diff options
| author | Kees Cook | 2014-04-03 13:29:50 -0700 |
|---|---|---|
| committer | Kees Cook | 2014-10-16 14:38:54 -0700 |
| commit | 80d6b0c2eed2a504f6740cd1f5ea76dc50abfc4d (patch) | |
| tree | 32f6d8a1c5a2250cc3f303df545dfbf52da62d19 /arch/arm/kernel | |
| parent | 1e6b48116a95046ec51f3d40f83aff8b006674d7 (diff) | |
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 <keescook@chromium.org>
Tested-by: Laura Abbott <lauraa@codeaurora.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Diffstat (limited to 'arch/arm/kernel')
| -rw-r--r-- | arch/arm/kernel/ftrace.c | 19 | ||||
| -rw-r--r-- | arch/arm/kernel/machine_kexec.c | 1 | ||||
| -rw-r--r-- | arch/arm/kernel/vmlinux.lds.S | 3 |
3 files changed, 23 insertions, 0 deletions
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 <linux/ftrace.h> #include <linux/uaccess.h> #include <linux/module.h> +#include <linux/stop_machine.h> #include <asm/cacheflush.h> #include <asm/opcodes.h> @@ -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; } diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 8f75250cbe30..4423a565ef6f 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -164,6 +164,7 @@ void machine_kexec(struct kimage *image) reboot_code_buffer = page_address(image->control_code_page); /* Prepare parameters for reboot_code_buffer*/ + set_kernel_text_rw(); kexec_start_address = image->start; kexec_indirection_page = page_list; kexec_mach_type = machine_arch_type; diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index 18fd68a295ea..3afcb6c2cf06 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -120,6 +120,9 @@ SECTIONS ARM_CPU_KEEP(PROC_INFO) } +#ifdef CONFIG_DEBUG_RODATA + . = ALIGN(1<<SECTION_SHIFT); +#endif RO_DATA(PAGE_SIZE) . = ALIGN(4); |