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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, "Chang S. Bae" <chang.seok.bae@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Arjan van de Ven <arjan@linux.intel.com>,
	kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Subject: [patch 02/31] x86/fpu: Update stale comments
Date: Tue, 12 Oct 2021 02:00:00 +0200 (CEST)	[thread overview]
Message-ID: <20211011223610.404292507@linutronix.de> (raw)
In-Reply-To: 20211011215813.558681373@linutronix.de

copy_fpstate_to_sigframe() does not have a slow path anymore. Neither does
the !ia32 restore in __fpu_restore_sig().

Update the comments accordingly.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/fpu/signal.c |   13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -155,10 +155,8 @@ static inline int copy_fpregs_to_sigfram
  *	buf == buf_fx for 64-bit frames and 32-bit fsave frame.
  *	buf != buf_fx for 32-bit frames with fxstate.
  *
- * Try to save it directly to the user frame with disabled page fault handler.
- * If this fails then do the slow path where the FPU state is first saved to
- * task's fpu->state and then copy it to the user frame pointed to by the
- * aligned pointer 'buf_fx'.
+ * Save it directly to the user frame with disabled page fault handler. If
+ * that faults, try to clear the frame which handles the page fault.
  *
  * If this is a 32-bit frame with fxstate, put a fsave header before
  * the aligned state at 'buf_fx'.
@@ -334,12 +332,7 @@ static bool __fpu_restore_sig(void __use
 	}
 
 	if (likely(!ia32_fxstate)) {
-		/*
-		 * Attempt to restore the FPU registers directly from user
-		 * memory. For that to succeed, the user access cannot cause page
-		 * faults. If it does, fall back to the slow path below, going
-		 * through the kernel buffer with the enabled pagefault handler.
-		 */
+		/* Restore the FPU registers directly from user memory. */
 		return restore_fpregs_from_user(buf_fx, user_xfeatures, fx_only,
 						state_size);
 	}


  parent reply	other threads:[~2021-10-12  0:08 UTC|newest]

