CVS commit: src/sys/arch/x86/x86

["Taylor R Campbell" <riastradh%netbsd.org@localhost>]

Module Name:    src
Committed By:   riastradh
Date:           Mon Jul 13 16:51:51 UTC 2020

Modified Files:
        src/sys/arch/x86/x86: fpu.c

Log Message:
Limit x86 fpu_kern_enter/leave to IPL_VM or below.

There are no users of crypto at IPL_SCHED or IPL_HIGH as far as I
know, and although we generally limit the amount of time spent in any
one crypto operation -- e.g., cgd is usually limited to processing
512 or 4096 bytes at a time -- it's better not to block IPL_SCHED and
IPL_HIGH interrupts at all.  This should make ddb a little more
accessible during crypto-heavy workloads.

This means the aes_* API cannot be used at IPL_SCHED or IPL_HIGH; the
same will go for any new crypto subsystems, like the ChaCha and
Poly1305 ones I'm drafting.  It might be better to prohibit them
altogether in hard interrupt context, but right now cprng_fast and
cprng_strong are both technically allowed at IPL_VM and are sometimes
used there (e.g., for opencrypto CBC IV generation).

KASSERT the ilevel to detect violation of this constraint in case I'm
wrong.


To generate a diff of this commit:
cvs rdiff -u -r1.67 -r1.68 src/sys/arch/x86/x86/fpu.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.