lkml.org 
[lkml]   [2009]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH -tip 5/4] Expands irq-off region in text_poke()
Mathieu Desnoyers wrote:
>>> I think irq off should cover the BUG_ON too. This safety check assumes
>>> we are the only ones modifying "addr".
>> I think others don't change without text_mutex, don't it?
>>
>
> They shouldn't, but given we decided to grow the irq off region to
> contain all the code that needs to be executed atomically, it should
> also contain the BUG_ON, because it is expected to be as atomic as the
> rest of the code.

Hm, sure, I updated the delta patch.

Expand irq-off region to cover fixmap using code and cache synchronizing.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/alternative.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6-tip/arch/x86/kernel/alternative.c
===================================================================
--- linux-2.6-tip.orig/arch/x86/kernel/alternative.c
+++ linux-2.6-tip/arch/x86/kernel/alternative.c
@@ -526,13 +526,12 @@ void *__kprobes text_poke(void *addr, co
pages[1] = virt_to_page(addr + PAGE_SIZE);
}
BUG_ON(!pages[0]);
+ local_irq_save(flags);
set_fixmap(FIX_TEXT_POKE0, page_to_phys(pages[0]));
if (pages[1])
set_fixmap(FIX_TEXT_POKE1, page_to_phys(pages[1]));
vaddr = (char *)fix_to_virt(FIX_TEXT_POKE0);
- local_irq_save(flags);
memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);
- local_irq_restore(flags);
clear_fixmap(FIX_TEXT_POKE0);
if (pages[1])
clear_fixmap(FIX_TEXT_POKE1);
@@ -542,5 +541,6 @@ void *__kprobes text_poke(void *addr, co
that causes hangs on some VIA CPUs. */
for (i = 0; i < len; i++)
BUG_ON(((char *)addr)[i] != ((char *)opcode)[i]);
+ local_irq_restore(flags);
return addr;
}
--
Masami Hiramatsu

Software Engineer
Hitachi Computer Products (America) Inc.
Software Solutions Division

e-mail: mhiramat@redhat.com



\
 
 \ /
  Last update: 2009-03-09 18:43    [from the cache]
©2003-2011 Jasper Spaans