Re: [PATCH v5 2/2] Add a testcase to check alignment of PT_LOAD segment

["H.J. Lu" <hjl.tools@gmail.com>]

On Fri, Dec 10, 2021 at 12:05 PM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 10/12/2021 15:56, H.J. Lu wrote:
> > On Fri, Dec 10, 2021 at 7:41 AM H.J. Lu <hjl.tools@gmail.com> wrote:
> >>
> >> On Fri, Dec 10, 2021 at 5:48 AM Adhemerval Zanella
> >> <adhemerval.zanella@linaro.org> wrote:
> >>>
> >>>
> >>>
> >>> On 10/12/2021 09:39, Rongwei Wang via Libc-alpha wrote:
> >>>> From: "H.J. Lu" <hjl.tools@gmail.com>
> >>>>
> >>>> This patch adds a testcase for PT_LOAD segment to check it is
> >>>> properly aligned when the alignment > the page size.
> >>>>
> >>>> Signed-off-by: "H.J. Lu" <hjl.tools@gmail.com>
> >>>> Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com>
> >>>> ---
> >>>>  elf/Makefile        | 14 ++++++++++++--
> >>>>  elf/tst-align3.c    | 37 +++++++++++++++++++++++++++++++++++++
> >>>>  elf/tst-alignmod3.c | 31 +++++++++++++++++++++++++++++++
> >>>>  3 files changed, 80 insertions(+), 2 deletions(-)
> >>>>  create mode 100644 elf/tst-align3.c
> >>>>  create mode 100644 elf/tst-alignmod3.c
> >>>>
> >>>> diff --git a/elf/Makefile b/elf/Makefile
> >>>> index ef36008673..b16128ac8b 100644
> >>>> --- a/elf/Makefile
> >>>> +++ b/elf/Makefile
> >>>> @@ -207,7 +207,7 @@ tests += restest1 preloadtest loadfail multiload origtest resolvfail \
> >>>>        tst-tls4 tst-tls5 \
> >>>>        tst-tls10 tst-tls11 tst-tls12 tst-tls13 tst-tls14 tst-tls15 \
> >>>>        tst-tls16 tst-tls17 tst-tls18 tst-tls19 tst-tls-dlinfo \
> >>>> -      tst-align tst-align2 \
> >>>> +      tst-align tst-align2 tst-align3 \
> >>>>        tst-dlmodcount tst-dlopenrpath tst-deep1 \
> >>>>        tst-dlmopen1 tst-dlmopen3 tst-dlmopen4 \
> >>>>        unload3 unload4 unload5 unload6 unload7 unload8 tst-global1 order2 \
> >>>> @@ -241,6 +241,9 @@ tests-internal += loadtest unload unload2 circleload1 \
> >>>>  tests-container += tst-pldd tst-dlopen-tlsmodid-container \
> >>>>    tst-dlopen-self-container tst-preload-pthread-libc
> >>>>  test-srcs = tst-pathopt
> >>>> +ifeq (yes,$(have-fpie))
> >>>> +tests-pie += tst-align3
> >>>> +endif
> >>>>  selinux-enabled := $(shell cat /selinux/enforce 2> /dev/null)
> >>>>  ifneq ($(selinux-enabled),1)
> >>>>  tests-execstack-yes = tst-execstack tst-execstack-needed tst-execstack-prog
> >>>> @@ -302,7 +305,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
> >>>>               circlemod3 circlemod3a \
> >>>>               reldep8mod1 reldep8mod2 reldep8mod3 \
> >>>>               reldep9mod1 reldep9mod2 reldep9mod3 \
> >>>> -             tst-alignmod tst-alignmod2 \
> >>>> +             tst-alignmod tst-alignmod2 tst-alignmod3 \
> >>>>               $(modules-execstack-$(have-z-execstack)) \
> >>>>               tst-dlopenrpathmod tst-deep1mod1 tst-deep1mod2 tst-deep1mod3 \
> >>>>               tst-dlmopen1mod tst-auditmod1 \
> >>>> @@ -1088,6 +1091,13 @@ CFLAGS-tst-alignmod.c += $(stack-align-test-flags)
> >>>>  CFLAGS-tst-alignmod2.c += $(stack-align-test-flags)
> >>>>  $(objpfx)tst-align.out: $(objpfx)tst-alignmod.so
> >>>>  $(objpfx)tst-align2: $(objpfx)tst-alignmod2.so
> >>>> +$(objpfx)tst-align3: $(objpfx)tst-alignmod3.so
> >>>> +ifeq (yes,$(have-fpie))
> >>>> +CFLAGS-tst-align3.c += $(PIE-ccflag)
> >>>> +endif
> >>>> +LDFLAGS-tst-align3 += -Wl,-z,max-page-size=0x200000
> >>>> +LDFLAGS-tst-alignmod3.so += -Wl,-z,max-page-size=0x200000
> >>>> +$(objpfx)tst-alignmod3.so: $(libsupport)
> >>>>
> >>>>  $(objpfx)unload3.out: $(objpfx)unload3mod1.so $(objpfx)unload3mod2.so \
> >>>>                     $(objpfx)unload3mod3.so $(objpfx)unload3mod4.so
> >>>> diff --git a/elf/tst-align3.c b/elf/tst-align3.c
> >>>> new file mode 100644
> >>>> index 0000000000..5697c0bbaf
> >>>> --- /dev/null
> >>>> +++ b/elf/tst-align3.c
> >>>> @@ -0,0 +1,37 @@
