From: AKASHI Takahiro Date: Wed, 30 Apr 2014 09:54:34 +0000 (+0100) Subject: arm64: ftrace: Add dynamic ftrace support X-Git-Tag: omap-for-v3.16/fixes-against-rc1~91^2~10^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bd7d38dbdf356e75eb3b1699158c9b8021fd6784;p=pandora-kernel.git arm64: ftrace: Add dynamic ftrace support This patch allows "dynamic ftrace" if CONFIG_DYNAMIC_FTRACE is enabled. Here we can turn on and off tracing dynamically per-function base. On arm64, this is done by patching single branch instruction to _mcount() inserted by gcc -pg option. The branch is replaced to NOP initially at kernel start up, and later on, NOP to branch to ftrace_caller() when enabled or branch to NOP when disabled. Please note that ftrace_caller() is a counterpart of _mcount() in case of 'static' ftrace. More details on architecture specific requirements are described in Documentation/trace/ftrace-design.txt. Acked-by: Will Deacon Signed-off-by: AKASHI Takahiro Signed-off-by: Will Deacon --- Reading git-diff-tree failed