Messages in this thread | | | Date | Wed, 16 Apr 2008 17:22:41 -0400 | From | Mathieu Desnoyers <> | Subject | Re: text_poke, vmap and vmalloc on x86_64 |
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* Mathieu Desnoyers (mathieu.desnoyers@polymtl.ca) wrote: > Hi, > > I am trying to figure out why the following code seems to work fine on > x86_32, but the update fails to happen on x86_64. Any idea why ? From > what I see the memcpy seems to fall in a memory area which is not the > same as the one I test at the end of the function. It only fails for > module addresses, which are vmalloc'd. Once I fix this, I'll be able to > send the patchset. >
Ah, found it. the is_vmalloc_addr() is somewhat misleading because it does not include the vmalloc'd memory for modules, which is in a different address space. I wonder if it has other unknown side-effects.
I used !core_kernel_text() instead.
Mathieu
> (from my own alternative.c) : > > 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; > > if (*((uint8_t *)addr - 1) != BREAKPOINT_INSTRUCTION) { > BUG_ON(len > sizeof(long)); > BUG_ON((((long)addr + len - 1) & ~(sizeof(long) - 1)) > - ((long)addr & ~(sizeof(long) - 1))); > } > if (is_vmalloc_addr(addr)) { > pages[0] = vmalloc_to_page(addr); > pages[1] = vmalloc_to_page(addr + PAGE_SIZE); > } else { > pages[0] = virt_to_page(addr); > pages[1] = virt_to_page(addr + PAGE_SIZE); > } > BUG_ON(!pages[0]); > if (!pages[1]) > nr_pages = 1; > vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL); > BUG_ON(!vaddr); > local_irq_save(flags); > memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len); > local_irq_restore(flags); > vunmap(vaddr); > sync_core(); > /* Could also do a CLFLUSH here to speed up CPU recovery; but > that causes hangs on some VIA CPUs. */ > for (i = 0; i < len; i++) > BUG_ON(((char *)addr)[i] != ((char *)opcode)[i]); > return addr; > } > > Mathieu > > -- > Mathieu Desnoyers > Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
-- 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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