Commit 0d80ebc0 authored by Jason Yan's avatar Jason Yan Committed by GUO Zihua
Browse files

powerpc/fsl_booke/kaslr: refactor kaslr_legal_offset() and kaslr_early_init() 

maillist inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8OHAZ
CVE: NA

Reference: https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200330022023.3691-2-yanaijie@huawei.com/



-------------------------------------------------

Some code refactor in kaslr_legal_offset() and kaslr_early_init(). No
functional change. This is a preparation for KASLR fsl_booke64.

Signed-off-by: default avatarJason Yan <yanaijie@huawei.com>
Cc: Scott Wood <oss@buserror.net>
Cc: Diana Craciun <diana.craciun@nxp.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: default avatarCui GaoSheng <cuigaosheng1@huawei.com>
Signed-off-by: default avatarGUO Zihua <guozihua@huawei.com>
parent d63a6b3e

arch/powerpc/mm/nohash/kaslr_booke.c

+18 −16
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ struct regions { 
	unsigned long pa_start;

	unsigned long pa_end;

	unsigned long kernel_size;

	unsigned long linear_sz;

	unsigned long dtb_start;

	unsigned long dtb_end;

	unsigned long initrd_start;
@@ -254,11 +255,23 @@ static __init void get_cell_sizes(const void *fdt, int node, int *addr_cells, 
		*size_cells = fdt32_to_cpu(*prop);

}



static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned long index,

					       unsigned long offset)

static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned long random)

{

	unsigned long koffset = 0;

	unsigned long start;

	unsigned long index;

	unsigned long offset;



	/*

	 * Decide which 64M we want to start

	 * Only use the low 8 bits of the random seed

	 */

	index = random & 0xFF;

	index %= regions.linear_sz / SZ_64M;



	/* Decide offset inside 64M */

	offset = random % (SZ_64M - regions.kernel_size);

	offset = round_down(offset, SZ_16K);



	while ((long)index >= 0) {

		offset = memstart_addr + index * SZ_64M + offset;
@@ -283,10 +296,9 @@ static inline __init bool kaslr_disabled(void) 
static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size,

						  unsigned long kernel_sz)

{

	unsigned long offset, random;

	unsigned long random;

	unsigned long ram, linear_sz;

	u64 seed;

	unsigned long index;



	kaslr_get_cmdline(dt_ptr);

	if (kaslr_disabled())
@@ -327,22 +339,12 @@ static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size 
	regions.dtb_start = __pa(dt_ptr);

	regions.dtb_end = __pa(dt_ptr) + fdt_totalsize(dt_ptr);

	regions.kernel_size = kernel_sz;

	regions.linear_sz = linear_sz;



	get_initrd_range(dt_ptr);

	get_crash_kernel(dt_ptr, ram);



	/*

	 * Decide which 64M we want to start

	 * Only use the low 8 bits of the random seed

	 */

	index = random & 0xFF;

	index %= linear_sz / SZ_64M;



	/* Decide offset inside 64M */

	offset = random % (SZ_64M - kernel_sz);

	offset = round_down(offset, SZ_16K);



	return kaslr_legal_offset(dt_ptr, index, offset);

	return kaslr_legal_offset(dt_ptr, random);

}



/*