linux-kernel - [PATCH v2 6/8] execmem: drop writable parameter from execmem_fill_trapping

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Message-ID: <20250709134933.3848895-7-rppt@kernel.org>
Date: Wed,  9 Jul 2025 16:49:31 +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 6/8] execmem: drop writable parameter from execmem_fill_trapping_insns()

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

After update of execmem_cache_free() that made memory writable before
updating it, there is no need to update read only memory, so the writable
parameter to execmem_fill_trapping_insns() is not needed. Drop it.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
---
 arch/x86/mm/init.c      | 8 ++------
 include/linux/execmem.h | 3 +--
 mm/execmem.c            | 4 ++--
 3 files changed, 5 insertions(+), 10 deletions(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 7456df985d96..dbc63f0d538f 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -1063,13 +1063,9 @@ unsigned long arch_max_swapfile_size(void)
 static struct execmem_info execmem_info __ro_after_init;
 
 #ifdef CONFIG_ARCH_HAS_EXECMEM_ROX
-void execmem_fill_trapping_insns(void *ptr, size_t size, bool writeable)
+void execmem_fill_trapping_insns(void *ptr, size_t size)
 {
-	/* fill memory with INT3 instructions */
-	if (writeable)
-		memset(ptr, INT3_INSN_OPCODE, size);
-	else
-		text_poke_set(ptr, INT3_INSN_OPCODE, size);
+	memset(ptr, INT3_INSN_OPCODE, size);
 }
 #endif
 
diff --git a/include/linux/execmem.h b/include/linux/execmem.h
index 4e510d1c609c..fe367bdadc3e 100644
--- a/include/linux/execmem.h
+++ b/include/linux/execmem.h
@@ -60,12 +60,11 @@ enum execmem_range_flags {
  *				 will trap
  * @ptr:	pointer to memory to fill
  * @size:	size of the range to fill
- * @writable:	is the memory poited by @ptr is writable or ROX
  *
  * A hook for architecures to fill execmem ranges with invalid instructions.
  * Architectures that use EXECMEM_ROX_CACHE must implement this.
  */
-void execmem_fill_trapping_insns(void *ptr, size_t size, bool writable);
+void execmem_fill_trapping_insns(void *ptr, size_t size);
 
 /**
  * execmem_restore_rox - restore read-only-execute permissions
diff --git a/mm/execmem.c b/mm/execmem.c
index 04c35c3a9361..0822305413ec 100644
--- a/mm/execmem.c
+++ b/mm/execmem.c
@@ -304,7 +304,7 @@ static int execmem_cache_populate(struct execmem_range *range, size_t size)
 		goto err_free_mem;
 
 	/* fill memory with instructions that will trap */
-	execmem_fill_trapping_insns(p, alloc_size, /* writable = */ true);
+	execmem_fill_trapping_insns(p, alloc_size);
 
 	err = set_memory_rox((unsigned long)p, vm->nr_pages);
 	if (err)
@@ -363,7 +363,7 @@ static int __execmem_cache_free(struct ma_state *mas, void *ptr, gfp_t gfp_mask)
 	if (err)
 		return err;
 
-	execmem_fill_trapping_insns(ptr, size, /* writable = */ true);
+	execmem_fill_trapping_insns(ptr, size);
 	execmem_restore_rox(ptr, size);
 
 	err = execmem_cache_add_locked(ptr, size, gfp_mask);
-- 
2.47.2