arm64 kexec kernel patches V8

Hi All,

This series adds the core support for kexec re-boots on arm64. This v8 of the series is mainly just a rebase to Linux-4.0-rc3, and a few very minor changes requested for v7.

To load a second stage kernel and execute a kexec re-boot on arm64 my patches to kexec-tools [2], which have not yet been merged upstream, are needed.

I have tested with the ARM VE fast model, the ARM Base model and the ARM Foundation model with various kernel config options for both the first and second stage kernels. Kexec on EFI systems works correctly. With the ACPI kernel patches from [3] applied, kexec on ACPI systems seeems to work correctly. More ACPI + kexec testing is needed.

Patch 1 here moves the macros from proc-macros.S to asm/assembler.h so that the dcache_line_size macro it defines can be uesd by kexec's relocate kernel routine.

Patches 2-4 rework the arm64 hcall mechanism to give the arm64 soft_restart() routine the ability to switch exception levels from EL1 to EL2 for kernels that were entered in EL2.

Patches 5-6 add the actual kexec support.

Please consider all patches for inclusion.

[1]  https://git.kernel.org/cgit/linux/kernel/git/geoff/linux-kexec.git
[2]  https://git.kernel.org/cgit/linux/kernel/git/geoff/kexec-tools.git
[3]  http://git.linaro.org/leg/acpi/acpi.git #acpi-topic-juno-fvp

Several things are known to have problems on kexec re-boot:

spin-table
----------

PROBLEM: The spin-table enable method does not implement all the methods needed for CPU hot-plug, so the first stage kernel cannot be shutdown properly.

WORK-AROUND: Upgrade to system firmware that provides PSCI enable method support, OR build the first stage kernel with CONFIG_SMP=n, OR pass 'maxcpus=1' on the first stage kernel command line.

FIX: Upgrade system firmware to provide PSCI enable method support or add missing spin-table support to the kernel.

KVM
---

PROBLEM: KVM acquires hypervisor resources on startup, but does not free those resources on shutdown, so the first stage kernel cannot be shutdown properly when using kexec.

WORK-AROUND: Build the first stage kernel with CONFIG_KVM=n, or apply KVM bug fix patches from [1].

FIX: Takahiro Akashi has preliminary patches to fix the KVM shutdown problem. I have those in my master branch at [1]. KVM + kexec works properly with that branch. Patches neeeded:

arm64: kvm: add a cpu tear-down function
arm64: kexec: fix kvm issue
arm64/kvm: Remove !KEXEC Kconfig dependency
arm64/kexec: Enable kexec in the arm64 defconfig

/memreserve/
----------

PROBLEM: Device tree /memreserve/ entries are not available in /proc/device-tree. For systems that have /memreserve/ entries and use /proc/device-tree during kexec, the second stage kernel will use the reserved regions and the system will become unstable.

WORK-AROUND: Enable the kernel config option CONFIG_SYSFS=y to expose a binary device tree to user space at /sys/firmware/fdt that includes /memreserve/ entries OR pass a user specified DTB using the kexec --dtb option.

FIX: This is expected behavior. To maximize user support, rework device tree definitions to not use /memreserve/ entries.

-Geoff

The following changes since commit 06e5801b8cb3fc057d88cb4dc03c0b64b2744cda:

Linux 4.0-rc4 (2015-03-15 17:38:20 -0700)

are available in the git repository at:

git://git.kernel.org/pub/scm/linux/kernel/git/geoff/linux-kexec.git kexec-v8

for you to fetch changes up to 9d94104463ae6e3472526fb69e8111201c4a1fa7:

arm64/kexec: Add pr_devel output (2015-03-19 12:21:43 -0700)

