Merge branch 'topic/kaslr-book3e32' into next

This is a slight rebase of Scott's next branch, which contained the
KASLR support for book3e 32-bit, to squash in a couple of small fixes.

See the	original pull request:
  https://lore.kernel.org/r/20191022232155.GA26174@home.buserror.net

Documentation/powerpc/index.rst

@@ -19,6 +19,7 @@ powerpc
     firmware-assisted-dump
     hvcs
     isa-versions
+    kaslr-booke32
     mpc52xx
     pci_iov_resource_on_powernv
     pmu-ebb

Documentation/powerpc/kaslr-booke32.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+===========================
+KASLR for Freescale BookE32
+===========================
+
+The word KASLR stands for Kernel Address Space Layout Randomization.
+
+This document tries to explain the implementation of the KASLR for
+Freescale BookE32. KASLR is a security feature that deters exploit
+attempts relying on knowledge of the location of kernel internals.
+
+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.
+
+Entropy is derived from the banner and timer base, which will change every
+build and boot. This not so much safe so additionally the bootloader may
+pass entropy via the /chosen/kaslr-seed node in device tree.
+
+We will use the first 512M of the low memory to randomize the kernel
+image. The memory will be split in 64M zones. We will use the lower 8
+bit of the entropy to decide the index of the 64M zone. Then we chose a
+16K aligned offset inside the 64M zone to put the kernel in::
+
+    KERNELBASE
+
+        |-->   64M   <--|
+        |               |
+        +---------------+    +----------------+---------------+
+        |               |....|    |kernel|    |               |
+        +---------------+    +----------------+---------------+
+        |                         |
+        |----->   offset    <-----|
+
+                              kernstart_virt_addr
+
+To enable KASLR, set CONFIG_RANDOMIZE_BASE = y. If KASLR is enable and you
+want to disable it at runtime, add "nokaslr" to the kernel cmdline.

arch/powerpc/Kconfig

@@ -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

@@ -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
@@ -221,6 +220,16 @@
 #define TLBILX_T_CLASS2			6
 #define TLBILX_T_CLASS3			7
 
+/*
+ * The mapping only needs to be cache-coherent on SMP, except on
+ * Freescale e500mc derivatives where it's also needed for coherent DMA.
+ */
+#if defined(CONFIG_SMP) || defined(CONFIG_PPC_E500MC)
+#define MAS2_M_IF_NEEDED	MAS2_M
+#else
+#define MAS2_M_IF_NEEDED	0
+#endif
+
 #ifndef __ASSEMBLY__
 #include <asm/bug.h>
 

arch/powerpc/include/asm/page.h

@@ -325,6 +325,13 @@ void arch_free_page(struct page *page, int order);
 
 struct vm_area_struct;
 
+extern unsigned long kernstart_virt_addr;
+
+static inline unsigned long kaslr_offset(void)
+{
+	return kernstart_virt_addr - KERNELBASE;
+}
+
 #include <asm-generic/memory_model.h>
 #endif /* __ASSEMBLY__ */
 #include <asm/slice.h>

arch/powerpc/kernel/early_32.c

@@ -19,10 +19,13 @@
  */
 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 */
-	memset(PTRRELOC(&__bss_start), 0, __bss_stop - __bss_start);
+	if (kva == KERNELBASE)
+		memset(PTRRELOC(&__bss_start), 0, __bss_stop - __bss_start);
 
 	/*
 	 * Identify the CPU type and fix up code sections
@@ -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/exceptions-64e.S

@@ -1346,16 +1346,6 @@ skpinv:	addi	r6,r6,1				/* Increment */
 	sync
 	isync
 
-/*
- * The mapping only needs to be cache-coherent on SMP, except on
- * Freescale e500mc derivatives where it's also needed for coherent DMA.
- */
-#if defined(CONFIG_SMP) || defined(CONFIG_PPC_E500MC)
-#define M_IF_NEEDED	MAS2_M
-#else
-#define M_IF_NEEDED	0
-#endif
-
 /* 6. Setup KERNELBASE mapping in TLB[0]
  *
  * r3 = MAS0 w/TLBSEL & ESEL for the entry we started in
@@ -1368,7 +1358,7 @@ skpinv:	addi	r6,r6,1				/* Increment */
 	ori	r6,r6,(MAS1_TSIZE(BOOK3E_PAGESZ_1GB))@l
 	mtspr	SPRN_MAS1,r6
 
