diff mbox series

[v2,32/46] hugetlb: add for_each_hgm_shift

Message ID 20230218002819.1486479-33-jthoughton@google.com (mailing list archive)
State New
Headers show
Series hugetlb: introduce HugeTLB high-granularity mapping | expand

Commit Message

James Houghton Feb. 18, 2023, 12:28 a.m. UTC 
This is a helper macro to loop through all the usable page sizes for a
high-granularity-enabled HugeTLB VMA. Given the VMA's hstate, it will
loop, in descending order, through the page sizes that HugeTLB supports
for this architecture. It always includes PAGE_SIZE.

This is done by looping through the hstates; however, there is no
hstate for PAGE_SIZE. To handle this case, the loop intentionally goes
out of bounds, and the out-of-bounds pointer is mapped to PAGE_SIZE.

Signed-off-by: James Houghton <jthoughton@google.com>
diff mbox series

Patch

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e20df8f6216e..667e82b7a0ff 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -7941,6 +7941,24 @@  bool hugetlb_hgm_enabled(struct vm_area_struct *vma)
 {
 	return vma && (vma->vm_flags & VM_HUGETLB_HGM);
 }
+/* Should only be used by the for_each_hgm_shift macro. */
+static unsigned int __shift_for_hstate(struct hstate *h)
+{
+	/* If h is out of bounds, we have reached the end, so give PAGE_SIZE */
+	if (h >= &hstates[hugetlb_max_hstate])
+		return PAGE_SHIFT;
+	return huge_page_shift(h);
+}
+
+/*
+ * Intentionally go out of bounds. An out-of-bounds hstate will be converted to
+ * PAGE_SIZE.
+ */
+#define for_each_hgm_shift(hstate, tmp_h, shift) \
+	for ((tmp_h) = hstate; (shift) = __shift_for_hstate(tmp_h), \
+			       (tmp_h) <= &hstates[hugetlb_max_hstate]; \
+			       (tmp_h)++)
+
 #endif /* CONFIG_HUGETLB_HIGH_GRANULARITY_MAPPING */
 
 /*