[PATCH] x86: Set header.feature_1 in TCB for always-on CET

[Adhemerval Zanella]

On 13/01/2021 09:14, H.J. Lu wrote:
> On Wed, Jan 13, 2021 at 4:09 AM H.J. Lu <hjl.tools@gmail.com> wrote:
>>
>> Update dl_cet_check() to set header.feature_1 in TCB when both IBT and
>> SHSTK are always on.
>> ---
>>  sysdeps/x86/Makefile         | 6 ++++++
>>  sysdeps/x86/dl-cet.c         | 5 ++++-
>>  sysdeps/x86/tst-setjmp-cet.c | 1 +
>>  3 files changed, 11 insertions(+), 1 deletion(-)
>>  create mode 100644 sysdeps/x86/tst-setjmp-cet.c
>>
>> diff --git a/sysdeps/x86/Makefile b/sysdeps/x86/Makefile
>> index c814d5a195..adaa2a92cd 100644
>> --- a/sysdeps/x86/Makefile
>> +++ b/sysdeps/x86/Makefile
>> @@ -48,6 +48,12 @@ endif # $(subdir) == math
>>  ifeq ($(subdir),setjmp)
>>  gen-as-const-headers += jmp_buf-ssp.sym
>>  sysdep_routines += __longjmp_cancel
>> +ifneq ($(enable-cet),no)
>> +ifneq ($(have-tunables),no)
>> +tests += tst-setjmp-cet
>> +tst-setjmp-cet-ENV = GLIBC_TUNABLES=glibc.cpu.x86_ibt=on:glibc.cpu.x86_shstk=on
>> +endif
>> +endif
>>  endif
>>
>>  ifeq ($(subdir),string)
>> diff --git a/sysdeps/x86/dl-cet.c b/sysdeps/x86/dl-cet.c
>> index ed7fd6d10d..a63b9c7164 100644
>> --- a/sysdeps/x86/dl-cet.c
>> +++ b/sysdeps/x86/dl-cet.c
>> @@ -47,7 +47,10 @@ dl_cet_check (struct link_map *m, const char *program)
>>    /* No legacy object check if both IBT and SHSTK are always on.  */
>>    if (enable_ibt_type == cet_always_on
>>        && enable_shstk_type == cet_always_on)
>> -    return;
>> +    {
>> +      THREAD_SETMEM (THREAD_SELF, header.feature_1, GL(dl_x86_feature_1));
>> +      return;
>> +    }
>>
>>    /* Check if IBT is enabled by kernel.  */
>>    bool ibt_enabled
>> diff --git a/sysdeps/x86/tst-setjmp-cet.c b/sysdeps/x86/tst-setjmp-cet.c
>> new file mode 100644
>> index 0000000000..42c795d2a8
>> --- /dev/null
>> +++ b/sysdeps/x86/tst-setjmp-cet.c
>> @@ -0,0 +1 @@
>> +#include <setjmp/tst-setjmp.c>
>> --
>> 2.29.2
>>
> 
> This fixed:
> 
> https://sourceware.org/bugzilla/show_bug.cgi?id=27177
> 
> I'd like to fix it for 2.33.
> 
> Thanks.
> 

Ok for 2.33.