-	LOAD_REG_IMMEDIATE(r6, PAGE_OFFSET | M_IF_NEEDED)
+	LOAD_REG_IMMEDIATE(r6, PAGE_OFFSET | MAS2_M_IF_NEEDED)
 	mtspr	SPRN_MAS2,r6
 
 	rlwinm	r5,r5,0,0,25

arch/powerpc/kernel/fsl_booke_entry_mapping.S

@@ -153,35 +153,24 @@ skpinv:	addi	r6,r6,1				/* Increment */
 	tlbivax 0,r9
 	TLBSYNC
 
-/*
- * The mapping only needs to be cache-coherent on SMP, except on
- * Freescale e500mc derivatives where it's also needed for coherent DMA.
- */
-#if defined(CONFIG_SMP) || defined(CONFIG_PPC_E500MC)
-#define M_IF_NEEDED	MAS2_M
-#else
-#define M_IF_NEEDED	0
-#endif
-
 #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, M_IF_NEEDED)@h
-	ori	r6,r6,MAS2_VAL(PAGE_OFFSET, BOOK3E_PAGESZ_64M, 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

@@ -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
 
@@ -1114,6 +1121,54 @@ __secondary_hold_acknowledge:
 	.long	-1
 #endif
 
+/*
+ * Create a 64M tlb by address and entry
+ * r3 - entry
+ * r4 - virtual address
+ * r5/r6 - physical address
+ */
+_GLOBAL(create_kaslr_tlb_entry)
+	lis     r7,0x1000               /* Set MAS0(TLBSEL) = 1 */
+	rlwimi  r7,r3,16,4,15           /* Setup MAS0 = TLBSEL | ESEL(r6) */
+	mtspr   SPRN_MAS0,r7            /* Write MAS0 */
+
+	lis     r3,(MAS1_VALID|MAS1_IPROT)@h
+	ori     r3,r3,(MAS1_TSIZE(BOOK3E_PAGESZ_64M))@l
+	mtspr   SPRN_MAS1,r3            /* Write MAS1 */
+
+	lis     r3,MAS2_EPN_MASK(BOOK3E_PAGESZ_64M)@h
+	ori     r3,r3,MAS2_EPN_MASK(BOOK3E_PAGESZ_64M)@l
+	and     r3,r3,r4
+	ori	r3,r3,MAS2_M_IF_NEEDED@l
+	mtspr   SPRN_MAS2,r3            /* Write MAS2(EPN) */
+
+#ifdef CONFIG_PHYS_64BIT
+	ori     r8,r6,(MAS3_SW|MAS3_SR|MAS3_SX)
+	mtspr   SPRN_MAS3,r8            /* Write MAS3(RPN) */
+	mtspr	SPRN_MAS7,r5
+#else
+	ori     r8,r5,(MAS3_SW|MAS3_SR|MAS3_SX)
+	mtspr   SPRN_MAS3,r8            /* Write MAS3(RPN) */
+#endif
+
+	tlbwe                           /* Write TLB */
+	isync
+	sync
+	blr
+
+/*
+ * Return to the start of the relocated kernel and run again
+ * r3 - virtual address of fdt
+ * r4 - entry of the kernel
+ */
+_GLOBAL(reloc_kernel_entry)
+	mfmsr	r7
+	rlwinm	r7, r7, 0, ~(MSR_IS | MSR_DS)
+
+	mtspr	SPRN_SRR0,r4
+	mtspr	SPRN_SRR1,r7
+	rfi
+
 /*
  * Create a tlb entry with the same effective and physical address as
  * the tlb entry used by the current running code. But set the TS to 1.

