Messages in this thread Patch in this message | | | Date | Fri, 13 Feb 2009 09:27:05 -0500 | From | Mathieu Desnoyers <> | Subject | [PATCH] x86: text_poke might sleep |
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* Peter Zijlstra (peterz@infradead.org) wrote:
> Now text_poke() uses local_irq_save/restore(), which conveys that it can > be called with IRQs disabled, which is exactly what happens in the trace > above, however we just established that vmap/vunmap() are not irq-safe. > > Anybody got an idea on how to fix this?
Add might_sleep(), comments and use local_irq_disable/enable in text_poke so people are really aware that it uses vmap, which sleeps.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> CC: Ingo Molnar <mingo@elte.hu> CC: Peter Zijlstra <peterz@infradead.org> CC: Nick Piggin <npiggin@suse.de> CC: akpm <akpm@linux-foundation.org> --- arch/x86/kernel/alternative.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
Index: linux-2.6-lttng/arch/x86/kernel/alternative.c =================================================================== --- linux-2.6-lttng.orig/arch/x86/kernel/alternative.c 2009-02-13 09:02:20.000000000 -0500 +++ linux-2.6-lttng/arch/x86/kernel/alternative.c 2009-02-13 09:05:05.000000000 -0500 @@ -494,16 +494,16 @@ void *text_poke_early(void *addr, const * Only atomic text poke/set should be allowed when not doing early patching. * 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. + * page. Should be called with preemption enabled. */ void *__kprobes text_poke(void *addr, const void *opcode, size_t len) { - unsigned long flags; char *vaddr; int nr_pages = 2; struct page *pages[2]; int i; + might_sleep(); if (!core_kernel_text((unsigned long)addr)) { pages[0] = vmalloc_to_page(addr); pages[1] = vmalloc_to_page(addr + PAGE_SIZE); @@ -517,9 +517,9 @@ void *__kprobes text_poke(void *addr, co nr_pages = 1; vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL); BUG_ON(!vaddr); - local_irq_save(flags); + local_irq_disable(); memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len); - local_irq_restore(flags); + local_irq_enable(); vunmap(vaddr); sync_core(); /* Could also do a CLFLUSH here to speed up CPU recovery; but -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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