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From: Souptick Joarder <jrdr.linux@gmail.com>
To: akpm@linux-foundation.org, willy@infradead.org, mhocko@suse.com,
	kirill.shutemov@linux.intel.com, vbabka@suse.cz,
	riel@surriel.com, sfr@canb.auug.org.au, rppt@linux.vnet.ibm.com,
	peterz@infradead.org, linux@armlinux.org.uk,
	robin.murphy@arm.com, iamjoonsoo.kim@lge.com, treding@nvidia.com,
	keescook@chromium.org, m.szyprowski@samsung.com,
	stefanr@s5r6.in-berlin.de, hjc@rock-chips.com, heiko@sntech.de,
	airlied@linux.ie, oleksandr_andrushchenko@epam.com,
	joro@8bytes.org, pawel@osciak.com, kyungmin.park@samsung.com,
	mchehab@kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com
Cc: linux-rockchip@lists.infradead.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, xen-devel@lists.xen.org,
	linux-mm@kvack.org, iommu@lists.linux-foundation.org,
	linux1394-devel@lists.sourceforge.net,
	linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org
Subject: [PATCHv2 1/9] mm: Introduce new vm_insert_range and vm_insert_range_buggy API
Date: Thu, 31 Jan 2019 08:38:12 +0530
Message-ID: <20190131030812.GA2174@jordon-HP-15-Notebook-PC> (raw)

Previouly drivers have their own way of mapping range of
kernel pages/memory into user vma and this was done by
invoking vm_insert_page() within a loop.

As this pattern is common across different drivers, it can
be generalized by creating new functions and use it across
the drivers.

vm_insert_range() is the API which could be used to mapped
kernel memory/pages in drivers which has considered vm_pgoff

vm_insert_range_buggy() is the API which could be used to map
range of kernel memory/pages in drivers which has not considered
vm_pgoff. vm_pgoff is passed default as 0 for those drivers.

We _could_ then at a later "fix" these drivers which are using
vm_insert_range_buggy() to behave according to the normal vm_pgoff
offsetting simply by removing the _buggy suffix on the function
name and if that causes regressions, it gives us an easy way to revert.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Suggested-by: Russell King <linux@armlinux.org.uk>
Suggested-by: Matthew Wilcox <willy@infradead.org>
---
 include/linux/mm.h |  4 +++
 mm/memory.c        | 81 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 mm/nommu.c         | 14 ++++++++++
 3 files changed, 99 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 80bb640..25752b0 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2565,6 +2565,10 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
 int remap_pfn_range(struct vm_area_struct *, unsigned long addr,
 			unsigned long pfn, unsigned long size, pgprot_t);
 int vm_insert_page(struct vm_area_struct *, unsigned long addr, struct page *);
+int vm_insert_range(struct vm_area_struct *vma, struct page **pages,
+				unsigned long num);
+int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages,
+				unsigned long num);
 vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn);
 vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
diff --git a/mm/memory.c b/mm/memory.c
index e11ca9d..0a4bf57 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1520,6 +1520,87 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL(vm_insert_page);
 
+/**
+ * __vm_insert_range - insert range of kernel pages into user vma
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ * @offset: user's requested vm_pgoff
+ *
+ * This allows drivers to insert range of kernel pages they've allocated
+ * into a user vma.
+ *
+ * If we fail to insert any page into the vma, the function will return
+ * immediately leaving any previously inserted pages present.  Callers
+ * from the mmap handler may immediately return the error as their caller
+ * will destroy the vma, removing any successfully inserted pages. Other
+ * callers should make their own arrangements for calling unmap_region().
+ *
+ * Context: Process context.
+ * Return: 0 on success and error code otherwise.
+ */
+static int __vm_insert_range(struct vm_area_struct *vma, struct page **pages,
+				unsigned long num, unsigned long offset)
+{
+	unsigned long count = vma_pages(vma);
+	unsigned long uaddr = vma->vm_start;
+	int ret, i;
+
+	/* Fail if the user requested offset is beyond the end of the object */
+	if (offset > num)
+		return -ENXIO;
+
+	/* Fail if the user requested size exceeds available object size */
+	if (count > num - offset)
+		return -ENXIO;
+
+	for (i = 0; i < count; i++) {
+		ret = vm_insert_page(vma, uaddr, pages[offset + i]);
+		if (ret < 0)
+			return ret;
+		uaddr += PAGE_SIZE;
+	}
+
+	return 0;
+}
+
+/**
+ * vm_insert_range - insert range of kernel pages starts with non zero offset
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ *
+ * Maps an object consisting of `num' `pages', catering for the user's
+ * requested vm_pgoff
+ *
+ * Context: Process context. Called by mmap handlers.
+ * Return: 0 on success and error code otherwise.
+ */
+int vm_insert_range(struct vm_area_struct *vma, struct page **pages,
+				unsigned long num)
+{
+	return __vm_insert_range(vma, pages, num, vma->vm_pgoff);
+}
+EXPORT_SYMBOL(vm_insert_range);
+
+/**
+ * vm_insert_range_buggy - insert range of kernel pages starts with zero offset
+ * @vma: user vma to map to
+ * @pages: pointer to array of source kernel pages
+ * @num: number of pages in page array
+ *
+ * Maps a set of pages, always starting at page[0]
+ *
+ * Context: Process context. Called by mmap handlers.
+ * Return: 0 on success and error code otherwise.
+ */
+int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages,
+				unsigned long num)
+{
+	return __vm_insert_range(vma, pages, num, 0);
+}
+EXPORT_SYMBOL(vm_insert_range_buggy);
+
 static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
 			pfn_t pfn, pgprot_t prot, bool mkwrite)
 {
diff --git a/mm/nommu.c b/mm/nommu.c
index 749276b..21d101e 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -473,6 +473,20 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 }
 EXPORT_SYMBOL(vm_insert_page);
 
+int vm_insert_range(struct vm_area_struct *vma, struct page **pages,
+			unsigned long num)
+{
+	return -EINVAL;
+}
+EXPORT_SYMBOL(vm_insert_range);
+
+int vm_insert_range_buggy(struct vm_area_struct *vma, struct page **pages,
+				unsigned long num)
+{
+	return -EINVAL;
+}
+EXPORT_SYMBOL(vm_insert_range_buggy);
+
 /*
  *  sys_brk() for the most part doesn't need the global kernel
  *  lock, except when an application is doing something nasty
-- 
1.9.1


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Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-31  3:08 Souptick Joarder [this message]
2019-01-31  8:38 ` Mike Rapoport
2019-01-31 10:13   ` Souptick Joarder
2019-01-31 11:06     ` Mike Rapoport
2019-02-07 15:49   ` Souptick Joarder
2019-02-07 15:57     ` Mike Rapoport
2019-02-07 16:07       ` Souptick Joarder
2019-02-07 16:04         ` Mike Rapoport
2019-02-07 16:47     ` Matthew Wilcox
2019-02-08  5:22       ` Souptick Joarder
2019-02-11 17:06         ` Souptick Joarder
2019-01-31 12:06 ` Heiko Stuebner
2019-01-31 12:31   ` Souptick Joarder
2019-01-31 12:34     ` Heiko Stuebner
2019-02-01 12:38       ` Souptick Joarder

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