lib/ioremap: ensure break-before-make is used for huge p4d mappings

Whilst no architectures actually enable support for huge p4d mappings in
the vmap area, the code that is implemented should be using
break-before-make, as we do for pud and pmd huge entries.

Link: http://lkml.kernel.org/r/1544120495-17438-6-git-send-email-will.deacon@arm.com
Signed-off-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Chintan Pandya <cpandya@codeaurora.org>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 21 insertions, 6 deletions

diff --git a/lib/ioremap.c b/lib/ioremap.c
index 10d7c5485c39..063213685563 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -156,6 +156,25 @@ static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr,
         return 0;
 }
 
+static int ioremap_try_huge_p4d(p4d_t *p4d, unsigned long addr,
+                                unsigned long end, phys_addr_t phys_addr,
+                                pgprot_t prot)
+{
+        if (!ioremap_p4d_enabled())
+                return 0;
+
+        if ((end - addr) != P4D_SIZE)
+                return 0;
+
+        if (!IS_ALIGNED(phys_addr, P4D_SIZE))
+                return 0;
+
+        if (p4d_present(*p4d) && !p4d_free_pud_page(p4d, addr))
+                return 0;
+
+        return p4d_set_huge(p4d, phys_addr, prot);
+}
+
 static inline int ioremap_p4d_range(pgd_t *pgd, unsigned long addr,
                 unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
 {
@@ -168,12 +187,8 @@ static inline int ioremap_p4d_range(pgd_t *pgd, unsigned long addr,
         do {
                 next = p4d_addr_end(addr, end);
 
-                if (ioremap_p4d_enabled() &&
-                    ((next - addr) == P4D_SIZE) &&
-                    IS_ALIGNED(phys_addr, P4D_SIZE)) {
-                        if (p4d_set_huge(p4d, phys_addr, prot))
-                                continue;
-                }
+                if (ioremap_try_huge_p4d(p4d, addr, next, phys_addr, prot))
+                        continue;
 
                 if (ioremap_pud_range(p4d, addr, next, phys_addr, prot))
                         return -ENOMEM;