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17 May 2024, 11:00:25 UTC
Revision 921ebd8f2c081b3cf6c3b29ef4103eef3ff26054 authored by Andrew Waterman on 25 October 2017, 21:32:16 UTC, committed by Palmer Dabbelt on 30 November 2017, 20:58:29 UTC 
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>
1 parent 08f051e
History
Tip revision: 921ebd8f2c081b3cf6c3b29ef4103eef3ff26054 authored by Andrew Waterman on 25 October 2017, 21:32:16 UTC
RISC-V: Allow userspace to flush the instruction cache
Tip revision: 921ebd8
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