linux-kernel - [PATCH v3 3/6] mm: Change ioremap to set up huge I/O mappings

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Date:	Tue,  3 Mar 2015 10:44:21 -0700
From:	Toshi Kani <toshi.kani@...com>
To:	akpm@...ux-foundation.org, hpa@...or.com, tglx@...utronix.de,
	mingo@...hat.com, arnd@...db.de
Cc:	linux-mm@...ck.org, x86@...nel.org, linux-kernel@...r.kernel.org,
	dave.hansen@...el.com, Elliott@...com,
	Toshi Kani <toshi.kani@...com>
Subject: [PATCH v3 3/6] mm: Change ioremap to set up huge I/O mappings

ioremap_pud_range() and ioremap_pmd_range() are changed to create
huge I/O mappings when their capability is enabled, and a request
meets required conditions -- both virtual & physical addresses
are aligned by their huge page size, and a requested range fufills
their huge page size.  When pud_set_huge() or pmd_set_huge() returns
zero, i.e. no-operation is performed, the code simply falls back to
the next level.

The changes are only enabled when CONFIG_HAVE_ARCH_HUGE_VMAP is
defined on the architecture.

Signed-off-by: Toshi Kani <toshi.kani@...com>
---
 include/asm-generic/pgtable.h |   15 +++++++++++++++
 lib/ioremap.c                 |   16 ++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 4d46085..bf6e86c 100644
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -6,6 +6,7 @@
 
 #include <linux/mm_types.h>
 #include <linux/bug.h>
+#include <linux/errno.h>
 
 /*
  * On almost all architectures and configurations, 0 can be used as the
@@ -697,4 +698,18 @@ static inline int pmd_protnone(pmd_t pmd)
 #define io_remap_pfn_range remap_pfn_range
 #endif
 
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot);
+int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot);
+#else	/* !CONFIG_HAVE_ARCH_HUGE_VMAP */
+static inline int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+static inline int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
+{
+	return 0;
+}
+#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */
+
 #endif /* _ASM_GENERIC_PGTABLE_H */
diff --git a/lib/ioremap.c b/lib/ioremap.c
index 0ce18aa..3055ada 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -81,6 +81,14 @@ static inline int ioremap_pmd_range(pud_t *pud, unsigned long addr,
 		return -ENOMEM;
 	do {
 		next = pmd_addr_end(addr, end);
+
+		if (ioremap_pmd_enabled() &&
+		    ((next - addr) == PMD_SIZE) &&
+		    IS_ALIGNED(phys_addr + addr, PMD_SIZE)) {
+			if (pmd_set_huge(pmd, phys_addr + addr, prot))
+				continue;
+		}
+
 		if (ioremap_pte_range(pmd, addr, next, phys_addr + addr, prot))
 			return -ENOMEM;
 	} while (pmd++, addr = next, addr != end);
@@ -99,6 +107,14 @@ static inline int ioremap_pud_range(pgd_t *pgd, unsigned long addr,
 		return -ENOMEM;
 	do {
 		next = pud_addr_end(addr, end);
+
+		if (ioremap_pud_enabled() &&
+		    ((next - addr) == PUD_SIZE) &&
+		    IS_ALIGNED(phys_addr + addr, PUD_SIZE)) {
+			if (pud_set_huge(pud, phys_addr + addr, prot))
+				continue;
+		}
+
 		if (ioremap_pmd_range(pud, addr, next, phys_addr + addr, prot))
 			return -ENOMEM;
 	} while (pud++, addr = next, addr != end);
--
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