efi/libstub: Fix gcc error around __umoddi3 for 32 bit builds

32bit gcc doesn't support modulo operation on 64 bit data. It results in
a __umoddi3 error while building EFI for 32 bit.

Use bitwise operations instead of modulo operations to fix the issue.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Link: https://lore.kernel.org/r/20200625234516.31406-2-atish.patra@wdc.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

diff --git a/drivers/firmware/efi/libstub/alignedmem.c b/drivers/firmware/efi/libstub/alignedmem.c
index cc89c4d..1de9878 100644 (file)
--- a/drivers/firmware/efi/libstub/alignedmem.c
+++ b/drivers/firmware/efi/libstub/alignedmem.c
@@ -44,7 +44,7 @@ efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,
        *addr = ALIGN((unsigned long)alloc_addr, align);
 
        if (slack > 0) {
-               int l = (alloc_addr % align) / EFI_PAGE_SIZE;
+               int l = (alloc_addr & (align - 1)) / EFI_PAGE_SIZE;
 
                if (l) {
                        efi_bs_call(free_pages, alloc_addr, slack - l + 1);