s390/mm/ptdump: Improve sorting of markers

Use the sort() from lib/sort.c to sort markers instead of the private
implementation. The current implementation does not sort markers
properly if they have to be moved downwards:

---[ Real Memory Copy Area Start ]---
0x0000035b903ff000-0x0000035b90400000         4K PTE I
---[ vmalloc Area Start ]---
---[ Real Memory Copy Area End ]---

Add a new member to each marker which indicates if a marker is start
of an area. If addresses of areas are equal consider an address which
defines the start of an area higher than the address which defines the
end of an area. In result the output is sorted as intended:

---[ Real Memory Copy Area Start ]---
0x0000019cedcff000-0x0000019cedd00000         4K PTE I
---[ Real Memory Copy Area End ]---
---[ vmalloc Area Start ]---
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/mm/dump_pagetables.c

@@ -3,6 +3,7 @@
 #include <linux/ptdump.h>
 #include <linux/seq_file.h>
 #include <linux/debugfs.h>
+#include <linux/sort.h>
 #include <linux/mm.h>
 #include <linux/kfence.h>
 #include <linux/kasan.h>
@@ -15,6 +16,7 @@
 static unsigned long max_addr;
 
 struct addr_marker {
+	int is_start;
 	unsigned long start_address;
 	const char *name;
 };
@@ -60,44 +62,44 @@ enum address_markers_idx {
 };
 
 static struct addr_marker address_markers[] = {
-	[KVA_NR]		= {0, "Kernel Virtual Address Space"},
-	[LOWCORE_START_NR]	= {0, "Lowcore Start"},
-	[LOWCORE_END_NR]	= {0, "Lowcore End"},
-	[IDENTITY_START_NR]	= {0, "Identity Mapping Start"},
-	[IDENTITY_END_NR]	= {0, "Identity Mapping End"},
-	[AMODE31_START_NR]	= {0, "Amode31 Area Start"},
-	[AMODE31_END_NR]	= {0, "Amode31 Area End"},
-	[KERNEL_START_NR]	= {(unsigned long)_stext, "Kernel Image Start"},
-	[KERNEL_END_NR]		= {(unsigned long)_end, "Kernel Image End"},
+	[KVA_NR]		= {0, 0, "Kernel Virtual Address Space"},
+	[LOWCORE_START_NR]	= {1, 0, "Lowcore Start"},
+	[LOWCORE_END_NR]	= {0, 0, "Lowcore End"},
+	[IDENTITY_START_NR]	= {1, 0, "Identity Mapping Start"},
+	[IDENTITY_END_NR]	= {0, 0, "Identity Mapping End"},
+	[AMODE31_START_NR]	= {1, 0, "Amode31 Area Start"},
+	[AMODE31_END_NR]	= {0, 0, "Amode31 Area End"},
+	[KERNEL_START_NR]	= {1, (unsigned long)_stext, "Kernel Image Start"},
+	[KERNEL_END_NR]		= {0, (unsigned long)_end, "Kernel Image End"},
 #ifdef CONFIG_KFENCE
-	[KFENCE_START_NR]	= {0, "KFence Pool Start"},
-	[KFENCE_END_NR]		= {0, "KFence Pool End"},
+	[KFENCE_START_NR]	= {1, 0, "KFence Pool Start"},
+	[KFENCE_END_NR]		= {0, 0, "KFence Pool End"},
 #endif
-	[VMEMMAP_NR]		= {0, "vmemmap Area Start"},
-	[VMEMMAP_END_NR]	= {0, "vmemmap Area End"},
-	[VMALLOC_NR]		= {0, "vmalloc Area Start"},
-	[VMALLOC_END_NR]	= {0, "vmalloc Area End"},
+	[VMEMMAP_NR]		= {1, 0, "vmemmap Area Start"},
+	[VMEMMAP_END_NR]	= {0, 0, "vmemmap Area End"},
+	[VMALLOC_NR]		= {1, 0, "vmalloc Area Start"},
+	[VMALLOC_END_NR]	= {0, 0, "vmalloc Area End"},
 #ifdef CONFIG_KMSAN
-	[KMSAN_VMALLOC_SHADOW_START_NR]	= {0, "Kmsan vmalloc Shadow Start"},
-	[KMSAN_VMALLOC_SHADOW_END_NR]	= {0, "Kmsan vmalloc Shadow End"},
-	[KMSAN_VMALLOC_ORIGIN_START_NR]	= {0, "Kmsan vmalloc Origins Start"},
-	[KMSAN_VMALLOC_ORIGIN_END_NR]	= {0, "Kmsan vmalloc Origins End"},
-	[KMSAN_MODULES_SHADOW_START_NR]	= {0, "Kmsan Modules Shadow Start"},
-	[KMSAN_MODULES_SHADOW_END_NR]	= {0, "Kmsan Modules Shadow End"},
-	[KMSAN_MODULES_ORIGIN_START_NR]	= {0, "Kmsan Modules Origins Start"},
-	[KMSAN_MODULES_ORIGIN_END_NR]	= {0, "Kmsan Modules Origins End"},
+	[KMSAN_VMALLOC_SHADOW_START_NR]	= {1, 0, "Kmsan vmalloc Shadow Start"},
+	[KMSAN_VMALLOC_SHADOW_END_NR]	= {0, 0, "Kmsan vmalloc Shadow End"},
+	[KMSAN_VMALLOC_ORIGIN_START_NR]	= {1, 0, "Kmsan vmalloc Origins Start"},
+	[KMSAN_VMALLOC_ORIGIN_END_NR]	= {0, 0, "Kmsan vmalloc Origins End"},
+	[KMSAN_MODULES_SHADOW_START_NR]	= {1, 0, "Kmsan Modules Shadow Start"},
+	[KMSAN_MODULES_SHADOW_END_NR]	= {0, 0, "Kmsan Modules Shadow End"},
+	[KMSAN_MODULES_ORIGIN_START_NR]	= {1, 0, "Kmsan Modules Origins Start"},
+	[KMSAN_MODULES_ORIGIN_END_NR]	= {0, 0, "Kmsan Modules Origins End"},
 #endif
-	[MODULES_NR]		= {0, "Modules Area Start"},
-	[MODULES_END_NR]	= {0, "Modules Area End"},
-	[ABS_LOWCORE_NR]	= {0, "Lowcore Area Start"},
-	[ABS_LOWCORE_END_NR]	= {0, "Lowcore Area End"},
-	[MEMCPY_REAL_NR]	= {0, "Real Memory Copy Area Start"},
-	[MEMCPY_REAL_END_NR]	= {0, "Real Memory Copy Area End"},
+	[MODULES_NR]		= {1, 0, "Modules Area Start"},
+	[MODULES_END_NR]	= {0, 0, "Modules Area End"},
+	[ABS_LOWCORE_NR]	= {1, 0, "Lowcore Area Start"},
+	[ABS_LOWCORE_END_NR]	= {0, 0, "Lowcore Area End"},
+	[MEMCPY_REAL_NR]	= {1, 0, "Real Memory Copy Area Start"},
+	[MEMCPY_REAL_END_NR]	= {0, 0, "Real Memory Copy Area End"},
 #ifdef CONFIG_KASAN
-	[KASAN_SHADOW_START_NR]	= {KASAN_SHADOW_START, "Kasan Shadow Start"},
-	[KASAN_SHADOW_END_NR]	= {KASAN_SHADOW_END, "Kasan Shadow End"},
+	[KASAN_SHADOW_START_NR]	= {1, KASAN_SHADOW_START, "Kasan Shadow Start"},
+	[KASAN_SHADOW_END_NR]	= {0, KASAN_SHADOW_END, "Kasan Shadow End"},
 #endif
-	{ -1, NULL }
+	{1, -1UL, NULL}
 };
 
