FreeBSD source tree https://cgit-dev.freebsd.org/src/atom?h=stable%2F13 2023-07-25T15:13:49Z 2023-07-25T15:13:49Z Warner Losh imp@FreeBSD.org 2023-05-10T15:40:58Z urn:sha1:caa41f641755c935b036e17440a3b49329c904ed The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch up to that fact and revert to their recommended match of BSD-2-Clause. Discussed with: pfg MFC After: 3 days Sponsored by: Netflix (cherry picked from commit 4d846d260e2b9a3d4d0a701462568268cbfe7a5b) 2021-11-01T13:57:30Z Mark Johnston markj@FreeBSD.org 2021-04-13T20:30:05Z urn:sha1:a3d4c8e21d645bc8022af53232c12e236285de25 The idea behind KASAN is to use a region of memory to track the validity of buffers in the kernel map. This region is the shadow map. The compiler inserts calls to the KASAN runtime for every emitted load and store, and the runtime uses the shadow map to decide whether the access is valid. Various kernel allocators call kasan_mark() to update the shadow map. Since the shadow map tracks only accesses to the kernel map, accesses to other kernel maps are not validated by KASAN. UMA_MD_SMALL_ALLOC is disabled when KASAN is configured to reduce usage of the direct map. Currently we have no mechanism to completely eliminate uses of the direct map, so KASAN's coverage is not comprehensive. The shadow map uses one byte per eight bytes in the kernel map. In pmap_bootstrap() we create an initial set of page tables for the kernel and preloaded data. When pmap_growkernel() is called, we call kasan_shadow_map() to extend the shadow map. kasan_shadow_map() uses pmap_kasan_enter() to allocate memory for the shadow region and map it. Reviewed by: kib MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D29417 (cherry picked from commit 6faf45b34b14da5f138774b43ec14fb5567ac584)