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Commit a88ce63b authored by Hoeun Ryu's avatar Hoeun Ryu Committed by Catalin Marinas
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arm64: kexec: have own crash_smp_send_stop() for crash dump for nonpanic cores 



 Commit 0ee59413 : (x86/panic: replace smp_send_stop() with kdump friendly
version in panic path) introduced crash_smp_send_stop() which is a weak
function and can be overridden by architecture codes to fix the side effect
caused by commit f06e5153 : (kernel/panic.c: add "crash_kexec_post_
notifiers" option).

 ARM64 architecture uses the weak version function and the problem is that
the weak function simply calls smp_send_stop() which makes other CPUs
offline and takes away the chance to save crash information for nonpanic
CPUs in machine_crash_shutdown() when crash_kexec_post_notifiers kernel
option is enabled.

 Calling smp_send_crash_stop() in machine_crash_shutdown() is useless
because all nonpanic CPUs are already offline by smp_send_stop() in this
case and smp_send_crash_stop() only works against online CPUs.

 The result is that secondary CPUs registers are not saved by
crash_save_cpu() and the vmcore file misreports these CPUs as being
offline.

 crash_smp_send_stop() is implemented to fix this problem by replacing the
existing smp_send_crash_stop() and adding a check for multiple calling to
the function. The function (strong symbol version) saves crash information
for nonpanic CPUs and machine_crash_shutdown() tries to save crash
information for nonpanic CPUs only when crash_kexec_post_notifiers kernel
option is disabled.

* crash_kexec_post_notifiers : false

  panic()
    __crash_kexec()
      machine_crash_shutdown()
        crash_smp_send_stop()    <= save crash dump for nonpanic cores

* crash_kexec_post_notifiers : true

  panic()
    crash_smp_send_stop()        <= save crash dump for nonpanic cores
    __crash_kexec()
      machine_crash_shutdown()
        crash_smp_send_stop()    <= just return.

Signed-off-by: default avatarHoeun Ryu <hoeun.ryu@gmail.com>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
Tested-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 8165f706

arch/arm64/include/asm/smp.h

+1 −1
Original line number Diff line number Diff line
@@ -148,7 +148,7 @@ static inline void cpu_panic_kernel(void) 
 */

bool cpus_are_stuck_in_kernel(void);



extern void smp_send_crash_stop(void);

extern void crash_smp_send_stop(void);

extern bool smp_crash_stop_failed(void);



#endif /* ifndef __ASSEMBLY__ */

arch/arm64/kernel/machine_kexec.c

+1 −1
Original line number Diff line number Diff line
@@ -252,7 +252,7 @@ void machine_crash_shutdown(struct pt_regs *regs) 
	local_irq_disable();



	/* shutdown non-crashing cpus */

	smp_send_crash_stop();

	crash_smp_send_stop();



	/* for crashing cpu */

	crash_save_cpu(regs, smp_processor_id());

arch/arm64/kernel/smp.c

+11 −1
Original line number Diff line number Diff line
@@ -977,11 +977,21 @@ void smp_send_stop(void) 
}



#ifdef CONFIG_KEXEC_CORE

void smp_send_crash_stop(void)

void crash_smp_send_stop(void)

{

	static int cpus_stopped;

	cpumask_t mask;

	unsigned long timeout;



	/*

	 * This function can be called twice in panic path, but obviously

	 * we execute this only once.

	 */

	if (cpus_stopped)

		return;



	cpus_stopped = 1;



	if (num_online_cpus() == 1)

		return;