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Message-Id: <1402599454-3526-5-git-send-email-j.glisse@gmail.com>
Date: Thu, 12 Jun 2014 14:57:34 -0400
From: j.glisse@...il.com
To: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
linux-mm@...ck.org
Cc: Jérôme Glisse <jglisse@...hat.com>
Subject: [PATCH 5/5] hmm/dummy: dummy driver to showcase the hmm api.
From: Jérôme Glisse <jglisse@...hat.com>
This is a dummy driver which full fill two purposes :
- showcase the hmm api and gives references on how to use it.
- provide an extensive user space api to stress test hmm.
This is a particularly dangerous module as it allow to access a
mirror of a process address space through its device file. Hence
it should not be enabled by default and only people actively
developing for hmm should use it.
Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
---
drivers/char/Kconfig | 9 +
drivers/char/Makefile | 1 +
drivers/char/hmm_dummy.c | 1136 ++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/hmm_dummy.h | 34 ++
4 files changed, 1180 insertions(+)
create mode 100644 drivers/char/hmm_dummy.c
create mode 100644 include/uapi/linux/hmm_dummy.h
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 6e9f74a..199e111 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -600,5 +600,14 @@ config TILE_SROM
device appear much like a simple EEPROM, and knows
how to partition a single ROM for multiple purposes.
+config HMM_DUMMY
+ tristate "hmm dummy driver to test hmm."
+ depends on HMM
+ default n
+ help
+ Say Y here if you want to build the hmm dummy driver that allow you
+ to test the hmm infrastructure by mapping a process address space
+ in hmm dummy driver device file. When in doubt, say "N".
+
endmenu
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index a324f93..83d89b8 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -61,3 +61,4 @@ obj-$(CONFIG_JS_RTC) += js-rtc.o
js-rtc-y = rtc.o
obj-$(CONFIG_TILE_SROM) += tile-srom.o
+obj-$(CONFIG_HMM_DUMMY) += hmm_dummy.o
diff --git a/drivers/char/hmm_dummy.c b/drivers/char/hmm_dummy.c
new file mode 100644
index 0000000..7acb642
--- /dev/null
+++ b/drivers/char/hmm_dummy.c
@@ -0,0 +1,1136 @@
+/*
+ * Copyright 2013 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Authors: Jérôme Glisse <jglisse@...hat.com>
+ */
+/* This is a dummy driver made to exercice the HMM (hardware memory management)
+ * API of the kernel. It allow an userspace program to map its whole address
+ * space through the hmm dummy driver file.
+ *
+ * In here mirror address are address in the process address space that is
+ * being mirrored. While virtual address are the address in the current
+ * process that has the hmm dummy dev file mapped (address of the file
+ * mapping).
+ *
+ * You must be carefull to not mix one and another.
+ */
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/major.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/rwsem.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/highmem.h>
+#include <linux/delay.h>
+#include <linux/hmm.h>
+
+#include <uapi/linux/hmm_dummy.h>
+
+#define HMM_DUMMY_DEVICE_NAME "hmm_dummy_device"
+#define HMM_DUMMY_DEVICE_MAX_MIRRORS 4
+
+struct hmm_dummy_device;
+
+struct hmm_dummy_mirror {
+ struct file *filp;
+ struct hmm_dummy_device *ddevice;
+ struct hmm_mirror mirror;
+ unsigned minor;
+ pid_t pid;
+ struct mm_struct *mm;
+ unsigned long *pgdp;
+ struct mutex mutex;
+ bool stop;
+};
+
+struct hmm_dummy_device {
+ struct cdev cdev;
+ struct hmm_device device;
+ dev_t dev;
+ int major;
+ struct mutex mutex;
+ char name[32];
+ /* device file mapping tracking (keep track of all vma) */
+ struct hmm_dummy_mirror *dmirrors[HMM_DUMMY_DEVICE_MAX_MIRRORS];
+ struct address_space *fmapping[HMM_DUMMY_DEVICE_MAX_MIRRORS];
+};
+
+/* We only create 2 device to show the inter device rmem sharing/migration
+ * capabilities.
+ */
+static struct hmm_dummy_device ddevices[2];
+
+static void hmm_dummy_device_print(struct hmm_dummy_device *device,
+ unsigned minor,
+ const char *format,
+ ...)
+{
+ va_list args;
+
+ printk(KERN_INFO "[%s:%d] ", device->name, minor);
+ va_start(args, format);
+ vprintk(format, args);
+ va_end(args);
+}
+
+
+/* hmm_dummy_pt - dummy page table, the dummy device fake its own page table.
+ *
+ * Helper function to manage the dummy device page table.
