From 0dac47cb6204dd08a92ef6b311b6107414c17c9a Mon Sep 17 00:00:00 2001
From: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Date: Thu, 2 Mar 2023 11:50:08 +0100
Subject: [PATCH] zipl/boot: Introduce write_addr_range() helper function
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Move code from write_dump_segment() to write_addr_range() function to use
it later for writing compressed dump segments as well.

Verify that passed address range is a multiple of dasd block size.

Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com>
Reviewed-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
---
 zipl/boot/eckd2dump.c | 43 ++++++++++++++++++++++++++++++-------------
 zipl/boot/eckd2dump.h |  1 +
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/zipl/boot/eckd2dump.c b/zipl/boot/eckd2dump.c
index c02b2e71..037ace16 100644
--- a/zipl/boot/eckd2dump.c
+++ b/zipl/boot/eckd2dump.c
@@ -447,25 +447,23 @@ void readblock(unsigned long blk, unsigned long addr, unsigned long blk_count)
 }
 
 /*
- * Write dump segment with the header to DASD and return the next free
- * block number
+ * Write len/device.blk_size blocks of data at start address starting from
+ * given block and return the next free block number. The len value must be
+ * a multiple of a block size (4096 bytes).
  */
-unsigned long write_dump_segment(unsigned long blk,
-				 struct df_s390_dump_segm_hdr *segm)
+unsigned long write_addr_range(unsigned long blk, unsigned long start, unsigned long len)
 {
 	unsigned long addr, start_blk, blk_count, zero_page;
 
-	/* Write the dump segment header itself (1 page) */
-	zero_page = get_zeroed_page();
-	writeblock(blk, (unsigned long)segm, m2b(PAGE_SIZE), zero_page);
-	free_page(zero_page);
-	blk += m2b(PAGE_SIZE);
-	/* Write the dump segment */
-	addr = segm->start;
+	/* Verify the range is a multiple of a block size */
+	if (len % device.blk_size)
+		panic(EINTERNAL, "Invalid address range: [%016x, %016x]",
+		      start, start + len);
+	addr = start;
 	start_blk = blk;
-	while (addr < segm->start + segm->len) {
+	while (addr < start + len) {
 		/* Remaining blocks to write */
-		blk_count = m2b(segm->len) - (blk - start_blk);
+		blk_count = m2b(len) - (blk - start_blk);
 		blk_count = MIN(blk_count, eckd_blk_max);
 		zero_page = get_zeroed_page();
 		writeblock(blk, addr, blk_count, zero_page);
@@ -477,6 +475,25 @@ unsigned long write_dump_segment(unsigned long blk,
 	return blk;
 }
 
+/*
+ * Write dump segment with the header to DASD and return the next free
+ * block number
+ */
+unsigned long write_dump_segment(unsigned long blk,
+				 struct df_s390_dump_segm_hdr *segm)
+{
+	unsigned long zero_page;
+
+	/* Write the dump segment header itself (1 page) */
+	zero_page = get_zeroed_page();
+	writeblock(blk, (unsigned long)segm,
+		   m2b(sizeof(struct df_s390_dump_segm_hdr)), zero_page);
+	free_page(zero_page);
+	blk += m2b(PAGE_SIZE);
+	/* Write the dump segment */
+	return write_addr_range(blk, segm->start, segm->len);
+}
+
 /*
  * Init ECKD common
  */
diff --git a/zipl/boot/eckd2dump.h b/zipl/boot/eckd2dump.h
index f7dc5701..702e1f95 100644
--- a/zipl/boot/eckd2dump.h
+++ b/zipl/boot/eckd2dump.h
@@ -51,5 +51,6 @@ void writeblock(unsigned long blk, unsigned long addr, unsigned long blk_count,
 void readblock(unsigned long blk, unsigned long addr, unsigned long blk_count);
 unsigned long write_dump_segment(unsigned long blk,
 				 struct df_s390_dump_segm_hdr *segm);
+unsigned long write_addr_range(unsigned long blk, unsigned long addr, unsigned long len);
 
 #endif /* ECKD2DUMP_H */