----------------------------------------------------------------
Geoff Levand (6):
arm64: Fold proc-macros.S into assembler.h
arm64: Convert hcalls to use HVC immediate value
arm64: Add new hcall HVC_CALL_FUNC
arm64: Add EL2 switch to soft_restart arm64/kexec: Add core kexec support arm64/kexec: Add pr_devel output

 arch/arm64/Kconfig                  |   9 ++
 arch/arm64/include/asm/assembler.h  |  37 ++++++-
 arch/arm64/include/asm/kexec.h      |  48 +++++++++
 arch/arm64/include/asm/proc-fns.h   |   4 +-
 arch/arm64/include/asm/virt.h       |  40 ++++++++
 arch/arm64/kernel/Makefile          |   1 +
 arch/arm64/kernel/hyp-stub.S        |  43 +++++---
 arch/arm64/kernel/machine_kexec.c   | 189 ++++++++++++++++++++++++++++++++++++
 arch/arm64/kernel/process.c         |   6 +-
 arch/arm64/kernel/relocate_kernel.S | 149 ++++++++++++++++++++++++++++
 arch/arm64/kvm/Kconfig              |   1 +
 arch/arm64/kvm/hyp.S                |  16 +--
 arch/arm64/mm/cache.S               |   2 -
 arch/arm64/mm/proc-macros.S         |  54 -----------
 arch/arm64/mm/proc.S                |  49 +++++++---
 include/uapi/linux/kexec.h          |   1 +
 16 files changed, 557 insertions(+), 92 deletions(-)
 create mode 100644 arch/arm64/include/asm/kexec.h
 create mode 100644 arch/arm64/kernel/machine_kexec.c
 create mode 100644 arch/arm64/kernel/relocate_kernel.S
 delete mode 100644 arch/arm64/mm/proc-macros.S

2.1.0


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To allow the assembler macros defined in arch/arm64/mm/proc-macros.S to be used outside the mm code move the contents of proc-macros.S to asm/assembler.h. Also, delete proc-macros.S, and fix up all references to proc-macros.S.

---
 arch/arm64/include/asm/assembler.h | 37 +++++++++++++++++++++++++-
 arch/arm64/mm/cache.S              |  2 --
 arch/arm64/mm/proc-macros.S        | 54 --------------------------------------
 arch/arm64/mm/proc.S               |  2 --
 4 files changed, 36 insertions(+), 59 deletions(-)
 delete mode 100644 arch/arm64/mm/proc-macros.S

index 750bac4..47962f6be 100644
@@ -1,5 +1,5 @@
 /*
- * Based on arch/arm/include/asm/assembler.h
+ * Based on arch/arm/include/asm/assembler.h, arch/arm/mm/proc-macros.S
  *
  * Copyright (C) 1996-2000 Russell King
  * Copyright (C) 2012 ARM Ltd.

@@ -23,6 +23,7 @@
 #ifndef __ASM_ASSEMBLER_H
 #define __ASM_ASSEMBLER_H
 
+#include <asm/asm-offsets.h>
 #include <asm/ptrace.h>
 #include <asm/thread_info.h>
 

@@ -159,4 +160,38 @@ lr	.req	x30		// link register
 	orr	\rd, \lbits, \hbits, lsl #32
 	.endm
 
+/*
+ * vma_vm_mm - get mm pointer from vma pointer (vma->vm_mm)
+ */
+	.macro	vma_vm_mm, rd, rn
+	ldr	\rd, [\rn, #VMA_VM_MM]
+	.endm
+
+/*
+ * mmid - get context id from mm pointer (mm->context.id)
+ */
+	.macro	mmid, rd, rn
+	ldr	\rd, [\rn, #MM_CONTEXT_ID]
+	.endm
+
+/*
+ * dcache_line_size - get the minimum D-cache line size from the CTR register.
+ */
+	.macro	dcache_line_size, reg, tmp
+	mrs	\tmp, ctr_el0			// read CTR
+	ubfm	\tmp, \tmp, #16, #19		// cache line size encoding
+	mov	\reg, #4			// bytes per word
+	lsl	\reg, \reg, \tmp		// actual cache line size
+	.endm
+
+/*
+ * icache_line_size - get the minimum I-cache line size from the CTR register.
+ */
+	.macro	icache_line_size, reg, tmp
+	mrs	\tmp, ctr_el0			// read CTR
+	and	\tmp, \tmp, #0xf		// cache line size encoding
+	mov	\reg, #4			// bytes per word
+	lsl	\reg, \reg, \tmp		// actual cache line size
+	.endm
+
 #endif	/* __ASM_ASSEMBLER_H */

index 2560e1e..2d7a67c 100644
@@ -24,8 +24,6 @@
 #include <asm/cpufeature.h>
 #include <asm/alternative-asm.h>
 
