[055/192] fs/proc/kcore: pfn_is_ram check only applies to KCORE_RAM

Commit Message

Andrew Morton July 1, 2021, 1:50 a.m. UTC

From: David Hildenbrand <[e-mail]>
Subject: fs/proc/kcore: pfn_is_ram check only applies to KCORE_RAM

Let's resturcture the code, using switch-case, and checking pfn_is_ram()
only when we are dealing with KCORE_RAM.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: David Hildenbrand <[e-mail]>
Reviewed-by: Mike Rapoport <[e-mail]>
Cc: Aili Yao <[e-mail]>
Cc: Alexey Dobriyan <[e-mail]>
Cc: Alex Shi <[e-mail]>
Cc: Haiyang Zhang <[e-mail]>
Cc: Jason Wang <[e-mail]>
Cc: Jiri Bohac <[e-mail]>
Cc: "K. Y. Srinivasan" <[e-mail]>
Cc: "Matthew Wilcox (Oracle)" <[e-mail]>
Cc: "Michael S. Tsirkin" <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Naoya Horiguchi <[e-mail]>
Cc: Oscar Salvador <[e-mail]>
Cc: Roman Gushchin <[e-mail]>
Cc: Stephen Hemminger <[e-mail]>
Cc: Steven Price <[e-mail]>
Cc: Wei Liu <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 fs/proc/kcore.c |   35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

Patch

--- a/fs/proc/kcore.c~fs-proc-kcore-pfn_is_ram-check-only-applies-to-kcore_ram
+++ a/fs/proc/kcore.c
@@ -483,25 +483,36 @@  read_kcore(struct file *file, char __use
 				goto out;
 			}
 			m = NULL;	/* skip the list anchor */
-		} else if (!pfn_is_ram(__pa(start) >> PAGE_SHIFT)) {
-			if (clear_user(buffer, tsz)) {
-				ret = -EFAULT;
-				goto out;
-			}
-		} else if (m->type == KCORE_VMALLOC) {
+			goto skip;
+		}
+
+		switch (m->type) {
+		case KCORE_VMALLOC:
 			vread(buf, (char *)start, tsz);
 			/* we have to zero-fill user buffer even if no read */
 			if (copy_to_user(buffer, buf, tsz)) {
 				ret = -EFAULT;
 				goto out;
 			}
-		} else if (m->type == KCORE_USER) {
+			break;
+		case KCORE_USER:
 			/* User page is handled prior to normal kernel page: */
 			if (copy_to_user(buffer, (char *)start, tsz)) {
 				ret = -EFAULT;
 				goto out;
 			}
-		} else {
+			break;
+		case KCORE_RAM:
+			if (!pfn_is_ram(__pa(start) >> PAGE_SHIFT)) {
+				if (clear_user(buffer, tsz)) {
+					ret = -EFAULT;
+					goto out;
+				}
+				break;
+			}
+			fallthrough;
+		case KCORE_VMEMMAP:
+		case KCORE_TEXT:
 			if (kern_addr_valid(start)) {
 				/*
 				 * Using bounce buffer to bypass the
@@ -525,7 +536,15 @@  read_kcore(struct file *file, char __use
 					goto out;
 				}
 			}
+			break;
+		default:
+			pr_warn_once("Unhandled KCORE type: %d\n", m->type);
+			if (clear_user(buffer, tsz)) {
+				ret = -EFAULT;
+				goto out;
+			}
 		}
+skip:
 		buflen -= tsz;
 		*fpos += tsz;
 		buffer += tsz;