[RFC PATCH 3/7] mm/ioremap: Track which page-table levels were modified

Joerg Roedel
2020-05-08T14:41:17Z

From: Joerg Roedel <jroedel@suse.de>

Track at which levels in the page-table entries were modified by
ioremap_page_range(). After the page-table has been modified, use that
information do decide whether the new arch_sync_kernel_mappings()
needs to be called. The iounmap path re-uses vunmap(), which has
already been taken care of.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
lib/ioremap.c | 46 +++++++++++++++++++++++++++++++---------------
1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/lib/ioremap.c b/lib/ioremap.c
index 3f0e18543de8..ad485f08173b 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -61,13 +61,14 @@ static inline int ioremap_pmd_enabled(void) { return 0; }
#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */

static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
- unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
+ unsigned long end, phys_addr_t phys_addr, pgprot_t prot,
+ pgtbl_mod_mask *mask)
{
pte_t *pte;
u64 pfn;

pfn = phys_addr >> PAGE_SHIFT;
- pte = pte_alloc_kernel(pmd, addr);
+ pte = pte_alloc_kernel_track(pmd, addr, mask);
if (!pte)
return -ENOMEM;
do {
@@ -75,6 +76,7 @@ static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
pfn++;
} while (pte++, addr += PAGE_SIZE, addr != end);
+ *mask |= PGTBL_PTE_MODIFIED;
return 0;
}

@@ -101,21 +103,24 @@ static int ioremap_try_huge_pmd(pmd_t *pmd, unsigned long addr,
}

static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
- unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
+ unsigned long end, phys_addr_t phys_addr, pgprot_t prot,
+ pgtbl_mod_mask *mask)
{
pmd_t *pmd;
unsigned long next;

- pmd = pmd_alloc(&init_mm, pud, addr);
+ pmd = pmd_alloc_track(&init_mm, pud, addr, mask);
if (!pmd)
return -ENOMEM;
do {
next = pmd_addr_end(addr, end);

- if (ioremap_try_huge_pmd(pmd, addr, next, phys_addr, prot))
+ if (ioremap_try_huge_pmd(pmd, addr, next, phys_addr, prot)) {
+ *mask |= PGTBL_PMD_MODIFIED;
continue;
+ }

- if (ioremap_pte_range(pmd, addr, next, phys_addr, prot))
+ if (ioremap_pte_range(pmd, addr, next, phys_addr, prot, mask))
return -ENOMEM;
} while (pmd++, phys_addr += (next - addr), addr = next, addr != end);
return 0;
@@ -144,21 +149,24 @@ static int ioremap_try_huge_pud(pud_t *pud, unsigned long addr,
}

static inline int ioremap_pud_range(p4d_t *p4d, unsigned long addr,
- unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
+ unsigned long end, phys_addr_t phys_addr, pgprot_t prot,
+ pgtbl_mod_mask *mask)
{
pud_t *pud;
unsigned long next;

- pud = pud_alloc(&init_mm, p4d, addr);
+ pud = pud_alloc_track(&init_mm, p4d, addr, mask);
if (!pud)
return -ENOMEM;
do {
next = pud_addr_end(addr, end);

- if (ioremap_try_huge_pud(pud, addr, next, phys_addr, prot))
+ if (ioremap_try_huge_pud(pud, addr, next, phys_addr, prot)) {
+ *mask |= PGTBL_PUD_MODIFIED;
continue;
+ }

- if (ioremap_pmd_range(pud, addr, next, phys_addr, prot))
+ if (ioremap_pmd_range(pud, addr, next, phys_addr, prot, mask))
return -ENOMEM;
} while (pud++, phys_addr += (next - addr), addr = next, addr != end);
return 0;
@@ -187,21 +195,24 @@ static int ioremap_try_huge_p4d(p4d_t *p4d, unsigned long addr,
}

static inline int ioremap_p4d_range(pgd_t *pgd, unsigned long addr,
- unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
+ unsigned long end, phys_addr_t phys_addr, pgprot_t prot,
+ pgtbl_mod_mask *mask)
{
p4d_t *p4d;
unsigned long next;

- p4d = p4d_alloc(&init_mm, pgd, addr);
+ p4d = p4d_alloc_track(&init_mm, pgd, addr, mask);
if (!p4d)
return -ENOMEM;
do {
next = p4d_addr_end(addr, end);

- if (ioremap_try_huge_p4d(p4d, addr, next, phys_addr, prot))
+ if (ioremap_try_huge_p4d(p4d, addr, next, phys_addr, prot)) {
+ *mask |= PGTBL_P4D_MODIFIED;
continue;
+ }

- if (ioremap_pud_range(p4d, addr, next, phys_addr, prot))
+ if (ioremap_pud_range(p4d, addr, next, phys_addr, prot, mask))
return -ENOMEM;
} while (p4d++, phys_addr += (next - addr), addr = next, addr != end);
return 0;
@@ -214,6 +225,7 @@ int ioremap_page_range(unsigned long addr,
unsigned long start;
unsigned long next;
int err;
+ pgtbl_mod_mask mask = 0;

might_sleep();
BUG_ON(addr >= end);
@@ -222,13 +234,17 @@ int ioremap_page_range(unsigned long addr,
pgd = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
- err = ioremap_p4d_range(pgd, addr, next, phys_addr, prot);
+ err = ioremap_p4d_range(pgd, addr, next, phys_addr, prot,
+ &mask);
if (err)
break;
} while (pgd++, phys_addr += (next - addr), addr = next, addr != end);

flush_cache_vmap(start, end);

+ if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
+ arch_sync_kernel_mappings(start, end);
+
return err;
}

--
2.17.1