Messages in this thread Patch in this message | | | Date | Mon, 10 Mar 2008 14:36:53 -0400 | From | Mathieu Desnoyers <> | Subject | [PATCH] x86 Fix test_poke for vmalloced pages |
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The shadow vmap for DEBUG_RODATA kernel text modification uses virt_to_page to get the pages from the pointer address.
However, I think vmalloc_to_page would be required in case the page is used for modules.
Since only the core kernel text is marked read-only, use kernel_text_address() to make sure we only shadow map the core kernel text, not modules.
It applies on top of the current x86 git tree.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: Ingo Molnar <mingo@elte.hu> --- arch/x86/kernel/alternative.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
Index: linux-2.6-x86/arch/x86/kernel/alternative.c =================================================================== --- linux-2.6-x86.orig/arch/x86/kernel/alternative.c 2008-03-10 10:34:11.000000000 -0400 +++ linux-2.6-x86/arch/x86/kernel/alternative.c 2008-03-10 10:50:38.000000000 -0400 @@ -511,7 +511,7 @@ 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)) { struct page *pages[2] = { virt_to_page(addr), virt_to_page(addr + PAGE_SIZE) }; if (!pages[1]) @@ -522,6 +522,13 @@ memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len); local_irq_restore(flags); vunmap(vaddr); + } else { + /* + * modules are in vmalloc'ed memory, always writable. + */ + local_irq_save(flags); + memcpy(addr, opcode, len); + local_irq_restore(flags); } sync_core(); /* Could also do a CLFLUSH here to speed up CPU recovery; but -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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