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Commit b7b66baa authored by Mathieu Desnoyers's avatar Mathieu Desnoyers Committed by Ingo Molnar
Browse files

x86: clean up text_poke() 



Clean up the codepath, remove alignment restrictions and do sanity
checking of the end result, to make sure we patched the right site.

Signed-off-by: default avatarMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 8b132ecb

arch/x86/kernel/alternative.c

+18 −20
Original line number Original line Diff line number Diff line
@@ -511,13 +511,17 @@ void *__kprobes text_poke(void *addr, const void *opcode, size_t len) 
	unsigned long flags;

	unsigned long flags;

	char *vaddr;

	char *vaddr;

	int nr_pages = 2;

	int nr_pages = 2;

	struct page *pages[2];

	int i;





	BUG_ON(len > sizeof(long));

	if (!core_kernel_text((unsigned long)addr)) {

	BUG_ON((((long)addr + len - 1) & ~(sizeof(long) - 1))

		pages[0] = vmalloc_to_page(addr);

		- ((long)addr & ~(sizeof(long) - 1)));

		pages[1] = vmalloc_to_page(addr + PAGE_SIZE);

	if (core_kernel_text((unsigned long)addr)) {

	} else {

		struct page *pages[2] = { virt_to_page(addr),

		pages[0] = virt_to_page(addr);

			virt_to_page(addr + PAGE_SIZE) };

		pages[1] = virt_to_page(addr + PAGE_SIZE);

	}

	BUG_ON(!pages[0]);

	if (!pages[1])

	if (!pages[1])

		nr_pages = 1;

		nr_pages = 1;

	vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);

	vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
@@ -526,16 +530,10 @@ void *__kprobes text_poke(void *addr, const void *opcode, size_t len) 
	memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);

	memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);

	local_irq_restore(flags);

	local_irq_restore(flags);

	vunmap(vaddr);

	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();

	sync_core();

	/* Could also do a CLFLUSH here to speed up CPU recovery; but

	/* Could also do a CLFLUSH here to speed up CPU recovery; but

	   that causes hangs on some VIA CPUs. */

	   that causes hangs on some VIA CPUs. */

	for (i = 0; i < len; i++)

		BUG_ON(((char *)addr)[i] != ((char *)opcode)[i]);

	return addr;

	return addr;

}
 
}