[PATCH v2 0/6] implement KASLR for powerpc/fsl_booke/64

[PATCH v2 0/6] implement KASLR for powerpc/fsl_booke/64

[Jason Yan]

This is a try to implement KASLR for Freescale BookE64 which is based on
my earlier implementation for Freescale BookE32:
https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=131718

The implementation for Freescale BookE64 is similar as BookE32. One
difference is that Freescale BookE64 set up a TLB mapping of 1G during
booting. Another difference is that ppc64 needs the kernel to be
64K-aligned. So we can randomize the kernel in this 1G mapping and make
it 64K-aligned. This can save some code to creat another TLB map at
early boot. The disadvantage is that we only have about 1G/64K = 16384
slots to put the kernel in.

    KERNELBASE

          64K                     |--> kernel <--|
           |                      |              |
        +--+--+--+    +--+--+--+--+--+--+--+--+--+    +--+--+
        |  |  |  |....|  |  |  |  |  |  |  |  |  |....|  |  |
        +--+--+--+    +--+--+--+--+--+--+--+--+--+    +--+--+
        |                         |                        1G
        |----->   offset    <-----|

                              kernstart_virt_addr

I'm not sure if the slot numbers is enough or the design has any
defects. If you have some better ideas, I would be happy to hear that.

Thank you all.

v1->v2:
  Add __kaslr_offset for the secondary cpu boot up.

Jason Yan (6):
  powerpc/fsl_booke/kaslr: refactor kaslr_legal_offset() and
    kaslr_early_init()
  powerpc/fsl_booke/64: introduce reloc_kernel_entry() helper
  powerpc/fsl_booke/64: implement KASLR for fsl_booke64
  powerpc/fsl_booke/64: do not clear the BSS for the second pass
  powerpc/fsl_booke/64: clear the original kernel if randomized
  powerpc/fsl_booke/kaslr: rename kaslr-booke32.rst to kaslr-booke.rst
    and add 64bit part

 .../{kaslr-booke32.rst => kaslr-booke.rst}    | 35 +++++++--
 arch/powerpc/Kconfig                          |  2 +-
 arch/powerpc/kernel/exceptions-64e.S          | 21 ++++++
 arch/powerpc/kernel/head_64.S                 | 14 ++++
 arch/powerpc/kernel/setup_64.c                |  4 +-
 arch/powerpc/mm/mmu_decl.h                    |  3 +-
 arch/powerpc/mm/nohash/kaslr_booke.c          | 71 +++++++++++++------
 7 files changed, 122 insertions(+), 28 deletions(-)
 rename Documentation/powerpc/{kaslr-booke32.rst => kaslr-booke.rst} (59%)

-- 
2.17.2

[PATCH v2 1/6] powerpc/fsl_booke/kaslr: refactor kaslr_legal_offset() and kaslr_early_init()

[Jason Yan]

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: Jason 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>
---
 arch/powerpc/mm/nohash/kaslr_booke.c | 40 ++++++++++++++--------------
 1 file changed, 20 insertions(+), 20 deletions(-)

diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
index 4a75f2d9bf0e..07b036e98353 100644
--- a/arch/powerpc/mm/nohash/kaslr_booke.c
+++ b/arch/powerpc/mm/nohash/kaslr_booke.c
@@ -25,6 +25,7 @@ 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;
@@ -260,11 +261,23 @@ 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;
@@ -289,10 +302,9 @@ 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())
@@ -333,22 +345,12 @@ 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);
 }
 
 /*
@@ -358,8 +360,6 @@ static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size
  */
 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;
 
@@ -375,8 +375,8 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
 	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);
+		unsigned long tlb_virt = round_down(kernstart_virt_addr, SZ_64M);
+		phys_addr_t tlb_phys = round_down(kernstart_addr, SZ_64M);
 
 		/* Create kernel map to relocate in */
 		create_kaslr_tlb_entry(1, tlb_virt, tlb_phys);
-- 
2.17.2

[PATCH v2 2/6] powerpc/fsl_booke/64: introduce reloc_kernel_entry() helper

[Jason Yan]

Like the 32bit code, we introduce reloc_kernel_entry() helper to prepare
for the KASLR 64bit version. And move the C declaration of this function
out of CONFIG_PPC32 and use long instead of int for the parameter 'addr'.

