memblock: add memblock_clear_nomap()

BugLink: https://bugs.launchpad.net/bugs/1694859
This function, with a combination of memblock_mark_nomap(), will be used
in a later kdump patch for arm64 when it temporarily isolates some range
of memory from the other memory blocks in order to create a specific
kernel mapping at boot time.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 4c546b8a34690ca858e50f2017b8bb6e358365d1)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>

diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index 14dbc4fd0a92b4a976849b42f30321470dab30d4..b9ad879f8f257d98cdfe1090e9fd3bd0576b38c8 100644 (file)
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -93,6 +93,7 @@ int memblock_mark_hotplug(phys_addr_t base, phys_addr_t size);
 int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
 int memblock_mark_mirror(phys_addr_t base, phys_addr_t size);
 int memblock_mark_nomap(phys_addr_t base, phys_addr_t size);
+int memblock_clear_nomap(phys_addr_t base, phys_addr_t size);
 ulong choose_memblock_flags(void);
 
 /* Low level functions */

diff --git a/mm/memblock.c b/mm/memblock.c
index a749101ed2a28914415c169d71cd028817551eed..f7c43b744eb4d86db54bce2a7780755f1523d344 100644 (file)
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -804,6 +804,18 @@ int __init_memblock memblock_mark_nomap(phys_addr_t base, phys_addr_t size)
        return memblock_setclr_flag(base, size, 1, MEMBLOCK_NOMAP);
 }
 
+/**
+ * memblock_clear_nomap - Clear flag MEMBLOCK_NOMAP for a specified region.
+ * @base: the base phys addr of the region
+ * @size: the size of the region
+ *
+ * Return 0 on success, -errno on failure.
+ */
+int __init_memblock memblock_clear_nomap(phys_addr_t base, phys_addr_t size)
+{
+       return memblock_setclr_flag(base, size, 0, MEMBLOCK_NOMAP);
+}
+
 /**
  * __next_reserved_mem_region - next function for for_each_reserved_region()
  * @idx: pointer to u64 loop variable