From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
dave.hansen@linux.intel.com, hpa@zytor.com,
andrew.cooper3@citrix.com, chang.seok.bae@intel.com
Subject: [PATCH v1 4/4] x86/fpu: Remove the unnecessary fpstate_reset() invocation
Date: Wed, 21 Jun 2023 05:09:42 -0700 [thread overview]
Message-ID: <20230621120942.121822-5-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20230621120942.121822-1-chang.seok.bae@intel.com>
fpstate_reset() initializes the fpstate container. But, when no state
has been established yet, calling this is not meaningful. In the
fpu__init_system() function, it is called immediately after the legacy
FPU size is determined. So, remove it as not causing any issues.
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
---
The change made by fpstate_reset() can be measured with this:
static struct fpstate fps;
void __init fpu__init_system(struct cpuinfo_x86 *c)
{
memcpy(&fps, ¤t->thread.fpu.__fpstate, sizeof(struct fpstate));
fpstate_reset(¤t->thread.fpu);
if (memcmp(&fps, ¤t->thread.fpu.__fpstate, sizeof(struct fpstate)))
pr_info("fpstate has reason to be inited at %s\n", __func__);
else
pr_info("fpstate has no reason to be inited at %s\n", __func__);
...
}
Although it looks to be a no-op, there might be some unknown
intention behind it. If there is a specific reason for invoking
fpstate_reset() at that point, this should be documented properly
instead of removing it.
---
arch/x86/kernel/fpu/init.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 998a08f17e33..95af3084c4cf 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -213,7 +213,6 @@ static void __init fpu__init_system_xstate_size_legacy(void)
*/
void __init fpu__init_system(void)
{
- fpstate_reset(¤t->thread.fpu);
fpu__init_system_early_generic();
/*
--
2.34.1
prev parent reply other threads:[~2023-06-21 12:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-21 12:09 [PATCH v1 0/4] x86/fpu: a few code cleanup Chang S. Bae
2023-06-21 12:09 ` [PATCH v1 1/4] x86/fpu/xstate: Convert get_xsave_addr() to a static function Chang S. Bae
2023-06-21 12:09 ` [PATCH v1 2/4] x86/fpu/xstate: Simplify xstate_calculate_size() Chang S. Bae
2023-06-21 12:09 ` [PATCH v1 3/4] x86/fpu/xstate: Simplify print_xstate_features() Chang S. Bae
2023-06-21 12:09 ` Chang S. Bae [this message]
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