[PATCH] riscv: mm: fix truncates issue on RV32

[PATCH] riscv: mm: fix truncates issue on RV32

[Jisheng Zhang]

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


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Re: [PATCH] riscv: mm: fix truncates issue on RV32

[Palmer Dabbelt]

On Mon, 10 Jul 2023 01:10:36 +0800, Jisheng Zhang wrote:
> 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.
> 
> [...]

Applied, thanks!

[1/1] riscv: mm: fix truncates issue on RV32
      https://git.kernel.org/palmer/c/b690e266dae2

Best regards,
-- 
Palmer Dabbelt <palmer@rivosinc.com>


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Re: [PATCH] riscv: mm: fix truncates issue on RV32

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (fixes)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Mon, 10 Jul 2023 01:10:36 +0800 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - riscv: mm: fix truncates issue on RV32
    https://git.kernel.org/riscv/c/b690e266dae2

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



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