[PATCH] x86, pkeys: update documentation about availability

[PATCH] x86, pkeys: update documentation about availability

[Dave Hansen]

From: Dave Hansen <dave.hansen@linux.intel.com>

Now that CPUs that implement Memory Protection Keys are publicly
available we can be a bit less oblique about where it is available.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
---

 b/Documentation/x86/protection-keys.txt |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff -puN Documentation/x86/protection-keys.txt~pkeys-update Documentation/x86/protection-keys.txt
--- a/Documentation/x86/protection-keys.txt~pkeys-update	2017-11-09 10:36:53.381467202 -0800
+++ b/Documentation/x86/protection-keys.txt	2017-11-09 10:43:15.527466249 -0800
@@ -1,5 +1,10 @@
-Memory Protection Keys for Userspace (PKU aka PKEYs) is a CPU feature
-which will be found on future Intel CPUs.
+Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature
+which is found on Intel's Skylake "Scalable Processor" Server CPUs.
+It will be avalable in future non-server parts.
+
+For anyone wishing to test or use this feature, it is available in
+Amazon's EC2 C5 instances and is known to work there using an Ubuntu
+17.04 image.
 
 Memory Protection Keys provides a mechanism for enforcing page-based
 protections, but without requiring modification of the page tables
_

Re: [PATCH] x86, pkeys: update documentation about availability

[Ingo Molnar]

* Dave Hansen <dave.hansen@linux.intel.com> wrote:

> 
> From: Dave Hansen <dave.hansen@linux.intel.com>
> 
> Now that CPUs that implement Memory Protection Keys are publicly
> available we can be a bit less oblique about where it is available.
> 
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> ---
> 
>  b/Documentation/x86/protection-keys.txt |    9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff -puN Documentation/x86/protection-keys.txt~pkeys-update Documentation/x86/protection-keys.txt
> --- a/Documentation/x86/protection-keys.txt~pkeys-update	2017-11-09 10:36:53.381467202 -0800
> +++ b/Documentation/x86/protection-keys.txt	2017-11-09 10:43:15.527466249 -0800
> @@ -1,5 +1,10 @@
> -Memory Protection Keys for Userspace (PKU aka PKEYs) is a CPU feature
> -which will be found on future Intel CPUs.
> +Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature
> +which is found on Intel's Skylake "Scalable Processor" Server CPUs.
> +It will be avalable in future non-server parts.
> +
> +For anyone wishing to test or use this feature, it is available in
> +Amazon's EC2 C5 instances and is known to work there using an Ubuntu
> +17.04 image.
>  
>  Memory Protection Keys provides a mechanism for enforcing page-based
>  protections, but without requiring modification of the page tables

Could we please first fix the pkeys self-test? One of the testcases doesn't build 
at all:

 gcc -m32 -o /home/mingo/tip/tools/testing/selftests/x86/protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall -no-pie  protection_keys.c -lrt -ldl -lm
 In file included from /usr/include/signal.h:57:0,
                  from protection_keys.c:33:
 protection_keys.c: In function ‘signal_handler’:
 protection_keys.c:253:6: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ 
 before ‘.’ token
   u64 si_pkey;
       ^

plus, on a related note, the MPX testcase produces annoying warnings:

 gcc -m32 -o /home/mingo/tip/tools/testing/selftests/x86/mpx-mini-test_32 -O2 -g -std=gnu99 -pthread -Wall -no-pie  mpx-mini-test.c -lrt -ldl -lm
 mpx-mini-test.c: In function ‘insn_test_failed’:
 mpx-mini-test.c:1406:3: warning: array subscript is above array bounds 
 [-Warray-bounds]
    printf("bte[1]: %lx\n", bte->contents[1]);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 mpx-mini-test.c:1407:3: warning: array subscript is above array bounds 
 [-Warray-bounds]
    printf("bte[2]: %lx\n", bte->contents[2]);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 mpx-mini-test.c:1408:3: warning: array subscript is above array bounds 
 [-Warray-bounds]
    printf("bte[3]: %lx\n", bte->contents[3]);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Thanks,