+ */
+#define HMM_DUMMY_PTE_VALID (1UL << 0UL)
+#define HMM_DUMMY_PTE_READ (1UL << 1UL)
+#define HMM_DUMMY_PTE_WRITE (1UL << 2UL)
+#define HMM_DUMMY_PTE_DIRTY (1UL << 3UL)
+#define HMM_DUMMY_PFN_SHIFT (PAGE_SHIFT)
+
+#define ARCH_PAGE_SIZE ((unsigned long)PAGE_SIZE)
+#define ARCH_PAGE_SHIFT ((unsigned long)PAGE_SHIFT)
+
+#define HMM_DUMMY_PTRS_PER_LEVEL (ARCH_PAGE_SIZE / sizeof(long))
+#ifdef CONFIG_64BIT
+#define HMM_DUMMY_BITS_PER_LEVEL (ARCH_PAGE_SHIFT - 3UL)
+#else
+#define HMM_DUMMY_BITS_PER_LEVEL (ARCH_PAGE_SHIFT - 2UL)
+#endif
+#define HMM_DUMMY_PLD_SHIFT (ARCH_PAGE_SHIFT)
+#define HMM_DUMMY_PMD_SHIFT (HMM_DUMMY_PLD_SHIFT + HMM_DUMMY_BITS_PER_LEVEL)
+#define HMM_DUMMY_PUD_SHIFT (HMM_DUMMY_PMD_SHIFT + HMM_DUMMY_BITS_PER_LEVEL)
+#define HMM_DUMMY_PGD_SHIFT (HMM_DUMMY_PUD_SHIFT + HMM_DUMMY_BITS_PER_LEVEL)
+#define HMM_DUMMY_PGD_NPTRS (1UL << HMM_DUMMY_BITS_PER_LEVEL)
+#define HMM_DUMMY_PMD_NPTRS (1UL << HMM_DUMMY_BITS_PER_LEVEL)
+#define HMM_DUMMY_PUD_NPTRS (1UL << HMM_DUMMY_BITS_PER_LEVEL)
+#define HMM_DUMMY_PLD_NPTRS (1UL << HMM_DUMMY_BITS_PER_LEVEL)
+#define HMM_DUMMY_PLD_SIZE (1UL << (HMM_DUMMY_PLD_SHIFT + HMM_DUMMY_BITS_PER_LEVEL))
+#define HMM_DUMMY_PMD_SIZE (1UL << (HMM_DUMMY_PMD_SHIFT + HMM_DUMMY_BITS_PER_LEVEL))
+#define HMM_DUMMY_PUD_SIZE (1UL << (HMM_DUMMY_PUD_SHIFT + HMM_DUMMY_BITS_PER_LEVEL))
+#define HMM_DUMMY_PGD_SIZE (1UL << (HMM_DUMMY_PGD_SHIFT + HMM_DUMMY_BITS_PER_LEVEL))
+#define HMM_DUMMY_PLD_MASK (~(HMM_DUMMY_PLD_SIZE - 1UL))
+#define HMM_DUMMY_PMD_MASK (~(HMM_DUMMY_PMD_SIZE - 1UL))
+#define HMM_DUMMY_PUD_MASK (~(HMM_DUMMY_PUD_SIZE - 1UL))
+#define HMM_DUMMY_PGD_MASK (~(HMM_DUMMY_PGD_SIZE - 1UL))
+#define HMM_DUMMY_MAX_ADDR (1UL << (HMM_DUMMY_PGD_SHIFT + HMM_DUMMY_BITS_PER_LEVEL))
+
+static inline unsigned long hmm_dummy_pld_index(unsigned long addr)
+{
+ return (addr >> HMM_DUMMY_PLD_SHIFT) & (HMM_DUMMY_PLD_NPTRS - 1UL);
+}
+
+static inline unsigned long hmm_dummy_pmd_index(unsigned long addr)
+{
+ return (addr >> HMM_DUMMY_PMD_SHIFT) & (HMM_DUMMY_PMD_NPTRS - 1UL);
+}
+
+static inline unsigned long hmm_dummy_pud_index(unsigned long addr)
+{
+ return (addr >> HMM_DUMMY_PUD_SHIFT) & (HMM_DUMMY_PUD_NPTRS - 1UL);
+}
+
+static inline unsigned long hmm_dummy_pgd_index(unsigned long addr)
+{
+ return (addr >> HMM_DUMMY_PGD_SHIFT) & (HMM_DUMMY_PGD_NPTRS - 1UL);
+}
+
+static inline unsigned long hmm_dummy_pld_base(unsigned long addr)
+{
+ return (addr & HMM_DUMMY_PLD_MASK);
+}
+
+static inline unsigned long hmm_dummy_pmd_base(unsigned long addr)
+{
+ return (addr & HMM_DUMMY_PMD_MASK);
+}
+
+static inline unsigned long hmm_dummy_pud_base(unsigned long addr)
+{
+ return (addr & HMM_DUMMY_PUD_MASK);
+}
+
+static inline unsigned long hmm_dummy_pgd_base(unsigned long addr)
+{
+ return (addr & HMM_DUMMY_PGD_MASK);
+}
+
+static inline unsigned long hmm_dummy_pld_next(unsigned long addr)
+{
+ return (addr & HMM_DUMMY_PLD_MASK) + HMM_DUMMY_PLD_SIZE;
+}
+
+static inline unsigned long hmm_dummy_pmd_next(unsigned long addr)
+{
+ return (addr & HMM_DUMMY_PMD_MASK) + HMM_DUMMY_PMD_SIZE;
+}
+
+static inline unsigned long hmm_dummy_pud_next(unsigned long addr)
+{
+ return (addr & HMM_DUMMY_PUD_MASK) + HMM_DUMMY_PUD_SIZE;
+}
+
+static inline unsigned long hmm_dummy_pgd_next(unsigned long addr)
+{
+ return (addr & HMM_DUMMY_PGD_MASK) + HMM_DUMMY_PGD_SIZE;
+}
+
+static inline struct page *hmm_dummy_pte_to_page(unsigned long pte)
+{
+ if (!(pte & HMM_DUMMY_PTE_VALID)) {
+ return NULL;
+ }
+ return pfn_to_page((pte >> HMM_DUMMY_PFN_SHIFT));
+}
+
+struct hmm_dummy_pt_map {
+ struct hmm_dummy_mirror *dmirror;
+ struct page *pud_page;
+ struct page *pmd_page;
