[PATCH v3 0/3] LoongArch: Add kexec/kdump support

[PATCH v3 0/3] LoongArch: Add kexec/kdump support

[Youling Tang]

This patch series to support kexec/kdump (only 64bit).

Kexec is a system call that enables you to load and boot into another kernel
from the currently running kernel. This is useful for kernel developers or
other people who need to reboot very quickly without waiting for the whole
BIOS boot process to finish.

Kdump uses kexec to quickly boot to a dump-capture kernel whenever a
dump of the system kernel's memory needs to be taken (for example, when
the system panics). The system kernel's memory image is preserved across
the reboot and is accessible to the dump-capture kernel.

For details, see Documentation/admin-guide/kdump/kdump.rst.

User tools kexec-tools see link [1].

TODO:
Currently kdump does not support the same binary image, the production kernel
and the capture kernel will be generated with different configurations. I will
support kernel relocation support in the near future. Then will go to implement
the same binary support based on kernel relocation support.

[1] Link: https://github.com/tangyouling/kexec-tools

Changes in v3:
 - Adjust the PE header (note that kexec-tools needs to be updated).
 - Add ibar in kexec_reboot().
 - boot_flag is replaced by efi_boot.
 - Adjust do_kexec parameter passing order.
 - Adjust the order of static variables to be consistent with do_kexec.
 - Remove a-series register save.
 - Some comments and register usage modification.
 - Add the opening and closing of the cpu core state.
 - Add a call to cpu_device_up to turn it on when the cpu core state is offline.

Changes in v2:
 - Add ibar.
 - Access via IOCSR.
 - Remove the settings of the tp, sp registers.
 - Remove the crash.c file and merge the relevant code into machine_kexec.c.
 - Adjust the use of CONFIG_SMP macro to avoid build errors under !SMP
   configuration.
 - Change the default value of PHYSICAL_START of the capture kernel to
   0x90000000a0000000.

Youling Tang (3):
  LoongArch: Add kexec support
  LoongArch: Add kdump support
  LoongArch: Enable CONFIG_KEXEC

 arch/loongarch/Kconfig                     |  33 +++
 arch/loongarch/Makefile                    |   4 +
 arch/loongarch/configs/loongson3_defconfig |   1 +
 arch/loongarch/include/asm/kexec.h         |  58 ++++
 arch/loongarch/kernel/Makefile             |   3 +
 arch/loongarch/kernel/crash_dump.c         |  19 ++
 arch/loongarch/kernel/head.S               |   6 +-
 arch/loongarch/kernel/machine_kexec.c      | 295 +++++++++++++++++++++
 arch/loongarch/kernel/mem.c                |   6 +
 arch/loongarch/kernel/relocate_kernel.S    | 111 ++++++++
 arch/loongarch/kernel/setup.c              |  49 ++++
 arch/loongarch/kernel/traps.c              |   4 +
 12 files changed, 588 insertions(+), 1 deletion(-)
 create mode 100644 arch/loongarch/include/asm/kexec.h
 create mode 100644 arch/loongarch/kernel/crash_dump.c
 create mode 100644 arch/loongarch/kernel/machine_kexec.c
 create mode 100644 arch/loongarch/kernel/relocate_kernel.S

-- 
2.36.0


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v3 0/3] LoongArch: Add kexec/kdump support

[Youling Tang]

This patch series to support kexec/kdump (only 64bit).

Kexec is a system call that enables you to load and boot into another kernel
from the currently running kernel. This is useful for kernel developers or
other people who need to reboot very quickly without waiting for the whole
BIOS boot process to finish.

Kdump uses kexec to quickly boot to a dump-capture kernel whenever a
dump of the system kernel's memory needs to be taken (for example, when
the system panics). The system kernel's memory image is preserved across
the reboot and is accessible to the dump-capture kernel.

For details, see Documentation/admin-guide/kdump/kdump.rst.

User tools kexec-tools see link [1].

TODO:
Currently kdump does not support the same binary image, the production kernel
and the capture kernel will be generated with different configurations. I will
support kernel relocation support in the near future. Then will go to implement
the same binary support based on kernel relocation support.

[1] Link: https://github.com/tangyouling/kexec-tools

Changes in v3:
 - Adjust the PE header (note that kexec-tools needs to be updated).
 - Add ibar in kexec_reboot().
 - boot_flag is replaced by efi_boot.
 - Adjust do_kexec parameter passing order.
 - Adjust the order of static variables to be consistent with do_kexec.
 - Remove a-series register save.
 - Some comments and register usage modification.
 - Add the opening and closing of the cpu core state.
 - Add a call to cpu_device_up to turn it on when the cpu core state is offline.

Changes in v2:
 - Add ibar.
 - Access via IOCSR.
 - Remove the settings of the tp, sp registers.
 - Remove the crash.c file and merge the relevant code into machine_kexec.c.
 - Adjust the use of CONFIG_SMP macro to avoid build errors under !SMP
   configuration.
 - Change the default value of PHYSICAL_START of the capture kernel to
   0x90000000a0000000.

Youling Tang (3):
  LoongArch: Add kexec support
  LoongArch: Add kdump support
  LoongArch: Enable CONFIG_KEXEC

 arch/loongarch/Kconfig                     |  33 +++
 arch/loongarch/Makefile                    |   4 +
 arch/loongarch/configs/loongson3_defconfig |   1 +
 arch/loongarch/include/asm/kexec.h         |  58 ++++
 arch/loongarch/kernel/Makefile             |   3 +
 arch/loongarch/kernel/crash_dump.c         |  19 ++
 arch/loongarch/kernel/head.S               |   6 +-
 arch/loongarch/kernel/machine_kexec.c      | 295 +++++++++++++++++++++
 arch/loongarch/kernel/mem.c                |   6 +
 arch/loongarch/kernel/relocate_kernel.S    | 111 ++++++++
 arch/loongarch/kernel/setup.c              |  49 ++++
 arch/loongarch/kernel/traps.c              |   4 +
 12 files changed, 588 insertions(+), 1 deletion(-)
 create mode 100644 arch/loongarch/include/asm/kexec.h
 create mode 100644 arch/loongarch/kernel/crash_dump.c
 create mode 100644 arch/loongarch/kernel/machine_kexec.c
 create mode 100644 arch/loongarch/kernel/relocate_kernel.S

-- 
2.36.0

[PATCH v3 1/3] LoongArch: Add kexec support

[Youling Tang]

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

Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in
PE format.

I tested this on  LoongArch 3A5000 machine and works as expected,

 $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline
 $ sudo kexec -e

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 arch/loongarch/Kconfig                  |  11 ++
 arch/loongarch/include/asm/kexec.h      |  58 +++++++
 arch/loongarch/kernel/Makefile          |   2 +
 arch/loongarch/kernel/head.S            |   6 +-
 arch/loongarch/kernel/machine_kexec.c   | 209 ++++++++++++++++++++++++
 arch/loongarch/kernel/relocate_kernel.S | 105 ++++++++++++
 6 files changed, 390 insertions(+), 1 deletion(-)
 create mode 100644 arch/loongarch/include/asm/kexec.h
 create mode 100644 arch/loongarch/kernel/machine_kexec.c
 create mode 100644 arch/loongarch/kernel/relocate_kernel.S

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 9b1f2ab878e9..08e063aaf847 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -422,6 +422,17 @@ config ARCH_IOREMAP
 	  protection support. However, you can enable LoongArch DMW-based
 	  ioremap() for better performance.
 
