[PATCH] LoongArch: Fix inconsistency in SHMLBA macro values between glibc and kernel

[PATCH] LoongArch: Fix inconsistency in SHMLBA macro values between glibc and kernel

[caiyinyu]

The LoongArch glibc was using the value of the SHMLBA macro from common code,
which is __getpagesize() (16k), but this was inconsistent with the value of
the SHMLBA macro in the kernel, which is SZ_64K (64k). This caused several
shmat-related tests in LTP (Linux Test Project) to fail. This commit fixes
the issue by ensuring that the glibc's SHMLBA macro value matches the value
used in the kernel like other architectures.
---
 .../unix/sysv/linux/loongarch/bits/shmlba.h   | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 sysdeps/unix/sysv/linux/loongarch/bits/shmlba.h

diff --git a/sysdeps/unix/sysv/linux/loongarch/bits/shmlba.h b/sysdeps/unix/sysv/linux/loongarch/bits/shmlba.h
new file mode 100644
index 0000000000..3c171ef7b6
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/loongarch/bits/shmlba.h
@@ -0,0 +1,24 @@
+/* Define SHMLBA.  LoongArch version.
+   Copyright (C) 2023 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/>.  */
+
+#ifndef _SYS_SHM_H
+# error "Never use <bits/shmlba.h> directly; include <sys/shm.h> instead."
+#endif
+
+/* Segment low boundary address multiple.  */
+#define SHMLBA		0x10000
-- 
2.31.1

Re: [PATCH] LoongArch: Fix inconsistency in SHMLBA macro values between glibc and kernel

[Florian Weimer]

> The LoongArch glibc was using the value of the SHMLBA macro from common code,
> which is __getpagesize() (16k), but this was inconsistent with the value of
> the SHMLBA macro in the kernel, which is SZ_64K (64k). This caused several
> shmat-related tests in LTP (Linux Test Project) to fail. This commit fixes
> the issue by ensuring that the glibc's SHMLBA macro value matches the value
> used in the kernel like other architectures.

Would it be possible to add a generic test like
sysdeps/unix/sysv/linux/tst-mman-consts.py against the UAPI headers?
Or is this constant not exported at all?

Thanks,
Florian

Re: [PATCH] LoongArch: Fix inconsistency in SHMLBA macro values between glibc and kernel

[Xi Ruoyao]

On Thu, 2023-05-25 at 13:01 +0200, Florian Weimer wrote:
> > The LoongArch glibc was using the value of the SHMLBA macro from
> > common code,
> > which is __getpagesize() (16k), but this was inconsistent with the
> > value of
> > the SHMLBA macro in the kernel, which is SZ_64K (64k). This caused
> > several
> > shmat-related tests in LTP (Linux Test Project) to fail. This commit
> > fixes
> > the issue by ensuring that the glibc's SHMLBA macro value matches
> > the value
> > used in the kernel like other architectures.
> 
> Would it be possible to add a generic test like
> sysdeps/unix/sysv/linux/tst-mman-consts.py against the UAPI headers?
> Or is this constant not exported at all?

SHMLBA seems not exist in a Linux 6.3.0 UAPI header installation (from
Gentoo on a LoongArch).


-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

Re: [PATCH] LoongArch: Fix inconsistency in SHMLBA macro values between glibc and kernel

[caiyinyu]

在 2023/5/25 下午7:01, Florian Weimer 写道:
>> The LoongArch glibc was using the value of the SHMLBA macro from common code,
>> which is __getpagesize() (16k), but this was inconsistent with the value of
>> the SHMLBA macro in the kernel, which is SZ_64K (64k). This caused several
>> shmat-related tests in LTP (Linux Test Project) to fail. This commit fixes
>> the issue by ensuring that the glibc's SHMLBA macro value matches the value
>> used in the kernel like other architectures.
> Would it be possible to add a generic test like
> sysdeps/unix/sysv/linux/tst-mman-consts.py against the UAPI headers?
> Or is this constant not exported at all?


The Linux kernel defines the architecture-dependent macro SHMLBA in 
arch/*/include/asm/shmparam.h.

This macro is also defined in the common code in 
include/asm-generic/shmparam.h.

However, neither of them are exported as part of the uapi.

>
> Thanks,
> Florian