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From:   "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
To:     Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Florent Revest <revest@chromium.org>
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        LKML <linux-kernel@vger.kernel.org>,
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        Jiri Olsa <jolsa@kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Alan Maguire <alan.maguire@oracle.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Guo Ren <guoren@kernel.org>
Subject: [PATCH v3 02/33] x86: tracing: Add ftrace_regs definition in the header
Date:   Mon, 27 Nov 2023 22:53:18 +0900
Message-Id: <170109319767.343914.9766180271697584732.stgit@devnote2>
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From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Add ftrace_regs definition for x86_64 in the ftrace header to
clarify what register will be accessible from ftrace_regs.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 Changes in v3:
  - Add rip to be saved.
 Changes in v2:
  - Newly added.
---
 arch/x86/include/asm/ftrace.h |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 897cf02c20b1..415cf7a2ec2c 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -36,6 +36,12 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
 
 #ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
 struct ftrace_regs {
+	/*
+	 * On the x86_64, the ftrace_regs saves;
+	 * rax, rcx, rdx, rdi, rsi, r8, r9, rbp, rip and rsp.
+	 * Also orig_ax is used for passing direct trampoline address.
+	 * x86_32 doesn't support ftrace_regs.
+	 */
 	struct pt_regs		regs;
 };