x86: Add a debugfs interface to dump PAT memtype

Add a debugfs interface to list out all the PAT memtype reservations.
Appears at debugfs x86/pat_memtype_list and output format is
type @ <start addr>-<end addr>

We do not hold the lock while printing the entire list. So, the list may not be
a consistent copy in case where regions are getting added or deleted
at the same time.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index d4585077977a0bd1c6c7234b09051d671851a6aa..0917a540a55e39374b09c74ab4026a07520ed121 100644 (file)
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -12,6 +12,8 @@
 #include <linux/gfp.h>
 #include <linux/fs.h>
 #include <linux/bootmem.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
 
 #include <asm/msr.h>
 #include <asm/tlbflush.h>
@@ -489,3 +491,89 @@ void unmap_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
 
        free_memtype(addr, addr + size);
 }
+
+#if defined(CONFIG_DEBUG_FS)
+
+/* get Nth element of the linked list */
+static struct memtype *memtype_get_idx(loff_t pos)
+{
+       struct memtype *list_node, *print_entry;
+       int i = 1;
+
+       print_entry  = kmalloc(sizeof(struct memtype), GFP_KERNEL);
+       if (!print_entry)
+               return NULL;
+
+       spin_lock(&memtype_lock);
+       list_for_each_entry(list_node, &memtype_list, nd) {
+               if (pos == i) {
+                       *print_entry = *list_node;
+                       spin_unlock(&memtype_lock);
+                       return print_entry;
+               }
+               ++i;
+       }
+       spin_unlock(&memtype_lock);
+       kfree(print_entry);
+       return NULL;
+}
+
+static void *memtype_seq_start(struct seq_file *seq, loff_t *pos)
+{
+       if (*pos == 0) {
+               ++*pos;
+               seq_printf(seq, "PAT memtype list:\n");
+       }
+
+       return memtype_get_idx(*pos);
+}
+
+static void *memtype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+       ++*pos;
+       return memtype_get_idx(*pos);
+}
+
+static void memtype_seq_stop(struct seq_file *seq, void *v)
+{
+}
+
+static int memtype_seq_show(struct seq_file *seq, void *v)
+{
+       struct memtype *print_entry = (struct memtype *)v;
+
+       seq_printf(seq, "%s @ 0x%Lx-0x%Lx\n", cattr_name(print_entry->type),
+                       print_entry->start, print_entry->end);
+       kfree(print_entry);
+       return 0;
+}
+
+static struct seq_operations memtype_seq_ops = {
+       .start = memtype_seq_start,
+       .next  = memtype_seq_next,
+       .stop  = memtype_seq_stop,
+       .show  = memtype_seq_show,
+};
+
+static int memtype_seq_open(struct inode *inode, struct file *file)
+{
+       return seq_open(file, &memtype_seq_ops);
+}
+
+static const struct file_operations memtype_fops = {
+       .open    = memtype_seq_open,
+       .read    = seq_read,
+       .llseek  = seq_lseek,
+       .release = seq_release,
+};
+
+static int __init pat_memtype_list_init(void)
+{
+       debugfs_create_file("pat_memtype_list", S_IRUSR, arch_debugfs_dir,
+                               NULL, &memtype_fops);
+       return 0;
+}
+
+late_initcall(pat_memtype_list_init);
+
+#endif /* CONFIG_DEBUG_FS */