* [PATCH] selftests/x86: Disable ldt_gdt_64 for now
@ 2016-01-06 19:51 Andy Lutomirski
2016-01-07 20:49 ` Shuah Khan
0 siblings, 1 reply; 5+ messages in thread
From: Andy Lutomirski @ 2016-01-06 19:51 UTC (permalink / raw)
To: x86; +Cc: Borislav Petkov, Shuah Khan, linux-kernel, Andy Lutomirski
ldt_gdt.c relies on cross-cpu invalidation of SS to do one of its
tests. On 32-bit builds, this works fine, but on 64-bit builds, it
only works if the kernel has proper SS sigcontext handling for
64-bit user programs.
Since the SS fixes are currently reverted, restrict the test case to
32 bits for now.
In principle, I could change the test to use a different segment
register, but it would be messy: CS can't point to the LDT for
64-bit code, and the other registers don't result in immediate
faults because they aren't reloaded on kernel -> user transitions.
When we fix sigcontext (in 4.6?), we can revert this.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
tools/testing/selftests/x86/Makefile | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
index 3d1a8ef500a0..c0c15ff179b7 100644
--- a/tools/testing/selftests/x86/Makefile
+++ b/tools/testing/selftests/x86/Makefile
@@ -4,10 +4,11 @@ include ../lib.mk
.PHONY: all all_32 all_64 warn_32bit_failure clean
-TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs ldt_gdt syscall_nt ptrace_syscall
+TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault sigreturn test_syscall_vdso unwind_vdso \
test_FCMOV test_FCOMI test_FISTTP \
- vdso_restorer
+ vdso_restorer \
+ ldt_gdt
TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)
BINARIES_32 := $(TARGETS_C_32BIT_ALL:%=%_32)
--
2.5.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now
2016-01-06 19:51 [PATCH] selftests/x86: Disable ldt_gdt_64 for now Andy Lutomirski
@ 2016-01-07 20:49 ` Shuah Khan
2016-01-11 10:59 ` Ingo Molnar
0 siblings, 1 reply; 5+ messages in thread
From: Shuah Khan @ 2016-01-07 20:49 UTC (permalink / raw)
To: Andy Lutomirski, x86; +Cc: Borislav Petkov, linux-kernel, Shuah Khan
On 01/06/2016 12:51 PM, Andy Lutomirski wrote:
> ldt_gdt.c relies on cross-cpu invalidation of SS to do one of its
> tests. On 32-bit builds, this works fine, but on 64-bit builds, it
> only works if the kernel has proper SS sigcontext handling for
> 64-bit user programs.
>
> Since the SS fixes are currently reverted, restrict the test case to
> 32 bits for now.
>
> In principle, I could change the test to use a different segment
> register, but it would be messy: CS can't point to the LDT for
> 64-bit code, and the other registers don't result in immediate
> faults because they aren't reloaded on kernel -> user transitions.
>
> When we fix sigcontext (in 4.6?), we can revert this.
>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> --
Andy,
This patch didn't apply to linux-kselftest next.
It probably has to go through x86.
thanks,
-- Shuah
--
Shuah Khan
Sr. Linux Kernel Developer
Open Source Innovation Group
Samsung Research America (Silicon Valley)
shuahkh@osg.samsung.com | (970) 217-8978
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now
2016-01-07 20:49 ` Shuah Khan
@ 2016-01-11 10:59 ` Ingo Molnar
2016-01-12 1:25 ` Andy Lutomirski
0 siblings, 1 reply; 5+ messages in thread
From: Ingo Molnar @ 2016-01-11 10:59 UTC (permalink / raw)
To: Shuah Khan; +Cc: Andy Lutomirski, x86, Borislav Petkov, linux-kernel
* Shuah Khan <shuahkh@osg.samsung.com> wrote:
> On 01/06/2016 12:51 PM, Andy Lutomirski wrote:
> > ldt_gdt.c relies on cross-cpu invalidation of SS to do one of its
> > tests. On 32-bit builds, this works fine, but on 64-bit builds, it
> > only works if the kernel has proper SS sigcontext handling for
> > 64-bit user programs.
> >
> > Since the SS fixes are currently reverted, restrict the test case to
> > 32 bits for now.
> >
> > In principle, I could change the test to use a different segment
> > register, but it would be messy: CS can't point to the LDT for
> > 64-bit code, and the other registers don't result in immediate
> > faults because they aren't reloaded on kernel -> user transitions.
> >
> > When we fix sigcontext (in 4.6?), we can revert this.