+config KEXEC
+	bool "Kexec system call"
+	select KEXEC_CORE
+	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.
+
+	  The name comes from the similarity to the exec system call.
+
 config SECCOMP
 	bool "Enable seccomp to safely compute untrusted bytecode"
 	depends on PROC_FS
diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h
new file mode 100644
index 000000000000..e5b022d335c7
--- /dev/null
+++ b/arch/loongarch/include/asm/kexec.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * kexec.h for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#ifndef _ASM_KEXEC_H
+#define _ASM_KEXEC_H
+
+#include <asm/stacktrace.h>
+#include <asm/page.h>
+
+/* Maximum physical address we can use pages from */
+#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
+/* Maximum address we can reach in physical address mode */
+#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
+ /* Maximum address we can use for the control code buffer */
+#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
+
+/* Reserve a page for the control code buffer */
+#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
+
+/* The native architecture */
+#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
+
+static inline void crash_setup_regs(struct pt_regs *newregs,
+				    struct pt_regs *oldregs)
+{
+	if (oldregs)
+		memcpy(newregs, oldregs, sizeof(*newregs));
+	else
+		prepare_frametrace(newregs);
+}
+
+#define ARCH_HAS_KIMAGE_ARCH
+
+struct kimage_arch {
+	unsigned long efi_boot;
+	unsigned long fdt_addr;
+};
+
+typedef void (*do_kexec_t)(unsigned long efi_boot,
+			   unsigned long fdt_addr,
+			   unsigned long jump_addr,
+			   unsigned long first_ind_entry);
+
+struct kimage;
+extern const unsigned char relocate_new_kernel[];
+extern const size_t relocate_new_kernel_size;
+extern void kexec_reboot(void);
+
+#ifdef CONFIG_SMP
+extern atomic_t kexec_ready_to_reboot;
+extern const unsigned char kexec_smp_wait[];
+#endif
+
+#endif /* !_ASM_KEXEC_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 7225916dd378..17dc8ce6b5ce 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -17,6 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU)	+= fpu.o
 obj-$(CONFIG_MODULES)		+= module.o module-sections.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 
+obj-$(CONFIG_KEXEC)             += machine_kexec.o relocate_kernel.o
+
 obj-$(CONFIG_PROC_FS)		+= proc.o
 
 obj-$(CONFIG_SMP)		+= smp.o
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index eb3f641d5915..c0d61b29fcaa 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -20,7 +20,11 @@
 
 _head:
 	.word	MZ_MAGIC		/* "MZ", MS-DOS header */
-	.org	0x3c			/* 0x04 ~ 0x3b reserved */
+	.org	0x8
+	.dword	kernel_entry		/* Kernel entry point */
+	.dword	_end - _text		/* Effective size of kernel image */
+	.quad	0			/* Image load offset from start of RAM */
+	.org	0x3c			/* 0x20 ~ 0x3b reserved */
 	.long	pe_header - _head	/* Offset to the PE header */
 
 pe_header:
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
new file mode 100644
index 000000000000..a2f3c3e65130
--- /dev/null
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * machine_kexec.c for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#include <linux/compiler.h>
+#include <linux/cpu.h>
+#include <linux/kexec.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+#include <linux/libfdt.h>
+#include <linux/of_fdt.h>
+
+#include <asm/bootinfo.h>
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+
+/* 0x100000 ~ 0x200000 is safe */
+#define KEXEC_CTRL_CODE	TO_CACHE(0x100000UL)
+#define KEXEC_BLOB_ADDR	TO_CACHE(0x108000UL)
+
+static unsigned long reboot_code_buffer;
+
+#ifdef CONFIG_SMP
+static void (*relocated_kexec_smp_wait)(void *);
+atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
+#endif
+
+static unsigned long efi_boot;
+static unsigned long fdt_addr;
+static unsigned long jump_addr;
+static unsigned long first_ind_entry;
+
+static void kexec_image_info(const struct kimage *kimage)
+{
+	unsigned long i;
+
+	pr_debug("kexec kimage info:\n");
+	pr_debug("\ttype:        %d\n", kimage->type);
+	pr_debug("\tstart:       %lx\n", kimage->start);
+	pr_debug("\thead:        %lx\n", kimage->head);
+	pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
+
+	for (i = 0; i < kimage->nr_segments; i++) {
+		pr_debug("\t    segment[%lu]: %016lx - %016lx", i,
+			kimage->segment[i].mem,
+			kimage->segment[i].mem + kimage->segment[i].memsz);
+		pr_debug("\t\t0x%lx bytes, %lu pages\n",
+			(unsigned long)kimage->segment[i].memsz,
+			(unsigned long)kimage->segment[i].memsz /  PAGE_SIZE);
+	}
+}
+
+int machine_kexec_prepare(struct kimage *kimage)
+{
+	int i;
+	void *dtb = (void *)KEXEC_BLOB_ADDR;
+
+	kexec_image_info(kimage);
+
+	/* Find the Flattened Device Tree */
+	for (i = 0; i < kimage->nr_segments; i++) {
+		if (!fdt_check_header(kimage->segment[i].buf)) {
+			memcpy(dtb, kimage->segment[i].buf, SZ_64K);
+			kimage->arch.efi_boot = fw_arg0;
+			kimage->arch.fdt_addr = (unsigned long) dtb;
+			break;
+		}
+		continue;
+	}
+
+	/* kexec need a safe page to save reboot_code_buffer */
+	kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
+
+	reboot_code_buffer =
+	  (unsigned long)page_address(kimage->control_code_page);
+	memcpy((void *)reboot_code_buffer, relocate_new_kernel,
+	       relocate_new_kernel_size);
+
+#ifdef CONFIG_SMP
+	/* All secondary cpus now may jump to kexec_smp_wait cycle */
+	relocated_kexec_smp_wait = reboot_code_buffer +
+		(void *)(kexec_smp_wait - relocate_new_kernel);
+#endif
+
+	return 0;
+}
+
+void machine_kexec_cleanup(struct kimage *kimage)
+{
+}
+
+void kexec_reboot(void)
+{
+	do_kexec_t do_kexec = NULL;
+
+	/*
+	 * We know we were online, and there will be no incoming IPIs at
+	 * this point.
+	 */
+	set_cpu_online(smp_processor_id(), true);
+
+	/* Ensure remote CPUs observe that we're online before rebooting. */
+	smp_mb__after_atomic();
+
+	/*
+	 * Make sure we get correct instructions written by the
+	 * machine_kexec_prepare() CPU.
+	 */
+	asm volatile ("\tibar 0\n"::);
+
+#ifdef CONFIG_SMP
+	/* All secondary cpus go to kexec_smp_wait */
+	if (smp_processor_id() > 0) {
+		relocated_kexec_smp_wait(NULL);
+		unreachable();
+	}
+#endif
+
+	do_kexec = (void *)reboot_code_buffer;
+	do_kexec(efi_boot, fdt_addr, jump_addr, first_ind_entry);
+
+	unreachable();
+}
+
+
+#ifdef CONFIG_SMP
+static void kexec_shutdown_secondary(void *)
+{
+	int cpu = smp_processor_id();
+
+	if (!cpu_online(cpu))
+		return;
+
+	/* We won't be sent IPIs any more. */
+	set_cpu_online(cpu, false);
+
+	local_irq_disable();
+	while (!atomic_read(&kexec_ready_to_reboot))
+		cpu_relax();
+
+	kexec_reboot();
+}
+#endif
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+}
+
+void machine_shutdown(void)
+{
+	int cpu;
+
+	/* All CPUs go to reboot_code_buffer */
+	for_each_possible_cpu(cpu)
+		if (!cpu_online(cpu))
+			cpu_device_up(get_cpu_device(cpu));
+
+#ifdef CONFIG_SMP
+	smp_call_function(kexec_shutdown_secondary, NULL, 0);
+#endif
+}
+
+void machine_kexec(struct kimage *image)
+{
+	unsigned long entry;
+	unsigned long *ptr;
+	struct kimage_arch *internal = &image->arch;
+
+	efi_boot = internal->efi_boot;
+	fdt_addr = internal->fdt_addr;
+
+	jump_addr = (unsigned long)phys_to_virt(image->start);
+
+	first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
+
+	/*
+	 * The generic kexec code builds a page list with physical
+	 * addresses. they are directly accessible through XKPRANGE
+	 * hence the phys_to_virt() call.
+	 */
+	for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
+	     ptr = (entry & IND_INDIRECTION) ?
+	       phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
+		if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
+		    *ptr & IND_DESTINATION)
+			*ptr = (unsigned long) phys_to_virt(*ptr);
+	}
+
+	/* Mark offline before disabling local irq. */
+	set_cpu_online(smp_processor_id(), false);
+
+	/* we do not want to be bothered. */
+	local_irq_disable();
+
+	pr_notice("Will call new kernel at %lx\n", jump_addr);
+	pr_notice("FDT image at %lx\n", fdt_addr);
+	pr_notice("Bye ...\n");
+
+	/* Make reboot code buffer available to the boot CPU. */
+	flush_cache_all();
+
+#ifdef CONFIG_SMP
+	atomic_set(&kexec_ready_to_reboot, 1);
+#endif
+
+	kexec_reboot();
+}
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
new file mode 100644
index 000000000000..0ea8b29242e6
--- /dev/null
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * relocate_kernel.S for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/kexec.h>
+
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/regdef.h>
+#include <asm/loongarch.h>
+#include <asm/stackframe.h>
+#include <asm/addrspace.h>
+
+SYM_CODE_START(relocate_new_kernel)
+	/*
+	 * a0: Boot flag passed to the new kernel
+	 * a1: Virt address of the FDT image
+	 * a2: Virt address to jump to after relocation
+	 * a3: Pointer to the current indirection page entry
+	 */
+
+	move		s0, a3
+
+process_entry:
+	PTR_L		s1, s0, 0
+	PTR_ADDI	s0, s0, SZREG
+
+	/* destination page */
+	andi		s2, s1, IND_DESTINATION
+	beqz		s2, 1f
+	li.w		t0, ~0x1
+	and		s3, s1, t0	/* store destination addr in s3 */
+	b		process_entry
+
+1:
+	/* indirection page, update s0	*/
+	andi		s2, s1, IND_INDIRECTION
+	beqz		s2, 1f
+	li.w		t0, ~0x2
+	and		s0, s1, t0
+	b		process_entry
+
+1:
+	/* done page */
+	andi		s2, s1, IND_DONE
+	beqz		s2, 1f
+	b		done
+1:
+	/* source page */
+	andi		s2, s1, IND_SOURCE
+	beqz		s2, process_entry
+	li.w		t0, ~0x8
+	and		s1, s1, t0
+	li.w		s5, (1 << _PAGE_SHIFT) / SZREG
+
+copy_word:
+	/* copy page word by word */
+	REG_L		s4, s1, 0
+	REG_S		s4, s3, 0
+	PTR_ADDI	s3, s3, SZREG
+	PTR_ADDI	s1, s1, SZREG
+	LONG_ADDI	s5, s5, -1
+	beqz		s5, process_entry
+	b		copy_word
+	b		process_entry
+
+done:
+	ibar		0
+	dbar		0
+
+	/*
+	 * Jump to the new kernel,
+	 * make sure the values of a0, a1 and a2 are not changed.
+	 */
+	jr		a2
+SYM_CODE_END(relocate_new_kernel)
+
+#ifdef CONFIG_SMP
+/*
+ * Other CPUs should wait until code is relocated and
+ * then start at entry (?) point.
+ */
+SYM_CODE_START(kexec_smp_wait)
+1:	li.w		t0, 0x100			/* wait for init loop */
+2:	addi.w		t0, t0, -1			/* limit mailbox access */
+	bnez		t0, 2b
+	li.w		t1, LOONGARCH_IOCSR_MBUF0
+	iocsrrd.w	s0, t1				/* check PC as an indicator */
+	beqz		s0, 1b
+	iocsrrd.d	s0, t1				/* get PC via mailbox */
+
+	li.d		t0, CACHE_BASE
+	or		s0, s0, t0			/* s0 = TO_CACHE(s0) */
+	jr		s0				/* jump to initial PC */
+SYM_CODE_END(kexec_smp_wait)
+#endif
+
+relocate_new_kernel_end:
+
+SYM_DATA_START(relocate_new_kernel_size)
+	PTR		relocate_new_kernel_end - relocate_new_kernel
+SYM_DATA_END(relocate_new_kernel_size)
-- 
2.36.0


