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| author | Jacob Bachmeyer <jcb62281+dev@gmail.com> | 2017-05-15 22:12:00 -0500 |
|---|---|---|
| committer | Andrew Waterman <andrew@sifive.com> | 2017-06-03 15:40:23 -0700 |
| commit | 285c81746fe664060b62ae0584865dbfa9f42e1a (patch) | |
| tree | 0b461baa14d601f5f68db7fd1870e1f7fc78b05e /src/machine.tex | |
| parent | b43657ca5a4266c39eb99b186a5af5449e913eb1 (diff) | |
| download | riscv-isa-manual-285c81746fe664060b62ae0584865dbfa9f42e1a.zip riscv-isa-manual-285c81746fe664060b62ae0584865dbfa9f42e1a.tar.gz riscv-isa-manual-285c81746fe664060b62ae0584865dbfa9f42e1a.tar.bz2 | |
Forbid S-mode execution from user memory
Diffstat (limited to 'src/machine.tex')
| -rw-r--r-- | src/machine.tex | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/src/machine.tex b/src/machine.tex index d92aa58..169956a 100644 --- a/src/machine.tex +++ b/src/machine.tex @@ -634,7 +634,7 @@ machine mode. \end{commentary} The SUM (permit Supervisor User Memory access) bit modifies the privilege with -which S-mode loads, stores, and instruction fetches access virtual memory. +which S-mode loads and stores access virtual memory. When SUM=0, S-mode memory accesses to pages that are accessible by U-mode (U=1 in Figure~\ref{sv32pte}) will fault. When SUM=1, these accesses are permitted. SUM has no effect when page-based virtual memory is not in effect. |