Signed-off-by: Jason 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>
---
 arch/powerpc/kernel/exceptions-64e.S | 13 +++++++++++++
 arch/powerpc/mm/mmu_decl.h           |  3 ++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index e4076e3c072d..1b9b174bee86 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -1679,3 +1679,16 @@ _GLOBAL(setup_ehv_ivors)
 _GLOBAL(setup_lrat_ivor)
 	SET_IVOR(42, 0x340) /* LRAT Error */
 	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
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 8e99649c24fc..3e1c85c7d10b 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -140,9 +140,10 @@ 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
+
+void reloc_kernel_entry(void *fdt, long addr);
 extern void loadcam_entry(unsigned int index);
 extern void loadcam_multi(int first_idx, int num, int tmp_idx);
 
-- 
2.17.2

[PATCH v2 3/6] powerpc/fsl_booke/64: implement KASLR for fsl_booke64

[Jason Yan]

The implementation for Freescale BookE64 is similar as BookE32. One
difference is that Freescale BookE64 set up a TLB mapping of 1G during
booting. Another difference is that ppc64 needs the kernel to be
64K-aligned. So we can randomize the kernel in this 1G mapping and make
it 64K-aligned. This can save some code to creat another TLB map at
early boot. The disadvantage is that we only have about 1G/64K = 16384
slots to put the kernel in.

To support secondary cpu boot up, a variable __kaslr_offset was added in
first_256B section. This can help secondary cpu get the kaslr offset
before the 1:1 mapping has been setup.

Signed-off-by: Jason 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>
---
 arch/powerpc/Kconfig                 |  2 +-
 arch/powerpc/kernel/exceptions-64e.S |  8 +++++++
 arch/powerpc/kernel/head_64.S        |  7 ++++++
 arch/powerpc/kernel/setup_64.c       |  4 +++-
 arch/powerpc/mm/nohash/kaslr_booke.c | 33 +++++++++++++++++++++++++---
 5 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c150a9d49343..754aeb96bb1c 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -568,7 +568,7 @@ config RELOCATABLE
 
 config RANDOMIZE_BASE
 	bool "Randomize the address of the kernel image"
-	depends on (FSL_BOOKE && FLATMEM && PPC32)
+	depends on (PPC_FSL_BOOK3E && FLATMEM)
 	depends on RELOCATABLE
 	help
 	  Randomizes the virtual address at which the kernel image is
diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 1b9b174bee86..121daeaf573d 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -1378,6 +1378,7 @@ skpinv:	addi	r6,r6,1				/* Increment */
 1:	mflr	r6
 	addi	r6,r6,(2f - 1b)
 	tovirt(r6,r6)
+	add	r6,r6,r19
 	lis	r7,MSR_KERNEL@h
 	ori	r7,r7,MSR_KERNEL@l
 	mtspr	SPRN_SRR0,r6
@@ -1400,6 +1401,7 @@ skpinv:	addi	r6,r6,1				/* Increment */
 
 	/* We translate LR and return */
 	tovirt(r8,r8)
+	add	r8,r8,r19
 	mtlr	r8
 	blr
 
@@ -1528,6 +1530,7 @@ a2_tlbinit_code_end:
  */
 _GLOBAL(start_initialization_book3e)
 	mflr	r28
+	li	r19, 0
 
 	/* First, we need to setup some initial TLBs to map the kernel
 	 * text, data and bss at PAGE_OFFSET. We don't have a real mode
@@ -1570,6 +1573,10 @@ _GLOBAL(book3e_secondary_core_init)
 	cmplwi	r4,0
 	bne	2f
 
