kernel/arch/riscv/include/asm/vdso/processor.h, branch linux-rolling-stable

riscv: errata: Fix the PAUSE Opcode for MIPS P8700

2025-09-19T16:33:56Z

Add ERRATA_MIPS and ERRATA_MIPS_P8700_PAUSE_OPCODE configs. Handle errata for the MIPS PAUSE instruction. Signed-off-by: Djordje Todorovic Signed-off-by: Aleksandar Rikalo Signed-off-by: Raj Vishwanathan4 Signed-off-by: Aleksa Paunovic Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/r/20250724-p8700-pause-v5-7-a6cbbe1c3412@htecgroup.com [pjw@kernel.org: updated to apply and compile; fixed a checkpatch issue] Signed-off-by: Paul Walmsley

riscv: Replace ASSEMBLY with ASSEMBLER in non-uapi headers

2025-09-16T22:25:30Z

While the GCC and Clang compilers already define __ASSEMBLER__ automatically when compiling assembly code, __ASSEMBLY__ is a macro that only gets defined by the Makefiles in the kernel. This can be very confusing when switching between userspace and kernelspace coding, or when dealing with uapi headers that rather should use __ASSEMBLER__ instead. So let's standardize on the __ASSEMBLER__ macro that is provided by the compilers now. This originally was a completely mechanical patch (done with a simple "sed -i" statement), with some manual fixups during rebasing of the patch later. Cc: Paul Walmsley Cc: Palmer Dabbelt Cc: Albert Ou Cc: Alexandre Ghiti Cc: linux-riscv@lists.infradead.org Signed-off-by: Thomas Huth Link: https://lore.kernel.org/r/20250606070952.498274-3-thuth@redhat.com Signed-off-by: Paul Walmsley

riscv: Provide a definition for 'pause'

2024-07-12T10:16:39Z

If we're going to provide the encoding for 'pause' in cpu_relax() anyway, then we can drop the toolchain checks and just always use it. The advantage of doing this is that other code that need pause don't need to also define it (yes, another use is coming). Add the definition to insn-def.h since it's an instruction definition and also because insn-def.h doesn't include much, so it's safe to include from asm/vdso/processor.h without concern for circular dependencies. Signed-off-by: Andrew Jones Link: https://lore.kernel.org/r/20240426100820.14762-9-ajones@ventanamicro.com Signed-off-by: Palmer Dabbelt

riscv: Using TOOLCHAIN_HAS_ZIHINTPAUSE marco replace zihintpause

2023-11-01T02:15:54Z

Actually it is a part of Conor's commit aae538cd03bc ("riscv: fix detection of toolchain Zihintpause support"). It is looks like a merge issue. Samuel's commit 0b1d60d6dd9e ("riscv: Fix build with CONFIG_CC_OPTIMIZE_FOR_SIZE=y") do not base on Conor's commit and revert to __riscv_zihintpause. So this patch can fix it. Signed-off-by: Minda Chen Fixes: 3c349eacc559 ("Merge patch "riscv: Fix build with CONFIG_CC_OPTIMIZE_FOR_SIZE=y"") Reviewed-by: Conor Dooley Link: https://lore.kernel.org/r/20230802064215.31111-1-minda.chen@starfivetech.com Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt

Merge patch "riscv: Fix build with CONFIG_CC_OPTIMIZE_FOR_SIZE=y"

2023-02-01T05:55:43Z

This is a single fix, but it conflicts with some recent features. I'm merging it on top of the commit it fixes to ease backporting. * b4-shazam-merge: riscv: Fix build with CONFIG_CC_OPTIMIZE_FOR_SIZE=y Link: https://lore.kernel.org/r/20220922060958.44203-1-samuel@sholland.org Signed-off-by: Palmer Dabbelt

