[PATCH v2 10/20] vmcore: read buffers for vmcore objects copied from old memory

[d.hatayama@xxxxxxxxxxxxxx (HATAYAMA Daisuke)]

If flag MEM_TYPE_CURRENT_KERNEL is set, the object is copied in the
buffer on the 2nd kernel, then read_vmcore() reads the buffer. If the
flag is not set, read_vmcore() reads old memory as usual.

Signed-off-by: HATAYAMA Daisuke <d.hatayama at jp.fujitsu.com>
---

 fs/proc/vmcore.c |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 09b7f34..c8899dc 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -158,10 +158,17 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
 			tsz = m->offset + m->size - *fpos;
 			if (buflen < tsz)
 				tsz = buflen;
-			start = m->paddr + *fpos - m->offset;
-			tmp = read_from_oldmem(buffer, tsz, &start, 1);
-			if (tmp < 0)
-				return tmp;
+			if (m->flag & MEM_TYPE_CURRENT_KERNEL) {
+				if (copy_to_user(buffer,
+						 m->buf + *fpos - m->offset,
+						 tsz))
+					return -EFAULT;
+			} else {
+				start = m->paddr + *fpos - m->offset;
+				tmp = read_from_oldmem(buffer, tsz, &start, 1);
+				if (tmp < 0)
+					return tmp;
+			}
 			buflen -= tsz;
 			*fpos += tsz;
 			buffer += tsz;