From: "Mike Rapoport (Microsoft)" <rppt@xxxxxxxxxx>
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.
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Mike Rapoport (Microsoft) <rppt@xxxxxxxxxx>
---
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
