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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>
Cc:     linux-trace-kernel@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Martin KaFai Lau <martin.lau@linux.dev>,
        bpf <bpf@vger.kernel.org>, Sven Schnelle <svens@linux.ibm.com>,
        Alexei Starovoitov <ast@kernel.org>,
        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>
Subject: [RFC PATCH v2 5/6] ftrace: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
Date:   Mon,  7 Aug 2023 15:49:22 +0900
Message-Id: <169139096244.324433.7237290521765120297.stgit@devnote2>
In-Reply-To: <169139090386.324433.6412259486776991296.stgit@devnote2>
References: <169139090386.324433.6412259486776991296.stgit@devnote2>
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From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Add ftrace_partial_regs() which converts the ftrace_regas to pt_regs.
If the architecture defines its own ftrace_regs, this copies partial
registers to pt_regs and returns it. If not, ftrace_regs is the same as
pt_regs and ftrace_partial_regs() will return ftrace_regs::regs.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 arch/arm64/include/asm/ftrace.h |   11 +++++++++++
 include/linux/ftrace.h          |   11 +++++++++++
 2 files changed, 22 insertions(+)

diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index ab158196480c..b108cd6718cf 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -137,6 +137,17 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs)
 	fregs->pc = fregs->lr;
 }
 
+static __always_inline struct pt_regs *
+ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+	memcpy(regs->regs, fregs->regs, sizeof(u64) * 10);
+	regs->sp = fregs->sp;
+	regs->pc = fregs->pc;
+	regs->x[29] = fregs->fp;
+	regs->x[30] = fregs->lr;
+	return regs;
+}
+
 int ftrace_regs_query_register_offset(const char *name);
 
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 3fb94a1a2461..7f45654441b7 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -155,6 +155,17 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs
 	return arch_ftrace_get_regs(fregs);
 }
 
+#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \
+	defined(CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS)
+
+static __always_inline struct pt_regs *
+ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+	return arch_ftrace_get_regs((struct ftrace_regs *)fregs);
+}
+
+#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS */
+
 /*
  * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs.
  * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.