Commit d239865a authored by Will Deacon's avatar Will Deacon Committed by Linus Torvalds
Browse files

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: default avatarWill Deacon <will.deacon@arm.com>
Reviewed-by: default avatarToshi Kani <toshi.kani@hpe.com>
Suggested-by: default avatarLinus 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c16eb000

lib/ioremap.c

+42 −14
Original line number Diff line number Diff line
@@ -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))

		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))

		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;

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