 struct pg_state {
@@ -287,22 +289,25 @@ static int ptdump_show(struct seq_file *m, void *v)
 DEFINE_SHOW_ATTRIBUTE(ptdump);
 #endif /* CONFIG_PTDUMP_DEBUGFS */
 
-/*
- * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
- * insertion sort to preserve the original order of markers with the same
- * start address.
- */
-static void sort_address_markers(void)
+static int ptdump_cmp(const void *a, const void *b)
 {
-	struct addr_marker tmp;
-	int i, j;
+	const struct addr_marker *ama = a;
+	const struct addr_marker *amb = b;
 
-	for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
-		tmp = address_markers[i];
-		for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
-			address_markers[j + 1] = address_markers[j];
-		address_markers[j + 1] = tmp;
-	}
+	if (ama->start_address > amb->start_address)
+		return 1;
+	if (ama->start_address < amb->start_address)
+		return -1;
+	/*
+	 * If the start addresses of two markers are identical consider the
+	 * marker which defines the start of an area higher than the one which
+	 * defines the end of an area. This keeps pairs of markers sorted.
+	 */
+	if (ama->is_start)
+		return 1;
+	if (amb->is_start)
+		return -1;
+	return 0;
 }
 
 static int pt_dump_init(void)
@@ -349,7 +354,8 @@ static int pt_dump_init(void)
 	address_markers[KMSAN_MODULES_ORIGIN_START_NR].start_address = KMSAN_MODULES_ORIGIN_START;
 	address_markers[KMSAN_MODULES_ORIGIN_END_NR].start_address = KMSAN_MODULES_ORIGIN_END;
 #endif
-	sort_address_markers();
+	sort(address_markers, ARRAY_SIZE(address_markers) - 1,
+	     sizeof(address_markers[0]), ptdump_cmp, NULL);
 #ifdef CONFIG_PTDUMP_DEBUGFS
 	debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
 #endif /* CONFIG_PTDUMP_DEBUGFS */