linux-kernel - Re: [PATCH v4] selftests: riscv: add misaligned access testing

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Message-ID: <mvma55cgm63.fsf@suse.de>
Date: Thu, 10 Jul 2025 16:23:00 +0200
From: Andreas Schwab <schwab@...e.de>
To: Clément Léger <cleger@...osinc.com>
Cc: linux-kernel@...r.kernel.org,  linux-kselftest@...r.kernel.org,
  linux-riscv@...ts.infradead.org,  Palmer Dabbelt <palmer@...belt.com>,
  Paul Walmsley <paul.walmsley@...ive.com>,  Shuah Khan <shuah@...nel.org>,
  Alexandre Ghiti <alex@...ti.fr>
Subject: Re: [PATCH v4] selftests: riscv: add misaligned access testing

On Jul 10 2025, Clément Léger wrote:

> On 10/07/2025 15:53, Andreas Schwab wrote:
>> On Jul 10 2025, Clément Léger wrote:
>> 
>>> This selftest tests all the currently emulated instructions (except for
>>> the RV32 compressed ones which are left as a future exercise for a RV32
>>> user). For the FPU instructions, all the FPU registers are tested.
>> 
>> If that didn't catch the missing sign extension that I just fixed in
>> <https://lore.kernel.org/linux-riscv/mvmikk0goil.fsf@suse.de>, you
>> should consider extending the tests.
>> 
>
> Hi Andreas, you link doesn't work and I didn't find anything about sign
> extension except a patch you wrote for arch_cmpxg().

lore.k.o is currently down, here's the patch I have sent:

>From 77c8255da24ee4fac54e2371594d7210d1ddee19 Mon Sep 17 00:00:00 2001
From: Andreas Schwab <schwab@...e.de>
Date: Thu, 10 Jul 2025 13:52:35 +0200
Subject: [PATCH] riscv: traps_misaligned: properly sign extend value in
 misaligned load handler

Add missing cast to signed long.

Signed-off-by: Andreas Schwab <schwab@...e.de>
---
 arch/riscv/kernel/traps_misaligned.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps_misaligned.c
index 93043924fe6c..f760e4fcc052 100644
--- a/arch/riscv/kernel/traps_misaligned.c
+++ b/arch/riscv/kernel/traps_misaligned.c
@@ -461,7 +461,7 @@ static int handle_scalar_misaligned_load(struct pt_regs *regs)
 	}
 
 	if (!fp)
-		SET_RD(insn, regs, val.data_ulong << shift >> shift);
+		SET_RD(insn, regs, (long)(val.data_ulong << shift) >> shift);
 	else if (len == 8)
 		set_f64_rd(insn, regs, val.data_u64);
 	else
-- 
2.50.0


-- 
Andreas Schwab, SUSE Labs, schwab@...e.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
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