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>

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 13b8036..b6f5aa5 100644 (file)
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1043,6 +1043,11 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
        return 1;
 }
 
+int p4d_free_pud_page(p4d_t *p4d, unsigned long addr)
+{
+       return 0;       /* Don't attempt a block mapping */
+}
+
 #ifdef CONFIG_MEMORY_HOTPLUG
 int arch_add_memory(int nid, u64 start, u64 size, struct vmem_altmap *altmap,
                    bool want_memblock)

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index e95a7d6..b0284ea 100644 (file)
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -794,6 +794,14 @@ int pmd_clear_huge(pmd_t *pmd)
        return 0;
 }
 
+/*
+ * Until we support 512GB pages, skip them in the vmap area.
+ */
+int p4d_free_pud_page(p4d_t *p4d, unsigned long addr)
+{
+       return 0;
+}
+
 #ifdef CONFIG_X86_64
 /**
  * pud_free_pmd_page - Clear pud entry and free pmd page.

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index a9cac82..05e61e6 100644 (file)
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1057,6 +1057,7 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot);
 int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot);
 int pud_clear_huge(pud_t *pud);
 int pmd_clear_huge(pmd_t *pmd);
+int p4d_free_pud_page(p4d_t *p4d, unsigned long addr);
 int pud_free_pmd_page(pud_t *pud, unsigned long addr);
 int pmd_free_pte_page(pmd_t *pmd, unsigned long addr);
 #else  /* !CONFIG_HAVE_ARCH_HUGE_VMAP */
@@ -1084,6 +1085,10 @@ static inline int pmd_clear_huge(pmd_t *pmd)
 {
        return 0;
 }
+static inline int p4d_free_pud_page(p4d_t *p4d, unsigned long addr)
+{
+       return 0;
+}
 static inline int pud_free_pmd_page(pud_t *pud, unsigned long addr)
 {
        return 0;

diff --git a/lib/ioremap.c b/lib/ioremap.c
index 10d7c54..0632136 100644 (file)
--- 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;