Subject: [PATCH v3 8/8] x86/module: enable ROX caches for module text

From: Mike Rapoport <[email-masked]>
Date: Mon, 9 Sep 2024 09:47:30 +0300

From: "Mike Rapoport (Microsoft)" <[email-masked]>

Enable execmem's cache of PMD_SIZE'ed pages mapped as ROX for module
text allocations.

Signed-off-by: Mike Rapoport (Microsoft) <[email-masked]>
---
 arch/x86/mm/init.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index eb503f53c319..a0ec99fb9385 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -1053,6 +1053,15 @@ unsigned long arch_max_swapfile_size(void)
 #ifdef CONFIG_EXECMEM
 static struct execmem_info execmem_info __ro_after_init;
 
+static void execmem_fill_trapping_insns(void *ptr, size_t size, bool writeable)
+{
+	/* fill memory with INT3 instructions */
+	if (writeable)
+		memset(ptr, INT3_INSN_OPCODE, size);
+	else
+		text_poke_set(ptr, INT3_INSN_OPCODE, size);
+}
+
 struct execmem_info __init *execmem_arch_setup(void)
 {
 	unsigned long start, offset = 0;
@@ -1063,8 +1072,23 @@ struct execmem_info __init *execmem_arch_setup(void)
 	start = MODULES_VADDR + offset;
 
 	execmem_info = (struct execmem_info){
+		.fill_trapping_insns = execmem_fill_trapping_insns,
 		.ranges = {
-			[EXECMEM_DEFAULT] = {
+			[EXECMEM_MODULE_TEXT] = {
+				.flags	= EXECMEM_KASAN_SHADOW | EXECMEM_ROX_CACHE,
+				.start	= start,
+				.end	= MODULES_END,
+				.pgprot	= PAGE_KERNEL_ROX,
+				.alignment = MODULE_ALIGN,
+			},
+			[EXECMEM_KPROBES ... EXECMEM_BPF] = {
+				.flags	= EXECMEM_KASAN_SHADOW,
+				.start	= start,
+				.end	= MODULES_END,
+				.pgprot	= PAGE_KERNEL,
+				.alignment = MODULE_ALIGN,
+			},
+			[EXECMEM_MODULE_DATA] = {
 				.flags	= EXECMEM_KASAN_SHADOW,
 				.start	= start,
 				.end	= MODULES_END,
-- 
2.43.0