FreeBSD src
ade2ea3c45
The pindex values are assigned from the L3 leaves upwards, meaning there are NUL2E L3 tables and then NUL1E L2 tables (with a futher NUL0E L1 tables in future when we implement Sv48 support). Therefore anything below NUL2E is an L3 table's page and anything above or equal to NUL2E is an L2 table's page (with the threshold of NUL2E + NUL1E marking the start of the L1 tables' pages in Sv48). Thus all the comparisons and arithmetic operations must use NUL2E to handle the L3/L2 allocation (and thus L2/L1 entry) transition point, not NUL1E as all but pmap_alloc_l2 were doing. To make matters confusing, the NUL1E and NUL2E definitions in the RISC-V pmap are based on a 4-level page hierarchy but we currently use the 3-level Sv39 format (as that's the only required one, and hardware support for the 4-level Sv48 is not widespread). This means that, in effect, the above bug cancels out with the bloated NULxE definitions such that things "work" (but are still technically wrong, and thus would break when adding Sv48 support), with one exception. pmap_enter_l2 is currently the only function to use the correct constant, but since _pmap_alloc_l3 uses the incorrect constant, it will do complete nonsense when it needs to allocate a new L2 table (which is rather rare). In this instance, _pmap_alloc_l3, whilst it would correctly determine the pindex was for an L2 table, would only subtract NUL1E when computing l1index and thus go way out of bounds (by 511*512*512 bytes, or 127.75 GiB) of its own L1 table and, thanks to pmap_distribute_l1, of every other pmap's L1 table in the whole system. This has likely never been hit as it would presumably instantly fault and panic. Reviewed by: markj MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D31087 |
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| .cirrus-ci | ||
| .github | ||
| bin | ||
| cddl | ||
| contrib | ||
| crypto | ||
| etc | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| stand | ||
| sys | ||
| targets | ||
| tests | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| .arcconfig | ||
| .arclint | ||
| .cirrus.yml | ||
| .clang-format | ||
| .gitattributes | ||
| .gitignore | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| Makefile.libcompat | ||
| Makefile.sys.inc | ||
| ObsoleteFiles.inc | ||
| README.md | ||
| RELNOTES | ||
| UPDATING | ||
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