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v3 1/3] LoongArch: Add kexec support

[Youling Tang]

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

Supports loading vmlinux (vmlinux.elf) in ELF format and vmlinux.efi in
PE format.

I tested this on  LoongArch 3A5000 machine and works as expected,

 $ sudo kexec -l /boot/vmlinux.efi --reuse-cmdline
 $ sudo kexec -e

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 arch/loongarch/Kconfig                  |  11 ++
 arch/loongarch/include/asm/kexec.h      |  58 +++++++
 arch/loongarch/kernel/Makefile          |   2 +
 arch/loongarch/kernel/head.S            |   6 +-
 arch/loongarch/kernel/machine_kexec.c   | 209 ++++++++++++++++++++++++
 arch/loongarch/kernel/relocate_kernel.S | 105 ++++++++++++
 6 files changed, 390 insertions(+), 1 deletion(-)
 create mode 100644 arch/loongarch/include/asm/kexec.h
 create mode 100644 arch/loongarch/kernel/machine_kexec.c
 create mode 100644 arch/loongarch/kernel/relocate_kernel.S

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 9b1f2ab878e9..08e063aaf847 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -422,6 +422,17 @@ config ARCH_IOREMAP
 	  protection support. However, you can enable LoongArch DMW-based
 	  ioremap() for better performance.
 
+config KEXEC
+	bool "Kexec system call"
+	select KEXEC_CORE
+	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.
+
+	  The name comes from the similarity to the exec system call.
+
 config SECCOMP
 	bool "Enable seccomp to safely compute untrusted bytecode"
 	depends on PROC_FS
diff --git a/arch/loongarch/include/asm/kexec.h b/arch/loongarch/include/asm/kexec.h
new file mode 100644
index 000000000000..e5b022d335c7
--- /dev/null
+++ b/arch/loongarch/include/asm/kexec.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * kexec.h for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#ifndef _ASM_KEXEC_H
+#define _ASM_KEXEC_H
+
+#include <asm/stacktrace.h>
+#include <asm/page.h>
+
+/* Maximum physical address we can use pages from */
+#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
+/* Maximum address we can reach in physical address mode */
+#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
+ /* Maximum address we can use for the control code buffer */
+#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
+
+/* Reserve a page for the control code buffer */
+#define KEXEC_CONTROL_PAGE_SIZE PAGE_SIZE
+
+/* The native architecture */
+#define KEXEC_ARCH KEXEC_ARCH_LOONGARCH
+
+static inline void crash_setup_regs(struct pt_regs *newregs,
+				    struct pt_regs *oldregs)
+{
+	if (oldregs)
+		memcpy(newregs, oldregs, sizeof(*newregs));
+	else
+		prepare_frametrace(newregs);
+}
+
+#define ARCH_HAS_KIMAGE_ARCH
+
+struct kimage_arch {
+	unsigned long efi_boot;
+	unsigned long fdt_addr;
+};
+
+typedef void (*do_kexec_t)(unsigned long efi_boot,
+			   unsigned long fdt_addr,
+			   unsigned long jump_addr,
+			   unsigned long first_ind_entry);
+
+struct kimage;
+extern const unsigned char relocate_new_kernel[];
+extern const size_t relocate_new_kernel_size;
+extern void kexec_reboot(void);
+
+#ifdef CONFIG_SMP
+extern atomic_t kexec_ready_to_reboot;
+extern const unsigned char kexec_smp_wait[];
+#endif
+
+#endif /* !_ASM_KEXEC_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 7225916dd378..17dc8ce6b5ce 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -17,6 +17,8 @@ obj-$(CONFIG_CPU_HAS_FPU)	+= fpu.o
 obj-$(CONFIG_MODULES)		+= module.o module-sections.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 
+obj-$(CONFIG_KEXEC)             += machine_kexec.o relocate_kernel.o
+
 obj-$(CONFIG_PROC_FS)		+= proc.o
 
 obj-$(CONFIG_SMP)		+= smp.o
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S
index eb3f641d5915..c0d61b29fcaa 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -20,7 +20,11 @@
 
 _head:
 	.word	MZ_MAGIC		/* "MZ", MS-DOS header */
-	.org	0x3c			/* 0x04 ~ 0x3b reserved */
+	.org	0x8
+	.dword	kernel_entry		/* Kernel entry point */
+	.dword	_end - _text		/* Effective size of kernel image */
+	.quad	0			/* Image load offset from start of RAM */
+	.org	0x3c			/* 0x20 ~ 0x3b reserved */
 	.long	pe_header - _head	/* Offset to the PE header */
 