	Ingo

Re: [PATCH] x86, pkeys: update documentation about availability

[Dave Hansen]

On 11/09/2017 10:12 PM, Ingo Molnar wrote:
> 
> * Dave Hansen <dave.hansen@linux.intel.com> wrote:
> 
>>
>> From: Dave Hansen <dave.hansen@linux.intel.com>
>>
>> Now that CPUs that implement Memory Protection Keys are publicly
>> available we can be a bit less oblique about where it is available.
>>
>> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
>> ---
>>
>>  b/Documentation/x86/protection-keys.txt |    9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff -puN Documentation/x86/protection-keys.txt~pkeys-update Documentation/x86/protection-keys.txt
>> --- a/Documentation/x86/protection-keys.txt~pkeys-update	2017-11-09 10:36:53.381467202 -0800
>> +++ b/Documentation/x86/protection-keys.txt	2017-11-09 10:43:15.527466249 -0800
>> @@ -1,5 +1,10 @@
>> -Memory Protection Keys for Userspace (PKU aka PKEYs) is a CPU feature
>> -which will be found on future Intel CPUs.
>> +Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature
>> +which is found on Intel's Skylake "Scalable Processor" Server CPUs.
>> +It will be avalable in future non-server parts.
>> +
>> +For anyone wishing to test or use this feature, it is available in
>> +Amazon's EC2 C5 instances and is known to work there using an Ubuntu
>> +17.04 image.
>>  
>>  Memory Protection Keys provides a mechanism for enforcing page-based
>>  protections, but without requiring modification of the page tables
> 
> Could we please first fix the pkeys self-test? One of the testcases doesn't build 
> at all:
> 
>  gcc -m32 -o /home/mingo/tip/tools/testing/selftests/x86/protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall -no-pie  protection_keys.c -lrt -ldl -lm
>  In file included from /usr/include/signal.h:57:0,
>                   from protection_keys.c:33:
>  protection_keys.c: In function ‘signal_handler’:
>  protection_keys.c:253:6: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ 
>  before ‘.’ token
>    u64 si_pkey;

That's odd.  I build them all the time.  I compiled it just now with
4.14-rc8 and gcc 4.8.4.

I wonder if this is more fallout from the glibc headers getting updated
to now contain pkey-related stuff.  si_pkey might be getting #defined
over for the siginfo si_pkey.

What distro are you seeing this on?

> plus, on a related note, the MPX testcase produces annoying warnings:
> 
>  gcc -m32 -o /home/mingo/tip/tools/testing/selftests/x86/mpx-mini-test_32 -O2 -g -std=gnu99 -pthread -Wall -no-pie  mpx-mini-test.c -lrt -ldl -lm
>  mpx-mini-test.c: In function ‘insn_test_failed’:
>  mpx-mini-test.c:1406:3: warning: array subscript is above array bounds 
>  [-Warray-bounds]
>     printf("bte[1]: %lx\n", bte->contents[1]);

This is kinda a weird structure:

> struct mpx_bt_entry {
>         union {
>                 char x[MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES];
>                 unsigned long contents[1];
>         };
> } __attribute__((packed));

I guess it should either be contents[0] or
contents[MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTE/sizeof(long)].  But, the
warning is harmless at least.

What gcc is this, btw?  I must be behind the times.

