Re: [PATCH v5 2/4] x86/ldt: Make modify_ldt synchronous

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 07/30/2015 02:14 PM, Andy Lutomirski wrote:
> On Thu, Jul 30, 2015 at 10:56 AM, Boris Ostrovsky
> <boris.ostrovsky@oracle.com> wrote:
>> On 07/28/2015 01:29 AM, Andy Lutomirski wrote:
>>
>>> +
>>> +static inline void load_mm_ldt(struct mm_struct *mm)
>>> +{
>>> +       struct ldt_struct *ldt;
>>> +       DEBUG_LOCKS_WARN_ON(!irqs_disabled());
>>
>>
>> I thought this was supposed to be checking preemptible()?
> v6 fixes that.  Check your future inbox :)  I'm goint to rework the
> Xen bit too based on the long discussion.
>
> Is that the only failure you're seeing?

Yes.

> ldt_gdt_32 passes on 64-bit for me

With your patch:

root@haswell> uname -a
Linux dhcp-burlington7-2nd-B-east-10-152-55-89.usdhcp.oraclecorp.com 
4.2.0-rc4 #107 SMP Thu Jul 30 11:05:19 EDT 2015 x86_64 x86_64 x86_64 
GNU/Linux
root@haswell> cd tmp/linux/tools/testing/selftests/x86/
root@haswell> ls -l ldt_gdt_32
-rwxr-xr-x 1 root root 25975 Jul 30 11:48 ldt_gdt_32
root@haswell> ./ldt_gdt_32
[OK]    LDT entry 0 has AR 0x0040FA00 and limit 0x0000000A
[OK]    LDT entry 0 has AR 0x00C0FA00 and limit 0x0000AFFF
[OK]    LDT entry 1 is invalid
[OK]    LDT entry 2 has AR 0x00C0FA00 and limit 0x0000AFFF
[OK]    LDT entry 1 is invalid
[OK]    LDT entry 2 has AR 0x00C0FA00 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D0FA00 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D07A00 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00907A00 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D07200 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D07000 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D07400 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00507600 and limit 0x0000000A
[OK]    LDT entry 2 has AR 0x00507E00 and limit 0x0000000A
[OK]    LDT entry 2 has AR 0x00507C00 and limit 0x0000000A
[OK]    LDT entry 2 has AR 0x00507A00 and limit 0x0000000A
[OK]    LDT entry 2 has AR 0x00507800 and limit 0x0000000A
[RUN]   Test fork
[OK]    LDT entry 2 has AR 0x00507800 and limit 0x0000000A
[OK]    LDT entry 1 is invalid
[OK]    Child succeeded
[RUN]   Test size
[DONE]  Size test
[OK]    modify_ldt failure 22
[OK]    LDT entry 0 has AR 0x0000F200 and limit 0x00000000
[OK]    LDT entry 0 has AR 0x00007200 and limit 0x00000000
[OK]    LDT entry 0 has AR 0x0000F000 and limit 0x00000000
[OK]    LDT entry 0 has AR 0x00007200 and limit 0x00000000
[OK]    LDT entry 0 has AR 0x00007000 and limit 0x00000001
[OK]    LDT entry 0 has AR 0x00007000 and limit 0x00000000
[OK]    LDT entry 0 is invalid
[OK]    LDT entry 0 has AR 0x0040F200 and limit 0x00000000
[OK]    LDT entry 0 is invalid
[RUN]   Cross-CPU LDT invalidation
Segmentation fault (core dumped)
root@haswell> dmesg | grep -i xen
[    2.953815] xenfs: not registering filesystem on non-xen platform
[   17.495141] IPv6: ADDRCONF(NETDEV_UP): xenbr0: link is not ready
[   20.913839] xenbr0: port 1(eth0) entered forwarding state
[   20.913907] xenbr0: port 1(eth0) entered forwarding state
[   20.914044] IPv6: ADDRCONF(NETDEV_CHANGE): xenbr0: link becomes ready


On a slightly older kernel:


root@haswell> uname -a
Linux dhcp-burlington7-2nd-B-east-10-152-55-89.usdhcp.oraclecorp.com 
4.1.0-rc2 #111 SMP Fri Jun 19 16:28:46 EDT 2015 x86_64 x86_64 x86_64 
GNU/Linux
root@haswell> cd tmp/linux/tools/testing/selftests/x86/
root@haswell> ls -l ldt_gdt_32
-rwxr-xr-x 1 root root 25975 Jul 30 11:48 ldt_gdt_32
root@haswell> ./ldt_gdt_32
[OK]    LDT entry 0 has AR 0x0040FA00 and limit 0x0000000A
[OK]    LDT entry 0 has AR 0x00C0FA00 and limit 0x0000AFFF

[OK]    LDT entry 1 is invalid
[OK]    LDT entry 2 has AR 0x00C0FA00 and limit 0x0000AFFF
[OK]    LDT entry 1 is invalid
[OK]    LDT entry 2 has AR 0x00C0FA00 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D0FA00 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D07A00 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00907A00 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D07200 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D07000 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00D07400 and limit 0x0000AFFF
[OK]    LDT entry 2 has AR 0x00507600 and limit 0x0000000A
[OK]    LDT entry 2 has AR 0x00507E00 and limit 0x0000000A
[OK]    LDT entry 2 has AR 0x00507C00 and limit 0x0000000A
[OK]    LDT entry 2 has AR 0x00507A00 and limit 0x0000000A
[OK]    LDT entry 2 has AR 0x00507800 and limit 0x0000000A
[RUN]   Test fork
[OK]    LDT entry 2 has AR 0x00507800 and limit 0x0000000A
[OK]    LDT entry 1 is invalid
[OK]    Child succeeded
[RUN]   Test size
[DONE]  Size test
[OK]    modify_ldt failure 22
[OK]    LDT entry 0 has AR 0x0000F200 and limit 0x00000000
[OK]    LDT entry 0 has AR 0x00007200 and limit 0x00000000
[OK]    LDT entry 0 has AR 0x0000F000 and limit 0x00000000
[OK]    LDT entry 0 has AR 0x00007200 and limit 0x00000000
[OK]    LDT entry 0 has AR 0x00007000 and limit 0x00000001
[OK]    LDT entry 0 has AR 0x00007000 and limit 0x00000000
[OK]    LDT entry 0 is invalid
[OK]    LDT entry 0 has AR 0x0040F200 and limit 0x00000000
[OK]    LDT entry 0 is invalid
[RUN]   Cross-CPU LDT invalidation
[FAIL]  5 of 5 iterations failed
root@haswell> dmesg | grep -i xen
[    2.971167] xenfs: not registering filesystem on non-xen platform
[   17.144879] IPv6: ADDRCONF(NETDEV_UP): xenbr0: link is not ready
[   20.588663] xenbr0: port 1(eth0) entered forwarding state
[   20.588706] xenbr0: port 1(eth0) entered forwarding state
[   20.588802] IPv6: ADDRCONF(NETDEV_CHANGE): xenbr0: link becomes ready