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authorLinus Torvalds <torvalds@linux-foundation.org>2024-02-18 18:22:48 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2024-02-18 18:22:48 +0100
commitddac3d8b8a48dda6447a7f7a15f8124020a5add2 (patch)
tree595092f1b30699c4a3dab125ee1437cff39b5f84
parentMerge tag 'irq_urgent_for_v6.8_rc5' of git://git.kernel.org/pub/scm/linux/ker... (diff)
parentx86/mm/ident_map: Use gbpages only where full GB page should be mapped. (diff)
downloadlinux-ddac3d8b8a48dda6447a7f7a15f8124020a5add2.tar.xz
linux-ddac3d8b8a48dda6447a7f7a15f8124020a5add2.zip
Merge tag 'x86_urgent_for_v6.8_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fix from Borislav Petkov: - Use a GB page for identity mapping only when memory of this size is requested so that mapping of reserved regions is prevented which would otherwise lead to system crashes on UV machines * tag 'x86_urgent_for_v6.8_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm/ident_map: Use gbpages only where full GB page should be mapped.
-rw-r--r--arch/x86/mm/ident_map.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c
index 968d7005f4a7..f50cc210a981 100644
--- a/arch/x86/mm/ident_map.c
+++ b/arch/x86/mm/ident_map.c
@@ -26,18 +26,31 @@ static int ident_pud_init(struct x86_mapping_info *info, pud_t *pud_page,
for (; addr < end; addr = next) {
pud_t *pud = pud_page + pud_index(addr);
pmd_t *pmd;
+ bool use_gbpage;
next = (addr & PUD_MASK) + PUD_SIZE;
if (next > end)
next = end;
- if (info->direct_gbpages) {
- pud_t pudval;
+ /* if this is already a gbpage, this portion is already mapped */
+ if (pud_large(*pud))
+ continue;
+
+ /* Is using a gbpage allowed? */
+ use_gbpage = info->direct_gbpages;
- if (pud_present(*pud))
- continue;
+ /* Don't use gbpage if it maps more than the requested region. */
+ /* at the begining: */
+ use_gbpage &= ((addr & ~PUD_MASK) == 0);
+ /* ... or at the end: */
+ use_gbpage &= ((next & ~PUD_MASK) == 0);
+
+ /* Never overwrite existing mappings */
+ use_gbpage &= !pud_present(*pud);
+
+ if (use_gbpage) {
+ pud_t pudval;
- addr &= PUD_MASK;
pudval = __pud((addr - info->offset) | info->page_flag);
set_pud(pud, pudval);
continue;