[PATCH v6 0/3] arm64: hibernate: Support DEBUG_PAGEALLOC

[PATCH v6 0/3] arm64: hibernate: Support DEBUG_PAGEALLOC

[James Morse]

Hi all,

These patches improve arm64's hibernate support by fixing the hibernate
problem with DEBUG_PAGEALLOC reported by Will.
This also addresses the outstanding comment from Catalin [0] regarding
cleaning of the whole kernel to the PoC. Now we clean three new sections
.mmuoff.{*.data,text}. The mmuoff data is split into two sections depending
on whether they are read or written the MMU off as the alignment is different.
The two mmuoff.data sections share their start/end markers as the difference
should only matter to the linker.

This series is based on v4.8-rc3, and can be retrieved from:
git://linux-arm.org/linux-jm.git -b hibernate/debug_pagealloc/v6

Changes since v5:
 * Moved .mmuoff.text into .idmap.text,
 * Moved ALIGN() out of .mmuoff.data.read in case this section gets removed.
 * Removed stray "don't"
 * Added pte_mkpresent() and pte_clear_rdonly(), used to make the bit masking
   in _copy_pte() more readable.
 * Removed 'pte_pfn(src_pte) == pfn' paranoia, replaced with BUG_ON().
 * Added comment against kern_page_present(), removed superfluous pte_none()

Changes since v4:
 * Moved alignment rules out of assembly into the linker script.
 * Split mmuoff.data into two sections one written with the mmu off, the other
   read with the mmu off. CWG alignment only applies to mmuoff.write.data.
 * Fixed PE/COFF alignment breakage.

Changes since v3:
 * Pad mmuoff.data section to CWG.
 * Specified the .mmuoff.data section for secondary_holding_pen_release in C
 * Added irqentry_text start/end to sections.h
 * Updated patch 1 for kprobes idmap/hyp_idmap declarations.

Changes since v2:
 * Added a mmuoff.data section for secondary_holding_pen_release etc.

Changes since v1:
 * Added .mmuoff.text section and gathered functions together.
 * Put sections.h in alphabetical order.

[v1] http://www.spinics.net/lists/arm-kernel/msg507805.html
[v2] http://permalink.gmane.org/gmane.linux.power-management.general/77467
[v3] https://www.spinics.net/lists/arm-kernel/msg514644.html
[v4] https://www.spinics.net/lists/arm-kernel/msg477769.html
[v5] https://www.spinics.net/lists/arm-kernel/msg525605.html

[0] http://www.spinics.net/lists/arm-kernel/msg499305.html


James Morse (3):
  arm64: Create sections.h
  arm64: vmlinux.ld: Add mmuoff data sections and move mmuoff text into
    idmap
  arm64: hibernate: Support DEBUG_PAGEALLOC

 arch/arm64/Kconfig                 |  1 -
 arch/arm64/include/asm/Kbuild      |  1 -
 arch/arm64/include/asm/pgtable.h   | 10 ++++++++
 arch/arm64/include/asm/sections.h  | 30 ++++++++++++++++++++++
 arch/arm64/include/asm/traps.h     |  6 +----
 arch/arm64/include/asm/virt.h      |  9 +------
 arch/arm64/kernel/alternative.c    |  7 +++---
 arch/arm64/kernel/head.S           | 25 +++++++++++--------
 arch/arm64/kernel/hibernate.c      | 51 +++++++++++++++++++++++++++-----------
 arch/arm64/kernel/probes/kprobes.c |  5 +---
 arch/arm64/kernel/sleep.S          |  2 +-
 arch/arm64/kernel/smp_spin_table.c |  3 ++-
 arch/arm64/kernel/vmlinux.lds.S    | 19 ++++++++++++++
 arch/arm64/mm/pageattr.c           | 41 +++++++++++++++++++++++++++++-
 arch/arm64/mm/proc.S               |  4 +++
 15 files changed, 163 insertions(+), 51 deletions(-)
 create mode 100644 arch/arm64/include/asm/sections.h

-- 
2.8.0.rc3

[PATCH v6 1/3] arm64: Create sections.h

[James Morse]

Each time new section markers are added, kernel/vmlinux.ld.S is updated,
and new extern char __start_foo[] definitions are scattered through the
tree.

