Merge branch 'akpm' (patches from Andrew)

Merge third patch-bomb from Andrew Morton:

 - more ocfs2 changes

 - a few hotfixes

 - Andy's compat cleanups

 - misc fixes to fatfs, ptrace, coredump, cpumask, creds, eventfd,
   panic, ipmi, kgdb, profile, kfifo, ubsan, etc.

 - many rapidio updates: fixes, new drivers.

 - kcov: kernel code coverage feature.  Like gcov, but not
   "prohibitively expensive".

 - extable code consolidation for various archs

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (81 commits)
  ia64/extable: use generic search and sort routines
  x86/extable: use generic search and sort routines
  s390/extable: use generic search and sort routines
  alpha/extable: use generic search and sort routines
  kernel/...: convert pr_warning to pr_warn
  drivers: dma-coherent: use memset_io for DMA_MEMORY_IO mappings
  drivers: dma-coherent: use MEMREMAP_WC for DMA_MEMORY_MAP
  memremap: add MEMREMAP_WC flag
  memremap: don't modify flags
  kernel/signal.c: add compile-time check for __ARCH_SI_PREAMBLE_SIZE
  mm/mprotect.c: don't imply PROT_EXEC on non-exec fs
  ipc/sem: make semctl setting sempid consistent
  ubsan: fix tree-wide -Wmaybe-uninitialized false positives
  kfifo: fix sparse complaints
  scripts/gdb: account for changes in module data structure
  scripts/gdb: add cmdline reader command
  scripts/gdb: add version command
  kernel: add kcov code coverage
  profile: hide unused functions when !CONFIG_PROC_FS
  hpwdt: use nmi_panic() when kernel panics in NMI handler
  ...

1 files changed, 18 insertions, 9 deletions

diff --git a/kernel/memremap.c b/kernel/memremap.c
index 584febd13e2e..a6d382312e6f 100644
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -41,11 +41,13 @@ static void *try_ram_remap(resource_size_t offset, size_t size)
  * memremap() - remap an iomem_resource as cacheable memory
  * @offset: iomem resource start address
  * @size: size of remap
- * @flags: either MEMREMAP_WB or MEMREMAP_WT
+ * @flags: any of MEMREMAP_WB, MEMREMAP_WT and MEMREMAP_WC
  *
  * memremap() is "ioremap" for cases where it is known that the resource
  * being mapped does not have i/o side effects and the __iomem
- * annotation is not applicable.
+ * annotation is not applicable. In the case of multiple flags, the different
+ * mapping types will be attempted in the order listed below until one of
+ * them succeeds.
  *
  * MEMREMAP_WB - matches the default mapping for System RAM on
  * the architecture.  This is usually a read-allocate write-back cache.
@@ -57,6 +59,10 @@ static void *try_ram_remap(resource_size_t offset, size_t size)
  * cache or are written through to memory and never exist in a
  * cache-dirty state with respect to program visibility.  Attempts to
  * map System RAM with this mapping type will fail.
+ *
+ * MEMREMAP_WC - establish a writecombine mapping, whereby writes may
+ * be coalesced together (e.g. in the CPU's write buffers), but is otherwise
+ * uncached. Attempts to map System RAM with this mapping type will fail.
  */
 void *memremap(resource_size_t offset, size_t size, unsigned long flags)
 {
@@ -64,6 +70,9 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
 				       IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
 	void *addr = NULL;
 
+	if (!flags)
+		return NULL;
+
 	if (is_ram == REGION_MIXED) {
 		WARN_ONCE(1, "memremap attempted on mixed range %pa size: %#lx\n",
 				&offset, (unsigned long) size);
@@ -72,7 +81,6 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
 
 	/* Try all mapping types requested until one returns non-NULL */
 	if (flags & MEMREMAP_WB) {
-		flags &= ~MEMREMAP_WB;
 		/*
 		 * MEMREMAP_WB is special in that it can be satisifed
 		 * from the direct map.  Some archs depend on the
@@ -86,21 +94,22 @@ void *memremap(resource_size_t offset, size_t size, unsigned long flags)
 	}
 
 	/*
-	 * If we don't have a mapping yet and more request flags are
-	 * pending then we will be attempting to establish a new virtual
+	 * If we don't have a mapping yet and other request flags are
+	 * present then we will be attempting to establish a new virtual
 	 * address mapping.  Enforce that this mapping is not aliasing
 	 * System RAM.
 	 */
-	if (!addr && is_ram == REGION_INTERSECTS && flags) {
+	if (!addr && is_ram == REGION_INTERSECTS && flags != MEMREMAP_WB) {
 		WARN_ONCE(1, "memremap attempted on ram %pa size: %#lx\n",
 				&offset, (unsigned long) size);
 		return NULL;
 	}
 
-	if (!addr && (flags & MEMREMAP_WT)) {
-		flags &= ~MEMREMAP_WT;
+	if (!addr && (flags & MEMREMAP_WT))
 		addr = ioremap_wt(offset, size);
-	}
+
+	if (!addr && (flags & MEMREMAP_WC))
+		addr = ioremap_wc(offset, size);
 
 	return addr;
 }