The shmlba.h file related to the LoongArch architecture was introduced
in commit 3eed5f3a1e to address the mismatch in the SHMLBA definition
between glibc and the kernel. See [1]. The SHMLBA definition was later
updated in commit d23b77953f5a. See [2]. Now, we adopt the definition
from the common layer.
[1]:
commit 3eed5f3a1e
Author: caiyinyu <caiyinyu@loongson.cn>
Date: Thu May 25 17:01:11 2023 +0800
LoongArch: Fix inconsistency in SHMLBA macro values between glibc and kernel
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.
[2]:
commit d23b77953f5a4fbf94c05157b186aac2a247ae32
Author: Huacai Chen <chenhuacai@kernel.org>
Date: Wed Jan 17 12:43:08 2024 +0800
LoongArch: Change SHMLBA from SZ_64K to PAGE_SIZE
LoongArch has hardware page coloring for L1 Cache, so we don't have
cache aliases. But SFB (Store Fill Buffer) still has aliases. So we
define SHMLBA to SZ_64K previously. But there are losts of applications
use PAGE_SIZE rather than SHMLBA to mmap() file pages and shared pages.
Of course we can fix them one by one, but not easy.
On the other hand, we can simply disable SFB for 4KB page size to fix
cache alias (there will be performance decrease, but acceptable), and
in future we will fix SFB in hardware. So we can safely define SHMLBA to
PAGE_SIZE (use the generic shmparam.h) to make life easier.
Signed-off-by: caiyinyu <caiyinyu@loongson.cn>
Reported-by: lixing <lixing@loongson.cn>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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.