Create asm/include/sections.h to collect these definitions (and include
the existing asm-generic version).

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
---
 arch/arm64/include/asm/Kbuild      |  1 -
 arch/arm64/include/asm/sections.h  | 29 +++++++++++++++++++++++++++++
 arch/arm64/include/asm/traps.h     |  6 +-----
 arch/arm64/include/asm/virt.h      |  9 +--------
 arch/arm64/kernel/alternative.c    |  7 +++----
 arch/arm64/kernel/hibernate.c      |  6 ------
 arch/arm64/kernel/probes/kprobes.c |  5 +----
 7 files changed, 35 insertions(+), 28 deletions(-)
 create mode 100644 arch/arm64/include/asm/sections.h

diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild
index f43d2c44c765..2b3d2d24acba 100644
--- a/arch/arm64/include/asm/Kbuild
+++ b/arch/arm64/include/asm/Kbuild
@@ -32,7 +32,6 @@ generic-y += poll.h
 generic-y += preempt.h
 generic-y += resource.h
 generic-y += rwsem.h
-generic-y += sections.h
 generic-y += segment.h
 generic-y += sembuf.h
 generic-y += serial.h
diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h
new file mode 100644
index 000000000000..237fcdd13445
--- /dev/null
+++ b/arch/arm64/include/asm/sections.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2016 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_SECTIONS_H
+#define __ASM_SECTIONS_H
+
+#include <asm-generic/sections.h>
+
+extern char __alt_instructions[], __alt_instructions_end[];
+extern char __exception_text_start[], __exception_text_end[];
+extern char __hibernate_exit_text_start[], __hibernate_exit_text_end[];
+extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[];
+extern char __hyp_text_start[], __hyp_text_end[];
+extern char __idmap_text_start[], __idmap_text_end[];
+extern char __irqentry_text_start[], __irqentry_text_end[];
+
+#endif /* __ASM_SECTIONS_H */
diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h
index 9cd03f3e812f..02e9035b0685 100644
--- a/arch/arm64/include/asm/traps.h
+++ b/arch/arm64/include/asm/traps.h
@@ -19,6 +19,7 @@
 #define __ASM_TRAP_H
 
 #include <linux/list.h>
+#include <asm/sections.h>
 
 struct pt_regs;
 
@@ -39,9 +40,6 @@ void arm64_notify_segfault(struct pt_regs *regs, unsigned long addr);
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 static inline int __in_irqentry_text(unsigned long ptr)
 {
-	extern char __irqentry_text_start[];
-	extern char __irqentry_text_end[];
-
 	return ptr >= (unsigned long)&__irqentry_text_start &&
 	       ptr < (unsigned long)&__irqentry_text_end;
 }
@@ -54,8 +52,6 @@ static inline int __in_irqentry_text(unsigned long ptr)
 
 static inline int in_exception_text(unsigned long ptr)
 {
-	extern char __exception_text_start[];
-	extern char __exception_text_end[];
 	int in;
 
 	in = ptr >= (unsigned long)&__exception_text_start &&
diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h
index 1788545f25bc..db5739413677 100644
--- a/arch/arm64/include/asm/virt.h
+++ b/arch/arm64/include/asm/virt.h
@@ -45,6 +45,7 @@
 #ifndef __ASSEMBLY__
 
 #include <asm/ptrace.h>
+#include <asm/sections.h>
 
 /*
  * __boot_cpu_mode records what mode CPUs were booted in.
@@ -87,14 +88,6 @@ extern void verify_cpu_run_el(void);
 static inline void verify_cpu_run_el(void) {}
 #endif
 
-/* The section containing the hypervisor idmap text */
-extern char __hyp_idmap_text_start[];
-extern char __hyp_idmap_text_end[];
-
-/* The section containing the hypervisor text */
-extern char __hyp_text_start[];
-extern char __hyp_text_end[];
-
 #endif /* __ASSEMBLY__ */
 
