[PATCH 3/3] MIPS: Loongson64: Add kexec/kdump support
Jinyang He
hejinyang at loongson.cn
Tue Sep 22 23:35:30 EDT 2020
Hi, Huacai,
On 09/23/2020 10:30 AM, Huacai Chen wrote:
> Add kexec/kdump support for Loongson64 by:
> 1, Provide Loongson-specific kexec functions: loongson_kexec_prepare,
> loongson_kexec_shutdown and loongson_crash_shutdown;
> 2, Provide Loongson-specific assembly code in kexec_smp_wait;
> 3, Clear mailbox in loongson3_smp_setup() since KEXEC bypass BIOS;
> 4, KEXEC always run at boot CPU, but KDUMP may triggered at non-boot
> CPU. Loongson64 assume boot CPU is the first possible cpu, so fix
> boot_cpu_id in prom_init_env();
>
> To start Loongson64, The boot CPU needs 3 parameters:
> fw_arg0: the number of arguments in cmdline (i.e., argc).
> fw_arg1: structure holds cmdline such as "root=/dev/sda1 console=tty"
> (i.e., argv).
> fw_arg2: environment (i.e., envp, additional boot parameters from LEFI).
>
> Non-boot CPUs do not need parameters at once. They query their own IPI
> mailbox to get PC, SP and GP in a loop until boot CPU brings them up.
>
> loongson_kexec_prepare(): Setup cmdline for kexec/kdump. The kexec/kdump
> cmdline comes from kexec's "append" option string. This structure will
> be parsed in fw_init_cmdline() of arch/mips/fw/lib/cmdline.c. Both image
> ->control_code_page and the cmdline need to be in a safe memory region
> (memory allocated by the old kernel may be corrupted by the new kernel).
> In order to maintain compatibility for the old firmware, the low 2MB is
> reserverd and safe for Loongson. So let KEXEC_CTRL_CODE and KEXEC_ARGV_
> ADDR be here. LEFI parameters may be corrupted at runtime, so backup it
> at mips_reboot_setup(), and then restore it at loongson_kexec_shutdown()
> /loongson_crash_shutdown().
>
> loongson_kexec_shutdown(): Wake up all present CPUs and let them go to
> reboot_code_buffer. Pass the kexec parameters to kexec_args.
>
> loongson_crash_shutdown(): Pass the kdump parameters to kexec_args.
>
> The assembly part in kexec_smp_wait provide a routine as BIOS does, in
> order to keep secondary CPUs in a querying loop.
>
> Cc: Eric Biederman <ebiederm at xmission.com>
> Signed-off-by: Huacai Chen <chenhc at lemote.com>
> Signed-off-by: Jinyang He <hejinyang at loongson.cn>
> Signed-off-by: Youling Tang <tangyouling at loongson.cn>
> ---
> arch/mips/kernel/relocate_kernel.S | 27 +++++++++
> arch/mips/loongson64/env.c | 7 +++
> arch/mips/loongson64/reset.c | 111 +++++++++++++++++++++++++++++++++++++
> arch/mips/loongson64/smp.c | 5 ++
> 4 files changed, 150 insertions(+)
>
> diff --git a/arch/mips/kernel/relocate_kernel.S b/arch/mips/kernel/relocate_kernel.S
> index ac87089..91b2932 100644
> --- a/arch/mips/kernel/relocate_kernel.S
> +++ b/arch/mips/kernel/relocate_kernel.S
> @@ -133,6 +133,33 @@ LEAF(kexec_smp_wait)
> #else
> sync
> #endif
> +
> +#ifdef CONFIG_CPU_LOONGSON64
> +#define MAILBOX_BASE 0x900000003ff01000
> + /* s0:prid s1:initfn */
> + /* t0:base t1:cpuid t2:node t9:count */
> + mfc0 t1, CP0_EBASE
> + andi t1, MIPS_EBASE_CPUNUM
> + dli t0, MAILBOX_BASE /* mailbox base */
> + dins t0, t1, 8, 2 /* insert core id*/
> + dext t2, t1, 2, 2
> + dins t0, t2, 44, 2 /* insert node id */
> + mfc0 s0, CP0_PRID
> + andi s0, s0, 0xf
> + blt s0, 0x6, 1f /* Loongson-3A1000 */
> + bgt s0, 0x7, 1f /* Loongson-3A2000/3A3000 */
> + dins t0, t2, 14, 2 /* Loongson-3B1000/3B1500 need bit 15~14 */
Here is right, and I have a trivial idea that machine type
can be passed by secondary_kexec_args.
