[PATCH v5 03/12] tracing: Add a comment about the requirements of the ftrace_regs

Masami Hiramatsu (Google)
2023-09-24T13:37:26Z

Add a comment about the requirements of the ftrace_regs if it is
implemented on the arch-dependent code with
CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
include/linux/ftrace.h | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index e8921871ef9a..5da70f238645 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -118,6 +118,14 @@ extern int ftrace_enabled;

#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS

+/*
+ * The ftrace_regs will be just a wrapper of the pt_regs if
+ * CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS is not set. If it is set on an
+ * architecture, it has to define the ftrace_regs data structure.
+ * The ftrace_regs is expected to save the registers for the function
+ * arguments, the registers for stack dump (e.g. stack pointer and the
+ * frame pointer) and the instruction pointer for reference.
+ */
struct ftrace_regs {
struct pt_regs regs;
};