[PATCH v3 1/6] arm64: Add ftrace support

On Wednesday 12 February 2014, Takahiro Akashi wrote:

quoted

If I build a large "randconfig" kernel or "allyesconfig", the kernel image
size exceeds 32MB, which means I can no longer link callers with a 26
bit signed immediate argument like the "bl _mcount" here. For any other
function calls, "gcc -mlong-calls" can be used to work around this, but
this particular instance is created by inserting assembly statements
into the output without considering the long-call options. Is there
a way to get the kernel to link anyway?

I hope that this won't happen on arm64 because a branch offset range is
+/- 128MB.

Yes, we should be safe for the next decade on arm64. My question was really
about arm32 here, hoping someone has an idea.

quoted

quoted

+#ifdef CONFIG_FUNCTION_GRAPH_TRACER

Here, again, you an remove the #ifdef by making the entire file built
only for CONFIG_FUNCTION_GRAPH_TRACER.

You're right as far as patch [1/6] is concerned, but once patch [2/6] is
applied,
this file (ftrace.c) may be compiled even if CONFIG_FUNCTION_GRAPH_TRACER
is not enabled. (That is CONFIG_DYNAMIC_FTRACE.)
Sorry for any confusion by poorly-divided patchset.

No, that was my fault. I saw it later after I had already sent out the
message.

	Arnd