arch/powerpc/kernel/machine_kexec.c

@@ -86,6 +86,7 @@ void arch_crash_save_vmcoreinfo(void)
 	VMCOREINFO_STRUCT_SIZE(mmu_psize_def);
 	VMCOREINFO_OFFSET(mmu_psize_def, shift);
 #endif
+	vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
 }
 
 /*

arch/powerpc/kernel/misc_64.S

@@ -330,18 +330,13 @@ kexec_create_tlb:
 	rlwimi	r9,r10,16,4,15		/* Setup MAS0 = TLBSEL | ESEL(r9) */
 
 /* Set up a temp identity mapping v:0 to p:0 and return to it. */
-#if defined(CONFIG_SMP) || defined(CONFIG_PPC_E500MC)
-#define M_IF_NEEDED	MAS2_M
-#else
-#define M_IF_NEEDED	0
-#endif
 	mtspr	SPRN_MAS0,r9
 
 	lis	r9,(MAS1_VALID|MAS1_IPROT)@h
 	ori	r9,r9,(MAS1_TSIZE(BOOK3E_PAGESZ_1GB))@l
 	mtspr	SPRN_MAS1,r9
 
-	LOAD_REG_IMMEDIATE(r9, 0x0 | M_IF_NEEDED)
+	LOAD_REG_IMMEDIATE(r9, 0x0 | MAS2_M_IF_NEEDED)
 	mtspr	SPRN_MAS2,r9
 
 	LOAD_REG_IMMEDIATE(r9, 0x0 | MAS3_SR | MAS3_SW | MAS3_SX)

arch/powerpc/kernel/setup-common.c

@@ -715,8 +715,28 @@ static struct notifier_block ppc_panic_block = {
 	.priority = INT_MIN /* may not return; must be done last */
 };
 
+/*
+ * Dump out kernel offset information on panic.
+ */
+static int dump_kernel_offset(struct notifier_block *self, unsigned long v,
+			      void *p)
+{
+	pr_emerg("Kernel Offset: 0x%lx from 0x%lx\n",
+		 kaslr_offset(), KERNELBASE);
+
+	return 0;
+}
+
+static struct notifier_block kernel_offset_notifier = {
+	.notifier_call = dump_kernel_offset
+};
+
 void __init setup_panic(void)
 {
+	if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && kaslr_offset() > 0)
+		atomic_notifier_chain_register(&panic_notifier_list,
+					       &kernel_offset_notifier);
+
 	/* PPC64 always does a hard irq disable in its panic handler */
 	if (!IS_ENABLED(CONFIG_PPC64) && !ppc_md.panic)
 		return;

arch/powerpc/mm/init-common.c

@@ -21,6 +21,13 @@
 #include <asm/pgtable.h>
 #include <asm/kup.h>
 
+phys_addr_t memstart_addr __ro_after_init = (phys_addr_t)~0ull;
+EXPORT_SYMBOL_GPL(memstart_addr);
+phys_addr_t kernstart_addr __ro_after_init;
+EXPORT_SYMBOL_GPL(kernstart_addr);
+unsigned long kernstart_virt_addr __ro_after_init = KERNELBASE;
+EXPORT_SYMBOL_GPL(kernstart_virt_addr);
+
 static bool disable_kuep = !IS_ENABLED(CONFIG_PPC_KUEP);
 static bool disable_kuap = !IS_ENABLED(CONFIG_PPC_KUAP);
 

arch/powerpc/mm/init_32.c

@@ -56,11 +56,6 @@
 phys_addr_t total_memory;
 phys_addr_t total_lowmem;
 
