[PATCH] elf: Disable some subtests of ifuncmain1, ifuncmain5 for !PIE

[Fangrui Song]

On 2022-11-04, H.J. Lu wrote:
>On Fri, Nov 4, 2022 at 11:26 AM Florian Weimer <fweimer@redhat.com> wrote:
>>
>> Tested on i686-linux-gnu, x86_64-linux-gnu (with glibc defaults on a
>> toolchain which is not PIE-by-default).  Built with build-many-glibcs.py
>> defaults (so GCC 12 and binutils 2.39).  The x86 failures are gone.
>>
>> ---
>>  elf/ifuncmain1.c | 13 +++++++++++++
>>  elf/ifuncmain5.c |  9 +++++++++
>>  2 files changed, 22 insertions(+)
>>
>> diff --git a/elf/ifuncmain1.c b/elf/ifuncmain1.c
>> index 747fc02648..6effce3d77 100644
>> --- a/elf/ifuncmain1.c
>> +++ b/elf/ifuncmain1.c
>> @@ -19,7 +19,14 @@ typedef int (*foo_p) (void);
>>  #endif
>>
>>  foo_p foo_ptr = foo;
>> +
>> +/* Address-significant access to protected symbols is not supported in
>> +   position-dependent mode on several architectures because GCC
>> +   generates relocations that assume that the address is local to the
>> +   main program.  */

Address-significant access to protected symbols in the same module is
fine.  To a protected symbol defined in another module is not.

The comment may need to clarify this.

Reviewed-by: Fangrui Song <maskray@google.com>

>> +#ifdef __PIE__
>>  foo_p foo_procted_ptr = foo_protected;
>> +#endif
>>
>>  extern foo_p get_foo_p (void);
>>  extern foo_p get_foo_hidden_p (void);
>> @@ -37,12 +44,16 @@ main (void)
>>    if ((*foo_ptr) () != -1)
>>      abort ();
>>
>> +#ifdef __PIE__
>>    if (foo_procted_ptr != foo_protected)
>>      abort ();
>> +#endif
>>    if (foo_protected () != 0)
>>      abort ();
>> +#ifdef __PIE__
>>    if ((*foo_procted_ptr) () != 0)
>>      abort ();
>> +#endif
>>
>>    p = get_foo_p ();
>>    if (p != foo)
>> @@ -55,8 +66,10 @@ main (void)
>>      abort ();
>>
>>    p = get_foo_protected_p ();
>> +#ifdef __PIE__
>>    if (p != foo_protected)
>>      abort ();
>> +#endif
>>    if (ret_foo_protected != 0 || (*p) () != ret_foo_protected)
>>      abort ();
>>
>> diff --git a/elf/ifuncmain5.c b/elf/ifuncmain5.c
>> index f398085cb4..6fda768fb6 100644
>> --- a/elf/ifuncmain5.c
>> +++ b/elf/ifuncmain5.c
>> @@ -14,12 +14,19 @@ get_foo (void)
>>    return foo;
>>  }
>>
>> +
>> +/* Address-significant access to protected symbols is not supported in
>> +   position-dependent mode on several architectures because GCC
>> +   generates relocations that assume that the address is local to the
>> +   main program.  */
>> +#ifdef __PIE__
>>  foo_p
>>  __attribute__ ((noinline))
>>  get_foo_protected (void)
>>  {
>>    return foo_protected;
>>  }
>> +#endif
>>
>>  int
>>  main (void)
>> @@ -30,9 +37,11 @@ main (void)
>>    if ((*p) () != -1)
>>      abort ();
>>
>> +#ifdef __PIE__
>>    p = get_foo_protected ();
>>    if ((*p) () != 0)
>>      abort ();
>> +#endif
>>
>>    return 0;
>>  }
>>
>> base-commit: 2ff48a4025515e93d722947a9eabb114f4a65b22
>>
>
>LGTM.
>
>Thanks.
>
>-- 
>H.J.