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SubjectRe: [PATCH] x86/alternatives: lockdep-enforce text_mutex in text_poke*()
On Tue, 28 Aug 2018 08:55:14 +0200 (CEST)
Jiri Kosina <jikos@kernel.org> wrote:

> From: Jiri Kosina <jkosina@suse.cz>
>
> text_poke() and text_poke_bp() must be called with text_mutex held.
> Let's put proper lockdep anotation in place instead of just mentioning
> the requirement in comment.

Thank you!

Acked-by: Masami Hiramatsu <mhiramat@kernel.org>

>
> Reported-by: Peter Zijlstra <peterz@infradead.org>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
> ---
> arch/x86/kernel/alternative.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
> index 014f214da581..b9d5e7c9ef43 100644
> --- a/arch/x86/kernel/alternative.c
> +++ b/arch/x86/kernel/alternative.c
> @@ -684,8 +684,6 @@ void *__init_or_module text_poke_early(void *addr, const void *opcode,
> * It means the size must be writable atomically and the address must be aligned
> * in a way that permits an atomic write. It also makes sure we fit on a single
> * page.
> - *
> - * Note: Must be called under text_mutex.
> */
> void *text_poke(void *addr, const void *opcode, size_t len)
> {
> @@ -700,6 +698,8 @@ void *text_poke(void *addr, const void *opcode, size_t len)
> */
> BUG_ON(!after_bootmem);
>
> + lockdep_assert_held(&text_mutex);
> +
> if (!core_kernel_text((unsigned long)addr)) {
> pages[0] = vmalloc_to_page(addr);
> pages[1] = vmalloc_to_page(addr + PAGE_SIZE);
> @@ -782,8 +782,6 @@ int poke_int3_handler(struct pt_regs *regs)
> * - replace the first byte (int3) by the first byte of
> * replacing opcode
> * - sync cores
> - *
> - * Note: must be called under text_mutex.
> */
> void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler)
> {
> @@ -792,6 +790,9 @@ void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler)
> bp_int3_handler = handler;
> bp_int3_addr = (u8 *)addr + sizeof(int3);
> bp_patching_in_progress = true;
> +
> + lockdep_assert_held(&text_mutex);
> +
> /*
> * Corresponding read barrier in int3 notifier for making sure the
> * in_progress and handler are correctly ordered wrt. patching.
>
> --
> Jiri Kosina
> SUSE Labs
>


--
Masami Hiramatsu <mhiramat@kernel.org>

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