 pe_header:
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
new file mode 100644
index 000000000000..a2f3c3e65130
--- /dev/null
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * machine_kexec.c for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+#include <linux/compiler.h>
+#include <linux/cpu.h>
+#include <linux/kexec.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+#include <linux/libfdt.h>
+#include <linux/of_fdt.h>
+
+#include <asm/bootinfo.h>
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+
+/* 0x100000 ~ 0x200000 is safe */
+#define KEXEC_CTRL_CODE	TO_CACHE(0x100000UL)
+#define KEXEC_BLOB_ADDR	TO_CACHE(0x108000UL)
+
+static unsigned long reboot_code_buffer;
+
+#ifdef CONFIG_SMP
+static void (*relocated_kexec_smp_wait)(void *);
+atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
+#endif
+
+static unsigned long efi_boot;
+static unsigned long fdt_addr;
+static unsigned long jump_addr;
+static unsigned long first_ind_entry;
+
+static void kexec_image_info(const struct kimage *kimage)
+{
+	unsigned long i;
+
+	pr_debug("kexec kimage info:\n");
+	pr_debug("\ttype:        %d\n", kimage->type);
+	pr_debug("\tstart:       %lx\n", kimage->start);
+	pr_debug("\thead:        %lx\n", kimage->head);
+	pr_debug("\tnr_segments: %lu\n", kimage->nr_segments);
+
+	for (i = 0; i < kimage->nr_segments; i++) {
+		pr_debug("\t    segment[%lu]: %016lx - %016lx", i,
+			kimage->segment[i].mem,
+			kimage->segment[i].mem + kimage->segment[i].memsz);
+		pr_debug("\t\t0x%lx bytes, %lu pages\n",
+			(unsigned long)kimage->segment[i].memsz,
+			(unsigned long)kimage->segment[i].memsz /  PAGE_SIZE);
+	}
+}
+
+int machine_kexec_prepare(struct kimage *kimage)
+{
+	int i;
+	void *dtb = (void *)KEXEC_BLOB_ADDR;
+
+	kexec_image_info(kimage);
+
+	/* Find the Flattened Device Tree */
+	for (i = 0; i < kimage->nr_segments; i++) {
+		if (!fdt_check_header(kimage->segment[i].buf)) {
+			memcpy(dtb, kimage->segment[i].buf, SZ_64K);
+			kimage->arch.efi_boot = fw_arg0;
+			kimage->arch.fdt_addr = (unsigned long) dtb;
+			break;
+		}
+		continue;
+	}
+
+	/* kexec need a safe page to save reboot_code_buffer */
+	kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
+
+	reboot_code_buffer =
+	  (unsigned long)page_address(kimage->control_code_page);
+	memcpy((void *)reboot_code_buffer, relocate_new_kernel,
+	       relocate_new_kernel_size);
+
+#ifdef CONFIG_SMP
+	/* All secondary cpus now may jump to kexec_smp_wait cycle */
+	relocated_kexec_smp_wait = reboot_code_buffer +
+		(void *)(kexec_smp_wait - relocate_new_kernel);
+#endif
+
+	return 0;
+}
+
+void machine_kexec_cleanup(struct kimage *kimage)
+{
+}
+
+void kexec_reboot(void)
+{
+	do_kexec_t do_kexec = NULL;
+
+	/*
+	 * We know we were online, and there will be no incoming IPIs at
+	 * this point.
+	 */
+	set_cpu_online(smp_processor_id(), true);
+
+	/* Ensure remote CPUs observe that we're online before rebooting. */
+	smp_mb__after_atomic();
+
+	/*
+	 * Make sure we get correct instructions written by the
+	 * machine_kexec_prepare() CPU.
+	 */
+	asm volatile ("\tibar 0\n"::);
+
+#ifdef CONFIG_SMP
+	/* All secondary cpus go to kexec_smp_wait */
+	if (smp_processor_id() > 0) {
+		relocated_kexec_smp_wait(NULL);
+		unreachable();
+	}
+#endif
+
+	do_kexec = (void *)reboot_code_buffer;
+	do_kexec(efi_boot, fdt_addr, jump_addr, first_ind_entry);
+
+	unreachable();
+}
+
+
+#ifdef CONFIG_SMP
+static void kexec_shutdown_secondary(void *)
+{
+	int cpu = smp_processor_id();
+
+	if (!cpu_online(cpu))
+		return;
+
+	/* We won't be sent IPIs any more. */
+	set_cpu_online(cpu, false);
+
+	local_irq_disable();
+	while (!atomic_read(&kexec_ready_to_reboot))
+		cpu_relax();
+
+	kexec_reboot();
+}
+#endif
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+}
+
+void machine_shutdown(void)
+{
+	int cpu;
+
+	/* All CPUs go to reboot_code_buffer */
+	for_each_possible_cpu(cpu)
+		if (!cpu_online(cpu))
+			cpu_device_up(get_cpu_device(cpu));
+
+#ifdef CONFIG_SMP
+	smp_call_function(kexec_shutdown_secondary, NULL, 0);
+#endif
+}
+
+void machine_kexec(struct kimage *image)
+{
+	unsigned long entry;
+	unsigned long *ptr;
+	struct kimage_arch *internal = &image->arch;
+
+	efi_boot = internal->efi_boot;
+	fdt_addr = internal->fdt_addr;
+
+	jump_addr = (unsigned long)phys_to_virt(image->start);
+
+	first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
+
+	/*
+	 * The generic kexec code builds a page list with physical
+	 * addresses. they are directly accessible through XKPRANGE
+	 * hence the phys_to_virt() call.
+	 */
+	for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE);
+	     ptr = (entry & IND_INDIRECTION) ?
+	       phys_to_virt(entry & PAGE_MASK) : ptr + 1) {
+		if (*ptr & IND_SOURCE || *ptr & IND_INDIRECTION ||
+		    *ptr & IND_DESTINATION)
+			*ptr = (unsigned long) phys_to_virt(*ptr);
+	}
+
+	/* Mark offline before disabling local irq. */
+	set_cpu_online(smp_processor_id(), false);
+
+	/* we do not want to be bothered. */
+	local_irq_disable();
+
+	pr_notice("Will call new kernel at %lx\n", jump_addr);
+	pr_notice("FDT image at %lx\n", fdt_addr);
+	pr_notice("Bye ...\n");
+
+	/* Make reboot code buffer available to the boot CPU. */
+	flush_cache_all();
+
+#ifdef CONFIG_SMP
+	atomic_set(&kexec_ready_to_reboot, 1);
+#endif
+
+	kexec_reboot();
+}
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
new file mode 100644
index 000000000000..0ea8b29242e6
--- /dev/null
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * relocate_kernel.S for kexec
+ *
+ * Copyright (C) 2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/kexec.h>
+
+#include <asm/asm.h>
+#include <asm/asmmacro.h>
+#include <asm/regdef.h>
+#include <asm/loongarch.h>
+#include <asm/stackframe.h>
+#include <asm/addrspace.h>
+
+SYM_CODE_START(relocate_new_kernel)
+	/*
+	 * a0: Boot flag passed to the new kernel
+	 * a1: Virt address of the FDT image
+	 * a2: Virt address to jump to after relocation
+	 * a3: Pointer to the current indirection page entry
+	 */
+
+	move		s0, a3
+
+process_entry:
+	PTR_L		s1, s0, 0
+	PTR_ADDI	s0, s0, SZREG
+
+	/* destination page */
+	andi		s2, s1, IND_DESTINATION
+	beqz		s2, 1f
+	li.w		t0, ~0x1
+	and		s3, s1, t0	/* store destination addr in s3 */
+	b		process_entry
+
+1:
+	/* indirection page, update s0	*/
+	andi		s2, s1, IND_INDIRECTION
+	beqz		s2, 1f
+	li.w		t0, ~0x2
+	and		s0, s1, t0
+	b		process_entry
+
+1:
+	/* done page */
+	andi		s2, s1, IND_DONE
+	beqz		s2, 1f
+	b		done
+1:
+	/* source page */
+	andi		s2, s1, IND_SOURCE
+	beqz		s2, process_entry
+	li.w		t0, ~0x8
+	and		s1, s1, t0
+	li.w		s5, (1 << _PAGE_SHIFT) / SZREG
+
+copy_word:
+	/* copy page word by word */
+	REG_L		s4, s1, 0
+	REG_S		s4, s3, 0
+	PTR_ADDI	s3, s3, SZREG
+	PTR_ADDI	s1, s1, SZREG
+	LONG_ADDI	s5, s5, -1
+	beqz		s5, process_entry
+	b		copy_word
+	b		process_entry
+
+done:
+	ibar		0
+	dbar		0
+
+	/*
+	 * Jump to the new kernel,
+	 * make sure the values of a0, a1 and a2 are not changed.
+	 */
+	jr		a2
+SYM_CODE_END(relocate_new_kernel)
+
+#ifdef CONFIG_SMP
+/*
+ * Other CPUs should wait until code is relocated and
+ * then start at entry (?) point.
+ */
+SYM_CODE_START(kexec_smp_wait)
+1:	li.w		t0, 0x100			/* wait for init loop */
+2:	addi.w		t0, t0, -1			/* limit mailbox access */
+	bnez		t0, 2b
+	li.w		t1, LOONGARCH_IOCSR_MBUF0
+	iocsrrd.w	s0, t1				/* check PC as an indicator */
+	beqz		s0, 1b
+	iocsrrd.d	s0, t1				/* get PC via mailbox */
+
+	li.d		t0, CACHE_BASE
+	or		s0, s0, t0			/* s0 = TO_CACHE(s0) */
+	jr		s0				/* jump to initial PC */
+SYM_CODE_END(kexec_smp_wait)
+#endif
+
+relocate_new_kernel_end:
+
+SYM_DATA_START(relocate_new_kernel_size)
+	PTR		relocate_new_kernel_end - relocate_new_kernel
+SYM_DATA_END(relocate_new_kernel_size)
-- 
2.36.0

[PATCH v3 2/3] LoongArch: Add kdump support

[Youling Tang]

This patch adds support for kdump, the kernel will reserve a region
for the crash kernel and jump there on panic.

