4.16-stable review patch. If anyone has any objections, please let me know.
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From: Russell King rmk+kernel@armlinux.org.uk
[ Upstream commit 2d7b3c64431245c95b05a441669c074da10db943 ]
When a panic() occurs, the kexec code uses smp_send_stop() to stop the other CPUs, but this results in the CPU register state not being saved, and gdb is unable to inspect the state of other CPUs.
Commit 0ee59413c967 ("x86/panic: replace smp_send_stop() with kdump friendly version in panic path") addressed the issue on x86, but ignored other architectures. Address the issue on ARM by splitting out the crash stop implementation to crash_smp_send_stop() and adding the necessary protection.
Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm/kernel/machine_kexec.c | 34 ++++++++++++++++++++++------------ 1 file changed, 22 insertions(+), 12 deletions(-)
--- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -95,6 +95,27 @@ void machine_crash_nonpanic_core(void *u cpu_relax(); }
+void crash_smp_send_stop(void) +{ + static int cpus_stopped; + unsigned long msecs; + + if (cpus_stopped) + return; + + atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); + smp_call_function(machine_crash_nonpanic_core, NULL, false); + msecs = 1000; /* Wait at most a second for the other cpus to stop */ + while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) { + mdelay(1); + msecs--; + } + if (atomic_read(&waiting_for_crash_ipi) > 0) + pr_warn("Non-crashing CPUs did not react to IPI\n"); + + cpus_stopped = 1; +} + static void machine_kexec_mask_interrupts(void) { unsigned int i; @@ -120,19 +141,8 @@ static void machine_kexec_mask_interrupt
void machine_crash_shutdown(struct pt_regs *regs) { - unsigned long msecs; - local_irq_disable(); - - atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1); - smp_call_function(machine_crash_nonpanic_core, NULL, false); - msecs = 1000; /* Wait at most a second for the other cpus to stop */ - while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) { - mdelay(1); - msecs--; - } - if (atomic_read(&waiting_for_crash_ipi) > 0) - pr_warn("Non-crashing CPUs did not react to IPI\n"); + crash_smp_send_stop();
crash_save_cpu(regs, smp_processor_id()); machine_kexec_mask_interrupts();