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From:   Jisheng Zhang <jszhang@kernel.org>
To:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>
Cc:     linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        Randy Dunlap <rdunlap@infradead.org>,
        kernel test robot <lkp@intel.com>
Subject: [PATCH] riscv: mm: fix truncates issue on RV32
Date:   Mon, 10 Jul 2023 01:10:36 +0800
Message-Id: <20230709171036.1906-1-jszhang@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

lkp reports below sparse warning when building for RV32:
arch/riscv/mm/init.c:1204:48: sparse: warning: cast truncates bits from
constant value (100000000 becomes 0)

IMO, the reason we didn't see this truncates bug in real world is "0"
means MEMBLOCK_ALLOC_ACCESSIBLE in memblock and there's no RV32 HW
with more than 4GB memory.

Fix it anyway to make sparse happy.

Fixes: decf89f86ecd ("riscv: try to allocate crashkern region from 32bit addressible memory")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306080034.SLiCiOMn-lkp@intel.com/
---
 arch/riscv/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 70fb31960b63..9ce504737d18 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -1346,7 +1346,7 @@ static void __init reserve_crashkernel(void)
 	 */
 	crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
 					       search_start,
-					       min(search_end, (unsigned long) SZ_4G));
+					       min(search_end, (unsigned long)(SZ_4G - 1)));
 	if (crash_base == 0) {
 		/* Try again without restricting region to 32bit addressible memory */
 		crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE,
-- 
2.40.1