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amd64: Increase sanitizers' static shadow memory reservation

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Because KASAN shadows the kernel image itself (KMSAN currently does
not), a shadow mapping of the boot stack must be created very early
during boot.  pmap_san_enter() reserves a fixed number of pages for the
purpose of creating and mapping this shadow region.

After commit 789df254cc ("amd64: Use a larger boot stack"), it could
happen that this reservation is insufficient; this happens when
bootstack crosses a PAGE_SHIFT + KASAN_SHADOW_SCALE_SHIFT boundary.
Update the calculation to take into account the new size of the boot
stack.

Fixes:		789df254cc ("amd64: Use a larger boot stack")
Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Mark Johnston 2023-08-04 12:25:50 -04:00
parent 9c2823bae9
commit 78cc000cba
1 changed files with 7 additions and 4 deletions
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11
sys/amd64/amd64/pmap.c
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@ -11642,13 +11642,16 @@ pmap_pkru_clear(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
/*
* Reserve enough memory to:
* 1) allocate PDP pages for the shadow map(s),
* 2) shadow one page of memory, so one PD page, one PT page, and one shadow
* page per shadow map.
* 2) shadow the boot stack of KSTACK_PAGES pages,
* so we need one PD page, one or two PT pages, and KSTACK_PAGES shadow pages
* per shadow map.
*/
#ifdef KASAN
#define SAN_EARLY_PAGES (NKASANPML4E + 3)
#define SAN_EARLY_PAGES \
(NKASANPML4E + 1 + 2 + howmany(KSTACK_PAGES, KASAN_SHADOW_SCALE))
#else
#define SAN_EARLY_PAGES (NKMSANSHADPML4E + NKMSANORIGPML4E + 2 * 3)
#define SAN_EARLY_PAGES \
(NKMSANSHADPML4E + NKMSANORIGPML4E + 2 * (1 + 2 + KSTACK_PAGES))
#endif
static uint64_t __nosanitizeaddress __nosanitizememory