linux-kernel - [PATCH 07/13] vmcore: modify read_vmcore() to read buffer on 2nd kernel

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Message-ID: <20130214101221.22466.97636.stgit@localhost6.localdomain6>
Date:	Thu, 14 Feb 2013 19:12:21 +0900
From:	HATAYAMA Daisuke <d.hatayama@...fujitsu.com>
To:	ebiederm@...ssion.com, vgoyal@...hat.com, cpw@....com,
	kumagai-atsushi@....nes.nec.co.jp, lisa.mitchell@...com
Cc:	kexec@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 07/13] vmcore: modify read_vmcore() to read buffer on 2nd
 kernel

If a given vmcore object has VMCORE_2ND_KERNEL type, target data is in
the buffer on 2nd kernel.

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

 fs/proc/vmcore.c |   64 ++++++++++++++++++++++++++----------------------------
 1 files changed, 31 insertions(+), 33 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 77e0a0e..4125a65 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -146,8 +146,7 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
 {
 	ssize_t acc = 0, tmp;
 	size_t tsz;
-	u64 start, nr_bytes;
-	struct vmcore *curr_m = NULL;
+	struct vmcore *m;
 
 	if (buflen == 0 || *fpos >= vmcore_size)
 		return 0;
@@ -173,39 +172,38 @@ static ssize_t read_vmcore(struct file *file, char __user *buffer,
 			return acc;
 	}
 
-	start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
-	if (!curr_m)
-        	return -EINVAL;
-	if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
-		tsz = buflen;
-
-	/* Calculate left bytes in current memory segment. */
-	nr_bytes = (curr_m->size - (start - curr_m->paddr));
-	if (tsz > nr_bytes)
-		tsz = nr_bytes;
-
-	while (buflen) {
-		tmp = read_from_oldmem(buffer, tsz, &start, 1);
-		if (tmp < 0)
-			return tmp;
-		buflen -= tsz;
-		*fpos += tsz;
-		buffer += tsz;
-		acc += tsz;
-		if (start >= (curr_m->paddr + curr_m->size)) {
-			if (curr_m->list.next == &vmcore_list)
-				return acc;	/*EOF*/
-			curr_m = list_entry(curr_m->list.next,
-						struct vmcore, list);
-			start = curr_m->paddr;
+	list_for_each_entry(m, &vmcore_list, list) {
+		if (*fpos < m->offset + m->size) {
+			tsz = m->offset + m->size - *fpos;
+			if (buflen < tsz)
+				tsz = buflen;
+			switch (m->type) {
+			case VMCORE_OLD_MEMORY: {
+				u64 paddr = m->paddr + *fpos - m->offset;
+
+				tmp = read_from_oldmem(buffer, tsz, &paddr, 1);
+				if (tmp < 0)
+					return tmp;
+				break;
+			}
+			case VMCORE_2ND_KERNEL:
+				if (copy_to_user(buffer,
+						 m->buf + (*fpos - m->offset),
+						 tsz))
+					return -EFAULT;
+				break;
+			}
+			buflen -= tsz;
+			*fpos += tsz;
+			buffer += tsz;
+			acc += tsz;
+
+			/* leave now if filled buffer already */
+			if (buflen == 0)
+				return acc;
 		}
-		if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
-			tsz = buflen;
-		/* Calculate left bytes in current memory segment. */
-		nr_bytes = (curr_m->size - (start - curr_m->paddr));
-		if (tsz > nr_bytes)
-			tsz = nr_bytes;
 	}
+
 	return acc;
 }
 

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