-phys_addr_t memstart_addr = (phys_addr_t)~0ull;
-EXPORT_SYMBOL(memstart_addr);
-phys_addr_t kernstart_addr;
-EXPORT_SYMBOL(kernstart_addr);
-
 #ifdef CONFIG_RELOCATABLE
 /* Used in __va()/__pa() */
 long long virt_phys_offset;

arch/powerpc/mm/init_64.c

@@ -63,11 +63,6 @@
 
 #include <mm/mmu_decl.h>
 
-phys_addr_t memstart_addr = ~0;
-EXPORT_SYMBOL_GPL(memstart_addr);
-phys_addr_t kernstart_addr;
-EXPORT_SYMBOL_GPL(kernstart_addr);
-
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 /*
  * Given an address within the vmemmap, determine the page that

arch/powerpc/mm/mmu_decl.h

@@ -139,10 +139,21 @@ extern unsigned long calc_cam_sz(unsigned long ram, unsigned long virt,
 extern void adjust_total_lowmem(void);
 extern int switch_to_as1(void);
 extern void restore_to_as0(int esel, int offset, void *dt_ptr, int bootcpu);
+void create_kaslr_tlb_entry(int entry, unsigned long virt, phys_addr_t phys);
+void reloc_kernel_entry(void *fdt, int addr);
+extern int is_second_reloc;
 #endif
 extern void loadcam_entry(unsigned int index);
 extern void loadcam_multi(int first_idx, int num, int tmp_idx);
 
+#ifdef CONFIG_RANDOMIZE_BASE
+void kaslr_early_init(void *dt_ptr, phys_addr_t size);
+void kaslr_late_init(void);
+#else
+static inline void kaslr_early_init(void *dt_ptr, phys_addr_t size) {}
+static inline void kaslr_late_init(void) {}
+#endif
+
 struct tlbcam {
 	u32	MAS0;
 	u32	MAS1;

arch/powerpc/mm/nohash/Makefile

@@ -8,6 +8,7 @@ obj-$(CONFIG_40x)		+= 40x.o
 obj-$(CONFIG_44x)		+= 44x.o
 obj-$(CONFIG_PPC_8xx)		+= 8xx.o
 obj-$(CONFIG_PPC_FSL_BOOK3E)	+= fsl_booke.o
+obj-$(CONFIG_RANDOMIZE_BASE)	+= kaslr_booke.o
 ifdef CONFIG_HUGETLB_PAGE
 obj-$(CONFIG_PPC_FSL_BOOK3E)	+= book3e_hugetlbpage.o
 endif

arch/powerpc/mm/nohash/fsl_booke.c

@@ -263,11 +263,13 @@ void setup_initial_memory_limit(phys_addr_t first_memblock_base,
 int __initdata is_second_reloc;
 notrace void __init relocate_init(u64 dt_ptr, phys_addr_t start)
 {
-	unsigned long base = KERNELBASE;
+	unsigned long base = kernstart_virt_addr;
+	phys_addr_t size;
 
 	kernstart_addr = start;
 	if (is_second_reloc) {
 		virt_phys_offset = PAGE_OFFSET - memstart_addr;
+		kaslr_late_init();
 		return;
 	}
 
@@ -291,7 +293,7 @@ notrace void __init relocate_init(u64 dt_ptr, phys_addr_t start)
 	start &= ~0x3ffffff;
 	base &= ~0x3ffffff;
 	virt_phys_offset = base - start;
-	early_get_first_memblock_info(__va(dt_ptr), NULL);
+	early_get_first_memblock_info(__va(dt_ptr), &size);
 	/*
 	 * We now get the memstart_addr, then we should check if this
 	 * address is the same as what the PAGE_OFFSET map to now. If
@@ -316,6 +318,8 @@ notrace void __init relocate_init(u64 dt_ptr, phys_addr_t start)
 		/* We should never reach here */
 		panic("Relocation error");
 	}
+
+	kaslr_early_init(__va(dt_ptr), size);
 }
 #endif
 #endif

