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/vdso.lds.S | |
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/vdso.lds.S')
-rw-r--r-- | arch/riscv/kernel/vdso/vdso.lds.S | 1 |
1 files changed, 1 insertions, 0 deletions
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: *; }; } |