include <linux/slab.h>

#include <linux/random.h>



#include <asm/asm.h>

#include <asm/branch.h>
@@ -116,7 +117,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, 
		    (!vmm || addr + len <= vmm->vm_start))

			return addr;

	}

	addr = TASK_UNMAPPED_BASE;

	addr = current->mm->mmap_base;

	if (do_color_align)

		addr = COLOUR_ALIGN(addr, pgoff);

	else
@@ -134,6 +135,24 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr, 
	}

}



void arch_pick_mmap_layout(struct mm_struct *mm)

{

	unsigned long random_factor = 0UL;



	if (current->flags & PF_RANDOMIZE) {

		random_factor = get_random_int();

		random_factor = random_factor << PAGE_SHIFT;

		if (TASK_IS_32BIT_ADDR)

			random_factor &= 0xfffffful;

		else

			random_factor &= 0xffffffful;

	}



	mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;

	mm->get_unmapped_area = arch_get_unmapped_area;

	mm->unmap_area = arch_unmap_area;

}



SYSCALL_DEFINE6(mips_mmap, unsigned long, addr, unsigned long, len,

	unsigned long, prot, unsigned long, flags, unsigned long,

	fd, off_t, offset)