arch/powerpc/mm/nohash/kaslr_booke.c

+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright (C) 2019 Jason Yan <yanaijie@huawei.com>
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/stddef.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/memblock.h>
+#include <linux/libfdt.h>
+#include <linux/crash_core.h>
+#include <asm/pgalloc.h>
+#include <asm/prom.h>
+#include <asm/kdump.h>
+#include <mm/mmu_decl.h>
+#include <generated/compile.h>
+#include <generated/utsrelease.h>
+
+struct regions {
+	unsigned long pa_start;
+	unsigned long pa_end;
+	unsigned long kernel_size;
+	unsigned long dtb_start;
+	unsigned long dtb_end;
+	unsigned long initrd_start;
+	unsigned long initrd_end;
+	unsigned long crash_start;
+	unsigned long crash_end;
+	int reserved_mem;
+	int reserved_mem_addr_cells;
+	int reserved_mem_size_cells;
+};
+
+/* Simplified build-specific string for starting entropy. */
+static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@"
+		LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION;
+
+struct regions __initdata regions;
+
+static __init void kaslr_get_cmdline(void *fdt)
+{
+	int node = fdt_path_offset(fdt, "/chosen");
+
+	early_init_dt_scan_chosen(node, "chosen", 1, boot_command_line);
+}
+
+static unsigned long __init rotate_xor(unsigned long hash, const void *area,
+				       size_t size)
+{
+	size_t i;
+	const unsigned long *ptr = area;
+
+	for (i = 0; i < size / sizeof(hash); i++) {
+		/* Rotate by odd number of bits and XOR. */
+		hash = (hash << ((sizeof(hash) * 8) - 7)) | (hash >> 7);
+		hash ^= ptr[i];
+	}
+
+	return hash;
+}
+
+/* Attempt to create a simple starting entropy. This can make it defferent for
+ * every build but it is still not enough. Stronger entropy should
+ * be added to make it change for every boot.
+ */
+static unsigned long __init get_boot_seed(void *fdt)
+{
+	unsigned long hash = 0;
+
+	hash = rotate_xor(hash, build_str, sizeof(build_str));
+	hash = rotate_xor(hash, fdt, fdt_totalsize(fdt));
+
+	return hash;
+}
+
+static __init u64 get_kaslr_seed(void *fdt)
+{
+	int node, len;
+	fdt64_t *prop;
+	u64 ret;
+
+	node = fdt_path_offset(fdt, "/chosen");
+	if (node < 0)
+		return 0;
+
+	prop = fdt_getprop_w(fdt, node, "kaslr-seed", &len);
+	if (!prop || len != sizeof(u64))
+		return 0;
+
+	ret = fdt64_to_cpu(*prop);
+	*prop = 0;
+	return ret;
+}
+
+static __init bool regions_overlap(u32 s1, u32 e1, u32 s2, u32 e2)
+{
+	return e1 >= s2 && e2 >= s1;
+}
+
+static __init bool overlaps_reserved_region(const void *fdt, u32 start,
+					    u32 end)
+{
+	int subnode, len, i;
+	u64 base, size;
+
+	/* check for overlap with /memreserve/ entries */
+	for (i = 0; i < fdt_num_mem_rsv(fdt); i++) {
+		if (fdt_get_mem_rsv(fdt, i, &base, &size) < 0)
+			continue;
+		if (regions_overlap(start, end, base, base + size))
+			return true;
+	}
+
+	if (regions.reserved_mem < 0)
+		return false;
+
+	/* check for overlap with static reservations in /reserved-memory */
+	for (subnode = fdt_first_subnode(fdt, regions.reserved_mem);
+	     subnode >= 0;
+	     subnode = fdt_next_subnode(fdt, subnode)) {
+		const fdt32_t *reg;
+		u64 rsv_end;
+
+		len = 0;
+		reg = fdt_getprop(fdt, subnode, "reg", &len);
+		while (len >= (regions.reserved_mem_addr_cells +
+			       regions.reserved_mem_size_cells)) {
