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/include/asm/vdso.h | |
| 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/include/asm/vdso.h')
| -rw-r--r-- | arch/riscv/include/asm/vdso.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h index 602f61257553..541544d64c33 100644 --- a/arch/riscv/include/asm/vdso.h +++ b/arch/riscv/include/asm/vdso.h @@ -38,4 +38,8 @@ struct vdso_data { (void __user *)((unsigned long)(base) + __vdso_##name); \ }) +#ifdef CONFIG_SMP +asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t); +#endif + #endif /* _ASM_RISCV_VDSO_H */ |