linux-kernel - [PATCH 11/13] ftrace: Add swap_func to ftrace_process

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Date:   Thu,  1 Jun 2023 13:12:55 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        "David S. Miller" <davem@...emloft.net>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Helge Deller <deller@....de>,
        Huacai Chen <chenhuacai@...nel.org>,
        Kent Overstreet <kent.overstreet@...ux.dev>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Mike Rapoport <rppt@...nel.org>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Russell King <linux@...linux.org.uk>,
        Song Liu <song@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Will Deacon <will@...nel.org>, bpf@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
        linux-mm@...ck.org, linux-modules@...r.kernel.org,
        linux-parisc@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-s390@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, loongarch@...ts.linux.dev,
        netdev@...r.kernel.org, sparclinux@...r.kernel.org, x86@...nel.org
Subject: [PATCH 11/13] ftrace: Add swap_func to ftrace_process_locs()

From: Song Liu <song@...nel.org>

ftrace_process_locs sorts module mcount, which is inside RO memory. Add a
ftrace_swap_func so that archs can use RO-memory-poke function to do the
sorting.

Signed-off-by: Song Liu <song@...nel.org>
---
 include/linux/ftrace.h |  2 ++
 kernel/trace/ftrace.c  | 13 ++++++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index b23bdd414394..fe443b8ed32c 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1166,4 +1166,6 @@ unsigned long arch_syscall_addr(int nr);
 
 #endif /* CONFIG_FTRACE_SYSCALLS */
 
+void ftrace_swap_func(void *a, void *b, int n);
+
 #endif /* _LINUX_FTRACE_H */
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 764668467155..f5ddc9d4cfb6 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6430,6 +6430,17 @@ static void test_is_sorted(unsigned long *start, unsigned long count)
 }
 #endif
 
+void __weak ftrace_swap_func(void *a, void *b, int n)
+{
+	unsigned long t;
+
+	WARN_ON_ONCE(n != sizeof(t));
+
+	t = *((unsigned long *)a);
+	*(unsigned long *)a = *(unsigned long *)b;
+	*(unsigned long *)b = t;
+}
+
 static int ftrace_process_locs(struct module *mod,
 			       unsigned long *start,
 			       unsigned long *end)
@@ -6455,7 +6466,7 @@ static int ftrace_process_locs(struct module *mod,
 	 */
 	if (!IS_ENABLED(CONFIG_BUILDTIME_MCOUNT_SORT) || mod) {
 		sort(start, count, sizeof(*start),
-		     ftrace_cmp_ips, NULL);
+		     ftrace_cmp_ips, ftrace_swap_func);
 	} else {
 		test_is_sorted(start, count);
 	}
-- 
2.35.1