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

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

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.

> +
> +int foo __attribute__ ((aligned (ALIGN))) = 1;
> +
> +void
> +do_load_test (void)
> +{
> +  printf ("foo: %p\n", &foo);
> +  TEST_VERIFY (is_aligned (&foo, ALIGN) == 0);
> +}
>