[OpenPower-Firmware] [PATCH 2/4] 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.

This is the backport of upstream commit b2a815a554a3 ("powerpc/fadump:
improve how crashed kernel's memory is reserved").

Signed-off-by: Hari Bathini <hbathini at linux.ibm.com>
---
 arch/powerpc/kernel/fadump.c |   53 ++++++++++++++++++++++++------------------
 1 file changed, 30 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 4eab972..4dacce3 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -33,6 +33,9 @@
 #include <asm/setup.h>
 
 static struct fw_dump fw_dump;
+
+static void __init fadump_reserve_crash_area(u64 base);
+
 static struct fadump_mem_struct fdm;
 static const struct fadump_mem_struct *fdm_active;
 #ifdef CONFIG_CMA
@@ -426,26 +429,6 @@ 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)
 {
 	unsigned long base, size, memory_boundary;
@@ -510,13 +493,13 @@ 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.
 		 */
 		base = fw_dump.boot_memory_size;
 		size = memory_boundary - base;
-		fadump_reserve_crash_area(base, size);
+		fadump_reserve_crash_area(base);
 
 		fw_dump.fadumphdr_addr =
 				be64_to_cpu(fdm_active->rmr_region.destination_address) +
@@ -1701,3 +1684,27 @@ int __init setup_fadump(void)
 	return 1;
 }
 subsys_initcall(setup_fadump);
+
+/* Preserve everything above the base address */
+static void __init fadump_reserve_crash_area(u64 base)
+{
+	struct memblock_region *reg;
+	u64 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 %lluMB of memory at %#016llx for preserving crash data",
+			(msize >> 20), mstart);
+		memblock_reserve(mstart, msize);
+	}
+}