linux-kernel - [RFC PATCH 01/11] efi: Fix gcc error around _

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Date:   Thu, 25 Jun 2020 16:45:06 -0700
From:   Atish Patra <atish.patra@....com>
To:     linux-kernel@...r.kernel.org
Cc:     Atish Patra <atish.patra@....com>,
        Ard Biesheuvel <ardb@...nel.org>, linux-efi@...r.kernel.org,
        linux-riscv@...ts.infradead.org,
        Masahiro Yamada <masahiroy@...nel.org>,
        Palmer Dabbelt <palmer@...belt.com>,
        Heinrich Schuchardt <xypron.glpk@....de>,
        linux-arm-kernel@...ts.infradead.org
Subject: [RFC PATCH 01/11] efi: 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@....com>
---
 drivers/firmware/efi/libstub/alignedmem.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/libstub/alignedmem.c b/drivers/firmware/efi/libstub/alignedmem.c
index cc89c4d6196f..1de9878ddd3a 100644
--- 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);
-- 
2.24.0