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authorLinus Torvalds <torvalds@linux-foundation.org>2021-02-22 17:45:02 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-22 17:45:02 -0800
commite913a8cdc297d51c832bb8e9914333b6ae3fe6ef (patch)
tree338c88d3eba453db70714811d44488af6f8cee1f /kernel
parent4b5f9254e4f4375ac845cb17f1732037dd8adeeb (diff)
parent636b21b50152d4e203223ee337aca1cb3c1bfe53 (diff)
downloadlinux-e913a8cdc297d51c832bb8e9914333b6ae3fe6ef.tar.gz
Merge tag 'topic/iomem-mmap-vs-gup-2021-02-22' of git://anongit.freedesktop.org/drm/drm
Pull follow_pfn() updates from Daniel Vetter: "Fixes around VM_FPNMAP and follow_pfn: - replace mm/frame_vector.c by get_user_pages in misc/habana and drm/exynos drivers, then move that into media as it's sole user - close race in generic_access_phys - s390 pci ioctl fix of this series landed in 5.11 already - properly revoke iomem mappings (/dev/mem, pci files)" * tag 'topic/iomem-mmap-vs-gup-2021-02-22' of git://anongit.freedesktop.org/drm/drm: PCI: Revoke mappings like devmem PCI: Also set up legacy files only after sysfs init sysfs: Support zapping of binary attr mmaps resource: Move devmem revoke code to resource framework /dev/mem: Only set filp->f_mapping PCI: Obey iomem restrictions for procfs mmap mm: Close race in generic_access_phys media: videobuf2: Move frame_vector into media subsystem mm/frame-vector: Use FOLL_LONGTERM misc/habana: Use FOLL_LONGTERM for userptr misc/habana: Stop using frame_vector helpers drm/exynos: Use FOLL_LONGTERM for g2d cmdlists drm/exynos: Stop using frame_vector helpers
Diffstat (limited to 'kernel')
-rw-r--r--kernel/resource.c98
1 files changed, 97 insertions, 1 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index 833394f9c608..627e61b0c124 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -18,12 +18,15 @@
#include <linux/spinlock.h>
#include <linux/fs.h>
#include <linux/proc_fs.h>
+#include <linux/pseudo_fs.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/device.h>
#include <linux/pfn.h>
#include <linux/mm.h>
+#include <linux/mount.h>
#include <linux/resource_ext.h>
+#include <uapi/linux/magic.h>
#include <asm/io.h>
@@ -1119,6 +1122,55 @@ resource_size_t resource_alignment(struct resource *res)
static DECLARE_WAIT_QUEUE_HEAD(muxed_resource_wait);
+static struct inode *iomem_inode;
+
+#ifdef CONFIG_IO_STRICT_DEVMEM
+static void revoke_iomem(struct resource *res)
+{
+ /* pairs with smp_store_release() in iomem_init_inode() */
+ struct inode *inode = smp_load_acquire(&iomem_inode);
+
+ /*
+ * Check that the initialization has completed. Losing the race
+ * is ok because it means drivers are claiming resources before
+ * the fs_initcall level of init and prevent iomem_get_mapping users
+ * from establishing mappings.
+ */
+ if (!inode)
+ return;
+
+ /*
+ * The expectation is that the driver has successfully marked
+ * the resource busy by this point, so devmem_is_allowed()
+ * should start returning false, however for performance this
+ * does not iterate the entire resource range.
+ */
+ if (devmem_is_allowed(PHYS_PFN(res->start)) &&
+ devmem_is_allowed(PHYS_PFN(res->end))) {
+ /*
+ * *cringe* iomem=relaxed says "go ahead, what's the
+ * worst that can happen?"
+ */
+ return;
+ }
+
+ unmap_mapping_range(inode->i_mapping, res->start, resource_size(res), 1);
+}
+#else
+static void revoke_iomem(struct resource *res) {}
+#endif
+
+struct address_space *iomem_get_mapping(void)
+{
+ /*
+ * This function is only called from file open paths, hence guaranteed
+ * that fs_initcalls have completed and no need to check for NULL. But
+ * since revoke_iomem can be called before the initcall we still need
+ * the barrier to appease checkers.
+ */
+ return smp_load_acquire(&iomem_inode)->i_mapping;
+}
+
/**
* __request_region - create a new busy resource region
* @parent: parent resource descriptor
@@ -1186,7 +1238,7 @@ struct resource * __request_region(struct resource *parent,
write_unlock(&resource_lock);
if (res && orig_parent == &iomem_resource)
- revoke_devmem(res);
+ revoke_iomem(res);
return res;
}
@@ -1786,4 +1838,48 @@ static int __init strict_iomem(char *str)
return 1;
}
+static int iomem_fs_init_fs_context(struct fs_context *fc)
+{
+ return init_pseudo(fc, DEVMEM_MAGIC) ? 0 : -ENOMEM;
+}
+
+static struct file_system_type iomem_fs_type = {
+ .name = "iomem",
+ .owner = THIS_MODULE,
+ .init_fs_context = iomem_fs_init_fs_context,
+ .kill_sb = kill_anon_super,
+};
+
+static int __init iomem_init_inode(void)
+{
+ static struct vfsmount *iomem_vfs_mount;
+ static int iomem_fs_cnt;
+ struct inode *inode;
+ int rc;
+
+ rc = simple_pin_fs(&iomem_fs_type, &iomem_vfs_mount, &iomem_fs_cnt);
+ if (rc < 0) {
+ pr_err("Cannot mount iomem pseudo filesystem: %d\n", rc);
+ return rc;
+ }
+
+ inode = alloc_anon_inode(iomem_vfs_mount->mnt_sb);
+ if (IS_ERR(inode)) {
+ rc = PTR_ERR(inode);
+ pr_err("Cannot allocate inode for iomem: %d\n", rc);
+ simple_release_fs(&iomem_vfs_mount, &iomem_fs_cnt);
+ return rc;
+ }
+
+ /*
+ * Publish iomem revocation inode initialized.
+ * Pairs with smp_load_acquire() in revoke_iomem().
+ */
+ smp_store_release(&iomem_inode, inode);
+
+ return 0;
+}
+
+fs_initcall(iomem_init_inode);
+
__setup("iomem=", strict_iomem);