+			base = fdt32_to_cpu(reg[0]);
+			if (regions.reserved_mem_addr_cells == 2)
+				base = (base << 32) | fdt32_to_cpu(reg[1]);
+
+			reg += regions.reserved_mem_addr_cells;
+			len -= 4 * regions.reserved_mem_addr_cells;
+
+			size = fdt32_to_cpu(reg[0]);
+			if (regions.reserved_mem_size_cells == 2)
+				size = (size << 32) | fdt32_to_cpu(reg[1]);
+
+			reg += regions.reserved_mem_size_cells;
+			len -= 4 * regions.reserved_mem_size_cells;
+
+			if (base >= regions.pa_end)
+				continue;
+
+			rsv_end = min(base + size, (u64)U32_MAX);
+
+			if (regions_overlap(start, end, base, rsv_end))
+				return true;
+		}
+	}
+	return false;
+}
+
+static __init bool overlaps_region(const void *fdt, u32 start,
+				   u32 end)
+{
+	if (regions_overlap(start, end, __pa(_stext), __pa(_end)))
+		return true;
+
+	if (regions_overlap(start, end, regions.dtb_start,
+			    regions.dtb_end))
+		return true;
+
+	if (regions_overlap(start, end, regions.initrd_start,
+			    regions.initrd_end))
+		return true;
+
+	if (regions_overlap(start, end, regions.crash_start,
+			    regions.crash_end))
+		return true;
+
+	return overlaps_reserved_region(fdt, start, end);
+}
+
+static void __init get_crash_kernel(void *fdt, unsigned long size)
+{
+#ifdef CONFIG_CRASH_CORE
+	unsigned long long crash_size, crash_base;
+	int ret;
+
+	ret = parse_crashkernel(boot_command_line, size, &crash_size,
+				&crash_base);
+	if (ret != 0 || crash_size == 0)
+		return;
+	if (crash_base == 0)
+		crash_base = KDUMP_KERNELBASE;
+
+	regions.crash_start = (unsigned long)crash_base;
+	regions.crash_end = (unsigned long)(crash_base + crash_size);
+
+	pr_debug("crash_base=0x%llx crash_size=0x%llx\n", crash_base, crash_size);
+#endif
+}
+
+static void __init get_initrd_range(void *fdt)
+{
+	u64 start, end;
+	int node, len;
+	const __be32 *prop;
+
+	node = fdt_path_offset(fdt, "/chosen");
+	if (node < 0)
+		return;
+
+	prop = fdt_getprop(fdt, node, "linux,initrd-start", &len);
+	if (!prop)
+		return;
+	start = of_read_number(prop, len / 4);
+
+	prop = fdt_getprop(fdt, node, "linux,initrd-end", &len);
+	if (!prop)
+		return;
+	end = of_read_number(prop, len / 4);
+
+	regions.initrd_start = (unsigned long)start;
+	regions.initrd_end = (unsigned long)end;
+
+	pr_debug("initrd_start=0x%llx  initrd_end=0x%llx\n", start, end);
+}
+
+static __init unsigned long get_usable_address(const void *fdt,
+					       unsigned long start,
+					       unsigned long offset)
+{
+	unsigned long pa;
+	unsigned long pa_end;
+
+	for (pa = offset; (long)pa > (long)start; pa -= SZ_16K) {
+		pa_end = pa + regions.kernel_size;
+		if (overlaps_region(fdt, pa, pa_end))
+			continue;
+
+		return pa;
+	}
+	return 0;
+}
+
+static __init void get_cell_sizes(const void *fdt, int node, int *addr_cells,
+				  int *size_cells)
+{
+	const int *prop;
+	int len;
+
+	/*
+	 * Retrieve the #address-cells and #size-cells properties
+	 * from the 'node', or use the default if not provided.
+	 */
+	*addr_cells = *size_cells = 1;
+
+	prop = fdt_getprop(fdt, node, "#address-cells", &len);
+	if (len == 4)
+		*addr_cells = fdt32_to_cpu(*prop);
+	prop = fdt_getprop(fdt, node, "#size-cells", &len);
+	if (len == 4)
+		*size_cells = fdt32_to_cpu(*prop);
+}
+
+static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned long index,
+					       unsigned long offset)
