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From: Ingo Molnar <mingo@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: Andy Lutomirski <luto@amacapital.net>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Fenghua Yu <fenghua.yu@intel.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Oleg Nesterov <oleg@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: [PATCH 172/208] x86/fpu: Clarify ancient comments in fpu__restore()
Date: Tue,  5 May 2015 19:57:56 +0200	[thread overview]
Message-ID: <1430848712-28064-12-git-send-email-mingo@kernel.org> (raw)
In-Reply-To: <1430848712-28064-1-git-send-email-mingo@kernel.org>

So this function still had ancient language about 'saving current
math information' - but we haven't been doing lazy FPU saves for
quite some time, we are doing lazy FPU restores.

Also remove IRQ13 related comment, which we don't support anymore
either.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/fpu/core.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 7e91a6f7564a..45ef4e51928b 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -319,14 +319,14 @@ static void fpu__activate_stopped(struct fpu *child_fpu)
 }
 
 /*
- * 'fpu__restore()' saves the current math information in the
- * old math state array, and gets the new ones from the current task
+ * 'fpu__restore()' is called to copy FPU registers from
+ * the FPU fpstate to the live hw registers and to activate
+ * access to the hardware registers, so that FPU instructions
+ * can be used afterwards.
  *
- * Careful.. There are problems with IBM-designed IRQ13 behaviour.
- * Don't touch unless you *really* know how it works.
- *
- * Must be called with kernel preemption disabled (eg with local
- * local interrupts as in the case of do_device_not_available).
+ * Must be called with kernel preemption disabled (for example
+ * with local interrupts disabled, as it is in the case of
+ * do_device_not_available()).
  */
 void fpu__restore(void)
 {
-- 
2.1.0


  parent reply	other threads:[~2015-05-05 18:13 UTC|newest]