+	LOAD_REG_ADDR_PIC(r19, __kaslr_offset)
+	lwz	r19,0(r19)
+	rlwinm  r19,r19,0,0,5
+
 	/* Setup TLB for this core */
 	bl	initial_tlb_book3e
 
@@ -1602,6 +1609,7 @@ _GLOBAL(book3e_secondary_core_init)
 	lis	r3,PAGE_OFFSET@highest
 	sldi	r3,r3,32
 	or	r28,r28,r3
+	add	r28,r28,r19
 1:	mtlr	r28
 	blr
 
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index ad79fddb974d..b4ececc4323d 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -104,6 +104,13 @@ __secondary_hold_acknowledge:
 	.8byte	0x0
 
 #ifdef CONFIG_RELOCATABLE
+#ifdef CONFIG_PPC_BOOK3E
+	. = 0x58
+	.globl	__kaslr_offset
+__kaslr_offset:
+DEFINE_FIXED_SYMBOL(__kaslr_offset)
+	.long	0
+#endif
 	/* This flag is set to 1 by a loader if the kernel should run
 	 * at the loaded address instead of the linked address.  This
 	 * is used by kexec-tools to keep the the kdump kernel in the
diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index 6104917a282d..a16b970a8d1a 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -66,7 +66,7 @@
 #include <asm/feature-fixups.h>
 #include <asm/kup.h>
 #include <asm/early_ioremap.h>
-
+#include <mm/mmu_decl.h>
 #include "setup.h"
 
 int spinning_secondaries;
@@ -300,6 +300,8 @@ void __init early_setup(unsigned long dt_ptr)
 	/* Enable early debugging if any specified (see udbg.h) */
 	udbg_early_init();
 
+	kaslr_early_init(__va(dt_ptr), 0);
+
 	udbg_printf(" -> %s(), dt_ptr: 0x%lx\n", __func__, dt_ptr);
 
 	/*
diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
index 07b036e98353..c6f5c1db1394 100644
--- a/arch/powerpc/mm/nohash/kaslr_booke.c
+++ b/arch/powerpc/mm/nohash/kaslr_booke.c
@@ -231,7 +231,7 @@ static __init unsigned long get_usable_address(const void *fdt,
 	unsigned long pa;
 	unsigned long pa_end;
 
-	for (pa = offset; (long)pa > (long)start; pa -= SZ_16K) {
+	for (pa = offset; (long)pa > (long)start; pa -= SZ_64K) {
 		pa_end = pa + regions.kernel_size;
 		if (overlaps_region(fdt, pa, pa_end))
 			continue;
@@ -265,14 +265,14 @@ static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned long rando
 {
 	unsigned long koffset = 0;
 	unsigned long start;
-	unsigned long index;
 	unsigned long offset;
 
+#ifdef CONFIG_PPC32
 	/*
 	 * Decide which 64M we want to start
 	 * Only use the low 8 bits of the random seed
 	 */
-	index = random & 0xFF;
+	unsigned long index = random & 0xFF;
 	index %= regions.linear_sz / SZ_64M;
 
 	/* Decide offset inside 64M */
@@ -287,6 +287,15 @@ static unsigned long __init kaslr_legal_offset(void *dt_ptr, unsigned long rando
 			break;
 		index--;
 	}
+#else
+	/* Decide kernel offset inside 1G */
+	offset = random % (SZ_1G - regions.kernel_size);
+	offset = round_down(offset, SZ_64K);
+
+	start = memstart_addr;
+	offset = memstart_addr + offset;
+	koffset = get_usable_address(dt_ptr, start, offset);
+#endif
 
 	if (koffset != 0)
 		koffset -= memstart_addr;
@@ -325,6 +334,7 @@ static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size
 	else
 		pr_warn("KASLR: No safe seed for randomizing the kernel base.\n");
 
