[PATCH v2 8/8] x86/module: enable ROX caches for module text

Mike Rapoport
2024-08-26T06:57:56Z

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

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
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