-#include "proc-macros.S"
-
 /*
  *	__flush_dcache_all()
  *

index 28eebfb..fe69f6e 100644
@@ -26,8 +26,6 @@
 #include <asm/pgtable-hwdef.h>
 #include <asm/pgtable.h>
 
-#include "proc-macros.S"
-
 #ifdef CONFIG_ARM64_64K_PAGES
 #define TCR_TG_FLAGS	TCR_TG0_64K | TCR_TG1_64K
 #else

2.1.0



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The existing arm64 hcall implementations are limited in that they only allow for two distinct hcalls; with the x0 register either zero or not zero. Also, the API of the hyp-stub exception vector routines and the KVM exception vector routines differ; hyp-stub uses a non-zero value in x0 to implement __hyp_set_vectors, whereas KVM uses it to implement kvm_call_hyp.

To allow for additional hcalls to be defined and to make the arm64 hcall API more consistent across exception vector routines, change the hcall implementations to use the 16 bit immediate value of the HVC instruction to specify the hcall type.

Define three new preprocessor macros HVC_CALL_HYP, HVC_GET_VECTORS, and HVC_SET_VECTORS to be used as hcall type specifiers and convert the existing __hyp_get_vectors(), __hyp_set_vectors() and kvm_call_hyp() routines to use these new macros when executing an HVC call. Also, change the corresponding hyp-stub and KVM el1_sync exception vector routines to use these new macros.

---
 arch/arm64/include/asm/virt.h | 27 +++++++++++++++++++++++++++
 arch/arm64/kernel/hyp-stub.S  | 32 +++++++++++++++++++++-----------
 arch/arm64/kvm/hyp.S          | 16 +++++++++-------
 3 files changed, 57 insertions(+), 18 deletions(-)

index 7a5df52..eb10368 100644
@@ -18,6 +18,33 @@
 #ifndef __ASM__VIRT_H
 #define __ASM__VIRT_H
 
+/*
+ * The arm64 hcall implementation uses the ISS field of the ESR_EL2 register to
+ * specify the hcall type.  The exception handlers are allowed to use registers
+ * x17 and x18 in their implementation.  Any routine issuing an hcall must not
+ * expect these registers to be preserved.
+ */
+
+/*
+ * HVC_CALL_HYP - Execute a hyp routine.
+ */
+
+#define HVC_CALL_HYP 0
+
+/*
+ * HVC_GET_VECTORS - Return the value of the vbar_el2 register.
+ */
+
+#define HVC_GET_VECTORS 1
+
+/*
+ * HVC_SET_VECTORS - Set the value of the vbar_el2 register.
+ *
+ * @x0: Physical address of the new vector table.
+ */
+
+#define HVC_SET_VECTORS 2
+
 #define BOOT_CPU_MODE_EL1	(0xe11)
 #define BOOT_CPU_MODE_EL2	(0xe12)
 

index a272f33..017ab519 100644
@@ -22,6 +22,7 @@
 #include <linux/irqchip/arm-gic-v3.h>
 
 #include <asm/assembler.h>
+#include <asm/kvm_arm.h>
 #include <asm/ptrace.h>
 #include <asm/virt.h>
 

@@ -53,14 +54,22 @@ ENDPROC(__hyp_stub_vectors)
 	.align 11
 
 el1_sync:
-	mrs	x1, esr_el2
-	lsr	x1, x1, #26
-	cmp	x1, #0x16
+	mrs	x18, esr_el2
+	lsr	x17, x18, #ESR_ELx_EC_SHIFT
+	and	x18, x18, #ESR_ELx_ISS_MASK
+
+	cmp	x17, #ESR_ELx_EC_HVC64
 	b.ne	2f				// Not an HVC trap
-	cbz	x0, 1f
-	msr	vbar_el2, x0			// Set vbar_el2
+
+	cmp	x18, #HVC_GET_VECTORS
+	b.ne	1f
+	mrs	x0, vbar_el2
 	b	2f
-1:	mrs	x0, vbar_el2			// Return vbar_el2
+
+1:	cmp	x18, #HVC_SET_VECTORS
+	b.ne	2f
+	msr	vbar_el2, x0
+
 2:	eret
 ENDPROC(el1_sync)
 

