diff mbox series

[v3.1,4/4] arm64: mm: Implement pte_devmap support

Message ID 13026c4e64abc17133bbfa07d7731ec6691c0bcd.1559050949.git.robin.murphy@arm.com (mailing list archive)
State New, archived
Headers show
Series None | expand

Commit Message

Robin Murphy May 28, 2019, 1:46 p.m. UTC 
In order for things like get_user_pages() to work on ZONE_DEVICE memory,
we need a software PTE bit to identify device-backed PFNs. Hook this up
along with the relevant helpers to join in with ARCH_HAS_PTE_DEVMAP.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---

Fix to build correctly under all combinations of
CONFIG_PGTABLE_LEVELS and CONFIG_TRANSPARENT_HUGEPAGE.

 arch/arm64/Kconfig                    |  1 +
 arch/arm64/include/asm/pgtable-prot.h |  1 +
 arch/arm64/include/asm/pgtable.h      | 21 +++++++++++++++++++++
 3 files changed, 23 insertions(+)

Comments

Will Deacon May 29, 2019, 10:03 a.m. UTC | #1 
On Tue, May 28, 2019 at 02:46:59PM +0100, Robin Murphy wrote:
> In order for things like get_user_pages() to work on ZONE_DEVICE memory,
> we need a software PTE bit to identify device-backed PFNs. Hook this up
> along with the relevant helpers to join in with ARCH_HAS_PTE_DEVMAP.
> 
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
> 
> Fix to build correctly under all combinations of
> CONFIG_PGTABLE_LEVELS and CONFIG_TRANSPARENT_HUGEPAGE.
> 
>  arch/arm64/Kconfig                    |  1 +
>  arch/arm64/include/asm/pgtable-prot.h |  1 +
>  arch/arm64/include/asm/pgtable.h      | 21 +++++++++++++++++++++
>  3 files changed, 23 insertions(+)

Acked-by: Will Deacon <will.deacon@arm.com>

Andrew -- please can you update the previous version of this patch, which
I think you picked up?

Thanks,

Will
diff mbox series

Patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 4780eb7af842..b5a4611fa4c6 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -23,6 +23,7 @@  config ARM64
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_KEEPINITRD
 	select ARCH_HAS_MEMBARRIER_SYNC_CORE
+	select ARCH_HAS_PTE_DEVMAP
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SETUP_DMA_OPS
 	select ARCH_HAS_SET_MEMORY
diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h
index 986e41c4c32b..af0b372d15e5 100644
--- a/arch/arm64/include/asm/pgtable-prot.h
+++ b/arch/arm64/include/asm/pgtable-prot.h
@@ -28,6 +28,7 @@ 
 #define PTE_WRITE		(PTE_DBM)		 /* same as DBM (51) */
 #define PTE_DIRTY		(_AT(pteval_t, 1) << 55)
 #define PTE_SPECIAL		(_AT(pteval_t, 1) << 56)
+#define PTE_DEVMAP		(_AT(pteval_t, 1) << 57)
 #define PTE_PROT_NONE		(_AT(pteval_t, 1) << 58) /* only when !PTE_VALID */
 
 #ifndef __ASSEMBLY__
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 2c41b04708fe..7a2cf6939311 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -90,6 +90,7 @@  extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)];
 #define pte_write(pte)		(!!(pte_val(pte) & PTE_WRITE))
 #define pte_user_exec(pte)	(!(pte_val(pte) & PTE_UXN))
 #define pte_cont(pte)		(!!(pte_val(pte) & PTE_CONT))
+#define pte_devmap(pte)		(!!(pte_val(pte) & PTE_DEVMAP))
 
 #define pte_cont_addr_end(addr, end)						\
 ({	unsigned long __boundary = ((addr) + CONT_PTE_SIZE) & CONT_PTE_MASK;	\
@@ -217,6 +218,11 @@  static inline pmd_t pmd_mkcont(pmd_t pmd)
 	return __pmd(pmd_val(pmd) | PMD_SECT_CONT);
 }
 
+static inline pte_t pte_mkdevmap(pte_t pte)
+{
+	return set_pte_bit(pte, __pgprot(PTE_DEVMAP));
+}
+
 static inline void set_pte(pte_t *ptep, pte_t pte)
 {
 	WRITE_ONCE(*ptep, pte);
@@ -381,6 +387,11 @@  static inline int pmd_protnone(pmd_t pmd)
 
 #define pmd_mkhuge(pmd)		(__pmd(pmd_val(pmd) & ~PMD_TABLE_BIT))
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+#define pmd_devmap(pmd)		pte_devmap(pmd_pte(pmd))
+#endif
+#define pmd_mkdevmap(pmd)	pte_pmd(pte_mkdevmap(pmd_pte(pmd)))
+
 #define __pmd_to_phys(pmd)	__pte_to_phys(pmd_pte(pmd))
 #define __phys_to_pmd_val(phys)	__phys_to_pte_val(phys)
 #define pmd_pfn(pmd)		((__pmd_to_phys(pmd) & PMD_MASK) >> PAGE_SHIFT)
@@ -666,6 +677,16 @@  static inline int pmdp_set_access_flags(struct vm_area_struct *vma,
 {
 	return ptep_set_access_flags(vma, address, (pte_t *)pmdp, pmd_pte(entry), dirty);
 }
+
+static inline int pud_devmap(pud_t pud)
+{
+	return 0;
+}
+
+static inline int pgd_devmap(pgd_t pgd)
+{
+	return 0;
+}
 #endif
 
 /*