diff options
Diffstat (limited to 'kernel/resource.c')
| -rw-r--r-- | kernel/resource.c | 132 |
1 files changed, 116 insertions, 16 deletions
diff --git a/kernel/resource.c b/kernel/resource.c index 3ae2f56cc79d..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> @@ -320,9 +323,8 @@ int release_resource(struct resource *old) EXPORT_SYMBOL(release_resource); /** - * Finds the lowest iomem resource that covers part of [@start..@end]. The - * caller must specify @start, @end, @flags, and @desc (which may be - * IORES_DESC_NONE). + * find_next_iomem_res - Finds the lowest iomem resource that covers part of + * [@start..@end]. * * If a resource is found, returns 0 and @*res is overwritten with the part * of the resource that's within [@start..@end]; if none is found, returns @@ -337,6 +339,9 @@ EXPORT_SYMBOL(release_resource); * @desc: descriptor the resource must have * @first_lvl: walk only the first level children, if set * @res: return ptr, if resource found + * + * The caller must specify @start, @end, @flags, and @desc + * (which may be IORES_DESC_NONE). */ static int find_next_iomem_res(resource_size_t start, resource_size_t end, unsigned long flags, unsigned long desc, @@ -416,11 +421,9 @@ static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end, } /** - * Walks through iomem resources and calls func() with matching resource - * ranges. This walks through whole tree and not just first level children. - * All the memory ranges which overlap start,end and also match flags and - * desc are valid candidates. - * + * walk_iomem_res_desc - Walks through iomem resources and calls func() + * with matching resource ranges. + * * * @desc: I/O resource descriptor. Use IORES_DESC_NONE to skip @desc check. * @flags: I/O resource flags * @start: start addr @@ -428,6 +431,10 @@ static int __walk_iomem_res_desc(resource_size_t start, resource_size_t end, * @arg: function argument for the callback @func * @func: callback function that is called for each qualifying resource area * + * This walks through whole tree and not just first level children. + * All the memory ranges which overlap start,end and also match flags and + * desc are valid candidates. + * * NOTE: For a new descriptor search, define a new IORES_DESC in * <linux/ioport.h> and set it in 'desc' of a target resource entry. */ @@ -557,13 +564,13 @@ int region_intersects(resource_size_t start, size_t size, unsigned long flags, } read_unlock(&resource_lock); - if (other == 0) - return type ? REGION_INTERSECTS : REGION_DISJOINT; + if (type == 0) + return REGION_DISJOINT; - if (type) - return REGION_MIXED; + if (other == 0) + return REGION_INTERSECTS; - return REGION_DISJOINT; + return REGION_MIXED; } EXPORT_SYMBOL_GPL(region_intersects); @@ -1115,6 +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 @@ -1182,7 +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; } @@ -1372,9 +1428,9 @@ static bool system_ram_resources_mergeable(struct resource *r1, !r1->child && !r2->child; } -/* +/** * merge_system_ram_resource - mark the System RAM resource mergeable and try to - * merge it with adjacent, mergeable resources + * merge it with adjacent, mergeable resources * @res: resource descriptor * * This interface is intended for memory hotplug, whereby lots of contiguous @@ -1782,4 +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); |