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.
Cc: Chintan Pandya <cpandya@xxxxxxxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Toshi Kani <toshi.kani@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
---
arch/arm64/mm/mmu.c | 5 +++++
arch/x86/mm/pgtable.c | 8 ++++++++
include/asm-generic/pgtable.h | 5 +++++
lib/ioremap.c | 27 +++++++++++++++++++++------
4 files changed, 39 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 786cfa6355be..cf9a26d3d7f5 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1028,3 +1028,8 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
pmd_free(NULL, table);
return 1;
}
+
+int p4d_free_pud_page(p4d_t *p4d, unsigned long addr)
+{
+ return 0; /* Don't attempt a block mapping */
+}
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index e95a7d6ac8f8..b0284eab14dc 100644
--- 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 359fb935ded6..e0381a4ce7d4 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1019,6 +1019,7 @@ 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 */
@@ -1046,6 +1047,10 @@ 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 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;
--
2.1.4
