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
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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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