linux-kernel - [RFC PATCH v4 07/17] powerpc/ftrace: Skip instruction patching if the instructions are the same

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2aba0401f39fee0726e3342b21160d2b05bfa53b.1720942106.git.naveen@kernel.org>
Date: Sun, 14 Jul 2024 13:57:43 +0530
From: Naveen N Rao <naveen@...nel.org>
To: <linuxppc-dev@...ts.ozlabs.org>,
	<linux-trace-kernel@...r.kernel.org>,
	<bpf@...r.kernel.org>,
	linux-kbuild@...r.kernel.org,
	<linux-kernel@...r.kernel.org>
Cc: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Andrii Nakryiko <andrii@...nel.org>,
	Masahiro Yamada <masahiroy@...nel.org>,
	Hari Bathini <hbathini@...ux.ibm.com>,
	Mahesh Salgaonkar <mahesh@...ux.ibm.com>,
	Vishal Chourasia <vishalc@...ux.ibm.com>
Subject: [RFC PATCH v4 07/17] powerpc/ftrace: Skip instruction patching if the instructions are the same

To simplify upcoming changes to ftrace, add a check to skip actual
instruction patching if the old and new instructions are the same. We
still validate that the instruction is what we expect, but don't
actually patch the same instruction again.

Signed-off-by: Naveen N Rao <naveen@...nel.org>
---
 arch/powerpc/kernel/trace/ftrace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index fe0546fbac8e..719517265d39 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -82,7 +82,7 @@ static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_
 {
 	int ret = ftrace_validate_inst(ip, old);
 
-	if (!ret)
+	if (!ret && !ppc_inst_equal(old, new))
 		ret = patch_instruction((u32 *)ip, new);
 
 	return ret;
-- 
2.45.2