+ struct page *pld_page;
+ unsigned long pgd_idx;
+ unsigned long pud_idx;
+ unsigned long pmd_idx;
+ unsigned long *pudp;
+ unsigned long *pmdp;
+ unsigned long *pldp;
+};
+
+static inline unsigned long *hmm_dummy_pt_pud_map(struct hmm_dummy_pt_map *pt_map,
+ unsigned long addr)
+{
+ struct hmm_dummy_mirror *dmirror = pt_map->dmirror;
+ unsigned long *pdep;
+
+ if (!dmirror->pgdp) {
+ return NULL;
+ }
+
+ if (!pt_map->pud_page || pt_map->pgd_idx != hmm_dummy_pgd_index(addr)) {
+ if (pt_map->pud_page) {
+ kunmap(pt_map->pud_page);
+ pt_map->pud_page = NULL;
+ pt_map->pudp = NULL;
+ }
+ pt_map->pgd_idx = hmm_dummy_pgd_index(addr);
+ pdep = &dmirror->pgdp[pt_map->pgd_idx];
+ if (!((*pdep) & HMM_DUMMY_PTE_VALID)) {
+ return NULL;
+ }
+ pt_map->pud_page = pfn_to_page((*pdep) >> HMM_DUMMY_PFN_SHIFT);
+ pt_map->pudp = kmap(pt_map->pud_page);
+ }
+ return pt_map->pudp;
+}
+
+static inline unsigned long *hmm_dummy_pt_pmd_map(struct hmm_dummy_pt_map *pt_map,
+ unsigned long addr)
+{
+ unsigned long *pdep;
+
+ if (!hmm_dummy_pt_pud_map(pt_map, addr)) {
+ return NULL;
+ }
+
+ if (!pt_map->pmd_page || pt_map->pud_idx != hmm_dummy_pud_index(addr)) {
+ if (pt_map->pmd_page) {
+ kunmap(pt_map->pmd_page);
+ pt_map->pmd_page = NULL;
+ pt_map->pmdp = NULL;
+ }
+ pt_map->pud_idx = hmm_dummy_pud_index(addr);
+ pdep = &pt_map->pudp[pt_map->pud_idx];
+ if (!((*pdep) & HMM_DUMMY_PTE_VALID)) {
+ return NULL;
+ }
+ pt_map->pmd_page = pfn_to_page((*pdep) >> HMM_DUMMY_PFN_SHIFT);
+ pt_map->pmdp = kmap(pt_map->pmd_page);
+ }
+ return pt_map->pmdp;
+}
+
+static inline unsigned long *hmm_dummy_pt_pld_map(struct hmm_dummy_pt_map *pt_map,
+ unsigned long addr)
+{
+ unsigned long *pdep;
+
+ if (!hmm_dummy_pt_pmd_map(pt_map, addr)) {
+ return NULL;
+ }
+
+ if (!pt_map->pld_page || pt_map->pmd_idx != hmm_dummy_pmd_index(addr)) {
+ if (pt_map->pld_page) {
+ kunmap(pt_map->pld_page);
+ pt_map->pld_page = NULL;
+ pt_map->pldp = NULL;
+ }
+ pt_map->pmd_idx = hmm_dummy_pmd_index(addr);
+ pdep = &pt_map->pmdp[pt_map->pmd_idx];
+ if (!((*pdep) & HMM_DUMMY_PTE_VALID)) {
+ return NULL;
+ }
+ pt_map->pld_page = pfn_to_page((*pdep) >> HMM_DUMMY_PFN_SHIFT);
+ pt_map->pldp = kmap(pt_map->pld_page);
+ }
+ return pt_map->pldp;
+}
+
+static inline void hmm_dummy_pt_pld_unmap(struct hmm_dummy_pt_map *pt_map)
+{
+ if (pt_map->pld_page) {
+ kunmap(pt_map->pld_page);
+ pt_map->pld_page = NULL;
+ pt_map->pldp = NULL;
+ }
+}
+
+static inline void hmm_dummy_pt_pmd_unmap(struct hmm_dummy_pt_map *pt_map)
+{
+ hmm_dummy_pt_pld_unmap(pt_map);
+ if (pt_map->pmd_page) {
+ kunmap(pt_map->pmd_page);
+ pt_map->pmd_page = NULL;
+ pt_map->pmdp = NULL;
+ }
+}
+
+static inline void hmm_dummy_pt_pud_unmap(struct hmm_dummy_pt_map *pt_map)
+{
+ hmm_dummy_pt_pmd_unmap(pt_map);
+ if (pt_map->pud_page) {
+ kunmap(pt_map->pud_page);
+ pt_map->pud_page = NULL;
+ pt_map->pudp = NULL;
+ }
+}
+
+static inline void hmm_dummy_pt_unmap(struct hmm_dummy_pt_map *pt_map)
+{
+ hmm_dummy_pt_pud_unmap(pt_map);
+}
+
+static int hmm_dummy_pt_alloc(struct hmm_dummy_mirror *dmirror,
+ unsigned long faddr,
+ unsigned long laddr)
+{
+ unsigned long *pgdp, *pudp, *pmdp;
+
+ if (dmirror->stop) {
+ return -EINVAL;
+ }
+
+ if (dmirror->pgdp == NULL) {
+ dmirror->pgdp = kzalloc(PAGE_SIZE, GFP_KERNEL);
+ if (dmirror->pgdp == NULL) {
+ return -ENOMEM;
+ }
+ }
+
+ for (; faddr < laddr; faddr = hmm_dummy_pld_next(faddr)) {
+ struct page *pud_page, *pmd_page;
+
+ pgdp = &dmirror->pgdp[hmm_dummy_pgd_index(faddr)];
+ if (!((*pgdp) & HMM_DUMMY_PTE_VALID)) {
+ pud_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!pud_page) {
+ return -ENOMEM;
+ }
