diff options
| author | Andrew Waterman <andrew@sifive.com> | 2017-10-25 14:32:16 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@sifive.com> | 2017-11-30 12:58:29 -0800 |
| commit | 921ebd8f2c081b3cf6c3b29ef4103eef3ff26054 (patch) | |
| tree | e3302d6371f434b91b4194da53342095c68363dd /arch/riscv/kernel/vdso | |
| parent | 08f051eda33b51e8ee0f45f05bcfe49d0f0caf6b (diff) | |
RISC-V: Allow userspace to flush the instruction cache
Despite RISC-V having a direct 'fence.i' instruction available to
userspace (which we can't trap!), that's not actually viable when
running on Linux because the kernel might schedule a process on another
hart. There is no way for userspace to handle this without invoking the
kernel (as it doesn't know the thread->hart mappings), so we've defined
a RISC-V specific system call to flush the instruction cache.
This patch adds both a system call and a VDSO entry. If possible, we'd
like to avoid having the system call be considered part of the
user-facing ABI and instead restrict that to the VDSO entry -- both just
in general to avoid having additional user-visible ABI to maintain, and
because we'd prefer that users just call the VDSO entry because there
might be a better way to do this in the future (ie, one that doesn't
require entering the kernel).
Signed-off-by: Andrew Waterman <andrew@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Diffstat (limited to 'arch/riscv/kernel/vdso')
| -rw-r--r-- | arch/riscv/kernel/vdso/Makefile | 1 | ||||
| -rw-r--r-- | arch/riscv/kernel/vdso/flush_icache.S | 31 | ||||
| -rw-r--r-- | arch/riscv/kernel/vdso/vdso.lds.S | 1 |
3 files changed, 33 insertions, 0 deletions
diff --git a/arch/riscv/kernel/vdso/Makefile b/arch/riscv/kernel/vdso/Makefile index 2dcc4f3070bc..324568d33921 100644 --- a/arch/riscv/kernel/vdso/Makefile +++ b/arch/riscv/kernel/vdso/Makefile @@ -6,6 +6,7 @@ vdso-syms += gettimeofday vdso-syms += clock_gettime vdso-syms += clock_getres vdso-syms += getcpu +vdso-syms += flush_icache # Files to link into the vdso obj-vdso = $(patsubst %, %.o, $(vdso-syms)) diff --git a/arch/riscv/kernel/vdso/flush_icache.S b/arch/riscv/kernel/vdso/flush_icache.S new file mode 100644 index 000000000000..b0fbad74e873 --- /dev/null +++ b/arch/riscv/kernel/vdso/flush_icache.S @@ -0,0 +1,31 @@ +/* + * Copyright (C) 2017 SiFive + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * 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. + */ + +#include <linux/linkage.h> +#include <asm/unistd.h> +#include <asm/vdso-syscalls.h> + + .text +/* int __vdso_flush_icache(void *start, void *end, unsigned long flags); */ +ENTRY(__vdso_flush_icache) + .cfi_startproc +#ifdef CONFIG_SMP + li a7, __NR_riscv_flush_icache + ecall +#else + fence.i + li a0, 0 +#endif + ret + .cfi_endproc +ENDPROC(__vdso_flush_icache) diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S index c7543c6a00f9..cd1d47e0724b 100644 --- a/arch/riscv/kernel/vdso/vdso.lds.S +++ b/arch/riscv/kernel/vdso/vdso.lds.S @@ -74,6 +74,7 @@ VERSION __vdso_clock_gettime; __vdso_clock_getres; __vdso_getcpu; + __vdso_flush_icache; local: *; }; } |