+#ifdef CONFIG_PPC32
 	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);
@@ -332,6 +342,7 @@ static unsigned long __init kaslr_choose_location(void *dt_ptr, phys_addr_t size
 	/* If the linear size is smaller than 64M, do not randmize */
 	if (linear_sz < SZ_64M)
 		return 0;
+#endif
 
 	/* check for a reserved-memory node and record its cell sizes */
 	regions.reserved_mem = fdt_path_offset(dt_ptr, "/reserved-memory");
@@ -363,6 +374,17 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
 	unsigned long offset;
 	unsigned long kernel_sz;
 
+#ifdef CONFIG_PPC64
+	unsigned int *__kaslr_offset = (unsigned int *)(KERNELBASE + 0x58);
+	unsigned int *__run_at_load = (unsigned int *)(KERNELBASE + 0x5c);
+
+	if (*__run_at_load == 1)
+		return;
+
+	/* Setup flat device-tree pointer */
+	initial_boot_params = dt_ptr;
+#endif
+
 	kernel_sz = (unsigned long)_end - (unsigned long)_stext;
 
 	offset = kaslr_choose_location(dt_ptr, size, kernel_sz);
@@ -372,6 +394,7 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
 	kernstart_virt_addr += offset;
 	kernstart_addr += offset;
 
+#ifdef CONFIG_PPC32
 	is_second_reloc = 1;
 
 	if (offset >= SZ_64M) {
@@ -381,6 +404,10 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
 		/* Create kernel map to relocate in */
 		create_kaslr_tlb_entry(1, tlb_virt, tlb_phys);
 	}
+#else
+	*__kaslr_offset = kernstart_virt_addr - KERNELBASE;
+	*__run_at_load = 1;
+#endif
 
 	/* Copy the kernel to it's new location and run */
 	memcpy((void *)kernstart_virt_addr, (void *)_stext, kernel_sz);
-- 
2.17.2

[PATCH v2 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass

[Jason Yan]

The BSS section has already cleared out in the first pass. No need to
clear it again. This can save some time when booting with KASLR
enabled.

Signed-off-by: Jason 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>
---
 arch/powerpc/kernel/head_64.S | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index b4ececc4323d..9ae7fd8bbf7c 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -914,6 +914,13 @@ start_here_multiplatform:
 	bl      relative_toc
 	tovirt(r2,r2)
 
+	/* Do not clear the BSS for the second pass if randomized */
+	LOAD_REG_ADDR(r3, kernstart_virt_addr)
+	lwz     r3,0(r3)
+	LOAD_REG_IMMEDIATE(r4, KERNELBASE)
+	cmpw	r3,r4
+	bne	4f
+
 	/* Clear out the BSS. It may have been done in prom_init,
 	 * already but that's irrelevant since prom_init will soon
 	 * be detached from the kernel completely. Besides, we need
-- 
2.17.2

[PATCH v2 5/6] powerpc/fsl_booke/64: clear the original kernel if randomized

[Jason Yan]

The original kernel still exists in the memory, clear it now.

Signed-off-by: Jason 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>
---
 arch/powerpc/mm/nohash/kaslr_booke.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
index c6f5c1db1394..ed1277059368 100644
--- a/arch/powerpc/mm/nohash/kaslr_booke.c
+++ b/arch/powerpc/mm/nohash/kaslr_booke.c
@@ -378,8 +378,10 @@ notrace void __init kaslr_early_init(void *dt_ptr, phys_addr_t size)
 	unsigned int *__kaslr_offset = (unsigned int *)(KERNELBASE + 0x58);
 	unsigned int *__run_at_load = (unsigned int *)(KERNELBASE + 0x5c);
 
-	if (*__run_at_load == 1)
+	if (*__run_at_load == 1) {
+		kaslr_late_init();
 		return;
+	}
 
 	/* Setup flat device-tree pointer */
 	initial_boot_params = dt_ptr;
-- 
2.17.2

[PATCH v2 6/6] powerpc/fsl_booke/kaslr: rename kaslr-booke32.rst to kaslr-booke.rst and add 64bit part

[Jason Yan]

Now we support both 32 and 64 bit KASLR for fsl booke. Add document for
64 bit part and rename kaslr-booke32.rst to kaslr-booke.rst.