+ *pgdp = (page_to_pfn(pud_page)<<HMM_DUMMY_PFN_SHIFT);
+ *pgdp |= HMM_DUMMY_PTE_VALID;
+ }
+
+ pud_page = pfn_to_page((*pgdp) >> HMM_DUMMY_PFN_SHIFT);
+ pudp = kmap(pud_page);
+ pudp = &pudp[hmm_dummy_pud_index(faddr)];
+ if (!((*pudp) & HMM_DUMMY_PTE_VALID)) {
+ pmd_page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!pmd_page) {
+ kunmap(pud_page);
+ return -ENOMEM;
+ }
+ *pudp = (page_to_pfn(pmd_page)<<HMM_DUMMY_PFN_SHIFT);
+ *pudp |= HMM_DUMMY_PTE_VALID;
+ }
+
+ pmd_page = pfn_to_page((*pudp) >> HMM_DUMMY_PFN_SHIFT);
+ pmdp = kmap(pmd_page);
+ pmdp = &pmdp[hmm_dummy_pmd_index(faddr)];
+ if (!((*pmdp) & HMM_DUMMY_PTE_VALID)) {
+ struct page *page;
+
+ page = alloc_page(GFP_KERNEL | __GFP_ZERO);
+ if (!page) {
+ kunmap(pmd_page);
+ kunmap(pud_page);
+ return -ENOMEM;
+ }
+ *pmdp = (page_to_pfn(page) << HMM_DUMMY_PFN_SHIFT);
+ *pmdp |= HMM_DUMMY_PTE_VALID;
+ }
+
+ kunmap(pmd_page);
+ kunmap(pud_page);
+ }
+
+ return 0;
+}
+
+static void hmm_dummy_pt_free_pmd(struct hmm_dummy_pt_map *pt_map,
+ unsigned long faddr,
+ unsigned long laddr)
+{
+ for (; faddr < laddr; faddr = hmm_dummy_pld_next(faddr)) {
+ unsigned long pfn, *pmdp, next;
+ struct page *page;
+
+ next = min(hmm_dummy_pld_next(faddr), laddr);
+ if (faddr > hmm_dummy_pld_base(faddr) || laddr < next) {
+ continue;
+ }
+ pmdp = hmm_dummy_pt_pmd_map(pt_map, faddr);
+ if (!pmdp) {
+ continue;
+ }
+ if (!(pmdp[hmm_dummy_pmd_index(faddr)] & HMM_DUMMY_PTE_VALID)) {
+ continue;
+ }
+ pfn = pmdp[hmm_dummy_pmd_index(faddr)] >> HMM_DUMMY_PFN_SHIFT;
+ page = pfn_to_page(pfn);
+ pmdp[hmm_dummy_pmd_index(faddr)] = 0;
+ __free_page(page);
+ }
+}
+
+static void hmm_dummy_pt_free_pud(struct hmm_dummy_pt_map *pt_map,
+ unsigned long faddr,
+ unsigned long laddr)
+{
+ for (; faddr < laddr; faddr = hmm_dummy_pmd_next(faddr)) {
+ unsigned long pfn, *pudp, next;
+ struct page *page;
+
+ next = min(hmm_dummy_pmd_next(faddr), laddr);
+ hmm_dummy_pt_free_pmd(pt_map, faddr, next);
+ hmm_dummy_pt_pmd_unmap(pt_map);
+ if (faddr > hmm_dummy_pmd_base(faddr) || laddr < next) {
+ continue;
+ }
+ pudp = hmm_dummy_pt_pud_map(pt_map, faddr);
+ if (!pudp) {
+ continue;
+ }
+ if (!(pudp[hmm_dummy_pud_index(faddr)] & HMM_DUMMY_PTE_VALID)) {
+ continue;
+ }
+ pfn = pudp[hmm_dummy_pud_index(faddr)] >> HMM_DUMMY_PFN_SHIFT;
+ page = pfn_to_page(pfn);
+ pudp[hmm_dummy_pud_index(faddr)] = 0;
+ __free_page(page);
+ }
+}
+
+static void hmm_dummy_pt_free(struct hmm_dummy_mirror *dmirror,
+ unsigned long faddr,
+ unsigned long laddr)
+{
+ struct hmm_dummy_pt_map pt_map = {0};
+
+ if (!dmirror->pgdp || (laddr - faddr) < HMM_DUMMY_PLD_SIZE) {
+ return;
+ }
+
+ pt_map.dmirror = dmirror;
+
+ for (; faddr < laddr; faddr = hmm_dummy_pud_next(faddr)) {
+ unsigned long pfn, *pgdp, next;
+ struct page *page;
+
+ next = min(hmm_dummy_pud_next(faddr), laddr);
+ pgdp = dmirror->pgdp;
+ hmm_dummy_pt_free_pud(&pt_map, faddr, next);
+ hmm_dummy_pt_pud_unmap(&pt_map);
+ if (faddr > hmm_dummy_pud_base(faddr) || laddr < next) {
+ continue;
+ }
+ if (!(pgdp[hmm_dummy_pgd_index(faddr)] & HMM_DUMMY_PTE_VALID)) {
+ continue;
+ }
+ pfn = pgdp[hmm_dummy_pgd_index(faddr)] >> HMM_DUMMY_PFN_SHIFT;
+ page = pfn_to_page(pfn);
+ pgdp[hmm_dummy_pgd_index(faddr)] = 0;
+ __free_page(page);
+ }
+ hmm_dummy_pt_unmap(&pt_map);
+}
+
+
+
+
+/* hmm_ops - hmm callback for the hmm dummy driver.
+ *
+ * Below are the various callback that the hmm api require for a device. The
+ * implementation of the dummy device driver is necessarily simpler that what
+ * a real device driver would do. We do not have interrupt nor any kind of
+ * command buffer on to which schedule memory invalidation and updates.
