[linux-yocto] [PATCH 17/26] arm64: kdump: implement machine_crash_shutdown()

[Daniel Dragomir]

From: AKASHI Takahiro <takahiro.akashi at linaro.org>

kdump calls machine_crash_shutdown() to shut down non-boot cpus and
save registers' status in per-cpu ELF notes before starting the crash
dump kernel. See kernel_kexec().

ipi_cpu_stop() is a bit modified and used to support this behavior.

Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
---
 arch/arm64/include/asm/kexec.h    | 34 +++++++++++++++++++++++++++++++++-
 arch/arm64/kernel/machine_kexec.c | 36 +++++++++++++++++++++++++++++++++---
 arch/arm64/kernel/smp.c           | 30 +++++++++++++++++++++---------
 3 files changed, 87 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 46d63cd..555a955 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, #16 *  0]\n"
+			"stp	 x2,   x3, [%3, #16 *  1]\n"
+			"stp	 x4,   x5, [%3, #16 *  2]\n"
+			"stp	 x6,   x7, [%3, #16 *  3]\n"
+			"stp	 x8,   x9, [%3, #16 *  4]\n"
+			"stp	x10,  x11, [%3, #16 *  5]\n"
+			"stp	x12,  x13, [%3, #16 *  6]\n"
+			"stp	x14,  x15, [%3, #16 *  7]\n"
+			"stp	x16,  x17, [%3, #16 *  8]\n"
+			"stp	x18,  x19, [%3, #16 *  9]\n"
+			"stp	x20,  x21, [%3, #16 * 10]\n"
+			"stp	x22,  x23, [%3, #16 * 11]\n"
+			"stp	x24,  x25, [%3, #16 * 12]\n"
+			"stp	x26,  x27, [%3, #16 * 13]\n"
+			"stp	x28,  x29, [%3, #16 * 14]\n"
+			"str	x30,	   [%3, #16 * 15]\n"
+			"mov	%0, sp\n"
+			"adr	%1, 1f\n"
+			"mrs	%2, spsr_el1\n"
+		"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 18517b8..06b9bc2 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -9,6 +9,7 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/kernel.h>
 #include <linux/kexec.h>
 #include <linux/of_fdt.h>
 #include <linux/slab.h>
@@ -23,6 +24,7 @@
 extern const unsigned char arm64_relocate_new_kernel[];
 extern const unsigned long arm64_relocate_new_kernel_size;
 
+bool in_crash_kexec;
 static unsigned long kimage_start;
 
 /**
@@ -181,7 +183,10 @@ void machine_kexec(struct kimage *kimage)
 	__flush_dcache_area(reboot_code_buffer, arm64_relocate_new_kernel_size);
 
 	/* Flush the kimage data. */
-	kexec_list_flush(kimage->head);
+	if (in_crash_kexec)
+		kexec_segment_flush(kimage);
+	else
+		kexec_list_flush(kimage->head);
 
 	pr_info("Bye!\n");
 
@@ -200,13 +205,38 @@ void machine_kexec(struct kimage *kimage)
 	 */
 
 	cpu_soft_restart(virt_to_phys(cpu_reset),
-		is_hyp_mode_available(),
+		in_crash_kexec ? 0 : is_hyp_mode_available(),
 		reboot_code_buffer_phys, kimage->head, kimage_start);
 
 	BUG(); /* Should never get here. */
 }
 
+/**
+ * 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 never 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 boot cpu */
+	crash_save_cpu(regs, smp_processor_id());
+
+	pr_info("Starting crashdump kernel...\n");
 }
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 38b47ea..476ccbf 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>
@@ -52,6 +53,8 @@
 #include <asm/tlbflush.h>
 #include <asm/ptrace.h>
 
+#include "cpu-reset.h"
+
 #define CREATE_TRACE_POINTS
 #include <trace/events/ipi.h>
 
@@ -542,20 +545,29 @@ 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) {
-		raw_spin_lock(&stop_lock);
-		pr_crit("CPU%u: stopping\n", cpu);
-		dump_stack();
-		raw_spin_unlock(&stop_lock);
-	}
+#ifdef CONFIG_KEXEC
+	/* printing messages may slow down the shutdown. */
+	if (!in_crash_kexec)
+#endif
+		if (system_state == SYSTEM_BOOTING ||
+		    system_state == SYSTEM_RUNNING) {
+			raw_spin_lock(&stop_lock);
+			pr_crit("CPU%u: stopping\n", cpu);
+			dump_stack();
+			raw_spin_unlock(&stop_lock);
+		}
 
 	set_cpu_online(cpu, false);
 
 	local_irq_disable();
 
+#ifdef CONFIG_KEXEC
+	if (in_crash_kexec)
+		crash_save_cpu(regs, cpu);
+#endif /* CONFIG_KEXEC */
+
 	while (1)
 		cpu_relax();
 }
@@ -586,7 +598,7 @@ 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;
 
-- 
2.7.4