Signed-off-by: Jason 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>
---
 .../{kaslr-booke32.rst => kaslr-booke.rst}    | 35 ++++++++++++++++---
 1 file changed, 31 insertions(+), 4 deletions(-)
 rename Documentation/powerpc/{kaslr-booke32.rst => kaslr-booke.rst} (59%)

diff --git a/Documentation/powerpc/kaslr-booke32.rst b/Documentation/powerpc/kaslr-booke.rst
similarity index 59%
rename from Documentation/powerpc/kaslr-booke32.rst
rename to Documentation/powerpc/kaslr-booke.rst
index 8b259fdfdf03..42121fed8249 100644
--- a/Documentation/powerpc/kaslr-booke32.rst
+++ b/Documentation/powerpc/kaslr-booke.rst
@@ -1,15 +1,18 @@
 .. SPDX-License-Identifier: GPL-2.0
 
-===========================
-KASLR for Freescale BookE32
-===========================
+=========================
+KASLR for Freescale BookE
+=========================
 
 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
+Freescale BookE. KASLR is a security feature that deters exploit
 attempts relying on knowledge of the location of kernel internals.
 
+KASLR for Freescale BookE32
+-------------------------
+
 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
@@ -38,5 +41,29 @@ bit of the entropy to decide the index of the 64M zone. Then we chose a
 
                               kernstart_virt_addr
 
+
+KASLR for Freescale BookE64
+---------------------------
+
+The implementation for Freescale BookE64 is similar as BookE32. One
+difference is that Freescale BookE64 set up a TLB mapping of 1G during
+booting. Another difference is that ppc64 needs the kernel to be
+64K-aligned. So we can randomize the kernel in this 1G mapping and make
+it 64K-aligned. This can save some code to creat another TLB map at early
+boot. The disadvantage is that we only have about 1G/64K = 16384 slots to
+put the kernel in::
+
+    KERNELBASE
+
+          64K                     |--> kernel <--|
+           |                      |              |
+        +--+--+--+    +--+--+--+--+--+--+--+--+--+    +--+--+
+        |  |  |  |....|  |  |  |  |  |  |  |  |  |....|  |  |
+        +--+--+--+    +--+--+--+--+--+--+--+--+--+    +--+--+
+        |                         |                        1G
+        |----->   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.
-- 
2.17.2

Re: [PATCH v2 3/6] powerpc/fsl_booke/64: implement KASLR for fsl_booke64

[kbuild test robot]

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Hi Jason,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on powerpc/next]
[also build test ERROR on v5.5 next-20200204]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Jason-Yan/implement-KASLR-for-powerpc-fsl_booke-64/20200205-105837
base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
config: powerpc-defconfig (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 7.5.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.5.0 make.cross ARCH=powerpc 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   arch/powerpc/kernel/setup_64.c: In function 'early_setup':
>> arch/powerpc/kernel/setup_64.c:303:2: error: implicit declaration of function 'kaslr_early_init'; did you mean 'udbg_early_init'? [-Werror=implicit-function-declaration]
     kaslr_early_init(__va(dt_ptr), 0);
     ^~~~~~~~~~~~~~~~
     udbg_early_init
   cc1: all warnings being treated as errors

