linux-kernel - [tip:x86/fpu] x86/fpu: Change math_error() to use unlazy_fpu(), kill (now) unused save_init

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <tip-08a744c6bfded3d5fa66f94263f81773226113d1@git.kernel.org>
Date:	Thu, 19 Feb 2015 03:32:58 -0800
From:	tip-bot for Oleg Nesterov <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	oleg@...hat.com, hpa@...or.com, tglx@...utronix.de, bp@...e.de,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	riel@...hat.com, mingo@...nel.org
Subject: [tip:x86/fpu] x86/fpu: Change math_error() to use unlazy_fpu(),
  kill (now) unused save_init_fpu()

Commit-ID:  08a744c6bfded3d5fa66f94263f81773226113d1
Gitweb:     http://git.kernel.org/tip/08a744c6bfded3d5fa66f94263f81773226113d1
Author:     Oleg Nesterov <oleg@...hat.com>
AuthorDate: Fri, 6 Feb 2015 15:02:00 -0500
Committer:  Borislav Petkov <bp@...e.de>
CommitDate: Thu, 19 Feb 2015 11:15:03 +0100

x86/fpu: Change math_error() to use unlazy_fpu(), kill (now) unused save_init_fpu()

math_error() calls save_init_fpu() after conditional_sti(), this means
that the caller can be preempted. If !use_eager_fpu() we can hit the
WARN_ON_ONCE(!__thread_has_fpu(tsk)) and/or save the wrong FPU state.

Change math_error() to use unlazy_fpu() and kill save_init_fpu().

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Signed-off-by: Rik van Riel <riel@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Link: http://lkml.kernel.org/r/1423252925-14451-4-git-send-email-riel@redhat.com
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/include/asm/fpu-internal.h | 18 ------------------
 arch/x86/kernel/traps.c             |  2 +-
 2 files changed, 1 insertion(+), 19 deletions(-)

diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h
index e97622f..02f2e08 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -518,24 +518,6 @@ static inline void __save_fpu(struct task_struct *tsk)
 }
 
 /*
- * These disable preemption on their own and are safe
- */
-static inline void save_init_fpu(struct task_struct *tsk)
-{
-	WARN_ON_ONCE(!__thread_has_fpu(tsk));
-
-	if (use_eager_fpu()) {
-		__save_fpu(tsk);
-		return;
-	}
-
-	preempt_disable();
-	__save_init_fpu(tsk);
-	__thread_fpu_end(tsk);
-	preempt_enable();
-}
-
-/*
  * i387 state interaction
  */
 static inline unsigned short get_fpu_cwd(struct task_struct *tsk)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 88900e2..9d889f7 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -663,7 +663,7 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr)
 	/*
 	 * Save the info for the exception handler and clear the error.
 	 */
-	save_init_fpu(task);
+	unlazy_fpu(task);
 	task->thread.trap_nr = trapnr;
 	task->thread.error_code = error_code;
 	info.si_signo = SIGFPE;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/