From 80d6b0c2eed2a504f6740cd1f5ea76dc50abfc4d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 3 Apr 2014 13:29:50 -0700 Subject: ARM: mm: allow text and rodata sections to be read-only This introduces CONFIG_DEBUG_RODATA, making kernel text and rodata read-only. Additionally, this splits rodata from text so that rodata can also be NX, which may lead to wasted memory when aligning to SECTION_SIZE. The read-only areas are made writable during ftrace updates and kexec. Signed-off-by: Kees Cook Tested-by: Laura Abbott Acked-by: Nicolas Pitre --- arch/arm/kernel/ftrace.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'arch/arm/kernel/ftrace.c') diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index af9a8a927a4e..b8c75e45a950 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -35,6 +36,22 @@ #define OLD_NOP 0xe1a00000 /* mov r0, r0 */ +static int __ftrace_modify_code(void *data) +{ + int *command = data; + + set_kernel_text_rw(); + ftrace_modify_all_code(*command); + set_kernel_text_ro(); + + return 0; +} + +void arch_ftrace_update_code(int command) +{ + stop_machine(__ftrace_modify_code, &command, NULL); +} + static unsigned long ftrace_nop_replace(struct dyn_ftrace *rec) { return rec->arch.old_mcount ? OLD_NOP : NOP; @@ -73,6 +90,8 @@ int ftrace_arch_code_modify_prepare(void) int ftrace_arch_code_modify_post_process(void) { set_all_modules_text_ro(); + /* Make sure any TLB misses during machine stop are cleared. */ + flush_tlb_all(); return 0; } -- cgit