@@ -100,11 +109,12 @@ ENDPROC(\label)
  * initialisation entry point.
  */
 
-ENTRY(__hyp_get_vectors)
-	mov	x0, xzr
-	// fall through
 ENTRY(__hyp_set_vectors)
-	hvc	#0
+	hvc	#HVC_SET_VECTORS
 	ret
-ENDPROC(__hyp_get_vectors)
 ENDPROC(__hyp_set_vectors)
+
+ENTRY(__hyp_get_vectors)
+	hvc	#HVC_GET_VECTORS
+	ret
+ENDPROC(__hyp_get_vectors)

index 5befd01..fd085ec 100644
@@ -27,6 +27,7 @@
 #include <asm/kvm_asm.h>
 #include <asm/kvm_mmu.h>
 #include <asm/memory.h>
+#include <asm/virt.h>
 
 #define CPU_GP_REG_OFFSET(x)	(CPU_GP_REGS + x)
 #define CPU_XREG_OFFSET(x)	CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x)

@@ -1129,12 +1130,9 @@ __hyp_panic_str:
  * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c).  Return values are
  * passed in r0 and r1.
  *
- * A function pointer with a value of 0 has a special meaning, and is
- * used to implement __hyp_get_vectors in the same way as in
- * arch/arm64/kernel/hyp_stub.S.
  */
 ENTRY(kvm_call_hyp)
-	hvc	#0
+	hvc	#HVC_CALL_HYP
 	ret
 ENDPROC(kvm_call_hyp)
 

@@ -1165,6 +1163,7 @@ el1_sync:					// Guest trapped into EL2
 
 	mrs	x1, esr_el2
 	lsr	x2, x1, #ESR_ELx_EC_SHIFT
+	and	x0, x1, #ESR_ELx_ISS_MASK
 
 	cmp	x2, #ESR_ELx_EC_HVC64
 	b.ne	el1_trap

@@ -1173,15 +1172,18 @@ el1_sync:					// Guest trapped into EL2
 	cbnz	x3, el1_trap			// called HVC
 
 	/* Here, we're pretty sure the host called HVC. */
+	mov	x18, x0
 	pop	x2, x3
 	pop	x0, x1
 
-	/* Check for __hyp_get_vectors */
-	cbnz	x0, 1f
+	cmp	x18, #HVC_GET_VECTORS
+	b.ne	1f
 	mrs	x0, vbar_el2
 	b	2f
 
-1:	push	lr, xzr
+1:	/* Default to HVC_CALL_HYP. */
+
+	push	lr, xzr
 
 	/*
 	 * Compute the function address in EL2, and shuffle the parameters.

2.1.0



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What is the status of this patch? I see it's not in 4.2. I ask because this patch might be breaking our 4.2-based kernel, and I'm just wondering if it's still applicable.

Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.

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I have it in my linux-kexec repo, which currently based on 4.3-rc2. I plan to submit it again in the next week or so after testing.

-Geoff

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Add the new hcall HVC_CALL_FUNC that allows execution of a function at EL2. During CPU reset the CPU must be brought to the exception level it had on entry to the kernel. The HVC_CALL_FUNC hcall will provide the mechanism needed for this exception level switch.

To allow the HVC_CALL_FUNC exception vector to work without a stack, which is needed to support an hcall at CPU reset, this implementation uses register x18 to store the link register across the caller provided function. This dictates that the caller provided function must preserve the contents of register x18.

