Re: [PATCH v2] tests: Remove target-specific huge-page size definition for THP-aware load segment alignment

On 01/08/26 18:09, Xi Ruoyao wrote:
> On MIPS64 and AArch64 systems with 16-KiB pages, the PMD size is 32MB.
> As we already have multiple platforms requiring such a large size and
> it's the maximum THP size we support to align the load segments, it's
> easier to raise the default instead of adding more special cases.
> 
> Link: https://sourceware.org/glibc/wiki/Testing/Tests/elf/tst-thp-1
> Signed-off-by: Xi Ruoyao <[email protected]>

LGTM, thanks.  This will increase the tst-thp-1{-pde,-static} and
tst-thp-1-no-s-code{-pde,-static}, but I think it should be ok.

Should we enforce MAX_THP_PAGESIZE <= 0x4000000 somewhere? I think
it unlikely an ABI will even set a large page as large as this.

Reviewed-by: Adhemerval Zanella  <[email protected]>

> ---
> 
> Tested on aarch64-linux with a 16 KiB page kernel.
> 
>  sysdeps/unix/sysv/linux/Makefile           | 16 ++++++----------
>  sysdeps/unix/sysv/linux/loongarch/Makefile |  3 ---
>  sysdeps/unix/sysv/linux/sparc/Makefile     |  5 -----
>  sysdeps/unix/sysv/linux/tst-thp-size.S     |  4 +++-
>  4 files changed, 9 insertions(+), 19 deletions(-)
> 
> diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
> index 14a56d5cc3..34856a3b2f 100644
> --- a/sysdeps/unix/sysv/linux/Makefile
> +++ b/sysdeps/unix/sysv/linux/Makefile
> @@ -730,21 +730,17 @@ tests-special += \
>    # tests-special
>  endif
>  
> -ifndef THP-PAGE-SIZE
>  # Align PT_LOAD segments in THP tests to THP page size so that kernel will
> -# map PIE to the address aligned to THP page size.  Default THP page size
> -# to 2MB which can be overridden in Makefile in subdirectories.
> -THP-PAGE-SIZE = 0x200000
> -endif
> -
> -THP-PAGE-SIZE-CFLAGS = -DTHP_PAGE_SIZE=$(THP-PAGE-SIZE)

We still have a lingering usage of this flag:

$ git grep -wn THP-PAGE-SIZE-CFLAGS
sysdeps/unix/sysv/linux/Makefile:792:ASFLAGS-tst-thp-size.S = $(THP-PAGE-SIZE-CFLAGS)

> -THP-PAGE-SIZE-LDFLAGS = -Wl,-z,max-page-size=$(THP-PAGE-SIZE)
> +# map PIE to the address aligned to THP page size.  The maximum THP size we
> +# support to align the load segments (and we skip the tests with even
> +# larger THP) is 32 MiB.
> +THP-PAGE-SIZE-LDFLAGS = -Wl,-z,max-page-size=0x2000000
>  
> -# -Wl,-z,max-page-size=$(THP-PAGE-SIZE) alone doesn't work for PDE when
> +# -Wl,-z,max-page-size=0x2000000 alone doesn't work for PDE when
>  # text-segment address is lower than the maximum page size:
>  # https://sourceware.org/bugzilla/show_bug.cgi?id=34184
>  ifneq (,$(load-address-ldflag))
> -LOAD-THP-ADDRESS-LDFLAGS = $(load-address-ldflag)=$(THP-PAGE-SIZE)
> +LOAD-THP-ADDRESS-LDFLAGS = $(load-address-ldflag)=0x2000000
>  endif
>  
>  LDFLAGS-tst-thp-size-mod.so = -Wl,-z,noseparate-code \
> diff --git a/sysdeps/unix/sysv/linux/loongarch/Makefile b/sysdeps/unix/sysv/linux/loongarch/Makefile
> index d5beb62440..0d5f087862 100644
> --- a/sysdeps/unix/sysv/linux/loongarch/Makefile
> +++ b/sysdeps/unix/sysv/linux/loongarch/Makefile
> @@ -12,6 +12,3 @@ abi-ilp32s-condition	:= __WORDSIZE == 32 && defined __loongarch_soft_float
>  abi-ilp32d-condition	:= __WORDSIZE == 32 && defined __loongarch_double_float
>  abi-lp64s-condition	:= __WORDSIZE == 64 && defined __loongarch_soft_float
>  abi-lp64d-condition	:= __WORDSIZE == 64 && defined __loongarch_double_float
> -
> -# Align THP tests to 32MB.
> -THP-PAGE-SIZE = 0x2000000
> diff --git a/sysdeps/unix/sysv/linux/sparc/Makefile b/sysdeps/unix/sysv/linux/sparc/Makefile
> index 57e73d0a14..e0056c9413 100644
> --- a/sysdeps/unix/sysv/linux/sparc/Makefile
> +++ b/sysdeps/unix/sysv/linux/sparc/Makefile
> @@ -14,8 +14,3 @@ endif
>  ifeq ($(subdir),signal)
>  sysdep_routines += sigreturn_stub
>  endif
> -
> -ifeq ($(subdir),elf)
> -# The sparc64 uses an 8KB base page and 8MB PMD transparent huge page
> -THP-PAGE-SIZE = 0x800000
> -endif
> diff --git a/sysdeps/unix/sysv/linux/tst-thp-size.S b/sysdeps/unix/sysv/linux/tst-thp-size.S
> index 29c5f4e750..154b167509 100644
> --- a/sysdeps/unix/sysv/linux/tst-thp-size.S
> +++ b/sysdeps/unix/sysv/linux/tst-thp-size.S
> @@ -17,4 +17,6 @@
>     <https://www.gnu.org/licenses/>.  */
>  
>  	.text
> -	.space 2 * THP_PAGE_SIZE
> +	/* 64 MiB, twice of MAX_THP_PAGESIZE in dl-map-segment-align.h and
> +	   tst-thp-align.c */

After some change MAX_THP_PAGESIZE is now defined at sysdeps/generic/hugepages.h.

> +	.space 0x4000000