 #endif /* ! __ASM__VIRT_H */
diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index d2ee1b21a10d..4434dabde898 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -25,14 +25,13 @@
 #include <asm/alternative.h>
 #include <asm/cpufeature.h>
 #include <asm/insn.h>
+#include <asm/sections.h>
 #include <linux/stop_machine.h>
 
 #define __ALT_PTR(a,f)		(u32 *)((void *)&(a)->f + (a)->f)
 #define ALT_ORIG_PTR(a)		__ALT_PTR(a, orig_offset)
 #define ALT_REPL_PTR(a)		__ALT_PTR(a, alt_offset)
 
-extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
-
 struct alt_region {
 	struct alt_instr *begin;
 	struct alt_instr *end;
@@ -124,8 +123,8 @@ static int __apply_alternatives_multi_stop(void *unused)
 {
 	static int patched = 0;
 	struct alt_region region = {
-		.begin	= __alt_instructions,
-		.end	= __alt_instructions_end,
+		.begin	= (struct alt_instr *)__alt_instructions,
+		.end	= (struct alt_instr *)__alt_instructions_end,
 	};
 
 	/* We always have a CPU 0 at this point (__init) */
diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 65d81f965e74..b4082017c4cb 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -54,12 +54,6 @@ extern int in_suspend;
 /* Do we need to reset el2? */
 #define el2_reset_needed() (is_hyp_mode_available() && !is_kernel_in_hyp_mode())
 
-/*
- * Start/end of the hibernate exit code, this must be copied to a 'safe'
- * location in memory, and executed from there.
- */
-extern char __hibernate_exit_text_start[], __hibernate_exit_text_end[];
-
 /* temporary el2 vectors in the __hibernate_exit_text section. */
 extern char hibernate_el2_vectors[];
 
diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index c6b0f40620d8..2dc1b42afaaa 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -31,7 +31,7 @@
 #include <asm/insn.h>
 #include <asm/uaccess.h>
 #include <asm/irq.h>
-#include <asm-generic/sections.h>
+#include <asm/sections.h>
 
 #include "decode-insn.h"
 
@@ -543,9 +543,6 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
 
 bool arch_within_kprobe_blacklist(unsigned long addr)
 {
-	extern char __idmap_text_start[], __idmap_text_end[];
-	extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[];
-
 	if ((addr >= (unsigned long)__kprobes_text_start &&
 	    addr < (unsigned long)__kprobes_text_end) ||
 	    (addr >= (unsigned long)__entry_text_start &&
-- 
2.8.0.rc3

[PATCH v6 2/3] arm64: vmlinux.ld: Add mmuoff data sections and move mmuoff text into idmap

[James Morse]

Resume from hibernate needs to clean any text executed by the kernel with
the MMU off to the PoC. Collect these functions together into the
.idmap.text section as all this code is tightly coupled and also needs
the same cleaning after resume.

Data is more complicated, secondary_holding_pen_release is written with
the MMU on, clean and invalidated, then read with the MMU off. In contrast
__boot_cpu_mode is written with the MMU off, the corresponding cache line
is invalidated, so when we read it with the MMU on we don't get stale data.
These cache maintenance operations conflict with each other if the values
are within a Cache Writeback Granule (CWG) of each other.
Collect the data into two sections .mmuoff.data.read and .mmuoff.data.write,
the linker script ensures mmuoff.data.write section is aligned to the
architectural maximum CWG of 2KB.

Signed-off-by: James Morse <james.morse@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>

---
Changes since v5:
 * Moved .mmuoff.text into .idmap.text,
 * Moved ALIGN() out of .mmuoff.data.read in case this section gets removed.
 * Removed stray "don't"

 arch/arm64/include/asm/sections.h  |  1 +
 arch/arm64/kernel/head.S           | 25 +++++++++++++++----------
 arch/arm64/kernel/sleep.S          |  2 +-
 arch/arm64/kernel/smp_spin_table.c |  3 ++-
 arch/arm64/kernel/vmlinux.lds.S    | 19 +++++++++++++++++++
 arch/arm64/mm/proc.S               |  4 ++++
 6 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h
index 237fcdd13445..4e7e7067afdb 100644
--- a/arch/arm64/include/asm/sections.h
+++ b/arch/arm64/include/asm/sections.h
@@ -25,5 +25,6 @@ extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[];
 extern char __hyp_text_start[], __hyp_text_end[];
 extern char __idmap_text_start[], __idmap_text_end[];
 extern char __irqentry_text_start[], __irqentry_text_end[];
+extern char __mmuoff_data_start[], __mmuoff_data_end[];
 
