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FROMGIT: arm64: kasan: mte: move GCR_EL1 switch to task switch when KASAN disabled

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It is not necessary to write to GCR_EL1 on every kernel entry and
exit when HW tag-based KASAN is disabled because the kernel will not
execute any IRG instructions in that mode. Since accessing GCR_EL1
can be expensive on some microarchitectures, avoid doing so by moving
the access to task switch when HW tag-based KASAN is disabled.

Signed-off-by: Peter Collingbourne <pcc@google.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://linux-review.googlesource.com/id/I78e90d60612a94c24344526f476ac4ff216e10d2
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210924010655.2886918-1-pcc@google.com
Signed-off-by: Will Deacon <will@kernel.org>
(cherry picked from commit e5af50a5df571c1d0268b02f924de49b742c990f
 https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/mte)
Change-Id: I0f06de2fce4dea2967c0fee608d1900915493d23
Bug: 192536783
This commit is contained in:
Peter Collingbourne
2021-09-23 18:06:55 -07:00
parent 6c6d1d7e42
commit 55b0b34791
3 changed files with 38 additions and 7 deletions
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9
include/linux/kasan.h
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@@ -89,7 +89,7 @@ static __always_inline bool kasan_enabled(void)
return static_branch_likely(&kasan_flag_enabled);
}
static inline bool kasan_has_integrated_init(void)
static inline bool kasan_hw_tags_enabled(void)
{
return kasan_enabled();
}
@@ -104,7 +104,7 @@ static inline bool kasan_enabled(void)
return IS_ENABLED(CONFIG_KASAN);
}
static inline bool kasan_has_integrated_init(void)
static inline bool kasan_hw_tags_enabled(void)
{
return false;
}
@@ -125,6 +125,11 @@ static __always_inline void kasan_free_pages(struct page *page,
#endif /* CONFIG_KASAN_HW_TAGS */
static inline bool kasan_has_integrated_init(void)
{
return kasan_hw_tags_enabled();
}
#ifdef CONFIG_KASAN
struct kasan_cache {