From: Ingo Molnar <mingo@kernel.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Andy Lutomirski <luto@amacapital.net>,
Dave Hansen <dave@sr71.net>, Brian Gerst <brgerst@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
"Chang S . Bae" <chang.seok.bae@intel.com>
Subject: Re: [PATCH tip/x86/fpu 6/6] x86/fpu: shift fpregs_assert_state_consistent() from arch_exit_work() to its caller
Date: Sun, 4 May 2025 10:36:14 +0200 [thread overview]
Message-ID: <aBcm_kkkJi8zGV6W@gmail.com> (raw)
In-Reply-To: <20250503143902.GA9012@redhat.com>
* Oleg Nesterov <oleg@redhat.com> wrote:
> If CONFIG_X86_DEBUG_FPU=Y, arch_exit_to_user_mode_prepare() calls
> arch_exit_work() even if ti_work == 0. There only reason is that we
> want to call fpregs_assert_state_consistent() if TIF_NEED_FPU_LOAD
> is not set.
>
> This looks confusing. arch_exit_to_user_mode_prepare() can just call
> fpregs_assert_state_consistent() unconditionally, it depends on
> CONFIG_X86_DEBUG_FPU and checks TIF_NEED_FPU_LOAD itself.
>
> Signed-off-by: Oleg Nesterov <oleg@redhat.com>
> ---
> arch/x86/include/asm/entry-common.h | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
Thanks Oleg! I've applied these improvements to tip:x86/fpu.
Note that there's still a 32-bit hardened-usercopy regression/crash
that Boris reported against tip:x86/fpu:
https://lore.kernel.org/r/20250503120712.GJaBYG8A-D77MllFZ3@fat_crate.local
Which may result in the subsequent rebasing of your commits - but
otherwise your series looks good to me.
Thanks,
Ingo
next prev parent reply other threads:[~2025-05-04 8:36 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-09 21:11 [PATCH -v5 0/8] sched: Make task_struct::thread constant size, x86/fpu: Remove thread::fpu Ingo Molnar
2025-04-09 21:11 ` [PATCH 1/8] x86/fpu: Introduce the x86_task_fpu() helper method Ingo Molnar
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-09 21:11 ` [PATCH 2/8] x86/fpu: Convert task_struct::thread.fpu accesses to use x86_task_fpu() Ingo Molnar
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-09 21:11 ` [PATCH 3/8] x86/fpu: Make task_struct::thread constant size Ingo Molnar
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-09 21:11 ` [PATCH 4/8] x86/fpu: Remove the thread::fpu pointer Ingo Molnar
2025-04-10 7:39 ` Peter Zijlstra
2025-04-10 10:10 ` Ingo Molnar
2025-04-10 10:30 ` Peter Zijlstra
2025-04-10 10:54 ` [PATCH] x86/fpu: Clarify FPU context cacheline alignment Ingo Molnar
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-10 10:51 ` [PATCH 4/8] x86/fpu: Remove the thread::fpu pointer Ingo Molnar
2025-04-10 14:04 ` Oleg Nesterov
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-09 21:11 ` [PATCH 5/8] x86/fpu: Push 'fpu' pointer calculation into the fpu__drop() call Ingo Molnar
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-09 21:11 ` [PATCH 6/8] x86/fpu: Make sure x86_task_fpu() doesn't get called for PF_KTHREAD|PF_USER_WORKER tasks during exit Ingo Molnar
2025-04-11 15:22 ` Chang S. Bae
2025-04-12 8:37 ` Ingo Molnar
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-09 21:11 ` [PATCH 7/8] x86/fpu: Remove init_task FPU state dependencies, add debugging warning for PF_KTHREAD tasks Ingo Molnar
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-09 21:11 ` [PATCH 8/8] x86/fpu: Use 'fpstate' variable names consistently Ingo Molnar
2025-04-14 7:34 ` [tip: x86/merge] " tip-bot2 for Ingo Molnar
2025-04-22 16:11 ` [PATCH -v5 0/8] sched: Make task_struct::thread constant size, x86/fpu: Remove thread::fpu Oleg Nesterov
2025-04-22 20:09 ` Ingo Molnar
2025-04-22 17:01 ` question about switch_fpu_prepare/switch_fpu_finish Oleg Nesterov
2025-04-22 20:11 ` Ingo Molnar
2025-05-03 14:38 ` [PATCH tip/x86/fpu 1/6] x86/fpu: simplify the switch_fpu_prepare() + switch_fpu_finish() logic Oleg Nesterov
2025-05-04 8:54 ` [tip: x86/fpu] x86/fpu: Simplify " tip-bot2 for Oleg Nesterov
2025-05-03 14:38 ` [PATCH tip/x86/fpu 2/6] x86/fpu: kill x86_init_fpu Oleg Nesterov
2025-05-04 8:54 ` [tip: x86/fpu] x86/fpu: Remove x86_init_fpu tip-bot2 for Oleg Nesterov
2025-05-03 14:38 ` [PATCH tip/x86/fpu 3/6] x86/fpu: kill DEFINE_EVENT(x86_fpu, x86_fpu_copy_src) Oleg Nesterov
2025-05-04 8:54 ` [tip: x86/fpu] x86/fpu: Remove " tip-bot2 for Oleg Nesterov
2025-05-03 14:38 ` [PATCH tip/x86/fpu 4/6] x86/fpu: arch_dup_task_struct: always use memcpy_and_pad() Oleg Nesterov
2025-05-04 8:54 ` [tip: x86/fpu] x86/fpu: Always use memcpy_and_pad() in arch_dup_task_struct() tip-bot2 for Oleg Nesterov
2025-05-03 14:38 ` [PATCH tip/x86/fpu 5/6] x86/fpu: fpu__drop: check TIF_NEED_FPU_LOAD instead of PF_KTHREAD|PF_USER_WORKER Oleg Nesterov
2025-05-04 8:54 ` [tip: x86/fpu] x86/fpu: Check TIF_NEED_FPU_LOAD instead of PF_KTHREAD|PF_USER_WORKER in fpu__drop() tip-bot2 for Oleg Nesterov
2025-05-03 14:39 ` [PATCH tip/x86/fpu 6/6] x86/fpu: shift fpregs_assert_state_consistent() from arch_exit_work() to its caller Oleg Nesterov
2025-05-04 8:36 ` Ingo Molnar [this message]
2025-05-04 8:54 ` [tip: x86/fpu] x86/fpu: Shift " tip-bot2 for Oleg Nesterov
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