Thread overview: 96+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-11 23:59 [patch 00/31] x86/fpu: Preparatory cleanups for AMX support (part 1) Thomas Gleixner
2021-10-11 23:59 ` [patch 01/31] x86/fpu: Remove pointless argument from switch_fpu_finish() Thomas Gleixner
2021-10-12  0:00 ` Thomas Gleixner [this message]
2021-10-12  0:00 ` [patch 03/31] x86/pkru: Remove useless include Thomas Gleixner
2021-10-12  0:00 ` [patch 04/31] x86/fpu: Restrict xsaves()/xrstors() to independent states Thomas Gleixner
2021-10-12 14:24   ` Borislav Petkov
2021-10-12  0:00 ` [patch 05/31] x86/fpu: Cleanup the on_boot_cpu clutter Thomas Gleixner
2021-10-12  0:00 ` [patch 06/31] x86/fpu: Remove pointless memset in fpu_clone() Thomas Gleixner
2021-10-12  0:00 ` [patch 07/31] x86/process: Clone FPU in copy_thread() Thomas Gleixner
2021-10-12  0:00 ` [patch 08/31] x86/fpu: Do not inherit FPU context for kernel and IO worker threads Thomas Gleixner
2021-10-12  0:00 ` [patch 09/31] x86/fpu: Do not inherit FPU context for CLONE_THREAD Thomas Gleixner
2021-10-12 16:10   ` Borislav Petkov
2021-10-12 18:52     ` Thomas Gleixner
2021-10-12 19:01       ` Thomas Gleixner
2021-10-12  0:00 ` [patch 10/31] x86/fpu: Cleanup xstate xcomp_bv initialization Thomas Gleixner
2021-10-12  0:00 ` [patch 11/31] x86/fpu/xstate: Provide and use for_each_xfeature() Thomas Gleixner
2021-10-12 16:45   ` Borislav Petkov
2021-10-12  0:00 ` [patch 12/31] x86/fpu/xstate: Mark all init only functions __init Thomas Gleixner
2021-10-12  0:00 ` [patch 13/31] x86/fpu: Move KVMs FPU swapping to FPU core Thomas Gleixner
2021-10-12 16:53   ` Borislav Petkov
2021-10-12 18:25     ` Thomas Gleixner
2021-10-12 18:26       ` Thomas Gleixner
2021-10-12 17:22   ` Paolo Bonzini
2021-10-13  6:15     ` Liu, Jing2
2021-10-13  6:26       ` Paolo Bonzini
2021-10-13  7:46         ` Liu, Jing2
2021-10-13  8:42           ` Paolo Bonzini
2021-10-13 10:14             ` Andy Lutomirski
2021-10-13 12:26               ` Paolo Bonzini
2021-10-13 14:14                 ` Thomas Gleixner
2021-10-13 14:24                   ` Thomas Gleixner
2021-10-13 14:59                 ` Andy Lutomirski
2021-10-13 15:05                   ` Paolo Bonzini
2021-10-13 10:25             ` Liu, Jing2
2021-10-13 12:37               ` Paolo Bonzini
2021-10-13 14:06             ` Thomas Gleixner
2021-10-14  6:50               ` Paolo Bonzini
2021-10-14  8:02                 ` Liu, Jing2
2021-10-14  9:01                   ` Paolo Bonzini
2021-10-14 11:21                     ` Liu, Jing2
2021-10-14 11:33                       ` Paolo Bonzini
2021-10-14 11:30                     ` Liu, Jing2
2021-10-14 11:39                       ` Paolo Bonzini
2021-11-22  8:50                         ` Liu, Jing2
2021-10-14 14:09                     ` Thomas Gleixner
2021-10-14 14:37                       ` Thomas Gleixner
2021-10-14 15:01                       ` Paolo Bonzini
2021-10-14 19:14                         ` Thomas Gleixner
2021-10-15  9:20                           ` Liu, Jing2
2021-10-15  9:36                           ` Thomas Gleixner
2021-10-15 14:24                             ` Liu, Jing2
2021-10-15 15:53                               ` Paolo Bonzini
2021-10-16 14:45                               ` Thomas Gleixner
2021-10-15  9:00                         ` Liu, Jing2
2021-10-15 10:50                           ` Thomas Gleixner
2021-10-15 11:17                             ` Paolo Bonzini
2021-10-15 13:01                             ` Liu, Jing2
2021-10-14 12:23                 ` Thomas Gleixner
2021-10-14 12:26                   ` Paolo Bonzini
2021-10-14 14:23                     ` Thomas Gleixner
2021-10-13 15:12       ` Thomas Gleixner
2021-10-14  8:21         ` Liu, Jing2
2021-10-14 13:08           ` Thomas Gleixner
2021-10-12  0:00 ` [patch 14/31] x86/fpu: Replace KVMs homebrewn FPU copy from user Thomas Gleixner
2021-10-12 17:00   ` Borislav Petkov
2021-10-13 14:57     ` Sean Christopherson
2021-10-13 15:12       ` Paolo Bonzini
2021-10-13 15:16       ` Thomas Gleixner
2021-10-12 17:30   ` Paolo Bonzini
2021-10-12  0:00 ` [patch 15/31] x86/fpu: Rework copy_xstate_to_uabi_buf() Thomas Gleixner
2021-10-12 17:30   ` Paolo Bonzini
2021-10-12  0:00 ` [patch 16/31] x86/fpu: Replace KVMs homebrewn FPU copy to user Thomas Gleixner
2021-10-12 17:10   ` Borislav Petkov
2021-10-12 17:36   ` Paolo Bonzini
2021-10-12 17:47     ` Thomas Gleixner
2021-10-12 18:40       ` [patch V2 16/31] x86/fpu: Replace KVMs home brewed " Thomas Gleixner
2021-10-13  5:34       ` [patch 16/31] x86/fpu: Replace KVMs homebrewn " Paolo Bonzini
2021-10-12  0:00 ` [patch 17/31] x86/fpu: Mark fpu__init_prepare_fx_sw_frame() as __init Thomas Gleixner
2021-10-12  0:00 ` [patch 18/31] x86/fpu: Move context switch and exit to user inlines into sched.h Thomas Gleixner
2021-10-12  0:00 ` [patch 19/31] x86/fpu: Clean up cpu feature tests Thomas Gleixner
2021-10-12  0:00 ` [patch 20/31] x86/fpu: Make os_xrstor_booting() private Thomas Gleixner
2021-10-12  0:00 ` [patch 21/31] x86/fpu: Move os_xsave() and os_xrstor() to core Thomas Gleixner
2021-10-12  0:00 ` [patch 22/31] x86/fpu: Move legacy ASM wrappers " Thomas Gleixner
2021-10-12  0:00 ` [patch 23/31] x86/fpu: Make WARN_ON_FPU() private Thomas Gleixner
2021-10-12  0:00 ` [patch 24/31] x86/fpu: Move fpregs_restore_userregs() to core Thomas Gleixner
2021-10-12 17:32   ` Borislav Petkov
2021-10-12  0:00 ` [patch 25/31] x86/fpu: Move mxcsr related code " Thomas Gleixner
2021-10-12  0:00 ` [patch 26/31] x86/fpu: Move fpstate functions to api.h Thomas Gleixner
2021-10-12 17:46   ` Borislav Petkov
2021-10-12  0:00 ` [patch 27/31] x86/fpu: Remove internal.h dependency from fpu/signal.h Thomas Gleixner
2021-10-12  0:00 ` [patch 28/31] x86/sev: Include fpu/xcr.h Thomas Gleixner
2021-10-12  7:24   ` Xiaoyao Li
2021-10-12  0:00 ` [patch 29/31] x86/fpu: Mop up the internal.h leftovers Thomas Gleixner
2021-10-12  0:00 ` [patch 30/31] x86/fpu: Replace the includes of fpu/internal.h Thomas Gleixner
2021-10-12  0:00 ` [patch 31/31] x86/fpu: Provide a proper function for ex_handler_fprestore() Thomas Gleixner
2021-10-12 21:15 ` [patch 00/31] x86/fpu: Preparatory cleanups for AMX support (part 1) Thomas Gleixner

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