 #endif /* __ASM_SECTIONS_H */
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index b77f58355da1..4413144f7ea4 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -465,7 +465,7 @@ ENDPROC(__primary_switched)
  * end early head section, begin head code that is also used for
  * hotplug and needs to have the same protections as the text region
  */
-	.section ".text","ax"
+	.section ".idmap.text","ax"
 
 ENTRY(kimage_vaddr)
 	.quad		_text - TEXT_OFFSET
@@ -621,17 +621,29 @@ set_cpu_boot_mode_flag:
 ENDPROC(set_cpu_boot_mode_flag)
 
 /*
+ * These values are written with the MMU off, but read with the MMU on.
+ * Writers will invalidate the corresponding address, discarding up to a
+ * 'Cache Writeback Granule' (CWG) worth of data. The linker script ensures
+ * sufficient alignment that the CWG doesn't overlap another section.
+ */
+	.pushsection ".mmuoff.data.write", "aw"
+/*
  * We need to find out the CPU boot mode long after boot, so we need to
  * store it in a writable variable.
  *
  * This is not in .bss, because we set it sufficiently early that the boot-time
  * zeroing of .bss would clobber it.
  */
-	.pushsection	.data..cacheline_aligned
-	.align	L1_CACHE_SHIFT
 ENTRY(__boot_cpu_mode)
 	.long	BOOT_CPU_MODE_EL2
 	.long	BOOT_CPU_MODE_EL1
+/*
+ * The booting CPU updates the failed status @__early_cpu_boot_status,
+ * with MMU turned off.
+ */
+ENTRY(__early_cpu_boot_status)
+	.long 	0
+
 	.popsection
 
 	/*
@@ -706,12 +718,6 @@ ENDPROC(__secondary_switched)
 	dc	ivac, \tmp1			// Invalidate potentially stale cache line
 	.endm
 
-	.pushsection	.data..cacheline_aligned
-	.align	L1_CACHE_SHIFT
-ENTRY(__early_cpu_boot_status)
-	.long 	0
-	.popsection
-
 /*
  * Enable the MMU.
  *
@@ -723,7 +729,6 @@ ENTRY(__early_cpu_boot_status)
  * Checks if the selected granule size is supported by the CPU.
  * If it isn't, park the CPU
  */
-	.section	".idmap.text", "ax"
 ENTRY(__enable_mmu)
 	mrs	x22, sctlr_el1			// preserve old SCTLR_EL1 value
 	mrs	x1, ID_AA64MMFR0_EL1
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index ccf79d849e0a..679b0ad1e9cd 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -97,6 +97,7 @@ ENTRY(__cpu_suspend_enter)
 ENDPROC(__cpu_suspend_enter)
 	.ltorg
 
+	.pushsection ".idmap.text", "ax"
 ENTRY(cpu_resume)
 	bl	el2_setup		// if in EL2 drop to EL1 cleanly
 	/* enable the MMU early - so we can access sleep_save_stash by va */
@@ -107,7 +108,6 @@ ENTRY(cpu_resume)
 	b	__cpu_setup
 ENDPROC(cpu_resume)
 
-	.pushsection	".idmap.text", "ax"
 _resume_switched:
 	ldr	x8, =_cpu_resume
 	br	x8
diff --git a/arch/arm64/kernel/smp_spin_table.c b/arch/arm64/kernel/smp_spin_table.c
index 18a71bcd26ee..9a00eee9acc8 100644
--- a/arch/arm64/kernel/smp_spin_table.c
+++ b/arch/arm64/kernel/smp_spin_table.c
@@ -29,7 +29,8 @@
 #include <asm/smp_plat.h>
 
 extern void secondary_holding_pen(void);
-volatile unsigned long secondary_holding_pen_release = INVALID_HWID;
+volatile unsigned long __section(".mmuoff.data.read")
+secondary_holding_pen_release = INVALID_HWID;
 
 static phys_addr_t cpu_release_addr[NR_CPUS];
 
