[PATCH 1/1] x86: fix text_poke

[Jiri Slaby <jirislaby@gmail.com>]

David Miller <davem@davemloft.net> wrote:
> From: Jiri Slaby <jirislaby@gmail.com>
> Date: Fri, 25 Apr 2008 19:10:37 +0200
> 
> > I'm going to bisect it, will be back in few hours ;).
> 
> Thanks for all of this hard work and investigation Jiri!

Thanks. Bisected mm down to git-x86.patch, bisected git-x86-latest down to
x86: enhance DEBUG_RODATA support - alternatives
The patch below fixes the problem for me. Comments welcome.

The 0xf0 pattern comes from alternatives_smp_lock:
text_poke(*ptr, ((unsigned char []){0xf0}), 1);

I grepped for it a long time ago, but not in a form of coumpound literal :/.

*Never* more :).

--

kernel_text_address returns true even for modules which is not wanted
in text_poke. Use core_kernel_text instead.

This is a regression introduced in e587cadd8f47e202a30712e2906a65a0606d5865
which caused occasionaly crashes after suspend/resume.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
CC: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
CC: Andi Kleen <andi@firstfloor.org>
CC: pageexec@freemail.hu
CC: H. Peter Anvin <hpa@zytor.com>
CC: Jeremy Fitzhardinge <jeremy@goop.org>
CC: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/kernel/alternative.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 5412fd7..0b074cb 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -515,7 +515,7 @@ void *__kprobes text_poke(void *addr, const void *opcode, size_t len)
 	BUG_ON(len > sizeof(long));
 	BUG_ON((((long)addr + len - 1) & ~(sizeof(long) - 1))
 		- ((long)addr & ~(sizeof(long) - 1)));
-	if (kernel_text_address((unsigned long)addr)) {
+	if (core_kernel_text((unsigned long)addr)) {
 		struct page *pages[2] = { virt_to_page(addr),
 			virt_to_page(addr + PAGE_SIZE) };
 		if (!pages[1])
-- 
1.5.4.5