[PATCH RFC 14/37] arm64: mte: Expose tag storage pages to the MIGRATE_METADATA freelist

Alexandru Elisei
2023-08-23T13:17:00Z

Add the MTE tag storage pages to the MIGRATE_METADATA freelist, which
allows the page allocator to manage them like (almost) regular pages.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
arch/arm64/kernel/mte_tag_storage.c | 47 +++++++++++++++++++++++++++++
include/linux/gfp.h | 8 +++++
mm/mm_init.c | 24 +++++++++++++--
3 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/mte_tag_storage.c b/arch/arm64/kernel/mte_tag_storage.c
index 5014dda9bf35..87160f53960f 100644
--- a/arch/arm64/kernel/mte_tag_storage.c
+++ b/arch/arm64/kernel/mte_tag_storage.c
@@ -5,10 +5,12 @@
* Copyright (C) 2023 ARM Ltd.
*/

+#include <linux/gfp.h>
#include <linux/memblock.h>
#include <linux/mm.h>
#include <linux/of_device.h>
#include <linux/of_fdt.h>
+#include <linux/pageblock-flags.h>
#include <linux/range.h>
#include <linux/string.h>
#include <linux/xarray.h>
@@ -190,6 +192,12 @@ static int __init fdt_init_tag_storage(unsigned long node, const char *uname,
return ret;
}

+ /* Pages are managed in pageblock_nr_pages chunks */
+ if (!IS_ALIGNED(tag_range->start | range_len(tag_range), pageblock_nr_pages)) {
+ pr_err("Tag storage region not aligned to 0x%lx", pageblock_nr_pages);
+ return -EINVAL;
+ }
+
ret = tag_storage_get_memory_node(node, &mem_node);
if (ret)
return ret;
@@ -260,3 +268,42 @@ void __init mte_tag_storage_init(void)
}
num_tag_regions = 0;
}
+
+static int __init mte_tag_storage_activate_regions(void)
+{
+ phys_addr_t dram_start, dram_end;
+ struct range *tag_range;
+ unsigned long pfn;
+ int i;
+
+ if (num_tag_regions == 0)
+ return 0;
+
+ dram_start = memblock_start_of_DRAM();
+ dram_end = memblock_end_of_DRAM();
+
+ for (i = 0; i < num_tag_regions; i++) {
+ tag_range = &tag_regions[i].tag_range;
+ /*
+ * Tag storage region was clipped by arm64_bootmem_init()
+ * enforcing addressing limits.
+ */
+ if (PFN_PHYS(tag_range->start) < dram_start ||
+ PFN_PHYS(tag_range->end) >= dram_end) {
+ pr_err("Tag storage region 0x%llx-0x%llx outside addressable memory",
+ PFN_PHYS(tag_range->start), PFN_PHYS(tag_range->end + 1));
+ return -EINVAL;
+ }
+ }
+
+ 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) {
+ init_metadata_reserved_pageblock(pfn_to_page(pfn));
+ totalmetadata_pages += pageblock_nr_pages;
+ }
+ }
+
+ return 0;
+}
+core_initcall(mte_tag_storage_activate_regions)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 665f06675c83..fb344baa9a9b 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -354,4 +354,12 @@ extern struct page *alloc_contig_pages(unsigned long nr_pages, gfp_t gfp_mask,
#endif
void free_contig_range(unsigned long pfn, unsigned long nr_pages);

+#ifdef CONFIG_MEMORY_METADATA
+extern void init_metadata_reserved_pageblock(struct page *page);
+#else
+static inline void init_metadata_reserved_pageblock(struct page *page)
+{
+}
+#endif
+
#endif /* __LINUX_GFP_H */
diff --git a/mm/mm_init.c b/mm/mm_init.c
index a1963c3322af..467c80e9dacc 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2329,8 +2329,9 @@ bool __init deferred_grow_zone(struct zone *zone, unsigned int order)

#endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */

-#ifdef CONFIG_CMA
-void __init init_cma_reserved_pageblock(struct page *page)
+#if defined(CONFIG_CMA) || defined(CONFIG_MEMORY_METADATA)
+static void __init init_reserved_pageblock(struct page *page,
+ enum migratetype migratetype)
{
unsigned i = pageblock_nr_pages;
struct page *p = page;
@@ -2340,15 +2341,32 @@ void __init init_cma_reserved_pageblock(struct page *page)
set_page_count(p, 0);
} while (++p, --i);

- set_pageblock_migratetype(page, MIGRATE_CMA);
+ set_pageblock_migratetype(page, migratetype);
set_page_refcounted(page);
__free_pages(page, pageblock_order);

adjust_managed_page_count(page, pageblock_nr_pages);
+}
+
+#ifdef CONFIG_CMA
+/* Free whole pageblock and set its migration type to MIGRATE_CMA. */
+void __init init_cma_reserved_pageblock(struct page *page)
+{
+ init_reserved_pageblock(page, MIGRATE_CMA);
page_zone(page)->cma_pages += pageblock_nr_pages;
}
#endif

+#ifdef CONFIG_MEMORY_METADATA
+/* Free whole pageblock and set its migration type to MIGRATE_METADATA. */
+void __init init_metadata_reserved_pageblock(struct page *page)
+{
+ init_reserved_pageblock(page, MIGRATE_METADATA);
+ page_zone(page)->metadata_pages += pageblock_nr_pages;
+}
+#endif
+#endif /* CONFIG_CMA || CONFIG_MEMORY_METADATA */
+
void set_zone_contiguous(struct zone *zone)
{
unsigned long block_start_pfn = zone->zone_start_pfn;
--
2.41.0