Commit 2b0e86cc authored by Jason Yan's avatar Jason Yan Committed by Michael Ellerman
Browse files

powerpc/fsl_booke/32: implement KASLR infrastructure 



This patch add support to boot kernel from places other than KERNELBASE.
Since CONFIG_RELOCATABLE has already supported, what we need to do is
map or copy kernel to a proper place and relocate. Freescale Book-E
parts expect lowmem to be mapped by fixed TLB entries(TLB1). The TLB1
entries are not suitable to map the kernel directly in a randomized
region, so we chose to copy the kernel to a proper place and restart to
relocate.

The offset of the kernel was not randomized yet(a fixed 64M is set). We
will randomize it in the next patch.

Signed-off-by: default avatarJason Yan <yanaijie@huawei.com>
Tested-by: default avatarDiana Craciun <diana.craciun@nxp.com>
Reviewed-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarScott Wood <oss@buserror.net>
[mpe: Use PTRRELOC() in early_init()]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c061b38a

arch/powerpc/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -551,6 +551,17 @@ config RELOCATABLE 
	  setting can still be useful to bootwrappers that need to know the

	  load address of the kernel (eg. u-boot/mkimage).



config RANDOMIZE_BASE

	bool "Randomize the address of the kernel image"

	depends on (FSL_BOOKE && FLATMEM && PPC32)

	depends on RELOCATABLE

	help

	  Randomizes the virtual address at which the kernel image is

	  loaded, as a security feature that deters exploit attempts

	  relying on knowledge of the location of kernel internals.



	  If unsure, say Y.



config RELOCATABLE_TEST

	bool "Test relocatable kernel"

	depends on (PPC64 && RELOCATABLE)

arch/powerpc/include/asm/nohash/mmu-book3e.h

+0 −1
Original line number Diff line number Diff line
@@ -75,7 +75,6 @@ 
#define MAS2_E			0x00000001

#define MAS2_WIMGE_MASK		0x0000001f

#define MAS2_EPN_MASK(size)		(~0 << (size + 10))

#define MAS2_VAL(addr, size, flags)	((addr) & MAS2_EPN_MASK(size) | (flags))



#define MAS3_RPN		0xFFFFF000

#define MAS3_U0			0x00000200

arch/powerpc/kernel/early_32.c

+6 −3
Original line number Diff line number Diff line
@@ -19,9 +19,12 @@ 
 */

notrace unsigned long __init early_init(unsigned long dt_ptr)

{

	unsigned long offset = reloc_offset();

	unsigned long kva, offset = reloc_offset();



	kva = *PTRRELOC(&kernstart_virt_addr);



	/* First zero the BSS */

	if (kva == KERNELBASE)

		memset(PTRRELOC(&__bss_start), 0, __bss_stop - __bss_start);



	/*
@@ -32,5 +35,5 @@ notrace unsigned long __init early_init(unsigned long dt_ptr) 


	apply_feature_fixups();



	return KERNELBASE + offset;

	return kva + offset;

}

arch/powerpc/kernel/fsl_booke_entry_mapping.S

+7 −8
Original line number Diff line number Diff line
@@ -155,23 +155,22 @@ skpinv: addi r6,r6,1 /* Increment */ 


#if defined(ENTRY_MAPPING_BOOT_SETUP)



/* 6. Setup KERNELBASE mapping in TLB1[0] */

/* 6. Setup kernstart_virt_addr mapping in TLB1[0] */

	lis	r6,0x1000		/* Set MAS0(TLBSEL) = TLB1(1), ESEL = 0 */

	mtspr	SPRN_MAS0,r6

	lis	r6,(MAS1_VALID|MAS1_IPROT)@h

	ori	r6,r6,(MAS1_TSIZE(BOOK3E_PAGESZ_64M))@l

	mtspr	SPRN_MAS1,r6

	lis	r6,MAS2_VAL(PAGE_OFFSET, BOOK3E_PAGESZ_64M, MAS2_M_IF_NEEDED)@h

	ori	r6,r6,MAS2_VAL(PAGE_OFFSET, BOOK3E_PAGESZ_64M, MAS2_M_IF_NEEDED)@l

	lis	r6,MAS2_EPN_MASK(BOOK3E_PAGESZ_64M)@h

	ori	r6,r6,MAS2_EPN_MASK(BOOK3E_PAGESZ_64M)@l

	and	r6,r6,r20

	ori	r6,r6,MAS2_M_IF_NEEDED@l

	mtspr	SPRN_MAS2,r6

	mtspr	SPRN_MAS3,r8

	tlbwe



/* 7. Jump to KERNELBASE mapping */

	lis	r6,(KERNELBASE & ~0xfff)@h

	ori	r6,r6,(KERNELBASE & ~0xfff)@l

	rlwinm	r7,r25,0,0x03ffffff

	add	r6,r7,r6

/* 7. Jump to kernstart_virt_addr mapping */

	mr	r6,r20



#elif defined(ENTRY_MAPPING_KEXEC_SETUP)

/*

arch/powerpc/kernel/head_fsl_booke.S

+10 −3
Original line number Diff line number Diff line
@@ -155,6 +155,8 @@ _ENTRY(_start); 
 */



_ENTRY(__early_start)

	LOAD_REG_ADDR_PIC(r20, kernstart_virt_addr)

	lwz     r20,0(r20)



#define ENTRY_MAPPING_BOOT_SETUP

#include "fsl_booke_entry_mapping.S"
@@ -277,8 +279,8 @@ set_ivor: 
	ori	r6, r6, swapper_pg_dir@l

	lis	r5, abatron_pteptrs@h

	ori	r5, r5, abatron_pteptrs@l

	lis	r4, KERNELBASE@h

	ori	r4, r4, KERNELBASE@l

	lis     r3, kernstart_virt_addr@ha

	lwz     r4, kernstart_virt_addr@l(r3)

	stw	r5, 0(r4)	/* Save abatron_pteptrs at a fixed location */

	stw	r6, 0(r5)
@@ -1067,7 +1069,12 @@ __secondary_start: 
	mr	r5,r25		/* phys kernel start */

	rlwinm	r5,r5,0,~0x3ffffff	/* aligned 64M */

	subf	r4,r5,r4	/* memstart_addr - phys kernel start */

	li	r5,0		/* no device tree */

	lis	r7,KERNELBASE@h

	ori	r7,r7,KERNELBASE@l

	cmpw	r20,r7		/* if kernstart_virt_addr != KERNELBASE, randomized */

	beq	2f

	li	r4,0

2:	li	r5,0		/* no device tree */

	li	r6,0		/* not boot cpu */

	bl	restore_to_as0

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