Arch-specific functions are added to allow for implementing a crash
dump file interface, /proc/vmcore, which can be viewed as a ELF file.

A user space tool, like kexec-tools, is responsible for allocating a
separate region for the core's ELF header within crash kdump kernel
memory and filling it in when executing kexec_load().

Then, its location will be advertised to crash dump kernel via a new
device-tree property, "linux,elfcorehdr", and crash dump kernel preserves
the region for later use with fdt_reserve_elfcorehdr() at boot time.

At the same time, it will also limit the crash kdump kernel to the
crashkernel area via a new device-tree property, "linux, usable-memory-range",
so as not to destroy the original kernel dump data.

On crash dump kernel, /proc/vmcore will access the primary kernel's memory
with copy_oldmem_page().

I tested this on  LoongArch 3A5000 machine and works as expected (Suggest
crashkernel parameter is "crashkernel=512M@2560M"), you may test it by
triggering a crash through /proc/sysrq_trigger:

 $ sudo kexec -p /boot/vmlinux-kdump --reuse-cmdline --append="nr_cpus=1"
 # echo c > /proc/sysrq_trigger

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 arch/loongarch/Kconfig                  | 22 ++++++
 arch/loongarch/Makefile                 |  4 +
 arch/loongarch/kernel/Makefile          |  1 +
 arch/loongarch/kernel/crash_dump.c      | 19 +++++
 arch/loongarch/kernel/machine_kexec.c   | 98 +++++++++++++++++++++++--
 arch/loongarch/kernel/mem.c             |  6 ++
 arch/loongarch/kernel/relocate_kernel.S |  6 ++
 arch/loongarch/kernel/setup.c           | 49 +++++++++++++
 arch/loongarch/kernel/traps.c           |  4 +
 9 files changed, 203 insertions(+), 6 deletions(-)
 create mode 100644 arch/loongarch/kernel/crash_dump.c

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 08e063aaf847..4eeeebf888c1 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -433,6 +433,28 @@ config KEXEC
 
 	  The name comes from the similarity to the exec system call.
 
+config CRASH_DUMP
+	bool "Build kdump crash kernel"
+	help
+	  Generate crash dump after being started by kexec. This should
+	  be normally only set in special crash dump kernels which are
+	  loaded in the main kernel with kexec-tools into a specially
+	  reserved region and then later executed after a crash by
+	  kdump/kexec.
+
+	  For more details see Documentation/admin-guide/kdump/kdump.rst
+
+config PHYSICAL_START
+	hex "Physical address where the kernel is loaded"
+	default "0x90000000a0000000" if 64BIT
+	depends on CRASH_DUMP
+	help
+	  This gives the XKPRANGE address where the kernel is loaded.
+	  If you plan to use kernel for capturing the crash dump change
+	  this value to start of the reserved region (the "X" value as
+	  specified in the "crashkernel=YM@XM" command line boot parameter
+	  passed to the panic-ed kernel).
+
 config SECCOMP
 	bool "Enable seccomp to safely compute untrusted bytecode"
 	depends on PROC_FS
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index 69b39ba3a09d..224274c1644e 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -66,7 +66,11 @@ endif
 cflags-y += -ffreestanding
 cflags-y += $(call cc-option, -mno-check-zero-division)
 
+ifdef CONFIG_PHYSICAL_START
+load-y		= $(CONFIG_PHYSICAL_START)
+else
 load-y		= 0x9000000000200000
+endif
 bootvars-y	= VMLINUX_LOAD_ADDRESS=$(load-y)
 
 drivers-$(CONFIG_PCI)		+= arch/loongarch/pci/
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 17dc8ce6b5ce..79eee7db1414 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_MODULES)		+= module.o module-sections.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 
 obj-$(CONFIG_KEXEC)             += machine_kexec.o relocate_kernel.o
+obj-$(CONFIG_CRASH_DUMP)        += crash_dump.o
 
 obj-$(CONFIG_PROC_FS)		+= proc.o
 
diff --git a/arch/loongarch/kernel/crash_dump.c b/arch/loongarch/kernel/crash_dump.c
new file mode 100644
index 000000000000..13e5d2f7870d
--- /dev/null
+++ b/arch/loongarch/kernel/crash_dump.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/highmem.h>
+#include <linux/crash_dump.h>
+#include <linux/io.h>
+
+ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
+			 size_t csize, unsigned long offset)
+{
+	void  *vaddr;
+
+	if (!csize)
+		return 0;
+
+	vaddr = kmap_local_pfn(pfn);
+	csize = copy_to_iter(vaddr + offset, csize, iter);
+	kunmap_local(vaddr);
+
+	return csize;
+}
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
index a2f3c3e65130..c042d5e3bcfd 100644
--- a/arch/loongarch/kernel/machine_kexec.c
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -6,11 +6,16 @@
  */
 #include <linux/compiler.h>
 #include <linux/cpu.h>
-#include <linux/kexec.h>
-#include <linux/mm.h>
+#include <linux/crash_dump.h>
 #include <linux/delay.h>
+#include <linux/irq.h>
+#include <linux/kexec.h>
 #include <linux/libfdt.h>
+#include <linux/mm.h>
 #include <linux/of_fdt.h>
+#include <linux/reboot.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 
 #include <asm/bootinfo.h>
 #include <asm/cacheflush.h>
@@ -21,6 +26,7 @@
 #define KEXEC_BLOB_ADDR	TO_CACHE(0x108000UL)
 
 static unsigned long reboot_code_buffer;
+static cpumask_t cpus_in_crash = CPU_MASK_NONE;
 
 #ifdef CONFIG_SMP
 static void (*relocated_kexec_smp_wait)(void *);
@@ -70,7 +76,7 @@ int machine_kexec_prepare(struct kimage *kimage)
 		continue;
 	}
 
-	/* kexec need a safe page to save reboot_code_buffer */
+	/* kexec/kdump need a safe page to save reboot_code_buffer */
 	kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
 
 	reboot_code_buffer =
@@ -97,7 +103,8 @@ void kexec_reboot(void)
 
 	/*
 	 * We know we were online, and there will be no incoming IPIs at
-	 * this point.
+	 * this point. Mark online again before rebooting so that the crash
+	 * analysis tool will see us correctly.
 	 */
 	set_cpu_online(smp_processor_id(), true);
 
@@ -142,10 +149,88 @@ static void kexec_shutdown_secondary(void *)
 
 	kexec_reboot();
 }
-#endif
+
+static void crash_shutdown_secondary(void *passed_regs)
+{
+	struct pt_regs *regs = passed_regs;
+	int cpu = smp_processor_id();
+
+	/*
+	 * If we are passed registers, use those.  Otherwise get the
+	 * regs from the last interrupt, which should be correct, as
+	 * we are in an interrupt.  But if the regs are not there,
+	 * pull them from the top of the stack.  They are probably
+	 * wrong, but we need something to keep from crashing again.
+	 */
+	if (!regs)
+		regs = get_irq_regs();
+	if (!regs)
+		regs = task_pt_regs(current);
+
+	/* We won't be sent IPIs any more. */
+	set_cpu_online(cpu, false);
+
+	local_irq_disable();
+	if (!cpumask_test_cpu(cpu, &cpus_in_crash))
+		crash_save_cpu(regs, cpu);
+	cpumask_set_cpu(cpu, &cpus_in_crash);
+
+	while (!atomic_read(&kexec_ready_to_reboot))
+		cpu_relax();
+
+	kexec_reboot();
+}
+
+void crash_smp_send_stop(void)
+{
+	static int cpus_stopped;
+	unsigned long timeout;
+	unsigned int ncpus;
+
+	/*
+	 * This function can be called twice in panic path, but obviously
+	 * we execute this only once.
+	 */
+	if (cpus_stopped)
+		return;
+
+	cpus_stopped = 1;
+
+	 /* Excluding the panic cpu */
+	ncpus = num_online_cpus() - 1;
+
+	smp_call_function(crash_shutdown_secondary, NULL, 0);
+	smp_wmb();
+
+	/*
+	 * The crash CPU sends an IPI and wait for other CPUs to
+	 * respond. Delay of at least 10 seconds.
+	 */
+	pr_emerg("Sending IPI to other cpus...\n");
+	timeout = USEC_PER_SEC * 10;
+	while ((cpumask_weight(&cpus_in_crash) < ncpus) && timeout--) {
+		cpu_relax();
+		udelay(1);
+	}
+}
+#endif /* defined(CONFIG_SMP) */
 
 void machine_crash_shutdown(struct pt_regs *regs)
 {
+	int crashing_cpu;
+
+	local_irq_disable();
+
+	crashing_cpu = smp_processor_id();
+	crash_save_cpu(regs, crashing_cpu);
+
+#ifdef CONFIG_SMP
+	/* shutdown non-crashing cpus */
+	crash_smp_send_stop();
+#endif
+	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
+
+	pr_info("Starting crashdump kernel...\n");
 }
 
 void machine_shutdown(void)
@@ -173,7 +258,8 @@ void machine_kexec(struct kimage *image)
 
 	jump_addr = (unsigned long)phys_to_virt(image->start);
 