---
 arch/arm64/include/asm/virt.h | 13 +++++++++++++
 arch/arm64/kernel/hyp-stub.S  | 13 ++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

index eb10368..3070096 100644
@@ -45,6 +45,19 @@
 
 #define HVC_SET_VECTORS 2
 
+/*
+ * HVC_CALL_FUNC - Execute a function at EL2.
+ *
+ * @x0: Physical address of the function to be executed.
+ * @x1: Passed as the first argument to the function.
+ * @x2: Passed as the second argument to the function.
+ * @x3: Passed as the third argument to the function.
+ *
+ * The called function must preserve the contents of register x18.
+ */
+
+#define HVC_CALL_FUNC 3
+
 #define BOOT_CPU_MODE_EL1	(0xe11)
 #define BOOT_CPU_MODE_EL2	(0xe12)
 

index 017ab519..e8febe9 100644
@@ -67,8 +67,19 @@ el1_sync:
 	b	2f
 
 1:	cmp	x18, #HVC_SET_VECTORS
-	b.ne	2f
+	b.ne	1f
 	msr	vbar_el2, x0
+	b	2f
+
+1:	cmp	x18, #HVC_CALL_FUNC
+	b.ne	2f
+	mov	x18, lr
+	mov	lr, x0
+	mov	x0, x1
+	mov	x1, x2
+	mov	x2, x3
+	blr	lr
+	mov	lr, x18
 
 2:	eret
 ENDPROC(el1_sync)

2.1.0



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When a CPU is reset it needs to be put into the exception level it had when it entered the kernel. Update cpu_reset() to accept an argument which signals if the soft reset address needs to be entered at EL1 or EL2.

This implementation updates cpu_soft_restart() and soft_restart() to pass the return value of is_hyp_mode_available() as the switch argument to cpu_reset(). Also, update the comments of cpu_reset(), cpu_soft_restart() and soft_restart() to reflect this change.

---
 arch/arm64/include/asm/proc-fns.h |  4 ++--
 arch/arm64/kernel/process.c       |  6 ++++-
 arch/arm64/mm/proc.S              | 47 +++++++++++++++++++++++++++++----------
 3 files changed, 42 insertions(+), 15 deletions(-)

index 9a8fd84..339394d 100644
@@ -32,8 +32,8 @@ extern void cpu_cache_off(void);
 extern void cpu_do_idle(void);
 extern void cpu_do_switch_mm(unsigned long pgd_phys, struct mm_struct *mm);
 extern void cpu_reset(unsigned long addr) __attribute__((noreturn));
-void cpu_soft_restart(phys_addr_t cpu_reset,
-		unsigned long addr) __attribute__((noreturn));
+void cpu_soft_restart(phys_addr_t cpu_reset, unsigned long el2_switch,
+		      unsigned long addr) __attribute__((noreturn));
 extern void cpu_do_suspend(struct cpu_suspend_ctx *ptr);
 extern u64 cpu_do_resume(phys_addr_t ptr, u64 idmap_ttbr);
 

index c6b1f3b..d894d3e 100644
@@ -51,6 +51,7 @@
 #include <asm/mmu_context.h>
 #include <asm/processor.h>
 #include <asm/stacktrace.h>
+#include <asm/virt.h>
 
 #ifdef CONFIG_CC_STACKPROTECTOR
 #include <linux/stackprotector.h>

@@ -61,7 +62,10 @@ EXPORT_SYMBOL(__stack_chk_guard);
 void soft_restart(unsigned long addr)
 {
 	setup_mm_for_reboot();
-	cpu_soft_restart(virt_to_phys(cpu_reset), addr);
+
+	cpu_soft_restart(virt_to_phys(cpu_reset),
+		is_hyp_mode_available(), addr);
+
 	/* Should never get here */
 	BUG();
 }

2.1.0



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Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to the arm64 architecture that add support for the kexec re-boot mechanism (CONFIG_KEXEC) on arm64 platforms.

With the addition of arm64 kexec support shutdown code paths through the kernel are executed that previously were not. To avoid system instability do to problems in the current arm64 KVM kernel implementation add a Kconfig dependency on !KEXEC to the arm64 KVM menu item.

