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Commit 9222f606 authored by Jiri Kosina's avatar Jiri Kosina Committed by Thomas Gleixner
Browse files

x86/alternatives: Lockdep-enforce text_mutex in text_poke*() 



text_poke() and text_poke_bp() must be called with text_mutex held.

Put proper lockdep anotation in place instead of just mentioning the
requirement in a comment.

Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/nycvar.YFH.7.76.1808280853520.25787@cbobk.fhfr.pm
parent f12d11c5

arch/x86/kernel/alternative.c

+5 −4
Original line number Diff line number Diff line
@@ -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.