LoongArch has similar problems explained in commit 7f0b1bf045
("arm64: Fix barriers used for page table modifications"), when hardware
page table walker (PTW) enabled, speculative accesses may cause spurious
page fault in kernel space. Theoretically, in order to completely avoid
spurious page fault we need a "dbar + ibar" pair between the page table
modifications and the subsequent memory accesses using the corresponding
virtual address. But "ibar" is too heavy for performace, so we only use
a "dbar 0b11000" in set_pte(). And let spurious_fault() filter the rest
rare spurious page faults which should be avoided by "ibar".
Besides, we replace the llsc loop with amo in set_pte() which has better
performace, and refactor mmu_context.h to 1) avoid any load/store/branch
instructions between the writing of CSR.ASID & CSR.PGDL, 2) ensure flush
tlb operation is after updating ASID.
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Currently several architectures have kerneldoc comments for
arch_atomic_*(), which is unhelpful as these live in a shared namespace
where they clash, and the arch_atomic_*() ops are now an implementation
detail of the raw_atomic_*() ops, which no-one should use those
directly.
Delete the kerneldoc comments for arch_atomic_*(), along with
pseudo-kerneldoc comments which are in the correct style but are missing
the leading '/**' necessary to be true kerneldoc comments.
There should be no functional change as a result of this patch.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-28-mark.rutland@arm.com
Most architectures define the atomic/atomic64 xchg and cmpxchg
operations in terms of arch_xchg and arch_cmpxchg respectfully.
Add fallbacks for these cases and remove the trivial cases from arch
code. On some architectures the existing definitions are kept as these
are used to build other arch_atomic*() operations.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-5-mark.rutland@arm.com
The content of LoongArch's compiler.h is trivial, with some unused
anywhere, so inline the definitions and remove the header.
Signed-off-by: Jun Yi <yijun@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Support for the syntactic sugar is present in upstream binutils port
from the beginning. Use it for shorter lines and better consistency.
Generated code should be identical.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
While B{EQ,NE}Z and B{EQ,NE} are different instructions, and the vastly
expanded range for branch destination does not really matter in the few
cases touched, use the B{EQ,NE}Z where possible for shorter lines and
better consistency (e.g. some places used "BEQ foo, zero", while some
used "BEQ zero, foo").
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Some of the assembly code in the LoongArch port likely originated
from a time when the assembler did not support pseudo-instructions like
"move" or "jr", so the desugared form was used and readability suffers
(to a minor degree) as a result.
As the upstream toolchain supports these pseudo-instructions from the
beginning, migrate the existing few usages to them for better
readability.
Signed-off-by: WANG Xuerui <git@xen0n.name>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
LoongArch-based procesors have 4, 8 or 16 cores per package. This patch
adds multi-processor (SMP) support for LoongArch.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Add common headers (atomic, bitops, barrier and locking) for basic
LoongArch support.
Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