> >>>> +/* Check alignment of PT_LOAD segment in a shared library.
> >>>> +   Copyright (C) 2021 Free Software Foundation, Inc.
> >>>> +   This file is part of the GNU C Library.
> >>>> +
> >>>> +   The GNU C Library is free software; you can redistribute it and/or
> >>>> +   modify it under the terms of the GNU Lesser General Public
> >>>> +   License as published by the Free Software Foundation; either
> >>>> +   version 2.1 of the License, or (at your option) any later version.
> >>>> +
> >>>> +   The GNU C Library is distributed in the hope that it will be useful,
> >>>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> >>>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> >>>> +   Lesser General Public License for more details.
> >>>> +
> >>>> +   You should have received a copy of the GNU Lesser General Public
> >>>> +   License along with the GNU C Library; if not, see
> >>>> +   <https://www.gnu.org/licenses/>.  */
> >>>> +
> >>>> +#include <support/check.h>
> >>>> +#include <tst-stack-align.h>
> >>>> +
> >>>> +#define ALIGN 0x200000
> >>>> +
> >>>> +int bar __attribute__ ((aligned (ALIGN))) = 1;
> >>>> +
> >>>> +extern int do_load_test (void);
> >>>> +
> >>>> +static int
> >>>> +do_test (void)
> >>>> +{
> >>>> +  printf ("bar: %p\n", &bar);
> >>>> +  TEST_VERIFY (is_aligned (&bar, ALIGN) == 0);
> >>>> +
> >>>> +  return do_load_test ();
> >>>> +}
> >>>> +
> >>>> +#include <support/test-driver.c>
> >>>> diff --git a/elf/tst-alignmod3.c b/elf/tst-alignmod3.c
> >>>> new file mode 100644
> >>>> index 0000000000..50ec08462c
> >>>> --- /dev/null
> >>>> +++ b/elf/tst-alignmod3.c
> >>>> @@ -0,0 +1,31 @@
> >>>> +/* Check alignment of PT_LOAD segment in a shared library.
> >>>> +   Copyright (C) 2021 Free Software Foundation, Inc.
> >>>> +   This file is part of the GNU C Library.
> >>>> +
> >>>> +   The GNU C Library is free software; you can redistribute it and/or
> >>>> +   modify it under the terms of the GNU Lesser General Public
> >>>> +   License as published by the Free Software Foundation; either
> >>>> +   version 2.1 of the License, or (at your option) any later version.
> >>>> +
> >>>> +   The GNU C Library is distributed in the hope that it will be useful,
> >>>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> >>>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> >>>> +   Lesser General Public License for more details.
> >>>> +
> >>>> +   You should have received a copy of the GNU Lesser General Public
> >>>> +   License along with the GNU C Library; if not, see
> >>>> +   <https://www.gnu.org/licenses/>.  */
> >>>> +
> >>>> +#include <support/check.h>
> >>>> +#include <tst-stack-align.h>
> >>>> +
> >>>> +#define ALIGN 0x200000
> >>>
> >>> I think it should cover all possible pagesize we current support.  Maybe add
> >>> a comment here or on Makefile about it.
> >>
> >> Here is the v2 patch I added
> >>
> >> /* This should cover all possible page sizes we currently support.  */
> >>
> >>>> +
> >>>> +int foo __attribute__ ((aligned (ALIGN))) = 1;
> >>>> +
> >>>> +void
> >>>> +do_load_test (void)
> >>>> +{
> >>>> +  printf ("foo: %p\n", &foo);
> >>>> +  TEST_VERIFY (is_aligned (&foo, ALIGN) == 0);
> >>>> +}
> >>>>
> >>
> >>
> >>
> >> --
> >> H.J.
> >
> > I am checking in this.
> >
>
> It fails to build for alpha:
>
> /tmp/cc0teHmf.s: Assembler messages:
> /tmp/cc0teHmf.s:206: Error: Alignment too large: 16. assumed
> make[2]: *** [../o-iterator.mk:9: /home/azanella/Projects/glibc/build/alpha-linux-gnu/elf/tst-align3.o] Error 1
> make[2]: Leaving directory '/home/azanella/Projects/glibc/glibc-git/elf'
> make[1]: *** [Makefile:483: elf/tests] Error 2
> make[1]: Leaving directory '/home/azanella/Projects/glibc/glibc-git'
> make: *** [Makefile:9: check] Error 2

The maximum alignment for alpha is 0x10000.  I will add a configure-time
check.

-- 
H.J.