riscv: Fix build with CONFIG_CC_OPTIMIZE_FOR_SIZE=y

2023-02-01T05:55:27Z

commit 8eb060e10185 ("arch/riscv: add Zihintpause support") broke building with CONFIG_CC_OPTIMIZE_FOR_SIZE enabled (gcc 11.1.0): CC arch/riscv/kernel/vdso/vgettimeofday.o In file included from : ./arch/riscv/include/asm/jump_label.h: In function 'cpu_relax': ././include/linux/compiler_types.h:285:33: warning: 'asm' operand 0 probably does not match constraints 285 | #define asm_volatile_goto(x...) asm goto(x) | ^~~ ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro 'asm_volatile_goto' 41 | asm_volatile_goto( | ^~~~~~~~~~~~~~~~~ ././include/linux/compiler_types.h:285:33: error: impossible constraint in 'asm' 285 | #define asm_volatile_goto(x...) asm goto(x) | ^~~ ./arch/riscv/include/asm/jump_label.h:41:9: note: in expansion of macro 'asm_volatile_goto' 41 | asm_volatile_goto( | ^~~~~~~~~~~~~~~~~ make[1]: *** [scripts/Makefile.build:249: arch/riscv/kernel/vdso/vgettimeofday.o] Error 1 make: *** [arch/riscv/Makefile:128: vdso_prepare] Error 2 Having a static branch in cpu_relax() is problematic because that function is widely inlined, including in some quite complex functions like in the VDSO. A quick measurement shows this static branch is responsible by itself for around 40% of the jump table. Drop the static branch, which ends up being the same number of instructions anyway. If Zihintpause is supported, we trade the nop from the static branch for a div. If Zihintpause is unsupported, we trade the jump from the static branch for (what gets interpreted as) a nop. Fixes: 8eb060e10185 ("arch/riscv: add Zihintpause support") Signed-off-by: Samuel Holland Reviewed-by: Conor Dooley Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt

riscv: fix detection of toolchain Zihintpause support

2022-10-27T22:13:06Z

It is not sufficient to check if a toolchain supports a particular extension without checking if the linker supports that extension too. For example, Clang 15 supports Zihintpause but GNU bintutils 2.35.2 does not, leading build errors like so: riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zihintpause2p0: Invalid or unknown z ISA extension: 'zihintpause' Add a TOOLCHAIN_HAS_ZIHINTPAUSE which checks if each of the compiler, assembler and linker support the extension. Replace the ifdef in the vdso with one depending on this new symbol. Fixes: 8eb060e10185 ("arch/riscv: add Zihintpause support") Signed-off-by: Conor Dooley Reviewed-by: Heiko Stuebner Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20221006173520.1785507-3-conor@kernel.org Signed-off-by: Palmer Dabbelt

arch/riscv: add Zihintpause support

2022-08-11T15:03:49Z

Implement support for the ZiHintPause extension. The PAUSE instruction is a HINT that indicates the current hart’s rate of instruction retirement should be temporarily reduced or paused. Reviewed-by: Heiko Stuebner Tested-by: Heiko Stuebner Signed-off-by: Dao Lu [Palmer: Some minor merge conflicts.] Link: https://lore.kernel.org/all/20220620201530.3929352-1-daolu@rivosinc.com/ Link: https://lore.kernel.org/all/20220811053356.17375-1-palmer@rivosinc.com/ Signed-off-by: Palmer Dabbelt

RISC-V: fix barrier() use in

2020-11-25T17:44:27Z

riscv's uses barrier() so it should include Fixes this build error: CC [M] drivers/net/ethernet/emulex/benet/be_main.o In file included from ./include/vdso/processor.h:10, from ./arch/riscv/include/asm/processor.h:11, from ./include/linux/prefetch.h:15, from drivers/net/ethernet/emulex/benet/be_main.c:14: ./arch/riscv/include/asm/vdso/processor.h: In function 'cpu_relax': ./arch/riscv/include/asm/vdso/processor.h:14:2: error: implicit declaration of function 'barrier' [-Werror=implicit-function-declaration] 14 | barrier(); This happens with a total of 5 networking drivers -- they all use . rv64 allmodconfig now builds cleanly after this patch. Fixes fallout from: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") Fixes: ad5d1122b82f ("riscv: use vDSO common flow to reduce the latency of the time-related functions") Reported-by: Andreas Schwab Signed-off-by: Randy Dunlap Acked-by: Arvind Sankar Signed-off-by: Palmer Dabbelt Reviewed-by: Nick Desaulniers Signed-off-by: Palmer Dabbelt

riscv: use vDSO common flow to reduce the latency of the time-related functions

2020-06-11T02:47:16Z

Even if RISC-V has supported the vDSO feature, the latency of the functions for obtaining the system time is still expensive. It is because these functions still trigger a corresponding system call in the process, which slows down the response time. If we want to remove the system call to reduce the latency, the kernel should have the ability to output the system clock information to userspace. This patch introduces the vDSO common flow to enable the kernel to achieve the above feature and uses "rdtime" instruction to obtain the current time in the user space. Under this condition, the latency cost by the ecall from U-mode to S-mode can be eliminated. After applying this patch, the latency of gettimeofday() measured on the HiFive unleashed board can be reduced by %61. Signed-off-by: Vincent Chen Reviewed-by: Atish Patra Signed-off-by: Palmer Dabbelt