[PATCH v5 24/31] powerpc/fadump: improve how crashed kernel's memory is reserved

[Hari Bathini]

The size parameter to fadump_reserve_crash_area() function is not needed
as all the memory above boot memory size must be preserved anyway. Update
the function by dropping this redundant parameter.

Signed-off-by: Hari Bathini <hbath...@linux.ibm.com>
---
 arch/powerpc/kernel/fadump.c |   53 +++++++++++++++++++++++-------------------
 1 file changed, 29 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 3981599..665104a 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -35,6 +35,8 @@
 
 static struct fw_dump fw_dump;
 
+static void __init fadump_reserve_crash_area(unsigned long base);
+
 static DEFINE_MUTEX(fadump_mutex);
 struct fadump_mrange_info crash_mrange_info = { "crash", NULL, 0, 0, 0 };
 struct fadump_mrange_info reserved_mrange_info = { "reserved", NULL, 0, 0, 0 };
@@ -262,26 +264,6 @@ static unsigned long get_fadump_area_size(void)
        return size;
 }
 
-static void __init fadump_reserve_crash_area(unsigned long base,
-                                            unsigned long size)
-{
-       struct memblock_region *reg;
-       unsigned long mstart, mend, msize;
-
-       for_each_memblock(memory, reg) {
-               mstart = max_t(unsigned long, base, reg->base);
-               mend = reg->base + reg->size;
-               mend = min(base + size, mend);
-
-               if (mstart < mend) {
-                       msize = mend - mstart;
-                       memblock_reserve(mstart, msize);
-                       pr_info("Reserved %ldMB of memory at %#016lx for saving 
crash dump\n",
-                               (msize >> 20), mstart);
-               }
-       }
-}
-
 int __init fadump_reserve_mem(void)
 {
        int ret = 1;
@@ -347,12 +329,11 @@ int __init fadump_reserve_mem(void)
 #endif
                /*
                 * If last boot has crashed then reserve all the memory
-                * above boot_memory_size so that we don't touch it until
+                * above boot memory size so that we don't touch it until
                 * dump is written to disk by userspace tool. This memory
-                * will be released for general use once the dump is saved.
+                * can be released for general use by invalidating fadump.
                 */
-               size = memory_boundary - base;
-               fadump_reserve_crash_area(base, size);
+               fadump_reserve_crash_area(base);
 
                pr_debug("fadumphdr_addr = %#016lx\n", fw_dump.fadumphdr_addr);
                pr_debug("Reserve dump area start address: 0x%lx\n",
@@ -1240,3 +1221,27 @@ int __init setup_fadump(void)
        return 1;
 }
 subsys_initcall(setup_fadump);
+
+/* Preserve everything above the base address */
+static void __init fadump_reserve_crash_area(unsigned long base)
+{
+       struct memblock_region *reg;
+       unsigned long mstart, msize;
+
+       for_each_memblock(memory, reg) {
+               mstart = reg->base;
+               msize  = reg->size;
+
+               if ((mstart + msize) < base)
+                       continue;
+
+               if (mstart < base) {
+                       msize -= (base - mstart);
+                       mstart = base;
+               }
+
+               pr_info("Reserving %luMB of memory at %#016lx for preserving 
crash data",
+                       (msize >> 20), mstart);
+               memblock_reserve(mstart, msize);
+       }
+}