Re: [PATCH 1/5] target/hppa: Fix unaligned double word accesses for hppa64

From: Helge Deller <deller@gmx.de>
To: Richard Henderson <richard.henderson@linaro.org>,
	deller@kernel.org, qemu-devel@nongnu.org
Subject: Re: [PATCH 1/5] target/hppa: Fix unaligned double word accesses for hppa64
Date: Sun, 3 Mar 2024 06:33:42 +0100	[thread overview]
Message-ID: <34a994a5-f815-415e-90a1-baf37e54a897@gmx.de> (raw)
In-Reply-To: <4f6bbf0f-20d2-4599-a8b3-5fb0a381d6dd@linaro.org>

On 3/3/24 03:10, Richard Henderson wrote:
> On 3/2/24 12:35, deller@kernel.org wrote:
>> From: Guenter Roeck <linux@roeck-us.net>
>>
>> Unaligned 64-bit accesses were found in Linux to clobber carry bits,
>> resulting in bad results if an arithmetic operation involving a
>> carry bit was executed after an unaligned 64-bit operation.
>>
>> hppa 2.0 defines additional carry bits in PSW register bits 32..39.
>> When restoring PSW after executing an unaligned instruction trap,
>> those bits were not cleared and ended up to be active all the time.
>> Clearing bit 32..39 in psw prior to restoring it solves the problem.
>>
>> Fixes: 931adff31478 ("target/hppa: Update cpu_hppa_get/put_psw for hppa64")
>> Cc: Richard Henderson <richard.henderson@linaro.org>
>> Cc: Charlie Jenkins <charlie@rivosinc.com>
>> Cc: Helge Deller <deller@gmx.de>
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
>> ---
>>   target/hppa/helper.c | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/target/hppa/helper.c b/target/hppa/helper.c
>> index 859644c47a..7b798d1227 100644
>> --- a/target/hppa/helper.c
>> +++ b/target/hppa/helper.c
>> @@ -76,7 +76,12 @@ void cpu_hppa_put_psw(CPUHPPAState *env, target_ulong psw)
>>       }
>>       psw &= ~reserved;
>> -    env->psw = psw & ~(PSW_N | PSW_V | PSW_CB);
>> +    if (hppa_is_pa20(env)) {
>> +        env->psw = psw & ~(PSW_N | PSW_V | PSW_CB | 0xff00000000ull);
>> +    } else {
>> +        env->psw = psw & ~(PSW_N | PSW_V | PSW_CB);
>> +    }
>
> https://patchew.org/QEMU/20240217015811.1975411-1-linux@roeck-us.net/
> was the better version.

Oh, yes. Will use that one in the pull request.
Thanks!
Helge