Commit 5e31a068 authored by Naveen N. Rao's avatar Naveen N. Rao Committed by Sasha Levin

powerpc/kprobes: Pause function_graph tracing during jprobes handling

[ Upstream commit a9f8553e ]

This fixes a crash when function_graph and jprobes are used together.
This is essentially commit 237d28db ("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: 6794c782 ("powerpc64: port of the function graph tracer")
Cc: stable@vger.kernel.org # v2.6.30+
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Acked-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarSasha Levin <alexander.levin@verizon.com>
parent 1c9eda6f
......@@ -514,6 +514,15 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
#endif
#endif
/*
* 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();
preempt_enable_no_resched();
return 1;
}
......
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