From 0fb1b1ed7dd92ca9775f8292cc7b85b93182dcb0 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Fri, 27 Nov 2020 17:41:23 +0100 Subject: /dev/mem: Only set filp->f_mapping MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When we care about pagecache maintenance, we need to make sure that both f_mapping and i_mapping point at the right mapping. But for iomem mappings we only care about the virtual/pte side of things, so f_mapping is enough. Also setting inode->i_mapping was confusing me as a driver maintainer, since in e.g. drivers/gpu we don't do that. Per Dan this seems to be copypasta from places which do care about pagecache consistency, but not needed. Hence remove it for slightly less confusion. Signed-off-by: Daniel Vetter Cc: Jason Gunthorpe Cc: Kees Cook Cc: Dan Williams Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Reviewed-by: Dan Williams Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20201127164131.2244124-10-daniel.vetter@ffwll.ch --- drivers/char/mem.c | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/char/mem.c') diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 94c2b556cf97..7dcf9e4ea79d 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -891,7 +891,6 @@ static int open_port(struct inode *inode, struct file *filp) * revocations when drivers want to take over a /dev/mem mapped * range. */ - inode->i_mapping = devmem_inode->i_mapping; filp->f_mapping = inode->i_mapping; return 0; -- cgit v1.2.3 From 71a1d8ed900f8cf53151beff17e3e2ff8e9283a1 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Fri, 27 Nov 2020 17:41:24 +0100 Subject: resource: Move devmem revoke code to resource framework MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We want all iomem mmaps to consistently revoke ptes when the kernel takes over and CONFIG_IO_STRICT_DEVMEM is enabled. This includes the pci bar mmaps available through procfs and sysfs, which currently do not revoke mappings. To prepare for this, move the code from the /dev/kmem driver to kernel/resource.c. During review Jason spotted that barriers are used somewhat inconsistently. Fix that up while we shuffle this code, since it doesn't have an actual impact at runtime. Otherwise no semantic and behavioural changes intended, just code extraction and adjusting comments and names. Reviewed-by: Greg Kroah-Hartman Signed-off-by: Daniel Vetter Cc: Jason Gunthorpe Cc: Kees Cook Cc: Dan Williams Cc: Andrew Morton Cc: John Hubbard Cc: Jérôme Glisse Cc: Jan Kara Cc: Dan Williams Cc: linux-mm@kvack.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-media@vger.kernel.org Cc: Arnd Bergmann Cc: Greg Kroah-Hartman Cc: Daniel Vetter Cc: David Hildenbrand Cc: "Rafael J. Wysocki" Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20201127164131.2244124-11-daniel.vetter@ffwll.ch --- drivers/char/mem.c | 85 +----------------------------------------------------- 1 file changed, 1 insertion(+), 84 deletions(-) (limited to 'drivers/char/mem.c') diff --git a/drivers/char/mem.c b/drivers/char/mem.c index 7dcf9e4ea79d..43c871dc7477 100644 --- a/drivers/char/mem.c +++ b/drivers/char/mem.c @@ -31,9 +31,6 @@ #include #include #include -#include -#include -#include #ifdef CONFIG_IA64 # include @@ -836,42 +833,6 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig) return ret; } -static struct inode *devmem_inode; - -#ifdef CONFIG_IO_STRICT_DEVMEM -void revoke_devmem(struct resource *res) -{ - /* pairs with smp_store_release() in devmem_init_inode() */ - struct inode *inode = smp_load_acquire(&devmem_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 /dev/mem 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); -} -#endif - static int open_port(struct inode *inode, struct file *filp) { int rc; @@ -891,7 +852,7 @@ static int open_port(struct inode *inode, struct file *filp) * revocations when drivers want to take over a /dev/mem mapped * range. */ - filp->f_mapping = inode->i_mapping; + filp->f_mapping = iomem_get_mapping(); return 0; } @@ -1023,48 +984,6 @@ static char *mem_devnode(struct device *dev, umode_t *mode) static struct class *mem_class; -static int devmem_fs_init_fs_context(struct fs_context *fc) -{ - return init_pseudo(fc, DEVMEM_MAGIC) ? 0 : -ENOMEM; -} - -static struct file_system_type devmem_fs_type = { - .name = "devmem", - .owner = THIS_MODULE, - .init_fs_context = devmem_fs_init_fs_context, - .kill_sb = kill_anon_super, -}; - -static int devmem_init_inode(void) -{ - static struct vfsmount *devmem_vfs_mount; - static int devmem_fs_cnt; - struct inode *inode; - int rc; - - rc = simple_pin_fs(&devmem_fs_type, &devmem_vfs_mount, &devmem_fs_cnt); - if (rc < 0) { - pr_err("Cannot mount /dev/mem pseudo filesystem: %d\n", rc); - return rc; - } - - inode = alloc_anon_inode(devmem_vfs_mount->mnt_sb); - if (IS_ERR(inode)) { - rc = PTR_ERR(inode); - pr_err("Cannot allocate inode for /dev/mem: %d\n", rc); - simple_release_fs(&devmem_vfs_mount, &devmem_fs_cnt); - return rc; - } - - /* - * Publish /dev/mem initialized. - * Pairs with smp_load_acquire() in revoke_devmem(). - */ - smp_store_release(&devmem_inode, inode); - - return 0; -} - static int __init chr_dev_init(void) { int minor; @@ -1086,8 +1005,6 @@ static int __init chr_dev_init(void) */ if ((minor == DEVPORT_MINOR) && !arch_has_dev_port()) continue; - if ((minor == DEVMEM_MINOR) && devmem_init_inode() != 0) - continue; device_create(mem_class, NULL, MKDEV(MEM_MAJOR, minor), NULL, devlist[minor].name); -- cgit v1.2.3