+{
+	unsigned long koffset = 0;
+	unsigned long start;
+
+	while ((long)index >= 0) {
+		offset = memstart_addr + index * SZ_64M + offset;
+		start = memstart_addr + index * SZ_64M;
+		koffset = get_usable_address(dt_ptr, start, offset);
+		if (koffset)
+			break;
+		index--;
+	}
+
+	if (koffset != 0)
+		koffset -= memstart_addr;
+
+	return koffset;
+}
+
+static inline __init bool kaslr_disabled(void)
+{
+	return strstr(boot_command_line, "nokaslr") != NULL;
+}
+
+static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size,
+						  unsigned long kernel_sz)
+{
+	unsigned long offset, random;
+	unsigned long ram, linear_sz;
+	u64 seed;
+	unsigned long index;
+
+	kaslr_get_cmdline(dt_ptr);
+	if (kaslr_disabled())
+		return 0;
+
+	random = get_boot_seed(dt_ptr);
+
+	seed = get_tb() << 32;
+	seed ^= get_tb();
+	random = rotate_xor(random, &seed, sizeof(seed));
+
+	/*
+	 * Retrieve (and wipe) the seed from the FDT
+	 */
+	seed = get_kaslr_seed(dt_ptr);
+	if (seed)
+		random = rotate_xor(random, &seed, sizeof(seed));
+	else
+		pr_warn("KASLR: No safe seed for randomizing the kernel base.\n");
+
+	ram = min_t(phys_addr_t, __max_low_memory, size);
+	ram = map_mem_in_cams(ram, CONFIG_LOWMEM_CAM_NUM, true);
+	linear_sz = min_t(unsigned long, ram, SZ_512M);
+
+	/* If the linear size is smaller than 64M, do not randmize */
+	if (linear_sz < SZ_64M)
+		return 0;
+
+	/* check for a reserved-memory node and record its cell sizes */
+	regions.reserved_mem = fdt_path_offset(dt_ptr, "/reserved-memory");
+	if (regions.reserved_mem >= 0)
+		get_cell_sizes(dt_ptr, regions.reserved_mem,
+			       &regions.reserved_mem_addr_cells,
+			       &regions.reserved_mem_size_cells);
+
+	regions.pa_start = memstart_addr;
+	regions.pa_end = memstart_addr + linear_sz;
+	regions.dtb_start = __pa(dt_ptr);
+	regions.dtb_end = __pa(dt_ptr) + fdt_totalsize(dt_ptr);
+	regions.kernel_size = kernel_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);
+}
+
+/*
+ * To see if we need to relocate the kernel to a random offset
+ * void *dt_ptr - address of the device tree
+ * phys_addr_t size - size of the first memory block
+ */
+notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
+{
+	unsigned long tlb_virt;
+	phys_addr_t tlb_phys;
+	unsigned long offset;
+	unsigned long kernel_sz;
+
+	kernel_sz = (unsigned long)_end - (unsigned long)_stext;
+
+	offset = kaslr_choose_location(dt_ptr, size, kernel_sz);
+	if (offset == 0)
+		return;
+
+	kernstart_virt_addr += offset;
+	kernstart_addr += offset;
+
+	is_second_reloc = 1;
+
+	if (offset >= SZ_64M) {
+		tlb_virt = round_down(kernstart_virt_addr, SZ_64M);
+		tlb_phys = round_down(kernstart_addr, SZ_64M);
+
+		/* Create kernel map to relocate in */
+		create_kaslr_tlb_entry(1, tlb_virt, tlb_phys);
+	}
+
+	/* Copy the kernel to it's new location and run */
+	memcpy((void *)kernstart_virt_addr, (void *)_stext, kernel_sz);
+	flush_icache_range(kernstart_virt_addr, kernstart_virt_addr + kernel_sz);
+
+	reloc_kernel_entry(dt_ptr, kernstart_virt_addr);
+}
+
+void __init kaslr_late_init(void)
+{
+	/* If randomized, clear the original kernel */
+	if (kernstart_virt_addr != KERNELBASE) {
+		unsigned long kernel_sz;
+
+		kernel_sz = (unsigned long)_end - kernstart_virt_addr;
+		memzero_explicit((void *)KERNELBASE, kernel_sz);
+	}
+}