-	first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
+	if (image->type == KEXEC_TYPE_DEFAULT)
+		first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
 
 	/*
 	 * The generic kexec code builds a page list with physical
diff --git a/arch/loongarch/kernel/mem.c b/arch/loongarch/kernel/mem.c
index 7423361b0ebc..c6def6ff81c8 100644
--- a/arch/loongarch/kernel/mem.c
+++ b/arch/loongarch/kernel/mem.c
@@ -5,6 +5,7 @@
 #include <linux/efi.h>
 #include <linux/initrd.h>
 #include <linux/memblock.h>
+#include <linux/of_fdt.h>
 
 #include <asm/bootinfo.h>
 #include <asm/loongson.h>
@@ -61,4 +62,9 @@ void __init memblock_init(void)
 
 	/* Reserve the initrd */
 	reserve_initrd_mem();
+
+	/* Mainly reserved memory for the elf core head */
+	early_init_fdt_scan_reserved_mem();
+	/* Parse linux,usable-memory-range is for crash dump kernel */
+	early_init_dt_check_for_usable_mem_range();
 }
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
index 0ea8b29242e6..a4176f2ae402 100644
--- a/arch/loongarch/kernel/relocate_kernel.S
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -24,6 +24,12 @@ SYM_CODE_START(relocate_new_kernel)
 
 	move		s0, a3
 
+	/*
+	 * In case of a kdump/crash kernel, the indirection page is not
+	 * populated as the kernel is directly copied to a reserved location
+	 */
+	beqz		s0, done
+
 process_entry:
 	PTR_L		s1, s0, 0
 	PTR_ADDI	s0, s0, SZREG
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 058c232c11e8..6974b88446a8 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -19,6 +19,8 @@
 #include <linux/memblock.h>
 #include <linux/initrd.h>
 #include <linux/ioport.h>
+#include <linux/kexec.h>
+#include <linux/crash_dump.h>
 #include <linux/root_dev.h>
 #include <linux/console.h>
 #include <linux/pfn.h>
@@ -185,6 +187,50 @@ static int __init early_parse_mem(char *p)
 }
 early_param("mem", early_parse_mem);
 
+static void __init loongarch_parse_crashkernel(void)
+{
+#ifdef CONFIG_KEXEC
+	unsigned long long start;
+	unsigned long long total_mem;
+	unsigned long long crash_size, crash_base;
+	int ret;
+
+	total_mem = memblock_phys_mem_size();
+	ret = parse_crashkernel(boot_command_line, total_mem,
+				&crash_size, &crash_base);
+	if (ret != 0 || crash_size <= 0)
+		return;
+
+
+	start = memblock_phys_alloc_range(crash_size, 1, crash_base,
+					crash_base + crash_size);
+	if (start != crash_base) {
+		pr_warn("Invalid memory region reserved for crash kernel\n");
+		return;
+	}
+
+	crashk_res.start = crash_base;
+	crashk_res.end	 = crash_base + crash_size - 1;
+#endif
+}
+
+static void __init request_crashkernel(struct resource *res)
+{
+#ifdef CONFIG_KEXEC
+	int ret;
+
+	if (crashk_res.start == crashk_res.end)
+		return;
+
+	ret = request_resource(res, &crashk_res);
+	if (!ret)
+		pr_info("Reserving %ldMB of memory at %ldMB for crashkernel\n",
+			(unsigned long)((crashk_res.end -
+					 crashk_res.start + 1) >> 20),
+			(unsigned long)(crashk_res.start  >> 20));
+#endif
+}
+
 void __init platform_init(void)
 {
 	efi_init();
@@ -228,6 +274,8 @@ static void __init arch_mem_init(char **cmdline_p)
 
 	check_kernel_sections_mem();
 
+	loongarch_parse_crashkernel();
+
 	/*
 	 * In order to reduce the possibility of kernel panic when failed to
 	 * get IO TLB memory under CONFIG_SWIOTLB, it is better to allocate
@@ -289,6 +337,7 @@ static void __init resource_init(void)
 		request_resource(res, &code_resource);
 		request_resource(res, &data_resource);
 		request_resource(res, &bss_resource);
+		request_crashkernel(res);
 	}
 }
 
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index aa1c95aaf595..0e610872f3f4 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -10,6 +10,7 @@
 #include <linux/entry-common.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/kexec.h>
 #include <linux/module.h>
 #include <linux/extable.h>
 #include <linux/mm.h>
@@ -246,6 +247,9 @@ void __noreturn die(const char *str, struct pt_regs *regs)
 
 	oops_exit();
 
+	if (regs && kexec_should_crash(current))
+		crash_kexec(regs);
+
 	if (in_interrupt())
 		panic("Fatal exception in interrupt");
 
-- 
2.36.0


_______________________________________________
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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v3 2/3] LoongArch: Add kdump support

[Youling Tang]

This patch adds support for kdump, the kernel will reserve a region
for the crash kernel and jump there on panic.

Arch-specific functions are added to allow for implementing a crash
dump file interface, /proc/vmcore, which can be viewed as a ELF file.

A user space tool, like kexec-tools, is responsible for allocating a
separate region for the core's ELF header within crash kdump kernel
memory and filling it in when executing kexec_load().

Then, its location will be advertised to crash dump kernel via a new
device-tree property, "linux,elfcorehdr", and crash dump kernel preserves
the region for later use with fdt_reserve_elfcorehdr() at boot time.

At the same time, it will also limit the crash kdump kernel to the
crashkernel area via a new device-tree property, "linux, usable-memory-range",
so as not to destroy the original kernel dump data.

On crash dump kernel, /proc/vmcore will access the primary kernel's memory
with copy_oldmem_page().

I tested this on  LoongArch 3A5000 machine and works as expected (Suggest
crashkernel parameter is "crashkernel=512M@2560M"), you may test it by
triggering a crash through /proc/sysrq_trigger:

 $ sudo kexec -p /boot/vmlinux-kdump --reuse-cmdline --append="nr_cpus=1"
 # echo c > /proc/sysrq_trigger

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 arch/loongarch/Kconfig                  | 22 ++++++
 arch/loongarch/Makefile                 |  4 +
 arch/loongarch/kernel/Makefile          |  1 +
 arch/loongarch/kernel/crash_dump.c      | 19 +++++
 arch/loongarch/kernel/machine_kexec.c   | 98 +++++++++++++++++++++++--
 arch/loongarch/kernel/mem.c             |  6 ++
 arch/loongarch/kernel/relocate_kernel.S |  6 ++
 arch/loongarch/kernel/setup.c           | 49 +++++++++++++
 arch/loongarch/kernel/traps.c           |  4 +
 9 files changed, 203 insertions(+), 6 deletions(-)
 create mode 100644 arch/loongarch/kernel/crash_dump.c

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 08e063aaf847..4eeeebf888c1 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -433,6 +433,28 @@ config KEXEC
 
 	  The name comes from the similarity to the exec system call.
 
+config CRASH_DUMP
+	bool "Build kdump crash kernel"
+	help
+	  Generate crash dump after being started by kexec. This should
+	  be normally only set in special crash dump kernels which are
+	  loaded in the main kernel with kexec-tools into a specially
+	  reserved region and then later executed after a crash by
+	  kdump/kexec.
+
+	  For more details see Documentation/admin-guide/kdump/kdump.rst
+
+config PHYSICAL_START
+	hex "Physical address where the kernel is loaded"
+	default "0x90000000a0000000" if 64BIT
+	depends on CRASH_DUMP
+	help
+	  This gives the XKPRANGE address where the kernel is loaded.
+	  If you plan to use kernel for capturing the crash dump change
+	  this value to start of the reserved region (the "X" value as
+	  specified in the "crashkernel=YM@XM" command line boot parameter
+	  passed to the panic-ed kernel).
+
 config SECCOMP
 	bool "Enable seccomp to safely compute untrusted bytecode"
 	depends on PROC_FS
diff --git a/arch/loongarch/Makefile b/arch/loongarch/Makefile
index 69b39ba3a09d..224274c1644e 100644
--- a/arch/loongarch/Makefile
+++ b/arch/loongarch/Makefile
@@ -66,7 +66,11 @@ endif
 cflags-y += -ffreestanding
 cflags-y += $(call cc-option, -mno-check-zero-division)
 