> +1: li t9, 0x100 /* wait for init loop */
> +2: addiu t9, -1 /* limit mailbox access */
> + bnez t9, 2b
> + ld s1, 0x20(t0) /* get PC via mailbox reg0 */
> + beqz s1, 1b
> + ld sp, 0x28(t0) /* get SP via mailbox reg1 */
> + ld gp, 0x30(t0) /* get GP via mailbox reg2 */
> + ld a1, 0x38(t0)
> + jr s1 /* jump to initial PC */
> +#endif
> +
> j s1
> END(kexec_smp_wait)
> #endif
> diff --git a/arch/mips/loongson64/env.c b/arch/mips/loongson64/env.c
> index 134cb8e..e937f31 100644
> --- a/arch/mips/loongson64/env.c
> +++ b/arch/mips/loongson64/env.c
> @@ -120,6 +120,13 @@ void __init prom_init_env(void)
> loongson_sysconf.nr_cpus = ecpu->nr_cpus;
> loongson_sysconf.boot_cpu_id = ecpu->cpu_startup_core_id;
> loongson_sysconf.reserved_cpus_mask = ecpu->reserved_cores_mask;
> +#ifdef CONFIG_KEXEC
> + loongson_sysconf.boot_cpu_id = get_ebase_cpunum();
> + loongson_sysconf.reserved_cpus_mask |=
> + (1 << loongson_sysconf.boot_cpu_id) - 1;
> + pr_info("Boot CPU ID is being fixed from %d to %d\n",
> + ecpu->cpu_startup_core_id, loongson_sysconf.boot_cpu_id);
> +#endif
I don't think secondary CPU will go here.
At arch/mips/kernel/machine_kexec.c: kexec_reboot(), CPU0 goes
relocate_new_kernel() and secondary CPUs go to smp_wait. Why
kdump may triggered at non-boot CPU?
> if (ecpu->nr_cpus > NR_CPUS || ecpu->nr_cpus == 0)
> loongson_sysconf.nr_cpus = NR_CPUS;
> loongson_sysconf.nr_nodes = (loongson_sysconf.nr_cpus +
> diff --git a/arch/mips/loongson64/reset.c b/arch/mips/loongson64/reset.c
> index 3bb8a1e..b1e71f37 100644
> --- a/arch/mips/loongson64/reset.c
> +++ b/arch/mips/loongson64/reset.c
> @@ -6,9 +6,14 @@
> * Copyright (C) 2009 Lemote, Inc.
> * Author: Zhangjin Wu, wuzhangjin at gmail.com
> */
> +#include <linux/cpu.h>
> +#include <linux/delay.h>
> #include <linux/init.h>
> +#include <linux/kexec.h>
> #include <linux/pm.h>
> +#include <linux/slab.h>
>
> +#include <asm/bootinfo.h>
> #include <asm/idle.h>
> #include <asm/reboot.h>
>
> @@ -47,12 +52,118 @@ static void loongson_halt(void)
> }
> }
>
> +#ifdef CONFIG_KEXEC
> +
> +/* 0X80000000~0X80200000 is safe */
> +#define MAX_ARGS 64
> +#define KEXEC_CTRL_CODE 0xFFFFFFFF80100000UL
> +#define KEXEC_ARGV_ADDR 0xFFFFFFFF80108000UL
> +#define KEXEC_ARGV_SIZE COMMAND_LINE_SIZE
> +#define KEXEC_ENVP_SIZE 4800
> +
> +static int kexec_argc;
> +static int kdump_argc;
> +static void *kexec_argv;
> +static void *kdump_argv;
> +static void *kexec_envp;
> +
> +static int loongson_kexec_prepare(struct kimage *image)
> +{
> + int i, argc = 0;
> + unsigned int *argv;
> + char *str, *ptr, *bootloader = "kexec";
> +
> + /* argv at offset 0, argv[] at offset KEXEC_ARGV_SIZE/2 */
> + if (image->type == KEXEC_TYPE_DEFAULT)
> + argv = (unsigned int *)kexec_argv;
> + else
> + argv = (unsigned int *)kdump_argv;
> +
> + argv[argc++] = (unsigned int)(KEXEC_ARGV_ADDR + KEXEC_ARGV_SIZE/2);
> +
> + for (i = 0; i < image->nr_segments; i++) {
> + if (!strncmp(bootloader, (char *)image->segment[i].buf,
> + strlen(bootloader))) {
> + /*
> + * convert command line string to array
> + * of parameters (as bootloader does).
