From 88b1a8547f4c00e55d54e081fc15e3980debf5c1 Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Thu, 19 Apr 2018 12:34:06 +0530 Subject: [PATCH] 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: Naveen N. Rao Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/machine_kexec.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c index 2694d078741d..936c7e2d421e 100644 --- a/arch/powerpc/kernel/machine_kexec.c +++ b/arch/powerpc/kernel/machine_kexec.c @@ -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. */