+ifdef CONFIG_PHYSICAL_START
+load-y		= $(CONFIG_PHYSICAL_START)
+else
 load-y		= 0x9000000000200000
+endif
 bootvars-y	= VMLINUX_LOAD_ADDRESS=$(load-y)
 
 drivers-$(CONFIG_PCI)		+= arch/loongarch/pci/
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 17dc8ce6b5ce..79eee7db1414 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_MODULES)		+= module.o module-sections.o
 obj-$(CONFIG_STACKTRACE)	+= stacktrace.o
 
 obj-$(CONFIG_KEXEC)             += machine_kexec.o relocate_kernel.o
+obj-$(CONFIG_CRASH_DUMP)        += crash_dump.o
 
 obj-$(CONFIG_PROC_FS)		+= proc.o
 
diff --git a/arch/loongarch/kernel/crash_dump.c b/arch/loongarch/kernel/crash_dump.c
new file mode 100644
index 000000000000..13e5d2f7870d
--- /dev/null
+++ b/arch/loongarch/kernel/crash_dump.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/highmem.h>
+#include <linux/crash_dump.h>
+#include <linux/io.h>
+
+ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
+			 size_t csize, unsigned long offset)
+{
+	void  *vaddr;
+
+	if (!csize)
+		return 0;
+
+	vaddr = kmap_local_pfn(pfn);
+	csize = copy_to_iter(vaddr + offset, csize, iter);
+	kunmap_local(vaddr);
+
+	return csize;
+}
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
index a2f3c3e65130..c042d5e3bcfd 100644
--- a/arch/loongarch/kernel/machine_kexec.c
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -6,11 +6,16 @@
  */
 #include <linux/compiler.h>
 #include <linux/cpu.h>
-#include <linux/kexec.h>
-#include <linux/mm.h>
+#include <linux/crash_dump.h>
 #include <linux/delay.h>
+#include <linux/irq.h>
+#include <linux/kexec.h>
 #include <linux/libfdt.h>
+#include <linux/mm.h>
 #include <linux/of_fdt.h>
+#include <linux/reboot.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
 
 #include <asm/bootinfo.h>
 #include <asm/cacheflush.h>
@@ -21,6 +26,7 @@
 #define KEXEC_BLOB_ADDR	TO_CACHE(0x108000UL)
 
 static unsigned long reboot_code_buffer;
+static cpumask_t cpus_in_crash = CPU_MASK_NONE;
 
 #ifdef CONFIG_SMP
 static void (*relocated_kexec_smp_wait)(void *);
@@ -70,7 +76,7 @@ int machine_kexec_prepare(struct kimage *kimage)
 		continue;
 	}
 
-	/* kexec need a safe page to save reboot_code_buffer */
+	/* kexec/kdump need a safe page to save reboot_code_buffer */
 	kimage->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
 
 	reboot_code_buffer =
@@ -97,7 +103,8 @@ void kexec_reboot(void)
 
 	/*
 	 * We know we were online, and there will be no incoming IPIs at
-	 * this point.
+	 * this point. Mark online again before rebooting so that the crash
+	 * analysis tool will see us correctly.
 	 */
 	set_cpu_online(smp_processor_id(), true);
 
@@ -142,10 +149,88 @@ static void kexec_shutdown_secondary(void *)
 
 	kexec_reboot();
 }
-#endif
+
+static void crash_shutdown_secondary(void *passed_regs)
+{
+	struct pt_regs *regs = passed_regs;
+	int cpu = smp_processor_id();
+
+	/*
+	 * If we are passed registers, use those.  Otherwise get the
+	 * regs from the last interrupt, which should be correct, as
+	 * we are in an interrupt.  But if the regs are not there,
+	 * pull them from the top of the stack.  They are probably
+	 * wrong, but we need something to keep from crashing again.
+	 */
+	if (!regs)
+		regs = get_irq_regs();
+	if (!regs)
+		regs = task_pt_regs(current);
+
+	/* We won't be sent IPIs any more. */
+	set_cpu_online(cpu, false);
+
+	local_irq_disable();
+	if (!cpumask_test_cpu(cpu, &cpus_in_crash))
+		crash_save_cpu(regs, cpu);
+	cpumask_set_cpu(cpu, &cpus_in_crash);
+
+	while (!atomic_read(&kexec_ready_to_reboot))
+		cpu_relax();
+
+	kexec_reboot();
+}
+
+void crash_smp_send_stop(void)
+{
+	static int cpus_stopped;
+	unsigned long timeout;
+	unsigned int ncpus;
+
+	/*
+	 * This function can be called twice in panic path, but obviously
+	 * we execute this only once.
+	 */
+	if (cpus_stopped)
+		return;
+
+	cpus_stopped = 1;
+
+	 /* Excluding the panic cpu */
+	ncpus = num_online_cpus() - 1;
+
+	smp_call_function(crash_shutdown_secondary, NULL, 0);
+	smp_wmb();
+
+	/*
+	 * The crash CPU sends an IPI and wait for other CPUs to
+	 * respond. Delay of at least 10 seconds.
+	 */
+	pr_emerg("Sending IPI to other cpus...\n");
+	timeout = USEC_PER_SEC * 10;
+	while ((cpumask_weight(&cpus_in_crash) < ncpus) && timeout--) {
+		cpu_relax();
+		udelay(1);
+	}
+}
+#endif /* defined(CONFIG_SMP) */
 
 void machine_crash_shutdown(struct pt_regs *regs)
 {
+	int crashing_cpu;
+
+	local_irq_disable();
+
+	crashing_cpu = smp_processor_id();
+	crash_save_cpu(regs, crashing_cpu);
+
+#ifdef CONFIG_SMP
+	/* shutdown non-crashing cpus */
+	crash_smp_send_stop();
+#endif
+	cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
+
+	pr_info("Starting crashdump kernel...\n");
 }
 
 void machine_shutdown(void)
@@ -173,7 +258,8 @@ void machine_kexec(struct kimage *image)
 
 	jump_addr = (unsigned long)phys_to_virt(image->start);
 
-	first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
+	if (image->type == KEXEC_TYPE_DEFAULT)
+		first_ind_entry = (unsigned long)phys_to_virt(image->head & PAGE_MASK);
 
 	/*
 	 * The generic kexec code builds a page list with physical
diff --git a/arch/loongarch/kernel/mem.c b/arch/loongarch/kernel/mem.c
index 7423361b0ebc..c6def6ff81c8 100644
--- a/arch/loongarch/kernel/mem.c
+++ b/arch/loongarch/kernel/mem.c
@@ -5,6 +5,7 @@
 #include <linux/efi.h>
 #include <linux/initrd.h>
 #include <linux/memblock.h>
+#include <linux/of_fdt.h>
 
 #include <asm/bootinfo.h>
 #include <asm/loongson.h>
@@ -61,4 +62,9 @@ void __init memblock_init(void)
 
 	/* Reserve the initrd */
 	reserve_initrd_mem();
+
+	/* Mainly reserved memory for the elf core head */
+	early_init_fdt_scan_reserved_mem();
+	/* Parse linux,usable-memory-range is for crash dump kernel */
+	early_init_dt_check_for_usable_mem_range();
 }
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
index 0ea8b29242e6..a4176f2ae402 100644
--- a/arch/loongarch/kernel/relocate_kernel.S
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -24,6 +24,12 @@ SYM_CODE_START(relocate_new_kernel)
 
 	move		s0, a3
 
+	/*
+	 * In case of a kdump/crash kernel, the indirection page is not
+	 * populated as the kernel is directly copied to a reserved location
+	 */
+	beqz		s0, done
+
 process_entry:
 	PTR_L		s1, s0, 0
 	PTR_ADDI	s0, s0, SZREG
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 058c232c11e8..6974b88446a8 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -19,6 +19,8 @@
 #include <linux/memblock.h>
 #include <linux/initrd.h>
 #include <linux/ioport.h>
+#include <linux/kexec.h>
+#include <linux/crash_dump.h>
 #include <linux/root_dev.h>
 #include <linux/console.h>
 #include <linux/pfn.h>
@@ -185,6 +187,50 @@ static int __init early_parse_mem(char *p)
 }
 early_param("mem", early_parse_mem);
 
