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Commit 3cebbafd authored by Chris Metcalf's avatar Chris Metcalf
Browse files

arch/tile: fix two bugs in the backtracer code 



The first is that we were using an incorrect hand-rolled variant
of __kernel_text_address() which didn't handle module PCs.  We now
just use the standard API.

The second was that we weren't accounting for the three-level
page table when we were trying to pre-verify the addresses on
the 64-bit TILE-Gx processor; we now do that correctly.

Signed-off-by: default avatarChris Metcalf <cmetcalf@tilera.com>
parent 6c4d1126

arch/tile/kernel/stack.c

+19 −9
Original line number Diff line number Diff line
@@ -44,13 +44,6 @@ static int in_kernel_stack(struct KBacktraceIterator *kbt, VirtualAddress sp) 
	return sp >= kstack_base && sp < kstack_base + THREAD_SIZE;

}



/* Is address in the specified kernel code? */

static int in_kernel_text(VirtualAddress address)

{

	return (address >= MEM_SV_INTRPT &&

		address < MEM_SV_INTRPT + HPAGE_SIZE);

}



/* Is address valid for reading? */

static int valid_address(struct KBacktraceIterator *kbt, VirtualAddress address)

{
@@ -63,6 +56,23 @@ static int valid_address(struct KBacktraceIterator *kbt, VirtualAddress address) 
	if (l1_pgtable == NULL)

		return 0;	/* can't read user space in other tasks */



#ifdef CONFIG_64BIT

	/* Find the real l1_pgtable by looking in the l0_pgtable. */

	pte = l1_pgtable[HV_L0_INDEX(address)];

	if (!hv_pte_get_present(pte))

		return 0;

	pfn = hv_pte_get_pfn(pte);

	if (pte_huge(pte)) {

		if (!pfn_valid(pfn)) {

			pr_err("L0 huge page has bad pfn %#lx\n", pfn);

			return 0;

		}

		return hv_pte_get_present(pte) && hv_pte_get_readable(pte);

	}

	page = pfn_to_page(pfn);

	BUG_ON(PageHighMem(page));  /* No HIGHMEM on 64-bit. */

	l1_pgtable = (HV_PTE *)pfn_to_kaddr(pfn);

#endif

	pte = l1_pgtable[HV_L1_INDEX(address)];

	if (!hv_pte_get_present(pte))

		return 0;
@@ -92,7 +102,7 @@ static bool read_memory_func(void *result, VirtualAddress address, 
{

	int retval;

	struct KBacktraceIterator *kbt = (struct KBacktraceIterator *)vkbt;

	if (in_kernel_text(address)) {

	if (__kernel_text_address(address)) {

		/* OK to read kernel code. */

	} else if (address >= PAGE_OFFSET) {

		/* We only tolerate kernel-space reads of this task's stack */
@@ -132,7 +142,7 @@ static struct pt_regs *valid_fault_handler(struct KBacktraceIterator* kbt) 
		}

	}

	if (EX1_PL(p->ex1) == KERNEL_PL &&

	    in_kernel_text(p->pc) &&

	    __kernel_text_address(p->pc) &&

	    in_kernel_stack(kbt, p->sp) &&

	    p->sp >= sp) {

		if (kbt->verbose)