> >
> > Signed-off-by: Andy Lutomirski <luto@kernel.org>
> > --
>
> Andy,
>
> This patch didn't apply to linux-kselftest next.
> It probably has to go through x86.
It doesn't apply to -tip either. Andy, which tree is this against?
Thanks,
Ingo
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now
2016-01-11 10:59 ` Ingo Molnar
@ 2016-01-12 1:25 ` Andy Lutomirski
2016-01-12 10:45 ` Ingo Molnar
0 siblings, 1 reply; 5+ messages in thread
From: Andy Lutomirski @ 2016-01-12 1:25 UTC (permalink / raw)
To: Ingo Molnar
Cc: Shuah Khan, Andy Lutomirski, X86 ML, Borislav Petkov, linux-kernel
On Mon, Jan 11, 2016 at 2:59 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Shuah Khan <shuahkh@osg.samsung.com> wrote:
>
>> On 01/06/2016 12:51 PM, Andy Lutomirski wrote:
>> > ldt_gdt.c relies on cross-cpu invalidation of SS to do one of its
>> > tests. On 32-bit builds, this works fine, but on 64-bit builds, it
>> > only works if the kernel has proper SS sigcontext handling for
>> > 64-bit user programs.
>> >
>> > Since the SS fixes are currently reverted, restrict the test case to
>> > 32 bits for now.
>> >
>> > In principle, I could change the test to use a different segment
>> > register, but it would be messy: CS can't point to the LDT for
>> > 64-bit code, and the other registers don't result in immediate
>> > faults because they aren't reloaded on kernel -> user transitions.
>> >
>> > When we fix sigcontext (in 4.6?), we can revert this.
>> >
>> > Signed-off-by: Andy Lutomirski <luto@kernel.org>
>> > --
>>
>> Andy,
>>
>> This patch didn't apply to linux-kselftest next.
>> It probably has to go through x86.
>
> It doesn't apply to -tip either. Andy, which tree is this against?
Oops, it applies on top of a new self-test that I forgot to send. I
send a v2 that should be better. I'll send the new selftest out as
well once -tip catches up with all the vdso patches.
--Andy
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] selftests/x86: Disable ldt_gdt_64 for now
2016-01-12 1:25 ` Andy Lutomirski
@ 2016-01-12 10:45 ` Ingo Molnar
0 siblings, 0 replies; 5+ messages in thread
From: Ingo Molnar @ 2016-01-12 10:45 UTC (permalink / raw)
To: Andy Lutomirski
Cc: Shuah Khan, Andy Lutomirski, X86 ML, Borislav Petkov, linux-kernel
* Andy Lutomirski <luto@amacapital.net> wrote:
> On Mon, Jan 11, 2016 at 2:59 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Shuah Khan <shuahkh@osg.samsung.com> wrote:
> >
> >> On 01/06/2016 12:51 PM, Andy Lutomirski wrote:
> >> > ldt_gdt.c relies on cross-cpu invalidation of SS to do one of its
> >> > tests. On 32-bit builds, this works fine, but on 64-bit builds, it
> >> > only works if the kernel has proper SS sigcontext handling for
> >> > 64-bit user programs.
> >> >
> >> > Since the SS fixes are currently reverted, restrict the test case to
> >> > 32 bits for now.
> >> >
> >> > In principle, I could change the test to use a different segment
> >> > register, but it would be messy: CS can't point to the LDT for
> >> > 64-bit code, and the other registers don't result in immediate
> >> > faults because they aren't reloaded on kernel -> user transitions.
> >> >
> >> > When we fix sigcontext (in 4.6?), we can revert this.
> >> >
> >> > Signed-off-by: Andy Lutomirski <luto@kernel.org>
> >> > --
> >>
> >> Andy,
> >>
> >> This patch didn't apply to linux-kselftest next.
> >> It probably has to go through x86.
> >
> > It doesn't apply to -tip either. Andy, which tree is this against?
>
> Oops, it applies on top of a new self-test that I forgot to send. I
> send a v2 that should be better. I'll send the new selftest out as
> well once -tip catches up with all the vdso patches.
Ok, sounds great!
Thanks,
Ingo
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2016-01-12 10:45 UTC | newest]
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2016-01-06 19:51 [PATCH] selftests/x86: Disable ldt_gdt_64 for now Andy Lutomirski
2016-01-07 20:49 ` Shuah Khan
2016-01-11 10:59 ` Ingo Molnar
2016-01-12 1:25 ` Andy Lutomirski
2016-01-12 10:45 ` Ingo Molnar
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