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Commit 88b1a854 authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Michael Ellerman
Browse files

powerpc64/kexec: Hard disable ftrace before switching to the new kernel 



If function_graph tracer is enabled during kexec, we see the below
exception in the simulator:
	root@(none):/# kexec -e
	kvm: exiting hardware virtualization
	kexec_core: Starting new kernel
	[   19.262020070,5] OPAL: Switch to big-endian OS
	kexec: Starting switchover sequence.
	Interrupt to 0xC000000000004380 from 0xC000000000004380
	** Execution stopped: Continuous Interrupt, Instruction caused exception,  **

Now that we have a more effective way to completely disable ftrace on
ppc64, let's also use that before switching to a new kernel during
kexec.

Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent a4bc64d3

arch/powerpc/kernel/machine_kexec.c

+2 −0
Original line number Diff line number Diff line
@@ -98,12 +98,14 @@ void machine_kexec(struct kimage *image) 
	int save_ftrace_enabled;



	save_ftrace_enabled = __ftrace_enabled_save();

	this_cpu_disable_ftrace();



	if (ppc_md.machine_kexec)

		ppc_md.machine_kexec(image);

	else

		default_machine_kexec(image);



	this_cpu_enable_ftrace();

	__ftrace_enabled_restore(save_ftrace_enabled);



	/* Fall back to normal restart if we're still alive. */