+ */
+static void hmm_dummy_device_destroy(struct hmm_device *device)
+{
+ /* No-op for the dummy driver. */
+}
+
+static void hmm_dummy_mirror_release(struct hmm_mirror *mirror)
+{
+ struct hmm_dummy_mirror *dmirror;
+
+ dmirror = container_of(mirror, struct hmm_dummy_mirror, mirror);
+ dmirror->stop = true;
+ mutex_lock(&dmirror->mutex);
+ hmm_dummy_pt_free(dmirror, 0, HMM_DUMMY_MAX_ADDR);
+ if (dmirror->pgdp) {
+ kfree(dmirror->pgdp);
+ dmirror->pgdp = NULL;
+ }
+ mutex_unlock(&dmirror->mutex);
+}
+
+static void hmm_dummy_mirror_destroy(struct hmm_mirror *mirror)
+{
+ /* No-op for the dummy driver. */
+ // FIXME print that the pid is no longer mirror
+}
+
+static int hmm_dummy_fence_wait(struct hmm_fence *fence)
+{
+ /* FIXME use some kind of fake event and delay dirty and dummy page
+ * clearing to this function.
+ */
+ return 0;
+}
+
+static void hmm_dummy_fence_destroy(struct hmm_fence *fence)
+{
+ /* We never allocate fence so how could we have to free one ? */
+ BUG();
+}
+
+static struct hmm_fence *hmm_dummy_update(struct hmm_mirror *mirror,
+ struct vm_area_struct *vma,
+ unsigned long faddr,
+ unsigned long laddr,
+ enum hmm_etype etype)
+{
+ struct hmm_dummy_mirror *dmirror;
+ struct hmm_dummy_pt_map pt_map = {0};
+ unsigned long addr, i, mask;
+
+ dmirror = container_of(mirror, struct hmm_dummy_mirror, mirror);
+ pt_map.dmirror = dmirror;
+
+ /* Sanity check for debugging hmm real device driver do not have to do that. */
+ switch (etype) {
+ case HMM_UNREGISTER:
+ case HMM_MUNMAP:
+ case HMM_MPROT_NONE:
+ mask = 0;
+ break;
+ case HMM_MPROT_RONLY:
+ mask = ~HMM_DUMMY_PTE_WRITE;
+ break;
+ default:
+ printk(KERN_ERR "%4d:%s invalid event type %d\n",
+ __LINE__, __func__, etype);
+ return ERR_PTR(-EIO);
+ }
+
+ mutex_lock(&dmirror->mutex);
+ for (i = 0, addr = faddr; addr < laddr; ++i, addr += PAGE_SIZE) {
+ unsigned long *pldp;
+
+ pldp = hmm_dummy_pt_pld_map(&pt_map, addr);
+ if (!pldp) {
+ continue;
+ }
+ if (((*pldp) & HMM_DUMMY_PTE_DIRTY)) {
+ struct page *page;
+
+ page = hmm_dummy_pte_to_page(*pldp);
+ if (page) {
+ set_page_dirty(page);
+ }
+ }
+ *pldp &= ~HMM_DUMMY_PTE_DIRTY;
+ *pldp &= mask;
+ }
+ hmm_dummy_pt_unmap(&pt_map);
+
+ switch (etype) {
+ case HMM_UNREGISTER:
+ case HMM_MUNMAP:
+ hmm_dummy_pt_free(dmirror, faddr, laddr);
+ break;
+ default:
+ break;
+ }
+ mutex_unlock(&dmirror->mutex);
+ return NULL;
+}
+
+static int hmm_dummy_fault(struct hmm_mirror *mirror,
+ unsigned long faddr,
+ unsigned long laddr,
+ pte_t *ptep,
+ struct hmm_event *event)
+{
+ struct hmm_dummy_mirror *dmirror;
+ struct hmm_dummy_pt_map pt_map = {0};
+ unsigned long i;
+ int ret = 0;
+
+ dmirror = container_of(mirror, struct hmm_dummy_mirror, mirror);
+ pt_map.dmirror = dmirror;
+
+ mutex_lock(&dmirror->mutex);
+ for (i = 0; faddr < laddr; ++i, ++ptep, faddr += PAGE_SIZE) {
+ unsigned long *pldp, pld_idx;
+ struct page *page;
+ bool write;
+
+ event->iaddr = faddr;
+ pldp = hmm_dummy_pt_pld_map(&pt_map, faddr);
+ if (!pldp) {
+ ret = -ENOMEM;
+ break;
+ }
+
+ page = hmm_pte_to_page(*ptep, &write);
+ if (!page) {
+ ret = -ENOENT;
+ break;
+ }
+ if (event->etype == HMM_WFAULT && !write) {
+ ret = -EACCES;
+ break;
+ }
+
+printk(KERN_INFO "%4d %16s [0x%016lx] 0x%016lx\n", __LINE__, __func__, faddr, page_to_pfn(page));
+ pld_idx = hmm_dummy_pld_index(faddr);
+ pldp[pld_idx] = (page_to_pfn(page) << HMM_DUMMY_PFN_SHIFT);
+ pldp[pld_idx] |= write ? HMM_DUMMY_PTE_WRITE : 0;
+ pldp[pld_idx] |= HMM_DUMMY_PTE_VALID | HMM_DUMMY_PTE_READ;
+ }
+ hmm_dummy_pt_unmap(&pt_map);
+ mutex_unlock(&dmirror->mutex);
+ return ret;
+}
+
+static const struct hmm_device_ops hmm_dummy_ops = {
+ .device_destroy = &hmm_dummy_device_destroy,
+ .mirror_release = &hmm_dummy_mirror_release,
+ .mirror_destroy = &hmm_dummy_mirror_destroy,
+ .fence_wait = &hmm_dummy_fence_wait,
+ .fence_destroy = &hmm_dummy_fence_destroy,
+ .update = &hmm_dummy_update,
+ .fault = &hmm_dummy_fault,
+};
+
+
+/* hmm_dummy_mmap - hmm dummy device file mmap operations.
+ *
+ * The hmm dummy driver does not allow mmap of its device file. The main reason
+ * is because the kernel lack the ability to insert page with specific custom
+ * protections inside a vma.