---
 arch/arm64/Kconfig                  |   9 +++
 arch/arm64/include/asm/kexec.h      |  48 ++++++++++++
 arch/arm64/kernel/Makefile          |   1 +
 arch/arm64/kernel/machine_kexec.c   | 125 ++++++++++++++++++++++++++++++
 arch/arm64/kernel/relocate_kernel.S | 149 ++++++++++++++++++++++++++++++++++++
 arch/arm64/kvm/Kconfig              |   1 +
 include/uapi/linux/kexec.h          |   1 +
 7 files changed, 334 insertions(+)
 create mode 100644 arch/arm64/include/asm/kexec.h
 create mode 100644 arch/arm64/kernel/machine_kexec.c
 create mode 100644 arch/arm64/kernel/relocate_kernel.S

index 1b8e973..5a606d1 100644
@@ -528,6 +528,15 @@ config SECCOMP
 	  and the task is only allowed to execute a few safe syscalls
 	  defined by each seccomp mode.
 
+config KEXEC
+	depends on (!SMP || PM_SLEEP_SMP)
+	bool "kexec system call"
+	---help---
+	  kexec is a system call that implements the ability to shutdown your
+	  current kernel, and to start another kernel.  It is like a reboot
+	  but it is independent of the system firmware.   And like a reboot
+	  you can start any kernel with it, not just Linux.
+
 config XEN_DOM0
 	def_bool y
 	depends on XEN

index 5ee07ee..da9a7ee 100644
@@ -35,6 +35,7 @@ arm64-obj-$(CONFIG_KGDB)		+= kgdb.o
 arm64-obj-$(CONFIG_EFI)			+= efi.o efi-stub.o efi-entry.o
 arm64-obj-$(CONFIG_PCI)			+= pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
+arm64-obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)

index f5590c8..30ae7a7 100644
@@ -18,6 +18,7 @@ if VIRTUALIZATION
 
 config KVM
 	bool "Kernel-based Virtual Machine (KVM) support"
+	depends on !KEXEC
 	select MMU_NOTIFIER
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES

index 99048e5..ccec467 100644
@@ -39,6 +39,7 @@
 #define KEXEC_ARCH_SH      (42 << 16)
 #define KEXEC_ARCH_MIPS_LE (10 << 16)
 #define KEXEC_ARCH_MIPS    ( 8 << 16)
+#define KEXEC_ARCH_ARM64   (183 << 16)
 
 /* The artificial cap on the number of segments passed to kexec_load. */
 #define KEXEC_SEGMENT_MAX 16

2.1.0



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Hi Suzuki,

dest is left over from when I had a generic list walk routine. I'll remove it.

Yes, now that the patch to define IND_FLAGS has been merged.

-Geoff

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Add three new files, kexec.h, machine_kexec.c and relocate_kernel.S to the arm64 architecture that add support for the kexec re-boot mechanism (CONFIG_KEXEC) on arm64 platforms.

With the addition of arm64 kexec support shutdown code paths through the kernel are executed that previously were not. To avoid system instability do to problems in the current arm64 KVM kernel implementation add a Kconfig dependency on !KEXEC to the arm64 KVM menu item.

---
I pushed this V2 out to my kexec-v9 branch:

git://git.kernel.org/pub/scm/linux/kernel/git/geoff/linux-kexec.git kexec-v9

-Geoff

 arch/arm64/Kconfig                  |   9 +++
 arch/arm64/include/asm/kexec.h      |  48 ++++++++++++
 arch/arm64/kernel/Makefile          |   1 +
 arch/arm64/kernel/machine_kexec.c   | 120 +++++++++++++++++++++++++++++
 arch/arm64/kernel/relocate_kernel.S | 149 ++++++++++++++++++++++++++++++++++++
 arch/arm64/kvm/Kconfig              |   1 +
 include/uapi/linux/kexec.h          |   1 +
 7 files changed, 329 insertions(+)
 create mode 100644 arch/arm64/include/asm/kexec.h
 create mode 100644 arch/arm64/kernel/machine_kexec.c
 create mode 100644 arch/arm64/kernel/relocate_kernel.S

index 23d51be..5716edf 100644
@@ -553,6 +553,15 @@ config SECCOMP
 	  and the task is only allowed to execute a few safe syscalls
 	  defined by each seccomp mode.
 
