Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-13 Thread Andy Lutomirski
On Mon, Nov 13, 2017 at 1:07 PM, Dave Hansen wrote: > On 11/12/2017 07:52 PM, Andy Lutomirski wrote: >> On Fri, Nov 10, 2017 at 3:04 PM, Dave Hansen >> wrote: >>> On 11/10/2017 02:06 PM, Andy Lutomirski wrote: I have nothing against disabling native. I object to breaking the weird bina

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-13 Thread Dave Hansen
On 11/12/2017 07:52 PM, Andy Lutomirski wrote: > On Fri, Nov 10, 2017 at 3:04 PM, Dave Hansen > wrote: >> On 11/10/2017 02:06 PM, Andy Lutomirski wrote: >>> I have nothing against disabling native. I object to breaking the >>> weird binary tracing behavior in the emulation mode, especially if >>>

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-12 Thread Andy Lutomirski
On Fri, Nov 10, 2017 at 3:04 PM, Dave Hansen wrote: > On 11/10/2017 02:06 PM, Andy Lutomirski wrote: >> On Thu, Nov 9, 2017 at 10:31 PM, Dave Hansen >> wrote: >>> On 11/09/2017 06:25 PM, Andy Lutomirski wrote: Here are two proposals to address this without breaking vsyscalls. 1. Se

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-10 Thread Dave Hansen
On 11/10/2017 02:06 PM, Andy Lutomirski wrote: > On Thu, Nov 9, 2017 at 10:31 PM, Dave Hansen > wrote: >> On 11/09/2017 06:25 PM, Andy Lutomirski wrote: >>> Here are two proposals to address this without breaking vsyscalls. >>> >>> 1. Set NX on low mappings that are _PAGE_USER. Don't set NX on hi

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-10 Thread Andy Lutomirski
On Thu, Nov 9, 2017 at 10:31 PM, Dave Hansen wrote: > On 11/09/2017 06:25 PM, Andy Lutomirski wrote: >> Here are two proposals to address this without breaking vsyscalls. >> >> 1. Set NX on low mappings that are _PAGE_USER. Don't set NX on high >> mappings but, optionally, warn if you see _PAGE_U

[PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-10 Thread Dave Hansen
From: Dave Hansen The KAISER code attempts to "poison" the user portion of the kernel page tables. It detects entries that it wants that it wants to poison in two ways: * Looking for addresses >= PAGE_OFFSET * Looking for entries without _PAGE_USER set But, to allow the _PAGE_USER check to w

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-09 Thread Dave Hansen
On 11/09/2017 06:25 PM, Andy Lutomirski wrote: > Here are two proposals to address this without breaking vsyscalls. > > 1. Set NX on low mappings that are _PAGE_USER. Don't set NX on high > mappings but, optionally, warn if you see _PAGE_USER on any address > that isn't the vsyscall page. > > 2.

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-09 Thread Andy Lutomirski
On Thu, Nov 9, 2017 at 5:22 PM, Dave Hansen wrote: > On 11/09/2017 05:04 PM, Andy Lutomirski wrote: >> On Thu, Nov 9, 2017 at 4:57 PM, Dave Hansen >> wrote: >>> On 11/09/2017 04:53 PM, Andy Lutomirski wrote: > The KAISER code attempts to "poison" the user portion of the kernel page > tab

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-09 Thread Dave Hansen
On 11/09/2017 05:04 PM, Andy Lutomirski wrote: > On Thu, Nov 9, 2017 at 4:57 PM, Dave Hansen > wrote: >> On 11/09/2017 04:53 PM, Andy Lutomirski wrote: The KAISER code attempts to "poison" the user portion of the kernel page tables. It detects the entries pages that it wants that it wa

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-09 Thread Andy Lutomirski
On Thu, Nov 9, 2017 at 4:57 PM, Dave Hansen wrote: > On 11/09/2017 04:53 PM, Andy Lutomirski wrote: >>> The KAISER code attempts to "poison" the user portion of the kernel page >>> tables. It detects the entries pages that it wants that it wants to >>> poison in two ways: >>> * Looking for addre

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-09 Thread Dave Hansen
On 11/09/2017 04:53 PM, Andy Lutomirski wrote: >> The KAISER code attempts to "poison" the user portion of the kernel page >> tables. It detects the entries pages that it wants that it wants to >> poison in two ways: >> * Looking for addresses >= PAGE_OFFSET >> * Looking for entries without _PAG

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-09 Thread Andy Lutomirski
On Thu, Nov 9, 2017 at 11:26 AM, Dave Hansen wrote: > On 11/09/2017 11:04 AM, Andy Lutomirski wrote: >> On Wed, Nov 8, 2017 at 11:47 AM, Dave Hansen >> wrote: >>> >>> From: Dave Hansen >>> >>> The VSYSCALL page is mapped by kernel page tables at a kernel address. >>> It is troublesome to support

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-09 Thread Dave Hansen
On 11/09/2017 11:04 AM, Andy Lutomirski wrote: > On Wed, Nov 8, 2017 at 11:47 AM, Dave Hansen > wrote: >> >> From: Dave Hansen >> >> The VSYSCALL page is mapped by kernel page tables at a kernel address. >> It is troublesome to support with KAISER in place, so disable the >> native case. >> >> Al

Re: [PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-09 Thread Andy Lutomirski
On Wed, Nov 8, 2017 at 11:47 AM, Dave Hansen wrote: > > From: Dave Hansen > > The VSYSCALL page is mapped by kernel page tables at a kernel address. > It is troublesome to support with KAISER in place, so disable the > native case. > > Also add some help text about how KAISER might affect the emu

[PATCH 24/30] x86, kaiser: disable native VSYSCALL

2017-11-08 Thread Dave Hansen
From: Dave Hansen The VSYSCALL page is mapped by kernel page tables at a kernel address. It is troublesome to support with KAISER in place, so disable the native case. Also add some help text about how KAISER might affect the emulation case as well. Signed-off-by: Dave Hansen Cc: Moritz Lipp