Re: [PATCH v7 2/3] ftrace: introduce FTRACE_IP_EXTENSION
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: 2019-12-26 02:45:54
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On Wed, 25 Dec 2019 09:42:52 +0000 Jisheng Zhang [off-list ref] wrote:
On some architectures, the DYNAMIC_FTRACE_WITH_REGS is implemented by gcc's -fpatchable-function-entry option. Take arm64 for example, arm64 makes use of GCC -fpatchable-function-entry=2 option to insert two nops. When the function is traced, the first nop will be modified to the LR saver, then the second nop to "bl <ftrace-entry>". we need to update ftrace_location() to recognise these two instructions as being part of ftrace. To do this, we introduce FTRACE_IP_EXTENSION to let ftrace_location search IP, IP + FTRACE_IP_EXTENSION range.
Looks good to me. Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Thanks!
quoted hunk ↗ jump to hunk
Signed-off-by: Jisheng Zhang <redacted> Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- include/linux/ftrace.h | 4 ++++ kernel/trace/ftrace.c | 2 +- 2 files changed, 5 insertions(+), 1 deletion(-)diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 7247d35c3d16..05a03b2a2f39 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h@@ -20,6 +20,10 @@ #include <asm/ftrace.h> +#ifndef FTRACE_IP_EXTENSION +#define FTRACE_IP_EXTENSION 0 +#endif + /* * If the arch supports passing the variable contents of * function_trace_op as the third parameter back from thediff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 74439ab5c2b6..a8cfea502369 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c@@ -1590,7 +1590,7 @@ unsigned long ftrace_location_range(unsigned long start, unsigned long end) */ unsigned long ftrace_location(unsigned long ip) { - return ftrace_location_range(ip, ip); + return ftrace_location_range(ip, ip + FTRACE_IP_EXTENSION); } /**-- 2.24.1
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