+config KEXEC
+	depends on (!SMP || PM_SLEEP_SMP)
+	bool "kexec system call"
+	---help---
+	  kexec is a system call that implements the ability to shutdown your
+	  current kernel, and to start another kernel.  It is like a reboot
+	  but it is independent of the system firmware.   And like a reboot
+	  you can start any kernel with it, not just Linux.
+
 config XEN_DOM0
 	def_bool y
 	depends on XEN

index b12e15b..ac3c2e2 100644
@@ -35,6 +35,7 @@ arm64-obj-$(CONFIG_KGDB)		+= kgdb.o
 arm64-obj-$(CONFIG_EFI)			+= efi.o efi-stub.o efi-entry.o
 arm64-obj-$(CONFIG_PCI)			+= pci.o
 arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
+arm64-obj-$(CONFIG_KEXEC)		+= machine_kexec.o relocate_kernel.o
 
 obj-y					+= $(arm64-obj-y) vdso/
 obj-m					+= $(arm64-obj-m)

index f5590c8..30ae7a7 100644
@@ -18,6 +18,7 @@ if VIRTUALIZATION
 
 config KVM
 	bool "Kernel-based Virtual Machine (KVM) support"
+	depends on !KEXEC
 	select MMU_NOTIFIER
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES

index 99048e5..ccec467 100644
@@ -39,6 +39,7 @@
 #define KEXEC_ARCH_SH      (42 << 16)
 #define KEXEC_ARCH_MIPS_LE (10 << 16)
 #define KEXEC_ARCH_MIPS    ( 8 << 16)
+#define KEXEC_ARCH_ARM64   (183 << 16)
 
 /* The artificial cap on the number of segments passed to kexec_load. */
 #define KEXEC_SEGMENT_MAX 16

2.1.0




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To aid in debugging kexec problems or when adding new functionality to kexec add a new routine kexec_image_info() and several inline pr_devel statements.

---
 arch/arm64/kernel/machine_kexec.c | 64 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)

index f1387d0..7aa2fa2 100644
@@ -24,6 +24,48 @@ extern unsigned long arm64_kexec_dtb_addr;
 extern unsigned long arm64_kexec_kimage_head;
 extern unsigned long arm64_kexec_kimage_start;
 
+/**
+ * kexec_is_dtb - Helper routine to check the device tree header signature.
+ */
+static bool kexec_is_dtb(const void *dtb)
+{
+	__be32 magic;
+
+	return get_user(magic, (__be32 *)dtb) ? false :
+		(be32_to_cpu(magic) == OF_DT_HEADER);
+}
+
+/**
+ * kexec_image_info - For debugging output.
+ */
+#define kexec_image_info(_i) _kexec_image_info(__func__, __LINE__, _i)
+static void _kexec_image_info(const char *func, int line,
+	const struct kimage *image)
+{
+	unsigned long i;
+
+#if !defined(DEBUG)
+	return;
+#endif
+	pr_devel("%s:%d:\n", func, line);
+	pr_devel("  kexec image info:\n");
+	pr_devel("    type:        %d\n", image->type);
+	pr_devel("    start:       %lx\n", image->start);
+	pr_devel("    head:        %lx\n", image->head);
+	pr_devel("    nr_segments: %lu\n", image->nr_segments);
+
+	for (i = 0; i < image->nr_segments; i++) {
+		pr_devel("      segment[%lu]: %016lx - %016lx, %lx bytes, %lu pages%s\n",
+			i,
+			image->segment[i].mem,
+			image->segment[i].mem + image->segment[i].memsz,
+			image->segment[i].memsz,
+			image->segment[i].memsz /  PAGE_SIZE,
+			(kexec_is_dtb(image->segment[i].buf) ?
+				", dtb segment" : ""));
+	}
+}
+
 void machine_kexec_cleanup(struct kimage *image)
 {
 	/* Empty routine needed to avoid build errors. */

