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authorNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>2017-06-01 16:18:15 +0530
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-29 12:48:51 +0200
commit3ee9033e228def8bef0e450d492421f0a6abaac4 (patch)
parentbc7b3e9984a8e83e3256c08a059ca745b5d0935c (diff)
powerpc/kprobes: Pause function_graph tracing during jprobes handling
commit a9f8553e935f26cb5447f67e280946b0923cd2dc upstream. This fixes a crash when function_graph and jprobes are used together. This is essentially commit 237d28db036e ("ftrace/jprobes/x86: Fix conflict between jprobes and function graph tracing"), but for powerpc. Jprobes breaks function_graph tracing since the jprobe hook needs to use jprobe_return(), which never returns back to the hook, but instead to the original jprobe'd function. The solution is to momentarily pause function_graph tracing before invoking the jprobe hook and re-enable it when returning back to the original jprobe'd function. Fixes: 6794c78243bf ("powerpc64: port of the function graph tracer") Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 7c053f281406..1138fec3dd65 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -514,6 +514,15 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
+ /*
+ * jprobes use jprobe_return() which skips the normal return
+ * path of the function, and this messes up the accounting of the
+ * function graph tracer.
+ *
+ * Pause function graph tracing while performing the jprobe function.
+ */
+ pause_graph_tracing();
return 1;
@@ -536,6 +545,8 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
* saved regs...
memcpy(regs, &kcb->jprobe_saved_regs, sizeof(struct pt_regs));
+ /* It's OK to start function graph tracing again */
+ unpause_graph_tracing();
return 1;