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index 659963d40bb4..5ce9b2929e0d 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -185,6 +185,25 @@ SECTIONS
 	_data = .;
 	_sdata = .;
 	RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
+
+	/*
+	 * Data written with the MMU off but read with the MMU on requires
+	 * cache lines to be invalidated, discarding up to a Cache Writeback
+	 * Granule (CWG) of data from the cache. Keep the section that
+	 * requires this type of maintenance to be in its own Cache Writeback
+	 * Granule (CWG) area so the cache maintenance operations don't
+	 * interfere with adjacent data.
+	 */
+	.mmuoff.data.write : ALIGN(SZ_2K) {
+		__mmuoff_data_start = .;
+		*(.mmuoff.data.write)
+	}
+	. = ALIGN(SZ_2K);
+	.mmuoff.data.read : {
+		*(.mmuoff.data.read)
+		__mmuoff_data_end = .;
+	}
+
 	PECOFF_EDATA_PADDING
 	_edata = .;
 
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 5bb61de23201..5eb35964ab8e 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -83,6 +83,7 @@ ENDPROC(cpu_do_suspend)
  *
  * x0: Address of context pointer
  */
+	.pushsection ".idmap.text", "ax"
 ENTRY(cpu_do_resume)
 	ldp	x2, x3, [x0]
 	ldp	x4, x5, [x0, #16]
@@ -111,6 +112,7 @@ ENTRY(cpu_do_resume)
 	isb
 	ret
 ENDPROC(cpu_do_resume)
+	.popsection
 #endif
 
 /*
@@ -172,6 +174,7 @@ ENDPROC(idmap_cpu_replace_ttbr1)
  *	Initialise the processor for turning the MMU on.  Return in x0 the
  *	value of the SCTLR_EL1 register.
  */
+	.pushsection ".idmap.text", "ax"
 ENTRY(__cpu_setup)
 	tlbi	vmalle1				// Invalidate local TLB
 	dsb	nsh
@@ -257,3 +260,4 @@ ENDPROC(__cpu_setup)
 crval:
 	.word	0xfcffffff			// clear
 	.word	0x34d5d91d			// set
+	.popsection
-- 
2.8.0.rc3

[PATCH v6 3/3] arm64: hibernate: Support DEBUG_PAGEALLOC

[James Morse]

DEBUG_PAGEALLOC removes the valid bit of page table entries to prevent
any access to unallocated memory. Hibernate uses this as a hint that those
pages don't need to be saved/restored. This patch adds the
kernel_page_present() function it uses.

hibernate.c copies the resume kernel's linear map for use during restore.
Add _copy_pte() to fill-in the holes made by DEBUG_PAGEALLOC in the resume
kernel, so we can restore data the original kernel had at these addresses.

Finally, DEBUG_PAGEALLOC means the linear-map alias of KERNEL_START to
KERNEL_END may have holes in it, so we can't lazily clean this whole
area to the PoC. Only clean the new mmuoff region, and the kernel/kvm
idmaps.

This reverts commit da24eb1f3f9e2c7b75c5f8c40d8e48e2c4789596.

Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
---
Changes since v5:
 * Added pte_mkpresent() and pte_clear_rdonly(), used to make the bit masking
   in _copy_pte() more readable.
 * Removed 'pte_pfn(src_pte) == pfn' paranoia, replaced with BUG_ON().
 * Added comment against kern_page_present(), removed superfluous pte_none()

 arch/arm64/Kconfig               |  1 -
 arch/arm64/include/asm/pgtable.h | 10 +++++++++
 arch/arm64/kernel/hibernate.c    | 45 ++++++++++++++++++++++++++++++++--------
 arch/arm64/mm/pageattr.c         | 41 +++++++++++++++++++++++++++++++++++-
 4 files changed, 86 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index bc3f00f586f1..9be0c164df4e 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -607,7 +607,6 @@ source kernel/Kconfig.preempt
 source kernel/Kconfig.hz
 
 config ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	depends on !HIBERNATION
 	def_bool y
 
 config ARCH_HAS_HOLES_MEMORYMODEL
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e20bd431184a..038d1cfa15cd 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -155,6 +155,16 @@ static inline pte_t pte_mknoncont(pte_t pte)
 	return clear_pte_bit(pte, __pgprot(PTE_CONT));
 }
 
