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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-22 17:45:02 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-02-22 17:45:02 -0800 |
commit | e913a8cdc297d51c832bb8e9914333b6ae3fe6ef (patch) | |
tree | 338c88d3eba453db70714811d44488af6f8cee1f /kernel | |
parent | 4b5f9254e4f4375ac845cb17f1732037dd8adeeb (diff) | |
parent | 636b21b50152d4e203223ee337aca1cb3c1bfe53 (diff) | |
download | linux-e913a8cdc297d51c832bb8e9914333b6ae3fe6ef.tar.bz2 |
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.c | 98 |
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); |