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Subject[v2 2/5] arm64: kdump: implement machine_crash_shutdown()
Date
kdump calls machine_crash_shutdown() to shut down non-boot cpus and
save per-cpu general-purpose registers before restarting the crash dump
kernel. See kernel_kexec().
ipi_cpu_stop() is used and a bit modified to support this behavior.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
---
arch/arm64/include/asm/kexec.h | 34 ++++++++++++++++++++++-
arch/arm64/kernel/machine_kexec.c | 55 ++++++++++++++++++++++++++++++++++++-
arch/arm64/kernel/smp.c | 12 ++++++--
3 files changed, 97 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 3530ff5..eaf3fcb 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -30,6 +30,8 @@

#if !defined(__ASSEMBLY__)

+extern bool in_crash_kexec;
+
/**
* crash_setup_regs() - save registers for the panic kernel
*
@@ -40,7 +42,37 @@
static inline void crash_setup_regs(struct pt_regs *newregs,
struct pt_regs *oldregs)
{
- /* Empty routine needed to avoid build errors. */
+ if (oldregs) {
+ memcpy(newregs, oldregs, sizeof(*newregs));
+ } else {
+ __asm__ __volatile__ (
+ "stp x0, x1, [%3]\n\t"
+ "stp x2, x3, [%3, 0x10]\n\t"
+ "stp x4, x5, [%3, 0x20]\n\t"
+ "stp x6, x7, [%3, 0x30]\n\t"
+ "stp x8, x9, [%3, 0x40]\n\t"
+ "stp x10, x11, [%3, 0x50]\n\t"
+ "stp x12, x13, [%3, 0x60]\n\t"
+ "stp x14, x15, [%3, 0x70]\n\t"
+ "stp x16, x17, [%3, 0x80]\n\t"
+ "stp x18, x19, [%3, 0x90]\n\t"
+ "stp x20, x21, [%3, 0xa0]\n\t"
+ "stp x22, x23, [%3, 0xb0]\n\t"
+ "stp x24, x25, [%3, 0xc0]\n\t"
+ "stp x26, x27, [%3, 0xd0]\n\t"
+ "stp x28, x29, [%3, 0xe0]\n\t"
+ "str x30, [%3, 0xf0]\n\t"
+ "mov %0, sp\n\t"
+ "adr %1, 1f\n\t"
+ "mrs %2, spsr_el1\n\t"
+ "1:"
+ : "=r" (newregs->sp),
+ "=r" (newregs->pc),
+ "=r" (newregs->pstate)
+ : "r" (&newregs->regs)
+ : "memory"
+ );
+ }
}

#endif /* !defined(__ASSEMBLY__) */
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index fd6b742..6f7887b 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -9,6 +9,8 @@
* published by the Free Software Foundation.
*/

+#include <linux/irq.h>
+#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/of_fdt.h>
#include <linux/slab.h>
@@ -24,6 +26,8 @@ extern unsigned long arm64_kexec_dtb_addr;
extern unsigned long arm64_kexec_kimage_head;
extern unsigned long arm64_kexec_kimage_start;

+bool in_crash_kexec = false;
+
/**
* kexec_is_dtb - Helper routine to check the device tree header signature.
*/
@@ -178,7 +182,56 @@ void machine_kexec(struct kimage *image)
soft_restart(reboot_code_buffer_phys);
}

+static void machine_kexec_mask_interrupts(void)
+{
+ unsigned int i;
+ struct irq_desc *desc;
+
+ for_each_irq_desc(i, desc) {
+ struct irq_chip *chip;
+
+ chip = irq_desc_get_chip(desc);
+ if (!chip)
+ continue;
+
+ if (chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
+ chip->irq_eoi(&desc->irq_data);
+
+ if (chip->irq_mask)
+ chip->irq_mask(&desc->irq_data);
+
+ if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data))
+ chip->irq_disable(&desc->irq_data);
+ }
+}
+
+/**
+ * machine_crash_shutdown - shutdown non-boot cpus and save registers
+ */
void machine_crash_shutdown(struct pt_regs *regs)
{
- /* Empty routine needed to avoid build errors. */
+ struct pt_regs dummy_regs;
+ int cpu;
+
+ local_irq_disable();
+
+ in_crash_kexec = true;
+
+ /*
+ * clear and initialize the per-cpu info. This is necessary
+ * because, otherwise, slots for offline cpus would not be
+ * filled up. See smp_send_stop().
+ */
+ memset(&dummy_regs, 0, sizeof(dummy_regs));
+ for_each_possible_cpu(cpu)
+ crash_save_cpu(&dummy_regs, cpu);
+
+ /* shutdown non-boot cpus */
+ smp_send_stop();
+
+ /* for this cpu */
+ crash_save_cpu(regs, smp_processor_id());
+ machine_kexec_mask_interrupts();
+
+ pr_info("Loading crashdump kernel...\n");
}
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index ffe8e1b..cf7f361 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -36,6 +36,7 @@
#include <linux/completion.h>
#include <linux/of.h>
#include <linux/irq_work.h>
+#include <linux/kexec.h>

#include <asm/alternative.h>
#include <asm/atomic.h>
@@ -542,7 +543,7 @@ static DEFINE_RAW_SPINLOCK(stop_lock);
/*
* ipi_cpu_stop - handle IPI from smp_send_stop()
*/
-static void ipi_cpu_stop(unsigned int cpu)
+static void ipi_cpu_stop(unsigned int cpu, struct pt_regs *regs)
{
if (system_state == SYSTEM_BOOTING ||
system_state == SYSTEM_RUNNING) {
@@ -556,6 +557,13 @@ static void ipi_cpu_stop(unsigned int cpu)

local_irq_disable();

+#ifdef CONFIG_KEXEC
+ if (in_crash_kexec) {
+ crash_save_cpu(regs, cpu);
+ flush_cache_all();
+ }
+#endif /* CONFIG_KEXEC */
+
while (1)
cpu_relax();
}
@@ -586,7 +594,7 @@ void handle_IPI(int ipinr, struct pt_regs *regs)

case IPI_CPU_STOP:
irq_enter();
- ipi_cpu_stop(cpu);
+ ipi_cpu_stop(cpu, regs);
irq_exit();
break;

--
1.7.9.5


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