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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 <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/r/20221006173520.1785507-3-conor@kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
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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 <heiko@sntech.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Dao Lu <daolu@rivosinc.com>
[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 <palmer@rivosinc.com>
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Implement generic vdso time namespace support which also enables time
namespaces for riscv. This is quite similar to what arm64 does.
selftest/timens test result:
1..10
ok 1 Passed for CLOCK_BOOTTIME (syscall)
ok 2 Passed for CLOCK_BOOTTIME (vdso)
ok 3 # SKIP CLOCK_BOOTTIME_ALARM isn't supported
ok 4 # SKIP CLOCK_BOOTTIME_ALARM isn't supported
ok 5 Passed for CLOCK_MONOTONIC (syscall)
ok 6 Passed for CLOCK_MONOTONIC (vdso)
ok 7 Passed for CLOCK_MONOTONIC_COARSE (syscall)
ok 8 Passed for CLOCK_MONOTONIC_COARSE (vdso)
ok 9 Passed for CLOCK_MONOTONIC_RAW (syscall)
ok 10 Passed for CLOCK_MONOTONIC_RAW (vdso)
# Totals: pass:8 fail:0 xfail:0 xpass:0 skip:2 error:0
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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riscv's <vdso/processor.h> uses barrier() so it should include
<asm/barrier.h>
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
<linux/prefetch.h>.
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 <schwab@linux-m68k.org>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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MIPS already uses and S390 will need the vdso data pointer in
__arch_get_hw_counter().
This works nicely as long as the architecture does not support time
namespaces in the VDSO. With time namespaces enabled the regular
accessor to the vdso data pointer __arch_get_vdso_data() will return the
namespace specific VDSO data page for tasks which are part of a
non-root time namespace. This would cause the architectures which need
the vdso data pointer in __arch_get_hw_counter() to access the wrong
vdso data page.
Add a vdso_data pointer argument to __arch_get_hw_counter() and hand it in
from the call sites in the core code. For architectures which do not need
the data pointer in their counter accessor function the compiler will just
optimize it out.
Fix up all existing architecture implementations and make MIPS utilize the
pointer instead of invoking the accessor function.
No functional change and no change in the resulting object code (except
MIPS).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/draft-87wo2ekuzn.fsf@nanos.tec.linutronix.de
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Now that 'smp_read_barrier_depends()' has gone the way of the Norwegian
Blue, drop the inclusion of <asm/barrier.h> in 'asm-generic/rwonce.h'.
This requires fixups to some architecture vdso headers which were
previously relying on 'asm/barrier.h' coming in via 'linux/compiler.h'.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will@kernel.org>
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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 <vincent.chen@sifive.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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