From: Peter Zijlstra <peterz@infradead.org>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Julien Thierry <julien.thierry@arm.com>,
Will Deacon <will.deacon@arm.com>,
Andy Lutomirski <luto@amacapital.net>,
Ingo Molnar <mingo@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
James Morse <james.morse@arm.com>,
valentin.schneider@arm.com, Brian Gerst <brgerst@gmail.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Denys Vlasenko <dvlasenk@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
jgross@suse.com
Subject: Re: [PATCH 1/8] kasan,x86: Frob kasan_report() in an exception
Date: Wed, 6 Mar 2019 18:37:15 +0100 [thread overview]
Message-ID: <20190306173715.GA32534@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190306171451.GZ32534@hirez.programming.kicks-ass.net>
On Wed, Mar 06, 2019 at 06:14:51PM +0100, Peter Zijlstra wrote:
> On Wed, Mar 06, 2019 at 02:13:47PM +0100, Peter Zijlstra wrote:
> > +static __always_inline unsigned long smap_save(void)
> > +{
> > + unsigned long flags = arch_local_save_flags();
> > + clac();
> > + return flags;
> > +}
> > +
> > +static __always_inline void smap_restore(unsigned long flags)
> > +{
> > + arch_local_irq_restore(flags);
> > +}
>
> ARGH; the bloody paravirt me harder nonsense makes that pvops calls.
>
> And that (obviously) explodes.. Anybody got any clue why that Xen
> trainwreck wants to paravirt: "PUSHF;POP" and "PUSH;POPF" !?
>
> Also; I suppose I can ALTERNATIVE the whole thing, because Xen will not
> be having SMAP in the first place I suppose.
The below seems to 'work'.
--- a/arch/x86/include/asm/smap.h
+++ b/arch/x86/include/asm/smap.h
@@ -46,8 +46,6 @@
#ifdef CONFIG_X86_SMAP
-#include <asm/irqflags.h>
-
static __always_inline void clac(void)
{
/* Note: a barrier is implicit in alternative() */
@@ -62,14 +60,19 @@ static __always_inline void stac(void)
static __always_inline unsigned long smap_save(void)
{
- unsigned long flags = arch_local_save_flags();
- clac();
+ unsigned long flags;
+
+ asm volatile (ALTERNATIVE("", "pushf; pop %0; " __stringify(__ASM_CLAC),
+ X86_FEATURE_SMAP)
+ : "=rm" (flags) : : "memory", "cc");
+
return flags;
}
static __always_inline void smap_restore(unsigned long flags)
{
- arch_local_irq_restore(flags);
+ asm volatile (ALTERNATIVE("", "push %0; popf", X86_FEATURE_SMAP)
+ : : "g" (flags) : "memory", "cc");
}
/* These macros can be used in asm() statements */
next prev parent reply other threads:[~2019-03-06 17:37 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-28 14:54 [PATCH 0/8] objtool: UACCESS validation v2 Peter Zijlstra
2019-02-28 14:54 ` [PATCH 1/8] kasan,x86: Frob kasan_report() in an exception Peter Zijlstra
2019-02-28 15:22 ` Dmitry Vyukov
2019-02-28 15:45 ` Peter Zijlstra
2019-02-28 15:52 ` Dmitry Vyukov
2019-02-28 16:01 ` Andrey Ryabinin
2019-02-28 16:03 ` Dmitry Vyukov
2019-02-28 17:46 ` Peter Zijlstra
2019-02-28 18:18 ` Dmitry Vyukov
2019-03-01 14:45 ` Peter Zijlstra
2019-03-01 15:06 ` Dmitry Vyukov
2019-03-01 15:23 ` Peter Zijlstra
2019-03-06 13:13 ` Peter Zijlstra
2019-03-06 13:39 ` Dmitry Vyukov
2019-03-06 13:57 ` Peter Zijlstra
2019-03-06 14:01 ` Dmitry Vyukov
2019-03-06 14:12 ` Peter Zijlstra
2019-03-06 14:34 ` Peter Zijlstra
2019-03-06 14:40 ` Dmitry Vyukov
2019-03-06 14:41 ` Dmitry Vyukov
2019-03-06 14:55 ` Peter Zijlstra
2019-03-06 15:01 ` Dmitry Vyukov
2019-03-06 17:14 ` Peter Zijlstra
2019-03-06 17:27 ` Linus Torvalds
2019-03-06 17:37 ` Peter Zijlstra [this message]
2019-03-06 17:59 ` Linus Torvalds
2019-03-07 13:49 ` Peter Zijlstra
2019-02-28 14:54 ` [PATCH 2/8] x86/ia32: Fix ia32_restore_sigcontext AC leak Peter Zijlstra
2019-02-28 14:54 ` [PATCH 3/8] objtool: Set insn->func for alternatives Peter Zijlstra
2019-02-28 14:54 ` [PATCH 4/8] objtool: Hande function aliases Peter Zijlstra
2019-02-28 14:54 ` [PATCH 5/8] objtool: Rewrite add_ignores() Peter Zijlstra
2019-02-28 14:54 ` [PATCH 6/8] i915,uaccess: Fix redundant CLAC Peter Zijlstra
2019-02-28 15:10 ` Chris Wilson
2019-02-28 15:24 ` Peter Zijlstra
2019-02-28 16:49 ` Linus Torvalds
2019-02-28 17:51 ` Peter Zijlstra
2019-02-28 18:01 ` Peter Zijlstra
2019-02-28 18:29 ` Linus Torvalds
2019-02-28 19:01 ` Peter Zijlstra
2019-03-01 10:34 ` Peter Zijlstra
2019-03-01 12:27 ` Peter Zijlstra
2019-03-01 12:57 ` Peter Zijlstra
2019-03-01 14:38 ` Peter Zijlstra
2019-03-01 15:27 ` Andy Lutomirski
2019-03-01 16:15 ` Linus Torvalds
2019-03-01 16:17 ` Linus Torvalds
2019-02-28 14:54 ` [PATCH 7/8] objtool: Add UACCESS validation Peter Zijlstra
2019-02-28 14:54 ` [PATCH 8/8] objtool: Add Direction Flag validation Peter Zijlstra
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