@@ -37,6 +79,7 @@ void machine_kexec_cleanup(struct kimage *image)
 int machine_kexec_prepare(struct kimage *image)
 {
 	arm64_kexec_kimage_start = image->start;
+	kexec_image_info(image);
 	return 0;
 }
 

@@ -91,6 +134,27 @@ void machine_kexec(struct kimage *image)
 	reboot_code_buffer_phys = page_to_phys(image->control_code_page);
 	reboot_code_buffer = phys_to_virt(reboot_code_buffer_phys);
 
+	kexec_image_info(image);
+
+	pr_devel("%s:%d: control_code_page:        %p\n", __func__, __LINE__,
+		image->control_code_page);
+	pr_devel("%s:%d: reboot_code_buffer_phys:  %pa\n", __func__, __LINE__,
+		&reboot_code_buffer_phys);
+	pr_devel("%s:%d: reboot_code_buffer:       %p\n", __func__, __LINE__,
+		reboot_code_buffer);
+	pr_devel("%s:%d: relocate_new_kernel:      %p\n", __func__, __LINE__,
+		relocate_new_kernel);
+	pr_devel("%s:%d: relocate_new_kernel_size: 0x%lx(%lu) bytes\n",
+		__func__, __LINE__, relocate_new_kernel_size,
+		relocate_new_kernel_size);
+
+	pr_devel("%s:%d: kexec_dtb_addr:           %lx\n", __func__, __LINE__,
+		arm64_kexec_dtb_addr);
+	pr_devel("%s:%d: kexec_kimage_head:        %lx\n", __func__, __LINE__,
+		arm64_kexec_kimage_head);
+	pr_devel("%s:%d: kexec_kimage_start:       %lx\n", __func__, __LINE__,
+		arm64_kexec_kimage_start);
+
 	/*
 	 * Copy relocate_new_kernel to the reboot_code_buffer for use
 	 * after the kernel is shut down.

2.1.0


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Hi Geoff,

As a heads-up, I'm not going to have the chanec to review this until after the FW summit next week.

[...]

These (or some descendents thereof) are going to be a prerequisite for kexec.

I'd say that requiring CONFIG_SYSFS is the real fix here. That's a kernel change that maximises compatibility with DTBs (which we don't really have control over).

I hope that the tools warn somehow if they cannot see the fdt.

Mark.

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Hi,

I rebased my series to the latest arm64 for-next/core (v4.0-rc4) and pushed it out to:

git://git.kernel.org/pub/scm/linux/kernel/git/geoff/linux-kexec.git kexec-v9

-Geoff

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Btw, I get the following build failure for kexec-tools master branch, with Linaro tool chain (crosstool-NG linaro-1.13.1-4.9-2014.09 - Linaro GCC 4.9-2014.09 )

  $ ./configure --host=aarch64-linux-gnu
  [...]
  $ make -j4
kexec/arch/arm64/kexec-arm64.c: In function ?machine_verify_elf_rel?:
kexec/arch/arm64/kexec-arm64.c:970:29: error: ?EM_AARCH64? undeclared 
(first use in this function)
   return (ehdr->e_machine == EM_AARCH64);
                              ^
kexec/arch/arm64/kexec-arm64.c:970:29: note: each undeclared identifier 
is reported only once for each function it appears in
kexec/arch/arm64/kexec-arm64.c:971:1: warning: control reaches end of 
non-void function [-Wreturn-type]
  }
  ^
make: *** [kexec/arch/arm64/kexec-arm64.o] Error 1
make: *** Waiting for unfinished jobs....
----

You may need to add the definition of EM_AARCH64 to include/elf.h and include that instead of linux/elf.h, like the other archs.

Cheers
Suzuki

Hi,

I guess that toolchain is using some ancient headers. As a workaround you can use configure CPPFLAGS='-DEM_AARCH64=183'.

-Geoff

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Hi Geoff,

I suppose there would be a next revision of kexec patches. When is the that expected?
Thanks a lot for working on this.

~Pratyush

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Hi Pratyush,

As I just replied to Marc's mail, I'll work on preparing a rebased kexec patch set the next chance I get. I'm hoping I can start on it his week.

-Geoff

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