Don't use the suspending kernel's VA mapping for the piglet. It's far

easier and much less error-prone to just identity map it in the resuming
kernel as we have more control over the VA space layout there (otherwise
we are at the mercy of the suspending kernel's placement of the piglet VA).

This diff also increases the size of the piglet to 4 chunks, to avoid an
overwrite issue seen in m2k14 where the start of the kernel text was
overwritten with a bounced chunk before unpack.

1 files changed, 14 insertions, 10 deletions

diff --git a/sys/kern/subr_hibernate.c b/sys/kern/subr_hibernate.c
index 6dc6e5c7284..d2e9f8919e3 100644
--- a/sys/kern/subr_hibernate.c
+++ b/sys/kern/subr_hibernate.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_hibernate.c,v 1.94 2014/07/09 14:10:25 mlarkin Exp $	*/
+/*	$OpenBSD: subr_hibernate.c,v 1.95 2014/07/09 15:03:12 mlarkin Exp $	*/
 
 /*
  * Copyright (c) 2011 Ariane van der Steldt <ariane@stack.nl>
@@ -39,7 +39,7 @@
  * Its phys and virt addrs are recorded in the signature block. The piglet is
  * used to guarantee an unused area of memory that can be used by the resuming
  * kernel for various things. The piglet is excluded during unpack operations.
- * The piglet size is presently 3*HIBERNATE_CHUNK_SIZE (typically 3*4MB).
+ * The piglet size is presently 4*HIBERNATE_CHUNK_SIZE (typically 4*4MB).
  *
  * Offset from piglet_base	Purpose
  * ----------------------------------------------------------------------------
@@ -55,7 +55,7 @@
  * ...				unused
  * HIBERNATE_CHUNK_SIZE		start of hibernate chunk table
  * 2*HIBERNATE_CHUNK_SIZE	bounce area for chunks being unpacked
- * 3*HIBERNATE_CHUNK_SIZE	end of piglet
+ * 4*HIBERNATE_CHUNK_SIZE	end of piglet
  */
 
 /* Temporary vaddr ranges used during hibernate */
@@ -720,7 +720,7 @@ get_hibernate_info(union hibernate_info *hib, int suspend)
 	if (suspend) {
 		/* Allocate piglet region */
 		if (uvm_pmr_alloc_piglet(&hib->piglet_va,
-		    &hib->piglet_pa, HIBERNATE_CHUNK_SIZE*3,
+		    &hib->piglet_pa, HIBERNATE_CHUNK_SIZE * 4,
 		    HIBERNATE_CHUNK_SIZE)) {
 			printf("Hibernate failed to allocate the piglet\n");
 			return (1);
@@ -761,7 +761,7 @@ get_hibernate_info(union hibernate_info *hib, int suspend)
 fail:
 	if (suspend)
 		uvm_pmr_free_piglet(hib->piglet_va,
-		    HIBERNATE_CHUNK_SIZE * 3);
+		    HIBERNATE_CHUNK_SIZE * 4);
 
 	return (1);
 }
@@ -1237,21 +1237,25 @@ hibernate_unpack_image(union hibernate_info *hib)
 	union hibernate_info local_hib;
 	paddr_t image_cur = global_pig_start;
 	short i, *fchunks;
-	char *pva = (char *)hib->piglet_va;
+	char *pva;
 	struct hibernate_zlib_state *hibernate_state;
 
 	hibernate_state =
 	    (struct hibernate_zlib_state *)HIBERNATE_HIBALLOC_PAGE;
 
-	/* Mask off based on arch-specific piglet page size */
-	pva = (char *)((paddr_t)pva & (PIGLET_PAGE_MASK));
+	/* Piglet will be identity mapped (VA == PA) */
+	pva = (char *)hib->piglet_pa;
+
 	fchunks = (short *)(pva + (4 * PAGE_SIZE));
 
-	chunks = (struct hibernate_disk_chunk *)(pva +  HIBERNATE_CHUNK_SIZE);
+	chunks = (struct hibernate_disk_chunk *)(pva + HIBERNATE_CHUNK_SIZE);
 
 	/* Can't use hiber_info that's passed in after this point */
 	bcopy(hib, &local_hib, sizeof(union hibernate_info));
 
+	/* VA == PA */
+	local_hib.piglet_va = local_hib.piglet_pa;
+
 	/*
 	 * Point of no return. Once we pass this point, only kernel code can
 	 * be accessed. No global variables or other kernel data structures
@@ -1898,7 +1902,7 @@ hibernate_free(void)
 {
 	if (global_piglet_va)
 		uvm_pmr_free_piglet(global_piglet_va,
-		    3*HIBERNATE_CHUNK_SIZE);
+		    4 * HIBERNATE_CHUNK_SIZE);
 
 	if (hibernate_copy_page)
 		pmap_kremove(hibernate_copy_page, PAGE_SIZE);