[PATCH v4 2/6] MIPS: kexec: Let the new kernel handle all CPUs

[Dengcheng Zhu <dzhu@wavecomp.com>]

Use play_dead() to prepare an environment for the new kernel. Do not rely
on non-crashing CPUs jumping to kexec_start_address.

Tested-by: Rachel Mozes <rachel.mozes@intel.com>
Reported-by: Rachel Mozes <rachel.mozes@intel.com>
Signed-off-by: Dengcheng Zhu <dzhu@wavecomp.com>
---
Changes:

* Use play_dead() without an extra parameter.

 arch/mips/cavium-octeon/setup.c  |  2 +-
 arch/mips/include/asm/kexec.h    |  3 ++-
 arch/mips/kernel/crash.c         |  4 +++-
 arch/mips/kernel/machine_kexec.c | 28 ++++++++++++++++++++++++----
 4 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/arch/mips/cavium-octeon/setup.c b/arch/mips/cavium-octeon/setup.c
index a8034d0dcade..3a1f7fa42413 100644
--- a/arch/mips/cavium-octeon/setup.c
+++ b/arch/mips/cavium-octeon/setup.c
@@ -95,7 +95,7 @@ static void octeon_kexec_smp_down(void *ignored)
 	"	sync						\n"
 	"	synci	($0)					\n");
 
-	relocated_kexec_smp_wait(NULL);
+	kexec_smp_reboot();
 }
 #endif
 
diff --git a/arch/mips/include/asm/kexec.h b/arch/mips/include/asm/kexec.h
index 493a3cc7c39a..a8e0bfc0da19 100644
--- a/arch/mips/include/asm/kexec.h
+++ b/arch/mips/include/asm/kexec.h
@@ -39,12 +39,13 @@ extern unsigned long kexec_args[4];
 extern int (*_machine_kexec_prepare)(struct kimage *);
 extern void (*_machine_kexec_shutdown)(void);
 extern void (*_machine_crash_shutdown)(struct pt_regs *regs);
-extern void default_machine_crash_shutdown(struct pt_regs *regs);
+void default_machine_crash_shutdown(struct pt_regs *regs);
 #ifdef CONFIG_SMP
 extern const unsigned char kexec_smp_wait[];
 extern unsigned long secondary_kexec_args[4];
 extern void (*relocated_kexec_smp_wait) (void *);
 extern atomic_t kexec_ready_to_reboot;
+void kexec_smp_reboot(void);
 extern void (*_crash_smp_send_stop)(void);
 #endif
 #endif
diff --git a/arch/mips/kernel/crash.c b/arch/mips/kernel/crash.c
index d455363d51c3..6d4320067cff 100644
--- a/arch/mips/kernel/crash.c
+++ b/arch/mips/kernel/crash.c
@@ -43,7 +43,9 @@ static void crash_shutdown_secondary(void *passed_regs)
 
 	while (!atomic_read(&kexec_ready_to_reboot))
 		cpu_relax();
-	relocated_kexec_smp_wait(NULL);
+
+	kexec_smp_reboot();
+
 	/* NOTREACHED */
 }
 
diff --git a/arch/mips/kernel/machine_kexec.c b/arch/mips/kernel/machine_kexec.c
index 8b574bcd39ba..900475ae256d 100644
--- a/arch/mips/kernel/machine_kexec.c
+++ b/arch/mips/kernel/machine_kexec.c
@@ -19,6 +19,10 @@ extern const size_t relocate_new_kernel_size;
 extern unsigned long kexec_start_address;
 extern unsigned long kexec_indirection_page;
 
+static unsigned long reboot_code_buffer;
+
+typedef void (*noretfun_t)(void) __noreturn;
+
 int (*_machine_kexec_prepare)(struct kimage *) = NULL;
 void (*_machine_kexec_shutdown)(void) = NULL;
 void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;
@@ -26,6 +30,20 @@ void (*_machine_crash_shutdown)(struct pt_regs *regs) = NULL;
 void (*relocated_kexec_smp_wait) (void *);
 atomic_t kexec_ready_to_reboot = ATOMIC_INIT(0);
 void (*_crash_smp_send_stop)(void) = NULL;
+
+void kexec_smp_reboot(void)
+{
+	if (smp_processor_id() > 0) {
+		/*
+		 * Instead of cpu_relax() or wait, this is needed for kexec
+		 * smp reboot. Kdump usually doesn't require an smp new
+		 * kernel, but kexec may do.
+		 */
+		play_dead();
+	} else {
+		((noretfun_t)reboot_code_buffer)();
+	}
+}
 #endif
 
 static void kexec_image_info(const struct kimage *kimage)
@@ -79,12 +97,9 @@ machine_crash_shutdown(struct pt_regs *regs)
 		default_machine_crash_shutdown(regs);
 }
 
-typedef void (*noretfun_t)(void) __noreturn;
-
 void
 machine_kexec(struct kimage *image)
 {
-	unsigned long reboot_code_buffer;
 	unsigned long entry;
 	unsigned long *ptr;
 
@@ -132,6 +147,11 @@ machine_kexec(struct kimage *image)
 		(void *)(kexec_smp_wait - relocate_new_kernel);
 	smp_wmb();
 	atomic_set(&kexec_ready_to_reboot, 1);
-#endif
+
+	kexec_smp_reboot();
+
+	/* NOT REACHED */
+#else
 	((noretfun_t) reboot_code_buffer)();
+#endif
 }
-- 
2.17.1