riscv: mm: fix truncation warning on RV32

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/
Link: https://lore.kernel.org/r/20230709171036.1906-1-jszhang@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 70fb319..9ce5047 100644 (file)
--- 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,