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Subject[PATCH v2 2/7] lib: Add huge I/O map capability interfaces
Date
Add ioremap_pud_enabled() and ioremap_pmd_enabled(), which
return 1 when I/O mappings of pud/pmd are enabled on the kernel.

ioremap_huge_init() calls arch_ioremap_pud_supported() and
arch_ioremap_pmd_supported() to initialize the capabilities.

A new kernel option "nohugeiomap" is also added, so that user
can disable the huge I/O map capabilities when necessary.

Signed-off-by: Toshi Kani <toshi.kani@hp.com>
---
Documentation/kernel-parameters.txt | 2 ++
include/linux/io.h | 7 ++++++
init/main.c | 2 ++
lib/ioremap.c | 38 +++++++++++++++++++++++++++++++++++
4 files changed, 49 insertions(+)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 176d4fe..1872b46 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2304,6 +2304,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
register save and restore. The kernel will only save
legacy floating-point registers on task switch.

+ nohugeiomap [KNL,x86] Disable kernel huge I/O mappings.
+
noxsave [BUGS=X86] Disables x86 extended register state save
and restore using xsave. The kernel will fallback to
enabling legacy floating-point and sse state.
diff --git a/include/linux/io.h b/include/linux/io.h
index fa02e55..9acc588a 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -38,6 +38,13 @@ static inline int ioremap_page_range(unsigned long addr, unsigned long end,
}
#endif

+void __init ioremap_huge_init(void);
+
+#ifdef CONFIG_HUGE_IOMAP
+int arch_ioremap_pud_supported(void);
+int arch_ioremap_pmd_supported(void);
+#endif
+
/*
* Managed iomap interface
*/
diff --git a/init/main.c b/init/main.c
index 61b99376..9f871ac 100644
--- a/init/main.c
+++ b/init/main.c
@@ -80,6 +80,7 @@
#include <linux/list.h>
#include <linux/integrity.h>
#include <linux/proc_ns.h>
+#include <linux/io.h>

#include <asm/io.h>
#include <asm/bugs.h>
@@ -497,6 +498,7 @@ static void __init mm_init(void)
percpu_init_late();
pgtable_init();
vmalloc_init();
+ ioremap_huge_init();
}

asmlinkage __visible void __init start_kernel(void)
diff --git a/lib/ioremap.c b/lib/ioremap.c
index 0c9216c..cafd83e 100644
--- a/lib/ioremap.c
+++ b/lib/ioremap.c
@@ -13,6 +13,44 @@
#include <asm/cacheflush.h>
#include <asm/pgtable.h>

+#ifdef CONFIG_HUGE_IOMAP
+int __read_mostly ioremap_pud_capable;
+int __read_mostly ioremap_pmd_capable;
+int __read_mostly ioremap_huge_disabled;
+
+static int __init set_nohugeiomap(char *str)
+{
+ ioremap_huge_disabled = 1;
+ return 0;
+}
+early_param("nohugeiomap", set_nohugeiomap);
+
+void __init ioremap_huge_init(void)
+{
+ if (!ioremap_huge_disabled) {
+ if (arch_ioremap_pud_supported())
+ ioremap_pud_capable = 1;
+ if (arch_ioremap_pmd_supported())
+ ioremap_pmd_capable = 1;
+ }
+}
+
+static inline int ioremap_pud_enabled(void)
+{
+ return ioremap_pud_capable;
+}
+
+static inline int ioremap_pmd_enabled(void)
+{
+ return ioremap_pmd_capable;
+}
+
+#else /* !CONFIG_HUGE_IOMAP */
+void __init ioremap_huge_init(void) { }
+static inline int ioremap_pud_enabled(void) { return 0; }
+static inline int ioremap_pmd_enabled(void) { return 0; }
+#endif /* CONFIG_HUGE_IOMAP */
+
static int ioremap_pte_range(pmd_t *pmd, unsigned long addr,
unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
{

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