[BUGFIX PATCH -tip] x86: Fix fixmap page order in text_poke()

Masami Hiramatsu
2009-07-01T21:00:16Z

Since the fixmap pages are assigned higher address to lower, text_poke()
has to use it with inverted order (FIX_TEXT_POKE1 to FIX_TEXT_POKE0).

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 | 14 +++++++++-----
1 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index f576587..4d8b40b 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -527,14 +527,18 @@ void *__kprobes text_poke(void *addr, const void *opcode, size_t len)
}
BUG_ON(!pages[0]);
local_irq_save(flags);
- set_fixmap(FIX_TEXT_POKE0, page_to_phys(pages[0]));
+ /*
+ * Since the fixmaps are assinged from higher address to lower,
+ * we use FIX_TEXT_POKE1 first, and FIX_TEXT_POKE0 second.
+ */
+ set_fixmap(FIX_TEXT_POKE1, 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);
+ set_fixmap(FIX_TEXT_POKE0, page_to_phys(pages[1]));
+ vaddr = (char *)fix_to_virt(FIX_TEXT_POKE1);
memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);
- clear_fixmap(FIX_TEXT_POKE0);
+ clear_fixmap(FIX_TEXT_POKE1);
if (pages[1])
- clear_fixmap(FIX_TEXT_POKE1);
+ clear_fixmap(FIX_TEXT_POKE0);
local_flush_tlb();
sync_core();
/* Could also do a CLFLUSH here to speed up CPU recovery; but

--
Masami Hiramatsu

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

e-mail: mhiramat@redhat.com