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ioremap: rework pXd_free_pYd_page() API 

The recently merged API for ensuring break-before-make on page-table
entries when installing huge mappings in the vmalloc/ioremap region is
fairly counter-intuitive, resulting in the arch freeing functions (e.g.
pmd_free_pte_page()) being called even on entries that aren't present.
This resulted in a minor bug in the arm64 implementation, giving rise to
spurious VM_WARN messages.

This patch moves the pXd_present() checks out into the core code,
refactoring the callsites at the same time so that we avoid the complex
conjunctions when determining whether or not we can put down a huge
mapping.

Link: http://lkml.kernel.org/r/1544120495-17438-2-git-send-email-will.deacon@arm.com
Signed-off-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Toshi Kani <toshi.kani@hpe.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
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>
This commit is contained in:
Will Deacon 2018-12-28 00:37:38 -08:00 committed by Linus Torvalds
parent c16eb000ca
commit d239865ac8
1 changed files with 42 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
lib/ioremap.c
View File

@ -76,6 +76,25 @@ static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
return 0;
}
static int ioremap_try_huge_pmd(pmd_t *pmd, unsigned long addr,
unsigned long end, phys_addr_t phys_addr,
pgprot_t prot)
{
if (!ioremap_pmd_enabled())
return 0;
if ((end - addr) != PMD_SIZE)
return 0;
if (!IS_ALIGNED(phys_addr, PMD_SIZE))
return 0;
if (pmd_present(*pmd) && !pmd_free_pte_page(pmd, addr))
return 0;
return pmd_set_huge(pmd, phys_addr, prot);
}
static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
{
@ -89,13 +108,8 @@ static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
do {
next = pmd_addr_end(addr, end);
if (ioremap_pmd_enabled() &&
((next - addr) == PMD_SIZE) &&
IS_ALIGNED(phys_addr + addr, PMD_SIZE) &&
pmd_free_pte_page(pmd, addr)) {
if (pmd_set_huge(pmd, phys_addr + addr, prot))
continue;
}
if (ioremap_try_huge_pmd(pmd, addr, next, phys_addr + addr, prot))
continue;
if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
return -ENOMEM;
@ -103,6 +117,25 @@ static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
return 0;
}
static int ioremap_try_huge_pud(pud_t *pud, unsigned long addr,
unsigned long end, phys_addr_t phys_addr,
pgprot_t prot)
{
if (!ioremap_pud_enabled())
return 0;
if ((end - addr) != PUD_SIZE)
return 0;
if (!IS_ALIGNED(phys_addr, PUD_SIZE))
return 0;
if (pud_present(*pud) && !pud_free_pmd_page(pud, addr))
return 0;
return pud_set_huge(pud, phys_addr, prot);
}
static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr,
unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
{
@ -116,13 +149,8 @@ static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr,
do {
next = pud_addr_end(addr, end);
if (ioremap_pud_enabled() &&
((next - addr) == PUD_SIZE) &&
IS_ALIGNED(phys_addr + addr, PUD_SIZE) &&
pud_free_pmd_page(pud, addr)) {
if (pud_set_huge(pud, phys_addr + addr, prot))
continue;
}
if (ioremap_try_huge_pud(pud, addr, next, phys_addr + addr, prot))
continue;
if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
return -ENOMEM;