From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Thomas Gleixner <tglx@linutronix.de>, Lars Wendler <wendler.lars@web.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
x86@kernel.org, Borislav Betkov <bp@alien8.de>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Greg KH <gregkh@linuxfoundation.org>,
Laura Abbott <labbott@redhat.com>,
Juergen Gross <jgross@suse.com>
Subject: Re: CONFIG_PAGE_TABLE_ISOLATION=y on x86_64 causes gcc to segfault when building x86_32 binaries
Date: Wed, 3 Jan 2018 21:44:25 -0500 [thread overview]
Message-ID: <e5371bcf-fb3e-eab2-e447-a29bb6e17610@oracle.com> (raw)
In-Reply-To: <alpine.DEB.2.20.1801031949200.1957@nanos>
On 01/03/2018 01:52 PM, Thomas Gleixner wrote:
> On Wed, 3 Jan 2018, Thomas Gleixner wrote:
>
>> On Wed, 3 Jan 2018, Lars Wendler wrote:
>>> Am Wed, 3 Jan 2018 13:05:38 +0100 (CET)
>>> schrieb Thomas Gleixner <tglx@linutronix.de>:
>>>> Also can you please try Linus v4.15-rc6 with PTI enabled so we can see
>>>> whether that's a backport issue or a general one?
>>> Same problem with 4.15-rc6. So I suppose that means it's a general
>>> issue.
>> Just a shot in the dark as I just decoded another issue on a AMD CPU. Can
>> you please try the patch below?
> Ok. Found the real issue. This is a problem on AMD boxen.
>
> Fix below.
>
> Can Xen folks please have a look at that as well?
(Apologies for the delay)
This is not an issue for PV guests.
-boris
>
> Thanks,
>
> tglx
>
> 8<-------------------
>
> arch/x86/entry/entry_64_compat.S | 13 ++++++-------
> 1 file changed, 6 insertions(+), 7 deletions(-)
>
> --- a/arch/x86/entry/entry_64_compat.S
> +++ b/arch/x86/entry/entry_64_compat.S
> @@ -190,8 +190,13 @@ ENTRY(entry_SYSCALL_compat)
> /* Interrupts are off on entry. */
> swapgs
>
> - /* Stash user ESP and switch to the kernel stack. */
> + /* Stash user ESP */
> movl %esp, %r8d
> +
> + /* Use %rsp as scratch reg. User ESP is stashed in r8 */
> + SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp
> +
> + /* Switch to the kernel stack */
> movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
>
> /* Construct struct pt_regs on stack */
> @@ -220,12 +225,6 @@ GLOBAL(entry_SYSCALL_compat_after_hwfram
> pushq $0 /* pt_regs->r15 = 0 */
>
> /*
> - * We just saved %rdi so it is safe to clobber. It is not
> - * preserved during the C calls inside TRACE_IRQS_OFF anyway.
> - */
> - SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi
> -
> - /*
> * User mode is traced as though IRQs are on, and SYSENTER
> * turned them off.
> */
next prev parent reply other threads:[~2018-01-04 2:46 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20180103123723.1dd26828@abudhabi.paradoxon.rec>
2018-01-03 11:57 ` CONFIG_PAGE_TABLE_ISOLATION=y on x86_64 causes gcc to segfault when building x86_32 binaries Thomas Gleixner
2018-01-03 12:05 ` Thomas Gleixner
2018-01-03 13:30 ` Lars Wendler
2018-01-03 15:21 ` Thomas Gleixner
2018-01-03 15:42 ` Dave Hansen
2018-01-03 18:52 ` Thomas Gleixner
2018-01-03 22:12 ` Laura Abbott
2018-01-03 22:14 ` Andy Lutomirski
2018-01-03 22:22 ` Thomas Gleixner
2018-01-03 23:43 ` Andy Lutomirski
2018-01-03 22:27 ` Dave Hansen
2018-01-03 22:25 ` [tip:x86/pti] x86/pti: Switch to kernel CR3 at early in entry_SYSCALL_compat() tip-bot for Thomas Gleixner
2018-01-03 23:46 ` CONFIG_PAGE_TABLE_ISOLATION=y on x86_64 causes gcc to segfault when building x86_32 binaries Lars Wendler
2018-01-04 2:44 ` Boris Ostrovsky [this message]
2018-01-03 15:40 ` Borislav Petkov
2018-01-03 23:22 ` Lars Wendler
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