Commit 5e1e6937 authored by Huacai Chen's avatar Huacai Chen Committed by Hongchen Zhang
Browse files

LoongArch: Change SHMLBA from SZ_64K to PAGE_SIZE 

mainline inclusion
from mainline-v6.8-rc1
commit d23b77953f5a4fbf94c05157b186aac2a247ae32
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/IAZ33N
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d23b77953f5a4fbf94c05157b186aac2a247ae32



----------------------------------------------------------------------

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: default avatarHuacai Chen <chenhuacai@loongson.cn>
parent 9a2058ed

arch/loongarch/include/asm/shmparam.h

deleted100644 → 0
+0 −12
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited

 */

#ifndef _ASM_SHMPARAM_H

#define _ASM_SHMPARAM_H



#define __ARCH_FORCE_SHMLBA	1



#define	SHMLBA	SZ_64K		 /* attach addr a multiple of this */



#endif /* _ASM_SHMPARAM_H */

arch/loongarch/kernel/head.S

+10 −0
Original line number Diff line number Diff line
@@ -74,6 +74,11 @@ SYM_CODE_START(kernel_entry) # kernel entry point 
	la.pcrel	t0, fw_arg2

	st.d		a2, t0, 0



#ifdef CONFIG_PAGE_SIZE_4KB

	li.d		t0, 0

	li.d		t1, CSR_STFILL

	csrxchg		t0, t1, LOONGARCH_CSR_IMPCTL1

#endif

	/* KSave3 used for percpu base, initialized as 0 */

	csrwr		zero, PERCPU_BASE_KS

	/* GPR21 used for percpu base (runtime), initialized as 0 */
@@ -126,6 +131,11 @@ SYM_CODE_START(smpboot_entry) 


	JUMP_VIRT_ADDR	t0, t1



#ifdef CONFIG_PAGE_SIZE_4KB

	li.d		t0, 0

	li.d		t1, CSR_STFILL

	csrxchg		t0, t1, LOONGARCH_CSR_IMPCTL1

#endif

	/* Enable PG */

	li.w		t0, 0xb0		# PLV=0, IE=0, PG=1

	csrwr		t0, LOONGARCH_CSR_CRMD