Re: [PATCH] MIPS: Loongson64: Add kexec/kdump support

[Jiaxun Yang]

于 2020年9月15日 GMT+08:00 下午9:07:43, Jinyang He <hejinyang@xxxxxxxxxxx> 写到:
>Add loongson_kexec_prepare(), loongson_kexec_shutdown() and
>loongson_kexec_crashdown() for passing the parameters of kexec_args.
>
>To start loongson64, CPU0 needs 3 parameters:
>fw_arg0: the number of cmd.
>fw_arg1: cmd structure which seems strange, the cmd array[index]'s
>         value is cmd string's address, index >= 1.
>fw_arg2: environment.
>
>Secondary CPUs do not need parameter at once. They query their
>mailbox to get PC, SP and GP in a loop before CPU0 brings them up
>and passes these parameters via mailbox.
>
>loongson_kexec_prepare(): Alloc new memory to save cmd for kexec.
>Combine the kexec append option string as cmd structure, and the cmd
>struct will be parsed in fw_init_cmdline() of arch/mips/fw/lib/cmdline.c.
>image->control_code_page need pointing to a safe memory page. In order to
>maintain compatibility for the old firmware the low 2MB is reserverd
>and safe for Loongson. So let it points here.
>
>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 provide a way like BIOS doing to keep secondary
>CPUs in a querying loop.
>
>This patch referenced [1][2][3].
>
>[1] arch/mips/cavium-octeon/setup.c
>[2] https://patchwork.kernel.org/patch/10799217/
>[3] https://gitee.com/loongsonlab/qemu/blob/master/hw/mips/loongson3a_rom.h
>
>Co-developed-by: Youling Tang <tangyouling@xxxxxxxxxxx>
>Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxxx>
>Signed-off-by: Jinyang He <hejinyang@xxxxxxxxxxx>
>---
> arch/mips/kernel/relocate_kernel.S | 19 ++++++++
> arch/mips/loongson64/reset.c       | 88 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 107 insertions(+)
>
>diff --git a/arch/mips/kernel/relocate_kernel.S b/arch/mips/kernel/relocate_kernel.S
>index ac87089..061cbfb 100644
>--- a/arch/mips/kernel/relocate_kernel.S
>+++ b/arch/mips/kernel/relocate_kernel.S
>@@ -133,6 +133,25 @@ LEAF(kexec_smp_wait)
> #else
> 	sync
> #endif
>+
>+#ifdef CONFIG_CPU_LOONGSON64
>+#define MAILBOX_BASE 0x900000003ff01000

Please avoid hardcoded SMP information. You're breaking Loongson 3B support.


Thank.

- Jiaxun


>+	mfc0  t1, CP0_EBASE
>+	andi  t1, MIPS_EBASE_CPUNUM
>+	dli   t0, MAILBOX_BASE
>+	andi  t3, t1, 0x3
>+	sll   t3, 8
>+	or    t0, t0, t3	/* insert core id */
>+	andi  t2, t1, 0xc
>+	dsll  t2, 42
>+	or    t0, t0, t2	/* insert node id */
>+1:	ld    s1, 0x20(t0)	/* get PC via mailbox0 */
>+	beqz  s1, 1b
>+	ld    sp, 0x28(t0)	/* get SP via mailbox1 */
>+	ld    gp, 0x30(t0)	/* get GP via mailbox2 */
>+	ld    a1, 0x38(t0)
>+	jr    s1
>+#endif
> 	j		s1
> 	END(kexec_smp_wait)
> #endif
>diff --git a/arch/mips/loongson64/reset.c b/arch/mips/loongson64/reset.c
>index 3bb8a1e..322c326 100644
>--- a/arch/mips/loongson64/reset.c
>+++ b/arch/mips/loongson64/reset.c
>@@ -47,12 +47,100 @@ static void loongson_halt(void)
> 	}
> }
> 
>+#ifdef CONFIG_KEXEC
>+#include <linux/cpu.h>
>+#include <linux/kexec.h>
>+
>+#include <asm/bootinfo.h>
>+
>+#define CONTROL_CODE_PAGE    0xFFFFFFFF80000000UL
>+static int kexec_argc;
>+static int kdump_argc;
>+static void *kexec_argv;
>+static void *kdump_argv;
>+
>+static int loongson_kexec_prepare(struct kimage *image)
>+{
>+	int i, offt, argc = 0;
>+	int *argv;
>+	char *str, *ptr, *bootloader = "kexec";
>+
>+	argv = kmalloc(COMMAND_LINE_SIZE, GFP_KERNEL);
>+	if (!argv)
>+		return -ENOMEM;
>+
>+	for (i = 0; i < image->nr_segments; i++) {
>+		if (!strncmp(bootloader, (char *)image->segment[i].buf,
>+				strlen(bootloader))) {
>+			argv[argc++] = fw_arg1 + COMMAND_LINE_SIZE/2;
>+			str = (char *)argv + COMMAND_LINE_SIZE/2;
>+			memcpy(str, image->segment[i].buf, COMMAND_LINE_SIZE/2);
>+			ptr = strchr(str, ' ');
>+			while (ptr) {
>+				*ptr = '\0';
>+				if (ptr[1] != ' ') {
>+					offt = (int)(ptr - str + 1);
>+					argv[argc++] = fw_arg1 + COMMAND_LINE_SIZE/2 + offt;
>+				}
>+				ptr = strchr(ptr + 1, ' ');
>+			}
>+			break;
>+		}
>+	}
>+
>+	/* Kexec/kdump needs a safe page to save reboot_code_buffer. */
>+	image->control_code_page = virt_to_page((void *)CONTROL_CODE_PAGE);
>+
>+	if (image->type == KEXEC_TYPE_CRASH) {
>+		kfree(kdump_argv);
>+		kdump_argc = argc;
>+		kdump_argv = argv;
>+	} else {
>+		kfree(kexec_argv);
>+		kexec_argc = argc;
>+		kexec_argv = argv;
>+	}
>+
>+	return 0;
>+}
>+
>+static void loongson_kexec_shutdown(void)
>+{
>+#ifdef CONFIG_SMP
>+	bringup_nonboot_cpus(loongson_sysconf.nr_cpus);
>+#endif
>+	fw_arg0 = kexec_argc;
>+	memcpy((void *)fw_arg1, kexec_argv, COMMAND_LINE_SIZE);
>+
>+	kexec_args[0] = fw_arg0;
>+	kexec_args[1] = fw_arg1;
>+	kexec_args[2] = fw_arg2;
>+}
>+
>+static void loongson_crash_shutdown(struct pt_regs *regs)
>+{
>+	default_machine_crash_shutdown(regs);
>+	fw_arg0 = kdump_argc;
>+	memcpy((void *)fw_arg1, kdump_argv, COMMAND_LINE_SIZE);
>+
>+	kexec_args[0] = fw_arg0;
>+	kexec_args[1] = fw_arg1;
>+	kexec_args[2] = fw_arg2;
>+}
>+#endif
>+
> static int __init mips_reboot_setup(void)
> {
> 	_machine_restart = loongson_restart;
> 	_machine_halt = loongson_halt;
> 	pm_power_off = loongson_poweroff;
> 
>+#ifdef CONFIG_KEXEC
>+	_machine_kexec_prepare = loongson_kexec_prepare;
>+	_machine_kexec_shutdown = loongson_kexec_shutdown;
>+	_machine_crash_shutdown = loongson_crash_shutdown;
>+#endif
>+
> 	return 0;
> }
>