+ */
+static int hmm_dummy_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ return VM_FAULT_SIGBUS;
+}
+
+static void hmm_dummy_mmap_open(struct vm_area_struct *vma)
+{
+ /* nop */
+}
+
+static void hmm_dummy_mmap_close(struct vm_area_struct *vma)
+{
+ /* nop */
+}
+
+static const struct vm_operations_struct mmap_mem_ops = {
+ .fault = hmm_dummy_mmap_fault,
+ .open = hmm_dummy_mmap_open,
+ .close = hmm_dummy_mmap_close,
+};
+
+
+/* hmm_dummy_fops - hmm dummy device file operations.
+ *
+ * The hmm dummy driver allow to read/write to the mirrored process through
+ * the device file. Below are the read and write and others device file
+ * callback that implement access to the mirrored address space.
+ */
+static int hmm_dummy_mirror_fault(struct hmm_dummy_mirror *dmirror,
+ unsigned long addr,
+ bool write)
+{
+ struct hmm_mirror *mirror = &dmirror->mirror;
+ struct hmm_event event;
+ unsigned long faddr, laddr, npages = 4;
+ int ret;
+
+ /* Showcase hmm api fault a 64k range centered on the address. */
+ event.faddr = faddr = addr > (npages << 8) ? addr - (npages << 8) : 0;
+ event.laddr = laddr = faddr + (npages << 10);
+ event.etype = write ? HMM_WFAULT : HMM_RFAULT;
+
+ /* Pre-allocate device page table. */
+ mutex_lock(&dmirror->mutex);
+ ret = hmm_dummy_pt_alloc(dmirror, faddr, laddr);
+ mutex_unlock(&dmirror->mutex);
+ if (ret) {
+ return ret;
+ }
+
+ for (; faddr < laddr; faddr = event.faddr) {
+ ret = hmm_mirror_fault(mirror, &event);
+ /* Ignore any error that do not concern the fault address. */
+ if (addr >= event.laddr) {
+ event.faddr = event.laddr;
+ event.laddr = laddr;
+ continue;
+ }
+ if (addr < event.laddr) {
+ /* The address was faulted successfully ignore error
+ * for address above the one we were interested in.
+ */
+ ret = 0;
+ }
+ break;
+ }
+
+ return ret;
+}
+
+static ssize_t hmm_dummy_fops_read(struct file *filp,
+ char __user *buf,
+ size_t count,
+ loff_t *ppos)
+{
+ struct hmm_dummy_device *ddevice;
+ struct hmm_dummy_mirror *dmirror;
+ struct hmm_dummy_pt_map pt_map = {0};
+ unsigned long faddr, laddr, offset;
+ unsigned minor;
+ ssize_t retval = 0;
+ void *tmp;
+ long r;
+
+ tmp = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!tmp) {
+ return -ENOMEM;
+ }
+
+ /* Check if we are mirroring anything */
+ minor = iminor(file_inode(filp));
+ ddevice = filp->private_data;
+ mutex_lock(&ddevice->mutex);
+ if (ddevice->dmirrors[minor] == NULL) {
+ mutex_unlock(&ddevice->mutex);
+ kfree(tmp);
+ return 0;
+ }
+ dmirror = ddevice->dmirrors[minor];
+ mutex_unlock(&ddevice->mutex);
+ if (dmirror->stop) {
+ kfree(tmp);
+ return 0;
+ }
+
+ /* The range of address to lookup. */
+ faddr = (*ppos) & PAGE_MASK;
+ offset = (*ppos) - faddr;
+ laddr = PAGE_ALIGN(faddr + count);
+ BUG_ON(faddr == laddr);
+ pt_map.dmirror = dmirror;
+
+ for (; count; faddr += PAGE_SIZE, offset = 0) {
+ unsigned long *pldp, pld_idx;
+ unsigned long size = min(PAGE_SIZE - offset, count);
+ struct page *page;
+ char *ptr;
+
+ mutex_lock(&dmirror->mutex);
+ pldp = hmm_dummy_pt_pld_map(&pt_map, faddr);
+ pld_idx = hmm_dummy_pld_index(faddr);
+ if (!pldp || !(pldp[pld_idx] & HMM_DUMMY_PTE_VALID)) {
+ hmm_dummy_pt_unmap(&pt_map);
+ mutex_unlock(&dmirror->mutex);
+ goto fault;
+ }
+ page = hmm_dummy_pte_to_page(pldp[pld_idx]);
+ if (!page) {
+ mutex_unlock(&dmirror->mutex);
+ BUG();
+ kfree(tmp);
+ return -EFAULT;
+ }
+printk(KERN_INFO "%4d %16s [0x%016lx] 0x%016lx\n", __LINE__, __func__, faddr, page_to_pfn(page));
+ ptr = kmap(page);
+ memcpy(tmp, ptr + offset, size);
+ kunmap(page);
+ hmm_dummy_pt_unmap(&pt_map);
+ mutex_unlock(&dmirror->mutex);
+
+ r = copy_to_user(buf, tmp, size);
+ if (r) {
+ kfree(tmp);
+ return -EFAULT;
+ }
+ retval += size;
+ *ppos += size;
+ count -= size;
+ buf += size;
+ }
+
+ return retval;
+
+fault:
+ kfree(tmp);
+ r = hmm_dummy_mirror_fault(dmirror, faddr, false);
+ if (r) {
+ return r;
+ }
+
+ /* Force userspace to retry read if nothing was read. */
+ return retval ? retval : -EINTR;
+}
+
+static ssize_t hmm_dummy_fops_write(struct file *filp,
+ const char __user *buf,