+static void __init loongarch_parse_crashkernel(void)
+{
+#ifdef CONFIG_KEXEC
+	unsigned long long start;
+	unsigned long long total_mem;
+	unsigned long long crash_size, crash_base;
+	int ret;
+
+	total_mem = memblock_phys_mem_size();
+	ret = parse_crashkernel(boot_command_line, total_mem,
+				&crash_size, &crash_base);
+	if (ret != 0 || crash_size <= 0)
+		return;
+
+
+	start = memblock_phys_alloc_range(crash_size, 1, crash_base,
+					crash_base + crash_size);
+	if (start != crash_base) {
+		pr_warn("Invalid memory region reserved for crash kernel\n");
+		return;
+	}
+
+	crashk_res.start = crash_base;
+	crashk_res.end	 = crash_base + crash_size - 1;
+#endif
+}
+
+static void __init request_crashkernel(struct resource *res)
+{
+#ifdef CONFIG_KEXEC
+	int ret;
+
+	if (crashk_res.start == crashk_res.end)
+		return;
+
+	ret = request_resource(res, &crashk_res);
+	if (!ret)
+		pr_info("Reserving %ldMB of memory at %ldMB for crashkernel\n",
+			(unsigned long)((crashk_res.end -
+					 crashk_res.start + 1) >> 20),
+			(unsigned long)(crashk_res.start  >> 20));
+#endif
+}
+
 void __init platform_init(void)
 {
 	efi_init();
@@ -228,6 +274,8 @@ static void __init arch_mem_init(char **cmdline_p)
 
 	check_kernel_sections_mem();
 
+	loongarch_parse_crashkernel();
+
 	/*
 	 * In order to reduce the possibility of kernel panic when failed to
 	 * get IO TLB memory under CONFIG_SWIOTLB, it is better to allocate
@@ -289,6 +337,7 @@ static void __init resource_init(void)
 		request_resource(res, &code_resource);
 		request_resource(res, &data_resource);
 		request_resource(res, &bss_resource);
+		request_crashkernel(res);
 	}
 }
 
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index aa1c95aaf595..0e610872f3f4 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -10,6 +10,7 @@
 #include <linux/entry-common.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/kexec.h>
 #include <linux/module.h>
 #include <linux/extable.h>
 #include <linux/mm.h>
@@ -246,6 +247,9 @@ void __noreturn die(const char *str, struct pt_regs *regs)
 
 	oops_exit();
 
+	if (regs && kexec_should_crash(current))
+		crash_kexec(regs);
+
 	if (in_interrupt())
 		panic("Fatal exception in interrupt");
 
-- 
2.36.0

[PATCH v3 3/3] LoongArch: Enable CONFIG_KEXEC

[Youling Tang]

Defaults enable CONFIG_KEXEC to convenient kexec operations.

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 arch/loongarch/configs/loongson3_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/configs/loongson3_defconfig
index 573f7a41f735..1ae85e797858 100644
--- a/arch/loongarch/configs/loongson3_defconfig
+++ b/arch/loongarch/configs/loongson3_defconfig
@@ -46,6 +46,7 @@ CONFIG_SMP=y
 CONFIG_HOTPLUG_CPU=y
 CONFIG_NR_CPUS=64
 CONFIG_NUMA=y
+CONFIG_KEXEC=y
 CONFIG_PAGE_SIZE_16KB=y
 CONFIG_HZ_250=y
 CONFIG_ACPI=y
-- 
2.36.0


_______________________________________________
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kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v3 3/3] LoongArch: Enable CONFIG_KEXEC

[Youling Tang]

Defaults enable CONFIG_KEXEC to convenient kexec operations.

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 arch/loongarch/configs/loongson3_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/loongarch/configs/loongson3_defconfig b/arch/loongarch/configs/loongson3_defconfig
index 573f7a41f735..1ae85e797858 100644
--- a/arch/loongarch/configs/loongson3_defconfig
+++ b/arch/loongarch/configs/loongson3_defconfig
@@ -46,6 +46,7 @@ CONFIG_SMP=y
 CONFIG_HOTPLUG_CPU=y
 CONFIG_NR_CPUS=64
 CONFIG_NUMA=y
+CONFIG_KEXEC=y
 CONFIG_PAGE_SIZE_16KB=y
 CONFIG_HZ_250=y
 CONFIG_ACPI=y
-- 
2.36.0

Re: [PATCH v3 1/3] LoongArch: Add kexec support

[Xi Ruoyao]

On Thu, 2022-09-15 at 10:53 +0800, Youling Tang wrote:
> +int machine_kexec_prepare(struct kimage *kimage)
> +{
> +       int i;
> +       void *dtb = (void *)KEXEC_BLOB_ADDR;
> +
> +       kexec_image_info(kimage);
> +
> +       /* Find the Flattened Device Tree */
> +       for (i = 0; i < kimage->nr_segments; i++) {
> +               if (!fdt_check_header(kimage->segment[i].buf)) {

Hi Youling,

When I build Huacai's tree
(https://github.com/loongson/linux/commits/loongarch-next), there is a
strange error linking vmlinux:

ld: arch/loongarch/kernel/machine_kexec.o: in function `machine_kexec_prepare':
/home/xry111/git-repos/linux/arch/loongarch/kernel/machine_kexec.c:70: undefined reference to `fdt_check_header'

Not sure why...

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

Re: [PATCH v3 1/3] LoongArch: Add kexec support

[Xi Ruoyao]

On Thu, 2022-09-15 at 10:53 +0800, Youling Tang wrote:
> +int machine_kexec_prepare(struct kimage *kimage)
> +{
> +       int i;
> +       void *dtb = (void *)KEXEC_BLOB_ADDR;
> +
> +       kexec_image_info(kimage);
> +
> +       /* Find the Flattened Device Tree */
> +       for (i = 0; i < kimage->nr_segments; i++) {
> +               if (!fdt_check_header(kimage->segment[i].buf)) {

Hi Youling,

When I build Huacai's tree
(https://github.com/loongson/linux/commits/loongarch-next), there is a
strange error linking vmlinux:

ld: arch/loongarch/kernel/machine_kexec.o: in function `machine_kexec_prepare':
/home/xry111/git-repos/linux/arch/loongarch/kernel/machine_kexec.c:70: undefined reference to `fdt_check_header'

Not sure why...

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

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Re: [PATCH v3 1/3] LoongArch: Add kexec support

[Youling Tang]

Hi, Ruoyao

On 09/22/2022 06:00 PM, Xi Ruoyao wrote:
> On Thu, 2022-09-15 at 10:53 +0800, Youling Tang wrote:
>> +int machine_kexec_prepare(struct kimage *kimage)
>> +{
>> +       int i;
>> +       void *dtb = (void *)KEXEC_BLOB_ADDR;
>> +
>> +       kexec_image_info(kimage);
>> +
>> +       /* Find the Flattened Device Tree */
>> +       for (i = 0; i < kimage->nr_segments; i++) {
>> +               if (!fdt_check_header(kimage->segment[i].buf)) {
>
> Hi Youling,
>
> When I build Huacai's tree
> (https://github.com/loongson/linux/commits/loongarch-next), there is a
> strange error linking vmlinux:
>
> ld: arch/loongarch/kernel/machine_kexec.o: in function `machine_kexec_prepare':
> /home/xry111/git-repos/linux/arch/loongarch/kernel/machine_kexec.c:70: undefined reference to `fdt_check_header'
>
> Not sure why...

This is because of the problem after efistub removes the fdt
modification, I will reimplement kexec/kdump. This build error can be
avoided by turning off CONFIG_KEXEC temporarily, tomorrow I will submit
a new kexec/kdump implementation.

Thanks,
Youling.
>

Re: [PATCH v3 1/3] LoongArch: Add kexec support

[Youling Tang]

Hi, Ruoyao

On 09/22/2022 06:00 PM, Xi Ruoyao wrote:
> On Thu, 2022-09-15 at 10:53 +0800, Youling Tang wrote:
>> +int machine_kexec_prepare(struct kimage *kimage)
>> +{
>> +       int i;
>> +       void *dtb = (void *)KEXEC_BLOB_ADDR;
>> +
>> +       kexec_image_info(kimage);
>> +
>> +       /* Find the Flattened Device Tree */
>> +       for (i = 0; i < kimage->nr_segments; i++) {
>> +               if (!fdt_check_header(kimage->segment[i].buf)) {
>
> Hi Youling,
>
> When I build Huacai's tree
> (https://github.com/loongson/linux/commits/loongarch-next), there is a
> strange error linking vmlinux:
>
> ld: arch/loongarch/kernel/machine_kexec.o: in function `machine_kexec_prepare':
> /home/xry111/git-repos/linux/arch/loongarch/kernel/machine_kexec.c:70: undefined reference to `fdt_check_header'
>
> Not sure why...

This is because of the problem after efistub removes the fdt
modification, I will reimplement kexec/kdump. This build error can be
avoided by turning off CONFIG_KEXEC temporarily, tomorrow I will submit
a new kexec/kdump implementation.

Thanks,
Youling.
>


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