The exported interface copy_oldmem_page passes user pointer without
__user annotation and does unnecessary user/kernel pointer
conversions during the pointer propagation.
Hence it is modified to have a new parameter for user pointer. However
instead of updating it directly a new interface copy_oldmem_page_buf()
is added as copy_oldmem_page() is used across different archs. This old
interface copy_oldmem_page() will be deleted after all the archs are
modified to use the new interface.
The weak implementation of both copy_oldmem_page() and
copy_oldmem_page_buf() are added temporarily to keep the kernel building
for the subsequent patches. As a consequence, crash dump is temporarily
broken for the archs till the patch where it implements its own
copy_oldmem_page_buf().
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: kexec <kexec@xxxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel <linux-fsdevel@xxxxxxxxxxxxxxx>
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@xxxxxxx>
---
fs/proc/vmcore.c | 27 +++++++++++++++++----------
include/linux/crash_dump.h | 3 +++
2 files changed, 20 insertions(+), 10 deletions(-)
diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index fa4492ef6124..d01b85c043dd 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -172,12 +172,9 @@ ssize_t read_from_oldmem(char __user *ubuf, char *kbuf, size_t count,
tmp = copy_oldmem_page_encrypted(pfn, ubuf,
kbuf, nr_bytes,
offset);
- else if (ubuf)
- tmp = copy_oldmem_page(pfn, (__force char *)ubuf,
- nr_bytes, offset, 1);
else
- tmp = copy_oldmem_page(pfn, kbuf, nr_bytes,
- offset, 0);
+ tmp = copy_oldmem_page_buf(pfn, ubuf, kbuf,
+ nr_bytes, offset);
}
if (tmp < 0) {
up_read(&vmcore_cb_rwsem);
@@ -244,11 +241,21 @@ ssize_t __weak
copy_oldmem_page_encrypted(unsigned long pfn, char __user *ubuf, char *kbuf,
size_t csize, unsigned long offset)
{
- if (ubuf)
- return copy_oldmem_page(pfn, (__force char *)ubuf, csize,
- offset, 1);
- else
- return copy_oldmem_page(pfn, kbuf, csize, offset, 0);
+ return copy_oldmem_page_buf(pfn, ubuf, kbuf, csize, offset);
+}
+
+ssize_t __weak
+copy_oldmem_page_buf(unsigned long pfn, char __user *ubuf, char *kbuf,
+ size_t csize, unsigned long offset)
+{
+ return -EOPNOTSUPP;
+}
+
+ssize_t __weak
+copy_oldmem_page(unsigned long pfn, char *ubuf, size_t csize,
+ unsigned long offset, int userbuf)
+{
+ return -EOPNOTSUPP;
}
/*
diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h
index 36a7f08f4ad2..725c4e053ecf 100644
--- a/include/linux/crash_dump.h
+++ b/include/linux/crash_dump.h
@@ -26,6 +26,9 @@ extern int remap_oldmem_pfn_range(struct vm_area_struct *vma,
extern ssize_t copy_oldmem_page(unsigned long, char *, size_t,
unsigned long, int);
+extern ssize_t copy_oldmem_page_buf(unsigned long pfn, char __user *ubuf,
+ char *kbuf, size_t csize,
+ unsigned long offset);
extern ssize_t copy_oldmem_page_encrypted(unsigned long pfn,
char __user *ubuf, char *kbuf,
size_t csize, unsigned long offset);
--
2.17.1
