Zicbop introduces cache blocks prefetching instructions, add the
necessary support for the kernel to use it in the coming commits.
Co-developed-by: Guo Ren <guoren@kernel.org>
Signed-off-by: Guo Ren <guoren@kernel.org>
Tested-by: Andrea Parri <parri.andrea@gmail.com>
Link: https://lore.kernel.org/r/20250421142441.395849-3-alexghiti@rivosinc.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
RISC-V code uses the generic ticket lock implementation, which calls
the macros smp_cond_load_relaxed() and smp_cond_load_acquire().
Introduce a RISC-V specific implementation of smp_cond_load_relaxed()
which applies WRS.NTO of the Zawrs extension in order to reduce power
consumption while waiting and allows hypervisors to enable guests to
trap while waiting. smp_cond_load_acquire() doesn't need a RISC-V
specific implementation as the generic implementation is based on
smp_cond_load_relaxed() and smp_acquire__after_ctrl_dep() sufficiently
provides the acquire semantics.
This implementation is heavily based on Arm's approach which is the
approach Andrea Parri also suggested.
The Zawrs specification can be found here:
https://github.com/riscv/riscv-zawrs/blob/main/zawrs.adoc
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>
Co-developed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20240426100820.14762-11-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The past form of RISCV_FENCE would cause checkpatch.pl to issue
error messages, the example is as follows:
ERROR: space required after that ',' (ctx:VxV)
26: FILE: arch/riscv/include/asm/barrier.h:27:
+#define __smp_mb() RISCV_FENCE(rw,rw)
^
fix the remaining of RISCV_FENCE.
Signed-off-by: Eric Chan <ericchancf@google.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20240217131328.3669364-1-ericchancf@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Disparate fence implementations are consolidated into fence.h.
Also introduce RISCV_FENCE_ASM to make fence macro more reusable.
Signed-off-by: Eric Chan <ericchancf@google.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20240217131316.3668927-1-ericchancf@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Introduce __{mb,rmb,wmb}, and rely on the generic definitions for
{mb,rmb,wmb}. Although KCSAN is not supported yet, the definitions can
be made more consistent with generic instrumentation. Also add a space
to make the changes pass check by checkpatch.pl.
Without the space, the error message is as below:
ERROR: space required after that ',' (ctx:VxV)
26: FILE: arch/riscv/include/asm/barrier.h:23:
+#define __mb() RISCV_FENCE(iorw,iorw)
^
Signed-off-by: Eric Chan <ericchancf@google.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20240217131249.3668103-1-ericchancf@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
NOP sequences tend to get used for padding out alternative sections
This change adds macros for generating these sequences as both inline
asm blocks, but also as strings suitable for embedding in other asm
blocks directly.
It essentially mimics similar functionality from arm64 introduced by
Wil Deacon in commit f99a250cb6 ("arm64: barriers: introduce nops
and __nops macros for NOP sequences").
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220607143059.1054074-2-heiko@sntech.de
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
While digging through the recent mmiowb preemption issue it came up that
we aren't actually preventing IO from crossing a scheduling boundary.
While it's a bit ugly to overload smp_mb__after_spinlock() with this
behavior, it's what PowerPC is doing so there's some precedent.
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation this program 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 general public license
for more details you should have received a copy of the gnu general
public license along with this program if not see http www gnu org
licenses
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 503 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Enrico Weigelt <info@metux.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Introduce __smp_{store_release,load_acquire}, and rely on the generic
definitions for smp_{store_release,load_acquire}. This avoids the use
of full ("rw,rw") fences on SMP.
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Introduce __smp_{mb,rmb,wmb}, and rely on the generic definitions
for smp_{mb,rmb,wmb}. A first consequence is that smp_{mb,rmb,wmb}
map to a compiler barrier on !SMP (while their definition remains
unchanged on SMP). As a further consequence, smp_load_acquire and
smp_store_release have "fence rw,rw" instead of "fence iorw,iorw".
Signed-off-by: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
I removed this last week because of an incorrect comment:
smp_mb__after_spinlock() is actually still used, and is necessary on
RISC-V. It's been resurrected, with a comment that describes what it
actually does this time. Thanks to Andrea for finding the bug!
Fixes: 3343eb6806 ("RISC-V: Remove smb_mb__{before,after}_spinlock()")
CC: Andrea Parri <parri.andrea@gmail.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This contains all the code that directly interfaces with the RISC-V
memory model. While this code corforms to the current RISC-V ISA
specifications (user 2.2 and priv 1.10), the memory model is somewhat
underspecified in those documents. There is a working group that hopes
to produce a formal memory model by the end of the year, but my
understanding is that the basic definitions we're relying on here won't
change significantly.
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
