From: David Hildenbrand <david@redhat.com>
To: Richard Henderson <richard.henderson@linaro.org>, qemu-devel@nongnu.org
Cc: ruixin.bao@ibm.com, jonathan.albrecht@linux.vnet.ibm.com,
cohuck@redhat.com, qemu-s390x@nongnu.org
Subject: Re: [PATCH 2/5] target/s390x: Do not modify cpu state in s390_cpu_get_psw_mask
Date: Tue, 15 Jun 2021 09:49:36 +0200 [thread overview]
Message-ID: <fcc8729a-cf2e-7005-b5d8-8e86fbb3ecd8@redhat.com> (raw)
In-Reply-To: <20210615030744.1252385-3-richard.henderson@linaro.org>
On 15.06.21 05:07, Richard Henderson wrote:
> We want to use this function for debugging, and debug should
> not modify cpu state (even non-architectural cpu state) lest
> we introduce heisenbugs.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> target/s390x/helper.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/target/s390x/helper.c b/target/s390x/helper.c
> index d311903b94..559fc3573f 100644
> --- a/target/s390x/helper.c
> +++ b/target/s390x/helper.c
> @@ -321,12 +321,12 @@ uint64_t s390_cpu_get_psw_mask(CPUS390XState *env)
> uint64_t r = env->psw.mask;
>
> if (tcg_enabled()) {
> - env->cc_op = calc_cc(env, env->cc_op, env->cc_src, env->cc_dst,
> - env->cc_vr);
> + uint64_t cc = calc_cc(env, env->cc_op, env->cc_src,
> + env->cc_dst, env->cc_vr);
>
> + assert(cc <= 3);
> r &= ~PSW_MASK_CC;
> - assert(!(env->cc_op & ~3));
> - r |= (uint64_t)env->cc_op << 44;
> + r |= cc << 44;
> }
>
> return r;
>
I wonder if this can actually suboptimal performance-wise, because we
might be recomputing the same thing. However, I guess it's rather a
corner case
Reviewed-by: David Hildenbrand <david@redhat.com>
--
Thanks,
David / dhildenb
next prev parent reply other threads:[~2021-06-15 7:55 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 3:07 [PATCH 0/5] linux-user/s390x: Fix psw.mask handling in signals Richard Henderson
2021-06-15 3:07 ` [PATCH 1/5] target/s390x: Expose load_psw and get_psw_mask to cpu.h Richard Henderson
2021-06-15 7:47 ` David Hildenbrand
2021-06-15 8:57 ` Alex Bennée
2021-06-15 3:07 ` [PATCH 2/5] target/s390x: Do not modify cpu state in s390_cpu_get_psw_mask Richard Henderson
2021-06-15 7:49 ` David Hildenbrand [this message]
2021-06-15 3:07 ` [PATCH 3/5] target/s390x: Improve s390_cpu_dump_state vs cc_op Richard Henderson
2021-06-15 7:51 ` David Hildenbrand
2021-06-15 3:07 ` [PATCH 4/5] target/s390x: Use s390_cpu_{set_psw, get_psw_mask} in gdbstub Richard Henderson
2021-06-15 7:52 ` David Hildenbrand
2021-06-15 3:07 ` [PATCH 5/5] linux-user/s390x: Save and restore psw.mask properly Richard Henderson
2021-06-15 7:59 ` David Hildenbrand
2021-06-15 9:02 ` [PATCH 0/5] linux-user/s390x: Fix psw.mask handling in signals Christian Borntraeger
2021-06-16 15:00 ` Cornelia Huck
2021-06-15 9:27 ` Alex Bennée
2021-06-15 9:51 ` Alex Bennée
2021-06-16 10:38 ` Cornelia Huck
2021-06-16 14:48 ` Richard Henderson
2021-06-16 14:59 ` Cornelia Huck
2021-06-15 18:03 ` jonathan.albrecht
2021-06-16 15:01 ` Cornelia Huck
2021-06-16 15:22 ` jonathan.albrecht
2021-06-17 8:33 ` Cornelia Huck
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