Hi, Huacai
On 09/09/2022 04:16 PM, Huacai Chen wrote:
Hi, Youling,
On Fri, Sep 9, 2022 at 11:20 AM Youling Tang <tangyouling@xxxxxxxxxxx> wrote:
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@xxxxxxxxxxx>
---
arch/loongarch/Kconfig | 11 ++
arch/loongarch/include/asm/kexec.h | 58 ++++++++
arch/loongarch/kernel/Makefile | 2 +
arch/loongarch/kernel/head.S | 7 +-
arch/loongarch/kernel/machine_kexec.c | 188 ++++++++++++++++++++++++
arch/loongarch/kernel/relocate_kernel.S | 106 +++++++++++++
6 files changed, 371 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..f23506725e00
--- /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 boot_flag;
+ unsigned long fdt_addr;
+};
I prefer to change boot_flag to efi_boot, the latter is better to
correspond the current usage, and keeps consistency with efistub.
OK.
+
+typedef void (*do_kexec_t)(unsigned long boot_flag,
+ unsigned long fdt_addr,
+ unsigned long first_ind_entry,
+ unsigned long jump_addr);
I prefer change the order of jump_addr and first_ind_entry here.
OK.
+
+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..0f786d670e66 100644
--- a/arch/loongarch/kernel/head.S
+++ b/arch/loongarch/kernel/head.S
@@ -20,7 +20,12 @@
_head:
.word MZ_MAGIC /* "MZ", MS-DOS header */
- .org 0x3c /* 0x04 ~ 0x3b reserved */
+ .org 0x8
+ .quad 0 /* Image load offset from start of RAM */
+ .dword _end - _text /* Effective size of kernel image */
+ .quad 0
+ .dword kernel_entry /* Kernel entry point */
+ .org 0x3c /* 0x28 ~ 0x3b reserved */
.long pe_header - _head /* Offset to the PE header */
As discussed before, I prefer kernel entry point before kernel image size.
I will modify it in the next version, and will modify the kexec-tools
tool at the same time.
pe_header:
diff --git a/arch/loongarch/kernel/machine_kexec.c b/arch/loongarch/kernel/machine_kexec.c
new file mode 100644
index 000000000000..7b3fea506c6d
--- /dev/null
+++ b/arch/loongarch/kernel/machine_kexec.c
@@ -0,0 +1,188 @@
+// 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 jump_addr;
+static unsigned long first_ind_entry;
+static unsigned long boot_flag;
+static unsigned long fdt_addr;
Keep the same order as do_kexec() may be better.
OK.
+
+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.boot_flag = 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;
+
The old implementation has an "ibar" here, I suppose it is still needed?
The new implementation no longer has to turn off the non-boot cpus and
then turn it back on when doing multi-core kexec operations, so I don't
think there's any need to use ibar to make sure the remote CPUs are
online (as I didn't make it go offline).
+#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(boot_flag, fdt_addr, first_ind_entry, jump_addr);
+
+ unreachable();
+}
+
+
+#ifdef CONFIG_SMP
+static void kexec_shutdown_secondary(void *)
+{
+ local_irq_disable();
+ while (!atomic_read(&kexec_ready_to_reboot))
+ cpu_relax();
+
+ kexec_reboot();
The old implementation has an unreachable() after kexec_reboot(), but
I don't know whether it is really needed.
I have marked as unreachable() in kexec_reboot, IMO, the place where
kexec_reboot is called no longer needs to be marked as unreachable().
+}
+#endif
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+}
+
+void machine_shutdown(void)
+{
+#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;
+
+ boot_flag = internal->boot_flag;
+ 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
+
+ /*
+ * 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();
+
+ kexec_reboot();
+}
diff --git a/arch/loongarch/kernel/relocate_kernel.S b/arch/loongarch/kernel/relocate_kernel.S
new file mode 100644
index 000000000000..05a0c1ccfab6
--- /dev/null
+++ b/arch/loongarch/kernel/relocate_kernel.S
@@ -0,0 +1,106 @@
+/* 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)
+ /*
+ * s0: Boot flag passed to the new kernel
+ * s1: Virt address of the FDT image
+ * s2: Pointer to the current entry
"Pointer to the current entry" can be "Pointer to the current
indirection page entry"? And I think we needn't backup Ax to Sx except
this one in the assembly below.
Since there are no function calls in between, I can remove the backup
of the a-series registers.
Thanks,
Youling.
Huacai
+ * s3: Virt address to jump to after relocation
+ */
+ move s0, a0
+ move s1, a1
+ move s2, a2
+ move s3, a3
+
+process_entry:
+ PTR_L s4, s2, 0
+ PTR_ADDI s2, s2, SZREG
+
+ /* destination page */
+ andi s5, s4, IND_DESTINATION
+ beqz s5, 1f
+ li.w t0, ~0x1
+ and s6, s4, t0 /* store destination addr in s6 */
+ b process_entry
+
+1:
+ /* indirection page, update s2 */
+ andi s5, s4, IND_INDIRECTION
+ beqz s5, 1f
+ li.w t0, ~0x2
+ and s2, s4, t0
+ b process_entry
+
+1:
+ /* done page */
+ andi s5, s4, IND_DONE
+ beqz s5, 1f
+ b done
+1:
+ /* source page */
+ andi s5, s4, IND_SOURCE
+ beqz s5, process_entry
+ li.w t0, ~0x8
+ and s4, s4, t0
+ li.w s8, (1 << _PAGE_SHIFT) / SZREG
+
+copy_word:
+ /* copy page word by word */
+ REG_L s7, s4, 0
+ REG_S s7, s6, 0
+ PTR_ADDI s6, s6, SZREG
+ PTR_ADDI s4, s4, SZREG
+ LONG_ADDI s8, s8, -1
+ beqz s8, process_entry
+ b copy_word
+ b process_entry
+
+done:
+ ibar 0
+ dbar 0
+
+ move a0, s0
+ move a1, s1
+ /* jump to the new kernel */
+ jr s3
+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 s1, t1 /* check PC as an indicator */
+ beqz s1, 1b
+ iocsrrd.d s1, t1 /* get PC via mailbox */
+
+ li.d t0, CACHE_BASE
+ or s1, s1, t0 /* s1 = TO_CACHE(s1) */
+ jr s1 /* 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
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