ARM: KVM: fix warning in mmu.c

Compiling with THP enabled leads to the following warning:

arch/arm/kvm/mmu.c: In function ‘unmap_range’:
arch/arm/kvm/mmu.c:177:39: warning: ‘pte’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   if (kvm_pmd_huge(*pmd) || page_empty(pte)) {
                                        ^
Code inspection reveals that these two cases are mutually exclusive,
so GCC is a bit overzealous here. Silence it anyway by initializing
pte to NULL and testing it later on.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
index d7e998c6a08fe9f4a2d060c39c6c2f34953489d7..80bb1e6c2c2906d0764ae5b696e72053c8faff9c 100644 (file)
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -144,6 +144,7 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
        while (addr < end) {
                pgd = pgdp + pgd_index(addr);
                pud = pud_offset(pgd, addr);
+               pte = NULL;
                if (pud_none(*pud)) {
                        addr = kvm_pud_addr_end(addr, end);
                        continue;
@@ -174,7 +175,7 @@ static void unmap_range(struct kvm *kvm, pgd_t *pgdp,
                /*
                 * If the pmd entry is to be cleared, walk back up the ladder
                 */
-               if (kvm_pmd_huge(*pmd) || page_empty(pte)) {
+               if (kvm_pmd_huge(*pmd) || (pte && page_empty(pte))) {
                        clear_pmd_entry(kvm, pmd, addr);
                        next = kvm_pmd_addr_end(addr, end);
                        if (page_empty(pmd) && !page_empty(pud)) {