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Subject[PATCH] MIPS: Loongson64: Add kexec/kdump support
Date
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@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
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
+ 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;
}

--
2.1.0
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