diff options
| author | Andrew Waterman <andrew@sifive.com> | 2018-03-26 17:29:08 -0700 |
|---|---|---|
| committer | Andrew Waterman <andrew@sifive.com> | 2018-03-26 17:30:11 -0700 |
| commit | fe3b416f2fed54d63e5e361edb48e74a36ce97eb (patch) | |
| tree | 299d58332c4a31025e58f6011c8a77878429b6b8 /src/supervisor.tex | |
| parent | 9346152202adc8269c1b3c33aeae352bf3106b17 (diff) | |
| download | riscv-isa-manual-fe3b416f2fed54d63e5e361edb48e74a36ce97eb.zip riscv-isa-manual-fe3b416f2fed54d63e5e361edb48e74a36ce97eb.tar.gz riscv-isa-manual-fe3b416f2fed54d63e5e361edb48e74a36ce97eb.tar.bz2 | |
Clarify that SUM does not permit supervisor execution from user pages
This is already written in the SUM section, but it's better to have it
in both places.
Diffstat (limited to 'src/supervisor.tex')
| -rw-r--r-- | src/supervisor.tex | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/src/supervisor.tex b/src/supervisor.tex index 975d7ba..e2f0c6a 100644 --- a/src/supervisor.tex +++ b/src/supervisor.tex @@ -1143,6 +1143,7 @@ in the {\tt sstatus} register is set, supervisor mode software may also access pages with U=1. However, supervisor code normally operates with the SUM bit clear, in which case, supervisor code will fault on accesses to user-mode pages. +Irrespective of SUM, the supervisor may not execute code on pages with U=1. \begin{commentary} An alternative PTE format would support different permissions for supervisor |