[POWERPC] pseries: phyp dump: Reserve and release memory

Initial patch for reserving memory in early boot, and freeing it
later.  If the previous boot had ended with a crash, the reserved
memory would contain a copy of the crashed kernel data.

Signed-off-by: Manish Ahuja <mahuja@us.ibm.com>
Signed-off-by: Linas Vepstas <linasvepstas@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 104 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 992ba67..bdae04b 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_HOTPLUG_CPU)	+= hotplug-cpu.o
 obj-$(CONFIG_HVC_CONSOLE)	+= hvconsole.o
 obj-$(CONFIG_HVCS)		+= hvcserver.o
 obj-$(CONFIG_HCALL_STATS)	+= hvCall_inst.o
+obj-$(CONFIG_PHYP_DUMP)	+= phyp_dump.o
diff --git a/arch/powerpc/platforms/pseries/phyp_dump.c b/arch/powerpc/platforms/pseries/phyp_dump.c
new file mode 100644
index 0000000..230286c
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/phyp_dump.c
@@ -0,0 +1,103 @@
+/*
+ * Hypervisor-assisted dump
+ *
+ * Linas Vepstas, Manish Ahuja 2008
+ * Copyright 2008 IBM Corp.
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/pfn.h>
+#include <linux/swap.h>
+
+#include <asm/page.h>
+#include <asm/phyp_dump.h>
+#include <asm/machdep.h>
+#include <asm/prom.h>
+
+/* Variables, used to communicate data between early boot and late boot */
+static struct phyp_dump phyp_dump_vars;
+struct phyp_dump *phyp_dump_info = &phyp_dump_vars;
+
+/**
+ * release_memory_range -- release memory previously lmb_reserved
+ * @start_pfn: starting physical frame number
+ * @nr_pages: number of pages to free.
+ *
+ * This routine will release memory that had been previously
+ * lmb_reserved in early boot. The released memory becomes
+ * available for genreal use.
+ */
+static void
+release_memory_range(unsigned long start_pfn, unsigned long nr_pages)
+{
+	struct page *rpage;
+	unsigned long end_pfn;
+	long i;
+
+	end_pfn = start_pfn + nr_pages;
+
+	for (i = start_pfn; i <= end_pfn; i++) {
+		rpage = pfn_to_page(i);
+		if (PageReserved(rpage)) {
+			ClearPageReserved(rpage);
+			init_page_count(rpage);
+			__free_page(rpage);
+			totalram_pages++;
+		}
+	}
+}
+
+static int __init phyp_dump_setup(void)
+{
+	unsigned long start_pfn, nr_pages;
+
+	/* If no memory was reserved in early boot, there is nothing to do */
+	if (phyp_dump_info->init_reserve_size == 0)
+		return 0;
+
+	/* Release memory that was reserved in early boot */
+	start_pfn = PFN_DOWN(phyp_dump_info->init_reserve_start);
+	nr_pages = PFN_DOWN(phyp_dump_info->init_reserve_size);
+	release_memory_range(start_pfn, nr_pages);
+
+	return 0;
+}
+machine_subsys_initcall(pseries, phyp_dump_setup);
+
+int __init early_init_dt_scan_phyp_dump(unsigned long node,
+		const char *uname, int depth, void *data)
+{
+	const unsigned int *sizes;
+
+	phyp_dump_info->phyp_dump_configured = 0;
+	phyp_dump_info->phyp_dump_is_active = 0;
+
+	if (depth != 1 || strcmp(uname, "rtas") != 0)
+		return 0;
+
+	if (of_get_flat_dt_prop(node, "ibm,configure-kernel-dump", NULL))
+		phyp_dump_info->phyp_dump_configured++;
+
+	if (of_get_flat_dt_prop(node, "ibm,dump-kernel", NULL))
+		phyp_dump_info->phyp_dump_is_active++;
+
+	sizes = of_get_flat_dt_prop(node, "ibm,configure-kernel-dump-sizes",
+				    NULL);
+	if (!sizes)
+		return 0;
+
+	if (sizes[0] == 1)
+		phyp_dump_info->cpu_state_size = *((unsigned long *)&sizes[1]);
+
+	if (sizes[3] == 2)
+		phyp_dump_info->hpte_region_size =
+						*((unsigned long *)&sizes[4]);
+	return 1;
+}