+ size_t count,
+ loff_t *ppos)
+{
+ struct hmm_dummy_device *ddevice;
+ struct hmm_dummy_mirror *dmirror;
+ struct hmm_dummy_pt_map pt_map = {0};
+ unsigned long faddr, laddr, offset;
+ unsigned minor;
+ ssize_t retval = 0;
+ void *tmp;
+ long r;
+
+ tmp = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ if (!tmp) {
+ return -ENOMEM;
+ }
+
+ /* Check if we are mirroring anything */
+ minor = iminor(file_inode(filp));
+ ddevice = filp->private_data;
+ mutex_lock(&ddevice->mutex);
+ if (ddevice->dmirrors[minor] == NULL) {
+ mutex_unlock(&ddevice->mutex);
+ kfree(tmp);
+ return 0;
+ }
+ dmirror = ddevice->dmirrors[minor];
+ mutex_unlock(&ddevice->mutex);
+ if (dmirror->stop) {
+ kfree(tmp);
+ return 0;
+ }
+
+ /* The range of address to lookup. */
+ faddr = (*ppos) & PAGE_MASK;
+ offset = (*ppos) - faddr;
+ laddr = PAGE_ALIGN(faddr + count);
+ BUG_ON(faddr == laddr);
+ pt_map.dmirror = dmirror;
+
+ for (; count; faddr += PAGE_SIZE, offset = 0) {
+ unsigned long *pldp, pld_idx;
+ unsigned long size = min(PAGE_SIZE - offset, count);
+ struct page *page;
+ char *ptr;
+
+ r = copy_from_user(tmp, buf, size);
+ if (r) {
+ kfree(tmp);
+ return -EFAULT;
+ }
+
+ mutex_lock(&dmirror->mutex);
+
+ pldp = hmm_dummy_pt_pld_map(&pt_map, faddr);
+ pld_idx = hmm_dummy_pld_index(faddr);
+ if (!pldp || !(pldp[pld_idx] & HMM_DUMMY_PTE_VALID)) {
+ hmm_dummy_pt_unmap(&pt_map);
+ mutex_unlock(&dmirror->mutex);
+ goto fault;
+ }
+ if (!(pldp[pld_idx] & HMM_DUMMY_PTE_WRITE)) {
+ hmm_dummy_pt_unmap(&pt_map);
+ mutex_unlock(&dmirror->mutex);
+ goto fault;
+ }
+ pldp[pld_idx] |= HMM_DUMMY_PTE_DIRTY;
+ page = hmm_dummy_pte_to_page(pldp[pld_idx]);
+ if (!page) {
+ mutex_unlock(&dmirror->mutex);
+ BUG();
+ kfree(tmp);
+ return -EFAULT;
+ }
+printk(KERN_INFO "%4d %16s [0x%016lx] 0x%016lx\n", __LINE__, __func__, faddr, page_to_pfn(page));
+ ptr = kmap(page);
+ memcpy(ptr + offset, tmp, size);
+ kunmap(page);
+ hmm_dummy_pt_unmap(&pt_map);
+ mutex_unlock(&dmirror->mutex);
+
+ retval += size;
+ *ppos += size;
+ count -= size;
+ buf += size;
+ }
+
+ kfree(tmp);
+ return retval;
+
+fault:
+ kfree(tmp);
+ r = hmm_dummy_mirror_fault(dmirror, faddr, true);
+ if (r) {
+ return r;
+ }
+
+ /* Force userspace to retry write if nothing was writen. */
+ return retval ? retval : -EINTR;
+}
+
+static int hmm_dummy_fops_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ return -EINVAL;
+}
+
+static int hmm_dummy_fops_open(struct inode *inode, struct file *filp)
+{
+ struct hmm_dummy_device *ddevice;
+ struct cdev *cdev = inode->i_cdev;
+ const int minor = iminor(inode);
+
+ /* No exclusive opens */
+ if (filp->f_flags & O_EXCL) {
+ return -EINVAL;
+ }
+
+ ddevice = container_of(cdev, struct hmm_dummy_device, cdev);
+ filp->private_data = ddevice;
+ ddevice->fmapping[minor] = &inode->i_data;
+
+ return 0;
+}
+
+static int hmm_dummy_fops_release(struct inode *inode,
+ struct file *filp)
+{
+ struct hmm_dummy_device *ddevice;
+ struct hmm_dummy_mirror *dmirror;
+ struct cdev *cdev = inode->i_cdev;
+ const int minor = iminor(inode);
+
+ ddevice = container_of(cdev, struct hmm_dummy_device, cdev);
+ dmirror = ddevice->dmirrors[minor];
+ if (dmirror && dmirror->filp == filp) {
+ if (!dmirror->stop) {
+ hmm_mirror_unregister(&dmirror->mirror);
+ }
+ ddevice->dmirrors[minor] = NULL;
+ kfree(dmirror);
+ }
+
+ return 0;
+}
+
+static long hmm_dummy_fops_unlocked_ioctl(struct file *filp,
+ unsigned int command,
+ unsigned long arg)
+{
+ struct hmm_dummy_device *ddevice;
+ struct hmm_dummy_mirror *dmirror;
+ unsigned minor;
+ int ret;
+
+ minor = iminor(file_inode(filp));
+ ddevice = filp->private_data;
+ switch (command) {
+ case HMM_DUMMY_EXPOSE_MM:
+ mutex_lock(&ddevice->mutex);
+ dmirror = ddevice->dmirrors[minor];
+ if (dmirror) {
+ mutex_unlock(&ddevice->mutex);
+ return -EBUSY;
+ }
+ /* Mirror this process address space */
+ dmirror = kzalloc(sizeof(*dmirror), GFP_KERNEL);
+ if (dmirror == NULL) {
+ mutex_unlock(&ddevice->mutex);
+ return -ENOMEM;
+ }
+ dmirror->mm = NULL;
+ dmirror->stop = false;
+ dmirror->pid = task_pid_nr(current);
+ dmirror->ddevice = ddevice;