+static inline pte_t pte_clear_rdonly(pte_t pte)
+{
+	return clear_pte_bit(pte, __pgprot(PTE_RDONLY));
+}
+
+static inline pte_t pte_mkpresent(pte_t pte)
+{
+	return set_pte_bit(pte, __pgprot(PTE_VALID));
+}
+
 static inline pmd_t pmd_mkcont(pmd_t pmd)
 {
 	return __pmd(pmd_val(pmd) | PMD_SECT_CONT);
diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index b4082017c4cb..71d82cfb62f5 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -235,6 +235,7 @@ out:
 	return rc;
 }
 
+#define dcache_clean_range(start, end)	__flush_dcache_area(start, (end - start))
 
 int swsusp_arch_suspend(void)
 {
@@ -252,8 +253,13 @@ int swsusp_arch_suspend(void)
 	if (__cpu_suspend_enter(&state)) {
 		ret = swsusp_save();
 	} else {
-		/* Clean kernel to PoC for secondary core startup */
-		__flush_dcache_area(LMADDR(KERNEL_START), KERNEL_END - KERNEL_START);
+		/* Clean kernel core startup/idle code to PoC*/
+		dcache_clean_range(__mmuoff_data_start, __mmuoff_data_end);
+		dcache_clean_range(__idmap_text_start, __idmap_text_end);
+
+		/* Clean kvm setup code to PoC? */
+		if (el2_reset_needed())
+			dcache_clean_range(__hyp_idmap_text_start, __hyp_idmap_text_end);
 
 		/*
 		 * Tell the hibernation core that we've just restored
@@ -269,6 +275,33 @@ int swsusp_arch_suspend(void)
 	return ret;
 }
 
+static void _copy_pte(pte_t *dst_pte, pte_t *src_pte, unsigned long addr)
+{
+	pte_t pte = *src_pte;
+
+	if (pte_valid(pte)) {
+		/*
+		 * Resume will overwrite areas that may be marked
+		 * read only (code, rodata). Clear the RDONLY bit from
+		 * the temporary mappings we use during restore.
+		 */
+		set_pte(dst_pte, pte_clear_rdonly(pte));
+	} else if (debug_pagealloc_enabled() && !pte_none(pte)) {
+		/*
+		 * debug_pagealloc will removed the PTE_VALID bit if
+		 * the page isn't in use by the resume kernel. It may have
+		 * been in use by the original kernel, in which case we need
+		 * to put it back in our copy to do the restore.
+		 *
+		 * Before marking this entry valid, check the pfn should
+		 * be mapped.
+		 */
+		BUG_ON(!pfn_valid(pte_pfn(pte)));
+
+		set_pte(dst_pte, pte_mkpresent(pte_clear_rdonly(pte)));
+	}
+}
+
 static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
 		    unsigned long end)
 {
@@ -284,13 +317,7 @@ static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
 
 	src_pte = pte_offset_kernel(src_pmd, start);
 	do {
-		if (!pte_none(*src_pte))
-			/*
-			 * Resume will overwrite areas that may be marked
-			 * read only (code, rodata). Clear the RDONLY bit from
-			 * the temporary mappings we use during restore.
-			 */
-			set_pte(dst_pte, __pte(pte_val(*src_pte) & ~PTE_RDONLY));
+		_copy_pte(dst_pte, src_pte, addr);
 	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
 