Re: [PATCH] x86, pkeys: update documentation about availability

[Ingo Molnar]

* Dave Hansen <dave.hansen@linux.intel.com> wrote:

> On 11/09/2017 10:12 PM, Ingo Molnar wrote:
> > 
> > * Dave Hansen <dave.hansen@linux.intel.com> wrote:
> > 
> >>
> >> From: Dave Hansen <dave.hansen@linux.intel.com>
> >>
> >> Now that CPUs that implement Memory Protection Keys are publicly
> >> available we can be a bit less oblique about where it is available.
> >>
> >> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> >> ---
> >>
> >>  b/Documentation/x86/protection-keys.txt |    9 +++++++--
> >>  1 file changed, 7 insertions(+), 2 deletions(-)
> >>
> >> diff -puN Documentation/x86/protection-keys.txt~pkeys-update Documentation/x86/protection-keys.txt
> >> --- a/Documentation/x86/protection-keys.txt~pkeys-update	2017-11-09 10:36:53.381467202 -0800
> >> +++ b/Documentation/x86/protection-keys.txt	2017-11-09 10:43:15.527466249 -0800
> >> @@ -1,5 +1,10 @@
> >> -Memory Protection Keys for Userspace (PKU aka PKEYs) is a CPU feature
> >> -which will be found on future Intel CPUs.
> >> +Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature
> >> +which is found on Intel's Skylake "Scalable Processor" Server CPUs.
> >> +It will be avalable in future non-server parts.
> >> +
> >> +For anyone wishing to test or use this feature, it is available in
> >> +Amazon's EC2 C5 instances and is known to work there using an Ubuntu
> >> +17.04 image.
> >>  
> >>  Memory Protection Keys provides a mechanism for enforcing page-based
> >>  protections, but without requiring modification of the page tables
> > 
> > Could we please first fix the pkeys self-test? One of the testcases doesn't build 
> > at all:
> > 
> >  gcc -m32 -o /home/mingo/tip/tools/testing/selftests/x86/protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall -no-pie  protection_keys.c -lrt -ldl -lm
> >  In file included from /usr/include/signal.h:57:0,
> >                   from protection_keys.c:33:
> >  protection_keys.c: In function ‘signal_handler’:
> >  protection_keys.c:253:6: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ 
> >  before ‘.’ token
> >    u64 si_pkey;
> 
> That's odd.  I build them all the time.  I compiled it just now with
> 4.14-rc8 and gcc 4.8.4.
> 
> I wonder if this is more fallout from the glibc headers getting updated
> to now contain pkey-related stuff.  si_pkey might be getting #defined
> over for the siginfo si_pkey.
> 
> What distro are you seeing this on?

Latest Ubuntu, 17.10:

  triton:~/tip> cat /etc/os-release 
  NAME="Ubuntu"
  VERSION="17.10 (Artful Aardvark)"

  triton:~/tip> apt-file find /usr/include/signal.h
  libc6-dev: /usr/include/signal.h

  triton:~/tip> dpkg -l libc6-dev
  Desired=Unknown/Install/Remove/Purge/Hold
  | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
  |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
  ||/ Name                                    Version                  Architecture             Description
  +++-=======================================-========================-========================-====================================================================================
  ii  libc6-dev:amd64                         2.26-0ubuntu2            amd64                    GNU C Library: Development Libraries and Header Files


> > plus, on a related note, the MPX testcase produces annoying warnings:
> > 
> >  gcc -m32 -o /home/mingo/tip/tools/testing/selftests/x86/mpx-mini-test_32 -O2 -g -std=gnu99 -pthread -Wall -no-pie  mpx-mini-test.c -lrt -ldl -lm
> >  mpx-mini-test.c: In function ‘insn_test_failed’:
> >  mpx-mini-test.c:1406:3: warning: array subscript is above array bounds 
> >  [-Warray-bounds]
> >     printf("bte[1]: %lx\n", bte->contents[1]);
> 
> This is kinda a weird structure:
> 
> > struct mpx_bt_entry {
> >         union {
> >                 char x[MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES];
> >                 unsigned long contents[1];
> >         };
> > } __attribute__((packed));
> 
> I guess it should either be contents[0] or
> contents[MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTE/sizeof(long)].  But, the
> warning is harmless at least.
> 
> What gcc is this, btw?  I must be behind the times.

gcc version 7.2.0 (Ubuntu 7.2.0-8ubuntu3) 

Thanks,

	Ingo