diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2014-05-19 20:41:36 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-06-05 12:30:11 +0200 |
| commit | 40814f6805a524130a5ec313871147f7aa9b5318 (patch) | |
| tree | 2605a03d0a7360c377126c590cb929e1ed9d0057 /kernel | |
| parent | uprobes: Shift ->readpage check from __copy_insn() to uprobe_register() (diff) | |
| download | linux-40814f6805a524130a5ec313871147f7aa9b5318.tar.xz linux-40814f6805a524130a5ec313871147f7aa9b5318.zip | |
uprobes: Teach copy_insn() to support tmpfs
tmpfs is widely used but as Denys reports shmem_aops doesn't have
->readpage() and thus you can't probe a binary on this filesystem.
As Hugh suggested we can use shmem_read_mapping_page() in this case,
just we need to check shmem_mapping() if ->readpage == NULL.
Reported-by: Denys Vlasenko <dvlasenk@redhat.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140519184136.GB6750@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/events/uprobes.c | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index c56b13e3b5e1..6bfb6717f878 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -36,6 +36,7 @@ #include "../../mm/internal.h" /* munlock_vma_page */ #include <linux/percpu-rwsem.h> #include <linux/task_work.h> +#include <linux/shmem_fs.h> #include <linux/uprobes.h> @@ -537,10 +538,14 @@ static int __copy_insn(struct address_space *mapping, struct file *filp, { struct page *page; /* - * Ensure that the page that has the original instruction is - * populated and in page-cache. + * Ensure that the page that has the original instruction is populated + * and in page-cache. If ->readpage == NULL it must be shmem_mapping(), + * see uprobe_register(). */ - page = read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT, filp); + if (mapping->a_ops->readpage) + page = read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT, filp); + else + page = shmem_read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT); if (IS_ERR(page)) return PTR_ERR(page); @@ -876,8 +881,8 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer * if (!uc->handler && !uc->ret_handler) return -EINVAL; - /* copy_insn()->read_mapping_page() needs ->readpage() */ - if (!inode->i_mapping->a_ops->readpage) + /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ + if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping)) return -EIO; /* Racy, just to catch the obvious mistakes */ if (offset > i_size_read(inode)) |