vim +303 arch/powerpc/kernel/setup_64.c

   262	
   263	/*
   264	 * Early initialization entry point. This is called by head.S
   265	 * with MMU translation disabled. We rely on the "feature" of
   266	 * the CPU that ignores the top 2 bits of the address in real
   267	 * mode so we can access kernel globals normally provided we
   268	 * only toy with things in the RMO region. From here, we do
   269	 * some early parsing of the device-tree to setup out MEMBLOCK
   270	 * data structures, and allocate & initialize the hash table
   271	 * and segment tables so we can start running with translation
   272	 * enabled.
   273	 *
   274	 * It is this function which will call the probe() callback of
   275	 * the various platform types and copy the matching one to the
   276	 * global ppc_md structure. Your platform can eventually do
   277	 * some very early initializations from the probe() routine, but
   278	 * this is not recommended, be very careful as, for example, the
   279	 * device-tree is not accessible via normal means at this point.
   280	 */
   281	
   282	void __init early_setup(unsigned long dt_ptr)
   283	{
   284		static __initdata struct paca_struct boot_paca;
   285	
   286		/* -------- printk is _NOT_ safe to use here ! ------- */
   287	
   288		/* Try new device tree based feature discovery ... */
   289		if (!dt_cpu_ftrs_init(__va(dt_ptr)))
   290			/* Otherwise use the old style CPU table */
   291			identify_cpu(0, mfspr(SPRN_PVR));
   292	
   293		/* Assume we're on cpu 0 for now. Don't write to the paca yet! */
   294		initialise_paca(&boot_paca, 0);
   295		setup_paca(&boot_paca);
   296		fixup_boot_paca();
   297	
   298		/* -------- printk is now safe to use ------- */
   299	
   300		/* Enable early debugging if any specified (see udbg.h) */
   301		udbg_early_init();
   302	
 > 303		kaslr_early_init(__va(dt_ptr), 0);
   304	
   305		udbg_printf(" -> %s(), dt_ptr: 0x%lx\n", __func__, dt_ptr);
   306	
   307		/*
   308		 * Do early initialization using the flattened device
   309		 * tree, such as retrieving the physical memory map or
   310		 * calculating/retrieving the hash table size.
   311		 */
   312		early_init_devtree(__va(dt_ptr));
   313	
   314		/* Now we know the logical id of our boot cpu, setup the paca. */
   315		if (boot_cpuid != 0) {
   316			/* Poison paca_ptrs[0] again if it's not the boot cpu */
   317			memset(&paca_ptrs[0], 0x88, sizeof(paca_ptrs[0]));
   318		}
   319		setup_paca(paca_ptrs[boot_cpuid]);
   320		fixup_boot_paca();
   321	
   322		/*
   323		 * Configure exception handlers. This include setting up trampolines
   324		 * if needed, setting exception endian mode, etc...
   325		 */
   326		configure_exceptions();
   327	
   328		/*
   329		 * Configure Kernel Userspace Protection. This needs to happen before
   330		 * feature fixups for platforms that implement this using features.
   331		 */
   332		setup_kup();
   333	
   334		/* Apply all the dynamic patching */
   335		apply_feature_fixups();
   336		setup_feature_keys();
   337	
   338		early_ioremap_setup();
   339	
   340		/* Initialize the hash table or TLB handling */
   341		early_init_mmu();
   342	
   343		/*
   344		 * After firmware and early platform setup code has set things up,
   345		 * we note the SPR values for configurable control/performance
   346		 * registers, and use those as initial defaults.
   347		 */
   348		record_spr_defaults();
   349	
   350		/*
   351		 * At this point, we can let interrupts switch to virtual mode
   352		 * (the MMU has been setup), so adjust the MSR in the PACA to
   353		 * have IR and DR set and enable AIL if it exists
   354		 */
   355		cpu_ready_for_interrupts();
   356	
   357		/*
   358		 * We enable ftrace here, but since we only support DYNAMIC_FTRACE, it
   359		 * will only actually get enabled on the boot cpu much later once
   360		 * ftrace itself has been initialized.
   361		 */
   362		this_cpu_enable_ftrace();
   363	
   364		udbg_printf(" <- %s()\n", __func__);
   365	

---
0-DAY kernel test infrastructure                 Open Source Technology Center
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org Intel Corporation

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