> + */
> + int offt;
> + str = (char *)argv + KEXEC_ARGV_SIZE/2;
> + memcpy(str, image->segment[i].buf, KEXEC_ARGV_SIZE/2);
> + ptr = strchr(str, ' ');
> +
> + while (ptr && (argc < MAX_ARGS)) {
> + *ptr = '\0';
> + if (ptr[1] != ' ') {
> + offt = (int)(ptr - str + 1);
> + argv[argc] = KEXEC_ARGV_ADDR + KEXEC_ARGV_SIZE/2 + offt;
> + argc++;
> + }
> + ptr = strchr(ptr + 1, ' ');
> + }
> + break;
> + }
> + }
> +
> + if (image->type == KEXEC_TYPE_DEFAULT)
> + kexec_argc = argc;
> + else
> + kdump_argc = argc;
> +
> + /* kexec/kdump need a safe page to save reboot_code_buffer */
> + image->control_code_page = virt_to_page((void *)KEXEC_CTRL_CODE);
I thought find a hole in Crash Kernel may better than a static position.
It just a trivial idea, too.
> +
> + return 0;
> +}
> +
> +static void loongson_kexec_shutdown(void)
> +{
> +#ifdef CONFIG_SMP
> + 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));
> +#endif
> + kexec_args[0] = kexec_argc;
> + kexec_args[1] = fw_arg1;
> + kexec_args[2] = fw_arg2;
> + memcpy((void *)fw_arg1, kexec_argv, KEXEC_ARGV_SIZE);
> + memcpy((void *)fw_arg2, kexec_envp, KEXEC_ENVP_SIZE);
> +}
> +
> +static void loongson_crash_shutdown(struct pt_regs *regs)
> +{
> + default_machine_crash_shutdown(regs);
> + kexec_args[0] = kdump_argc;
> + kexec_args[1] = fw_arg1;
> + kexec_args[2] = fw_arg2;
> + memcpy((void *)fw_arg1, kdump_argv, KEXEC_ARGV_SIZE);
> + memcpy((void *)fw_arg2, kexec_envp, KEXEC_ENVP_SIZE);
> +}
> +
> +#endif
> +
> static int __init mips_reboot_setup(void)
> {
> _machine_restart = loongson_restart;
> _machine_halt = loongson_halt;
> pm_power_off = loongson_poweroff;
>
> +#ifdef CONFIG_KEXEC
> + kexec_argv = kmalloc(KEXEC_ARGV_SIZE, GFP_KERNEL);
> + kdump_argv = kmalloc(KEXEC_ARGV_SIZE, GFP_KERNEL);
> + kexec_envp = kmalloc(KEXEC_ENVP_SIZE, GFP_KERNEL);
> + fw_arg1 = KEXEC_ARGV_ADDR;
> + memcpy(kexec_envp, (void *)fw_arg2, KEXEC_ENVP_SIZE);
> +
> + _machine_kexec_prepare = loongson_kexec_prepare;
> + _machine_kexec_shutdown = loongson_kexec_shutdown;
> + _machine_crash_shutdown = loongson_crash_shutdown;
> +#endif
> +
> return 0;
> }
>
> diff --git a/arch/mips/loongson64/smp.c b/arch/mips/loongson64/smp.c
> index e744e1b..55697ac 100644
> --- a/arch/mips/loongson64/smp.c
> +++ b/arch/mips/loongson64/smp.c
> @@ -420,6 +420,11 @@ static void __init loongson3_smp_setup(void)
> ipi_status0_regs_init();
> ipi_en0_regs_init();
> ipi_mailbox_buf_init();
> +
> + /* BIOS clear the mailbox, but KEXEC bypass BIOS so clear here */
> + for (i = 0; i < loongson_sysconf.nr_cpus; i++)
> + loongson3_ipi_write64(0, (void *)(ipi_mailbox_buf[i]+0x0));
> +
Does it need? It take a long time after secondary CPUs geting PC in a loop.
Or you can clear it early.
Thanks,
- Jinyang.
> cpu_set_core(&cpu_data[0],
> cpu_logical_map(0) % loongson_sysconf.cores_per_package);
> cpu_data[0].package = cpu_logical_map(0) / loongson_sysconf.cores_per_package;
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