+ dmirror->minor = minor;
+ dmirror->filp = filp;
+ dmirror->pgdp = NULL;
+ mutex_init(&dmirror->mutex);
+ ddevice->dmirrors[minor] = dmirror;
+ mutex_unlock(&ddevice->mutex);
+
+ ret = hmm_mirror_register(&dmirror->mirror,
+ &ddevice->device,
+ current->mm);
+ if (ret) {
+ mutex_lock(&ddevice->mutex);
+ ddevice->dmirrors[minor] = NULL;
+ mutex_unlock(&ddevice->mutex);
+ kfree(dmirror);
+ return ret;
+ }
+ /* Success. */
+ hmm_dummy_device_print(ddevice, dmirror->minor,
+ "mirroring address space of %d\n",
+ dmirror->pid);
+ return 0;
+ default:
+ return -EINVAL;
+ }
+ return 0;
+}
+
+static const struct file_operations hmm_dummy_fops = {
+ .read = hmm_dummy_fops_read,
+ .write = hmm_dummy_fops_write,
+ .mmap = hmm_dummy_fops_mmap,
+ .open = hmm_dummy_fops_open,
+ .release = hmm_dummy_fops_release,
+ .unlocked_ioctl = hmm_dummy_fops_unlocked_ioctl,
+ .llseek = default_llseek,
+ .owner = THIS_MODULE,
+};
+
+
+/*
+ * char device driver
+ */
+static int hmm_dummy_device_init(struct hmm_dummy_device *ddevice)
+{
+ int ret, i;
+
+ ret = alloc_chrdev_region(&ddevice->dev, 0,
+ HMM_DUMMY_DEVICE_MAX_MIRRORS,
+ ddevice->name);
+ if (ret < 0) {
+ printk(KERN_ERR "alloc_chrdev_region() failed for hmm_dummy\n");
+ goto error;
+ }
+ ddevice->major = MAJOR(ddevice->dev);
+
+ cdev_init(&ddevice->cdev, &hmm_dummy_fops);
+ ret = cdev_add(&ddevice->cdev, ddevice->dev, HMM_DUMMY_DEVICE_MAX_MIRRORS);
+ if (ret) {
+ unregister_chrdev_region(ddevice->dev, HMM_DUMMY_DEVICE_MAX_MIRRORS);
+ goto error;
+ }
+
+ /* Register the hmm device. */
+ for (i = 0; i < HMM_DUMMY_DEVICE_MAX_MIRRORS; i++) {
+ ddevice->dmirrors[i] = NULL;
+ }
+ mutex_init(&ddevice->mutex);
+ ddevice->device.ops = &hmm_dummy_ops;
+
+ ret = hmm_device_register(&ddevice->device,
+ ddevice->name);
+ if (ret) {
+ cdev_del(&ddevice->cdev);
+ unregister_chrdev_region(ddevice->dev, HMM_DUMMY_DEVICE_MAX_MIRRORS);
+ goto error;
+ }
+
+ return 0;
+
+error:
+ return ret;
+}
+
+static void hmm_dummy_device_fini(struct hmm_dummy_device *ddevice)
+{
+ unsigned i;
+
+ /* First finish hmm. */
+ for (i = 0; i < HMM_DUMMY_DEVICE_MAX_MIRRORS; i++) {
+ struct hmm_dummy_mirror *dmirror;
+
+ dmirror = ddevices->dmirrors[i];
+ if (!dmirror) {
+ continue;
+ }
+ hmm_mirror_unregister(&dmirror->mirror);
+ kfree(dmirror);
+ }
+ hmm_device_unref(&ddevice->device);
+
+ cdev_del(&ddevice->cdev);
+ unregister_chrdev_region(ddevice->dev,
+ HMM_DUMMY_DEVICE_MAX_MIRRORS);
+}
+
+static int __init hmm_dummy_init(void)
+{
+ int ret;
+
+ snprintf(ddevices[0].name, sizeof(ddevices[0].name),
+ "%s%d", HMM_DUMMY_DEVICE_NAME, 0);
+ ret = hmm_dummy_device_init(&ddevices[0]);
+ if (ret) {
+ return ret;
+ }
+
+ snprintf(ddevices[1].name, sizeof(ddevices[1].name),
+ "%s%d", HMM_DUMMY_DEVICE_NAME, 1);
+ ret = hmm_dummy_device_init(&ddevices[1]);
+ if (ret) {
+ hmm_dummy_device_fini(&ddevices[0]);
+ return ret;
+ }
+
+ printk(KERN_INFO "hmm_dummy loaded THIS IS A DANGEROUS MODULE !!!\n");
+ return 0;
+}
+
+static void __exit hmm_dummy_exit(void)
+{
+ hmm_dummy_device_fini(&ddevices[1]);
+ hmm_dummy_device_fini(&ddevices[0]);
+}
+
+module_init(hmm_dummy_init);
+module_exit(hmm_dummy_exit);
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/hmm_dummy.h b/include/uapi/linux/hmm_dummy.h
new file mode 100644
index 0000000..16ae0d3
--- /dev/null
+++ b/include/uapi/linux/hmm_dummy.h
@@ -0,0 +1,34 @@
+/*
+ * Copyright 2013 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Authors: Jérôme Glisse <jglisse@...hat.com>
+ */
+/* This is a dummy driver made to exercice the HMM (hardware memory management)
+ * API of the kernel. It allow an userspace program to map its whole address
+ * space through the hmm dummy driver file.
+ */
+#ifndef _UAPI_LINUX_HMM_DUMMY_H
+#define _UAPI_LINUX_HMM_DUMMY_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+#include <linux/irqnr.h>
+
+/* Expose the address space of the calling process through hmm dummy dev file */
+#define HMM_DUMMY_EXPOSE_MM _IO( 'R', 0x00 )
+
+#endif /* _UAPI_LINUX_RANDOM_H */
--
1.9.0
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