linux-kernel - [PATCH v2 8/8] x86/ftrace: enable EXECMEM_ROX

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Message-ID: <20250709134933.3848895-9-rppt@kernel.org>
Date: Wed,  9 Jul 2025 16:49:33 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Daniel Gomez <da.gomez@...sung.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Ingo Molnar <mingo@...hat.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mike Rapoport <rppt@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Petr Pavlu <petr.pavlu@...e.com>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Yann Ylavic <ylavic.dev@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	linux-modules@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	x86@...nel.org
Subject: [PATCH v2 8/8] x86/ftrace: enable EXECMEM_ROX_CACHE for ftrace allocations

From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>

For the most part ftrace uses text poking and can handle ROX memory.
The only place that requires writable memory is create_trampoline() that
updates the allocated memory and in the end makes it ROX.

Use execmem_alloc_rw() in x86::ftrace::alloc_tramp() and enable ROX cache
for EXECMEM_FTRACE when configuration and CPU features allow that.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
---
 arch/x86/kernel/ftrace.c | 2 +-
 arch/x86/mm/init.c       | 9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 252e82bcfd2f..4450acec9390 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -263,7 +263,7 @@ void arch_ftrace_update_code(int command)
 
 static inline void *alloc_tramp(unsigned long size)
 {
-	return execmem_alloc(EXECMEM_FTRACE, size);
+	return execmem_alloc_rw(EXECMEM_FTRACE, size);
 }
 static inline void tramp_free(void *tramp)
 {
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 442fafd8ff52..bb57e93b4caf 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -1105,7 +1105,14 @@ struct execmem_info __init *execmem_arch_setup(void)
 				.pgprot	= PAGE_KERNEL_ROX,
 				.alignment = MODULE_ALIGN,
 			},
-			[EXECMEM_FTRACE ... EXECMEM_BPF] = {
+			[EXECMEM_FTRACE] = {
+				.flags	= flags,
+				.start	= start,
+				.end	= MODULES_END,
+				.pgprot	= pgprot,
+				.alignment = MODULE_ALIGN,
+			},
+			[EXECMEM_BPF] = {
 				.flags	= EXECMEM_KASAN_SHADOW,
 				.start	= start,
 				.end	= MODULES_END,
-- 
2.47.2