[PATCH RFC v2 14/27] arm64: mte: Disable dynamic tag storage management if HW KASAN is enabled
From: Alexandru Elisei <hidden>
Date: 2023-11-19 16:58:53
Also in:
kvmarm, linux-arch, linux-fsdevel, linux-mm, linux-trace-kernel, lkml
Subsystem:
arm64 port (aarch64 architecture), the rest · Maintainers:
Catalin Marinas, Will Deacon, Linus Torvalds
To be able to reserve the tag storage associated with a page requires that the tag storage page can be migrated. When HW KASAN is enabled, the kernel allocates pages, which are now tagged, in non-preemptible contexts, which can make reserving the associate tag storage impossible. Keep the tag storage pages reserved if HW KASAN is enabled. Signed-off-by: Alexandru Elisei <redacted> --- arch/arm64/kernel/mte_tag_storage.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/arch/arm64/kernel/mte_tag_storage.c b/arch/arm64/kernel/mte_tag_storage.c
index 427f4f1909f3..8b9bedf7575d 100644
--- a/arch/arm64/kernel/mte_tag_storage.c
+++ b/arch/arm64/kernel/mte_tag_storage.c@@ -308,6 +308,19 @@ static int __init mte_tag_storage_activate_regions(void) goto out_disabled; } + /* + * The kernel allocates memory in non-preemptible contexts, which makes + * migration impossible when reserving the associated tag storage. + * + * The check is safe to make because KASAN HW tags are enabled before + * the rest of the init functions are called, in smp_prepare_boot_cpu(). + */ + if (kasan_hw_tags_enabled()) { + pr_info("KASAN HW tags incompatible with MTE tag storage management"); + ret = 0; + goto out_disabled; + } + for (i = 0; i < num_tag_regions; i++) { tag_range = &tag_regions[i].tag_range; for (pfn = tag_range->start; pfn <= tag_range->end; pfn += pageblock_nr_pages)
--
2.42.1
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