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powerpc/function_graph: Simplify with function_graph_enter()

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The function_graph_enter() function does the work of calling the function
graph hook function and the management of the shadow stack, simplifying the
work done in the architecture dependent prepare_ftrace_return().

Have powerpc use the new code, and remove the shadow stack management as well as
having to set up the trace structure.

This is needed to prepare for a fix of a design bug on how the curr_ret_stack
is used.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: stable@kernel.org
Fixes: 03274a3ffb ("tracing/fgraph: Adjust fgraph depth before calling trace return callback")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (VMware) 2018-11-18 17:28:53 -05:00
parent a87532c78d
commit fe60522ec6
1 changed files with 2 additions and 13 deletions
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15
arch/powerpc/kernel/trace/ftrace.c
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@ -950,7 +950,6 @@ int ftrace_disable_ftrace_graph_caller(void)
*/
unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
{
struct ftrace_graph_ent trace;
unsigned long return_hooker;
if (unlikely(ftrace_graph_is_dead()))
@ -961,18 +960,8 @@ unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip)
return_hooker = ppc_function_entry(return_to_handler);
trace.func = ip;
trace.depth = current->curr_ret_stack + 1;
/* Only trace if the calling function expects to */
if (!ftrace_graph_entry(&trace))
goto out;
if (ftrace_push_return_trace(parent, ip, &trace.depth, 0,
NULL) == -EBUSY)
goto out;
parent = return_hooker;
if (!function_graph_enter(parent, ip, 0, NULL))
parent = return_hooker;
out:
return parent;
}