 	return 0;
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index ca6d268e3313..8def55e7249b 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -139,4 +139,43 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
 					__pgprot(0),
 					__pgprot(PTE_VALID));
 }
-#endif
+#ifdef CONFIG_HIBERNATION
+/*
+ * When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
+ * is used to determine if a linear map page has been marked as not-valid by
+ * CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
+ * This is based on kern_addr_valid(), which almost does what we need.
+ *
+ * Because this is only called on the kernel linear map,  p?d_sect() implies
+ * p?d_present(). When debug_pagealloc is enabled, sections mappings are
+ * disabled.
+ */
+bool kernel_page_present(struct page *page)
+{
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+	unsigned long addr = (unsigned long)page_address(page);
+
+	pgd = pgd_offset_k(addr);
+	if (pgd_none(*pgd))
+		return false;
+
+	pud = pud_offset(pgd, addr);
+	if (pud_none(*pud))
+		return false;
+	if (pud_sect(*pud))
+		return true;
+
+	pmd = pmd_offset(pud, addr);
+	if (pmd_none(*pmd))
+		return false;
+	if (pmd_sect(*pmd))
+		return true;
+
+	pte = pte_offset_kernel(pmd, addr);
+	return pte_valid(*pte);
+}
+#endif /* CONFIG_HIBERNATION */
+#endif /* CONFIG_DEBUG_PAGEALLOC */
-- 
2.8.0.rc3

[PATCH v6 1/3] arm64: Create sections.h

[Catalin Marinas]

On Wed, Aug 24, 2016 at 06:27:28PM +0100, James Morse wrote:
> Each time new section markers are added, kernel/vmlinux.ld.S is updated,
> and new extern char __start_foo[] definitions are scattered through the
> tree.
> 
> Create asm/include/sections.h to collect these definitions (and include
> the existing asm-generic version).
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Mark Rutland <mark.rutland@arm.com>
> Tested-by: Mark Rutland <mark.rutland@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

[PATCH v6 2/3] arm64: vmlinux.ld: Add mmuoff data sections and move mmuoff text into idmap

[Catalin Marinas]

On Wed, Aug 24, 2016 at 06:27:29PM +0100, James Morse wrote:
> Resume from hibernate needs to clean any text executed by the kernel with
> the MMU off to the PoC. Collect these functions together into the
> .idmap.text section as all this code is tightly coupled and also needs
> the same cleaning after resume.
> 
> Data is more complicated, secondary_holding_pen_release is written with
> the MMU on, clean and invalidated, then read with the MMU off. In contrast
> __boot_cpu_mode is written with the MMU off, the corresponding cache line
> is invalidated, so when we read it with the MMU on we don't get stale data.
> These cache maintenance operations conflict with each other if the values
> are within a Cache Writeback Granule (CWG) of each other.
> Collect the data into two sections .mmuoff.data.read and .mmuoff.data.write,
> the linker script ensures mmuoff.data.write section is aligned to the
> architectural maximum CWG of 2KB.
> 
> Signed-off-by: James Morse <james.morse@arm.com>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Mark Rutland <mark.rutland@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

[PATCH v6 3/3] arm64: hibernate: Support DEBUG_PAGEALLOC

[Catalin Marinas]

On Wed, Aug 24, 2016 at 06:27:30PM +0100, James Morse wrote:
> DEBUG_PAGEALLOC removes the valid bit of page table entries to prevent
> any access to unallocated memory. Hibernate uses this as a hint that those
> pages don't need to be saved/restored. This patch adds the
> kernel_page_present() function it uses.
> 
> hibernate.c copies the resume kernel's linear map for use during restore.
> Add _copy_pte() to fill-in the holes made by DEBUG_PAGEALLOC in the resume
> kernel, so we can restore data the original kernel had at these addresses.
> 
> Finally, DEBUG_PAGEALLOC means the linear-map alias of KERNEL_START to
> KERNEL_END may have holes in it, so we can't lazily clean this whole
> area to the PoC. Only clean the new mmuoff region, and the kernel/kvm
> idmaps.
> 
> This reverts commit da24eb1f3f9e2c7b75c5f8c40d8e48e2c4789596.
> 
> Reported-by: Will Deacon <will.deacon@arm.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>