Thread overview: 74+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-05 17:57 [PATCH 000/208] big x86 FPU code rewrite Ingo Molnar
2015-05-05 17:57 ` [PATCH 162/208] x86/fpu, crypto x86/cast6_avx: Simplify the cast6_init() xfeature checks Ingo Molnar
2015-05-05 17:57 ` [PATCH 163/208] x86/fpu, crypto x86/sha1_ssse3: Simplify the sha1_ssse3_mod_init() " Ingo Molnar
2015-05-05 17:57 ` [PATCH 164/208] x86/fpu, crypto x86/serpent_avx2: Simplify the init() " Ingo Molnar
2015-05-05 17:57 ` [PATCH 165/208] x86/fpu, crypto x86/sha1_mb: Remove FPU internal headers from sha1_mb.c Ingo Molnar
2015-05-05 17:57 ` [PATCH 166/208] x86/fpu: Move asm/xcr.h to asm/fpu/internal.h Ingo Molnar
2015-05-05 17:57 ` [PATCH 167/208] x86/fpu: Rename sanitize_i387_state() to fpstate_sanitize_xstate() Ingo Molnar
2015-05-05 17:57 ` [PATCH 168/208] x86/fpu: Simplify fpstate_sanitize_xstate() calls Ingo Molnar
2015-05-05 17:57 ` [PATCH 169/208] x86/fpu: Pass 'struct fpu' to fpstate_sanitize_xstate() Ingo Molnar
2015-05-05 17:57 ` [PATCH 170/208] x86/fpu: Rename save_xstate_sig() to copy_fpstate_to_sigframe() Ingo Molnar
2015-05-05 17:57 ` [PATCH 171/208] x86/fpu: Rename save_user_xstate() to copy_fpregs_to_sigframe() Ingo Molnar
2015-05-05 17:57 ` Ingo Molnar [this message]
2015-05-05 17:57 ` [PATCH 173/208] x86/fpu: Rename user_has_fpu() to fpregs_active() Ingo Molnar
2015-05-05 17:57 ` [PATCH 174/208] x86/fpu: Initialize fpregs in fpu__init_cpu_generic() Ingo Molnar
2015-05-05 17:57 ` [PATCH 175/208] x86/fpu: Clean up fpu__clear() state handling Ingo Molnar
2015-05-05 17:58 ` [PATCH 176/208] x86/alternatives, x86/fpu: Add 'alternatives_patched' debug flag and use it in xsave_state() Ingo Molnar
2015-05-05 22:47   ` Borislav Petkov
2015-05-06  2:57     ` Ingo Molnar
2015-05-05 17:58 ` [PATCH 177/208] x86/fpu: Synchronize the naming of drop_fpu() and fpu_reset_state() Ingo Molnar
2015-05-05 17:58 ` [PATCH 178/208] x86/fpu: Rename restore_fpu_checking() to copy_fpstate_to_fpregs() Ingo Molnar
2015-05-05 17:58 ` [PATCH 179/208] x86/fpu: Move all the fpu__*() high level methods closer to each other Ingo Molnar
2015-05-05 17:58 ` [PATCH 180/208] x86/fpu: Move fpu__clear() to 'struct fpu *' parameter passing Ingo Molnar
2015-05-05 17:58 ` [PATCH 181/208] x86/fpu: Rename restore_xstate_sig() to fpu__restore_sig() Ingo Molnar
2015-05-05 17:58 ` [PATCH 182/208] x86/fpu: Move the signal frame handling code closer to each other Ingo Molnar
2015-05-05 17:58 ` [PATCH 183/208] x86/fpu: Merge fpu__reset() and fpu__clear() Ingo Molnar
2015-05-05 17:58 ` [PATCH 184/208] x86/fpu: Move is_ia32*frame() helpers out of fpu/internal.h Ingo Molnar
2015-05-05 17:58 ` [PATCH 185/208] x86/fpu: Split out fpu/signal.h from fpu/internal.h for signal frame handling functions Ingo Molnar
2015-05-05 17:58 ` [PATCH 186/208] x86/fpu: Factor out fpu/regset.h from fpu/internal.h Ingo Molnar
2015-05-05 17:58 ` [PATCH 187/208] x86/fpu: Remove run-once init quirks Ingo Molnar
2015-05-05 17:58 ` [PATCH 188/208] x86/fpu: Factor out the exception error code handling code Ingo Molnar
2015-05-05 17:58 ` [PATCH 189/208] x86/fpu: Harmonize the names of the fpstate_init() helper functions Ingo Molnar
2015-05-05 17:58 ` [PATCH 190/208] x86/fpu: Create 'union thread_xstate' helper for fpstate_init() Ingo Molnar
2015-05-05 17:58 ` [PATCH 191/208] x86/fpu: Generalize 'init_xstate_ctx' Ingo Molnar
2015-05-05 17:58 ` [PATCH 192/208] x86/fpu: Move restore_init_xstate() out of fpu/internal.h Ingo Molnar
2015-05-05 17:58 ` [PATCH 193/208] x86/fpu: Rename all the fpregs, xregs, fxregs and fregs handling functions Ingo Molnar
2015-05-12 21:54   ` Dave Hansen
2015-05-05 17:58 ` [PATCH 194/208] x86/fpu: Factor out fpu/signal.c Ingo Molnar
2015-05-05 17:58 ` [PATCH 195/208] x86/fpu: Factor out the FPU regset code into fpu/regset.c Ingo Molnar
2015-05-05 17:58 ` [PATCH 196/208] x86/fpu: Harmonize FPU register state types Ingo Molnar
2015-05-05 17:58 ` [PATCH 197/208] x86/fpu: Change fpu->fpregs_active from 'int' to 'char', add lazy switching comments Ingo Molnar
2015-05-05 17:58 ` [PATCH 198/208] x86/fpu: Document the various fpregs state formats Ingo Molnar
2015-05-05 19:52   ` Dave Hansen
2015-05-05 22:55     ` Yu, Fenghua
2015-05-06  4:20     ` Ingo Molnar
2015-05-05 17:58 ` [PATCH 199/208] x86/fpu: Move debugging check from kernel_fpu_begin() to __kernel_fpu_begin() Ingo Molnar
2015-05-05 17:58 ` [PATCH 200/208] x86/fpu/xstate: Don't assume the first zero xfeatures zero bit means the end Ingo Molnar
2015-05-05 20:10   ` Dave Hansen
2015-05-05 23:04   ` Yu, Fenghua
2015-05-06  4:13     ` Ingo Molnar
2015-05-05 17:58 ` [PATCH 201/208] x86/fpu: Clean up xstate feature reservation Ingo Molnar
2015-05-05 20:12   ` Dave Hansen
2015-05-06  4:54     ` Ingo Molnar
2015-05-05 17:58 ` [PATCH 202/208] x86/fpu/xstate: Clean up setup_xstate_comp() call Ingo Molnar
2015-05-05 17:58 ` [PATCH 203/208] x86/fpu/init: Propagate __init annotations Ingo Molnar
2015-05-05 17:58 ` [PATCH 204/208] x86/fpu: Pass 'struct fpu' to fpu__restore() Ingo Molnar
2015-05-05 17:58 ` [PATCH 205/208] x86/fpu: Fix the 'nofxsr' boot parameter to also clear X86_FEATURE_FXSR_OPT Ingo Molnar
2015-05-05 17:58 ` [PATCH 206/208] x86/fpu: Add CONFIG_X86_DEBUG_FPU=y FPU debugging code Ingo Molnar
2015-05-05 19:41   ` Borislav Petkov
2015-05-06  3:35     ` Ingo Molnar
2015-05-05 17:58 ` [PATCH 207/208] x86/fpu: Add FPU performance measurement subsystem Ingo Molnar
2015-05-05 19:15   ` Dave Hansen
2015-05-05 19:22     ` Borislav Petkov
2015-05-06  4:11     ` Ingo Molnar
2015-05-06  0:52   ` Andy Lutomirski
2015-05-06  4:52     ` Ingo Molnar
2015-05-06 15:53       ` Borislav Petkov
2015-05-07  2:52       ` Andy Lutomirski
2015-05-05 17:58 ` [PATCH 208/208] x86/fpu: Reorganize fpu/internal.h Ingo Molnar
2015-05-12 17:46 ` [PATCH 000/208] big x86 FPU code rewrite Dave Hansen
2015-05-29 18:53   ` Ingo Molnar
2015-05-19 21:41 ` Ingo Molnar
2015-05-27  1:22   ` Bobby Powers
2015-05-27 10:42     ` [PATCH] x86/fpu: Fix FPU register read access to the current task Ingo Molnar
2015-05-29 13:12       ` Bobby Powers

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