Messages in this thread | | | Date | Wed, 16 Apr 2008 16:10:45 -0400 | From | Mathieu Desnoyers <> | Subject | text_poke, vmap and vmalloc on x86_64 |
| |
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.
(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
| |