The patch titled
Subject: lib/ioremap: ensure break-before-make is used for huge p4d mappings
has been added to the -mm tree. Its filename is
lib-ioremap-ensure-break-before-make-is-used-for-huge-p4d-mappings.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/lib-ioremap-ensure-break-before-make-is-used-for-huge-p4d-mappings.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/lib-ioremap-ensure-break-before-make-is-used-for-huge-p4d-mappings.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Will Deacon <will.deacon@xxxxxxx>
Subject: 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@xxxxxxx
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Reviewed-by: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Chintan Pandya <cpandya@xxxxxxxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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(-)
--- a/arch/arm64/mm/mmu.c~lib-ioremap-ensure-break-before-make-is-used-for-huge-p4d-mappings
+++ a/arch/arm64/mm/mmu.c
@@ -1028,3 +1028,8 @@ int pud_free_pmd_page(pud_t *pudp, unsig
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 */
+}
--- a/arch/x86/mm/pgtable.c~lib-ioremap-ensure-break-before-make-is-used-for-huge-p4d-mappings
+++ a/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.
--- a/include/asm-generic/pgtable.h~lib-ioremap-ensure-break-before-make-is-used-for-huge-p4d-mappings
+++ a/include/asm-generic/pgtable.h
@@ -1019,6 +1019,7 @@ int pud_set_huge(pud_t *pud, phys_addr_t
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 *
{
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;
--- a/lib/ioremap.c~lib-ioremap-ensure-break-before-make-is-used-for-huge-p4d-mappings
+++ a/lib/ioremap.c
@@ -156,6 +156,25 @@ static inline int ioremap_pud_range(p4d_
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_
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;
_
Patches currently in -mm which might be from will.deacon@xxxxxxx are
ioremap-rework-pxd_free_pyd_page-api.patch
arm64-mmu-drop-pxd_present-checks-from-pxd_free_pyd_table.patch
x86-pgtable-drop-pxd_none-checks-from-pxd_free_pyd_table.patch
lib-ioremap-ensure-phys_addr-actually-corresponds-to-a-physical-address.patch
lib-ioremap-ensure-break-before-make-is-used-for-huge-p4d-mappings.patch
