[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>

4 files changed, 197 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index ff600ef0b4d6..e6c022ef12ee 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -51,6 +51,7 @@
 #include <asm/machdep.h>
 #include <asm/pSeries_reconfig.h>
 #include <asm/pci-bridge.h>
+#include <asm/phyp_dump.h>
 #include <asm/kexec.h>
 
 #ifdef DEBUG
@@ -1040,6 +1041,51 @@ static void __init early_reserve_mem(void)
 #endif
 }
 
+#ifdef CONFIG_PHYP_DUMP
+/**
+ * phyp_dump_reserve_mem() - reserve all not-yet-dumped mmemory
+ *
+ * This routine may reserve memory regions in the kernel only
+ * if the system is supported and a dump was taken in last
+ * boot instance or if the hardware is supported and the
+ * scratch area needs to be setup. In other instances it returns
+ * without reserving anything. The memory in case of dump being
+ * active is freed when the dump is collected (by userland tools).
+ */
+static void __init phyp_dump_reserve_mem(void)
+{
+        unsigned long base, size;
+        if (!phyp_dump_info->phyp_dump_configured) {
+                printk(KERN_ERR "Phyp-dump not supported on this hardware\n");
+                return;
+        }
+
+        if (phyp_dump_info->phyp_dump_is_active) {
+                /* Reserve *everything* above RMR.Area freed by userland tools*/
+                base = PHYP_DUMP_RMR_END;
+                size = lmb_end_of_DRAM() - base;
+
+                /* XXX crashed_ram_end is wrong, since it may be beyond
+                 * the memory_limit, it will need to be adjusted. */
+                lmb_reserve(base, size);
+
+                phyp_dump_info->init_reserve_start = base;
+                phyp_dump_info->init_reserve_size = size;
+        } else {
+                size = phyp_dump_info->cpu_state_size +
+                        phyp_dump_info->hpte_region_size +
+                        PHYP_DUMP_RMR_END;
+                base = lmb_end_of_DRAM() - size;
+                lmb_reserve(base, size);
+                phyp_dump_info->init_reserve_start = base;
+                phyp_dump_info->init_reserve_size = size;
+        }
+}
+#else
+static inline void __init phyp_dump_reserve_mem(void) {}
+#endif /* CONFIG_PHYP_DUMP  && CONFIG_PPC_RTAS */
+
+
 void __init early_init_devtree(void *params)
 {
         DBG(" -> early_init_devtree(%p)\n", params);
@@ -1052,6 +1098,11 @@ void __init early_init_devtree(void *params)
         of_scan_flat_dt(early_init_dt_scan_rtas, NULL);
 #endif
 
+#ifdef CONFIG_PHYP_DUMP
+        /* scan tree to see if dump occured during last boot */
+        of_scan_flat_dt(early_init_dt_scan_phyp_dump, NULL);
+#endif
+
         /* Retrieve various informations from the /chosen node of the
          * device-tree, including the platform type, initrd location and
          * size, TCE reserve, and more ...
@@ -1072,6 +1123,7 @@ void __init early_init_devtree(void *params)
         reserve_kdump_trampoline();
         reserve_crashkernel();
         early_reserve_mem();
+        phyp_dump_reserve_mem();
 
         lmb_enforce_memory_limit(memory_limit);
         lmb_analyze();
diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 992ba6753cf2..bdae04bb7a01 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 000000000000..230286cafffe
--- /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;
+}
diff --git a/include/asm-powerpc/phyp_dump.h b/include/asm-powerpc/phyp_dump.h
new file mode 100644
index 000000000000..e2d988dcdc99
--- /dev/null
+++ b/include/asm-powerpc/phyp_dump.h
@@ -0,0 +1,41 @@
+/*
+ * 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.
+ */
+
+#ifndef _PPC64_PHYP_DUMP_H
+#define _PPC64_PHYP_DUMP_H
+
+#ifdef CONFIG_PHYP_DUMP
+
+/* The RMR region will be saved for later dumping
+ * whenever the kernel crashes. Set this to 256MB. */
+#define PHYP_DUMP_RMR_START 0x0
+#define PHYP_DUMP_RMR_END   (1UL<<28)
+
+struct phyp_dump {
+        /* Memory that is reserved during very early boot. */
+        unsigned long init_reserve_start;
+        unsigned long init_reserve_size;
+        /* Check status during boot if dump supported, active & present*/
+        unsigned long phyp_dump_configured;
+        unsigned long phyp_dump_is_active;
+        /* store cpu & hpte size */
+        unsigned long cpu_state_size;
+        unsigned long hpte_region_size;
+};
+
+extern struct phyp_dump *phyp_dump_info;
+
+int early_init_dt_scan_phyp_dump(unsigned long node,
+                const char *uname, int depth, void *data);
+
+#endif /* CONFIG_PHYP_DUMP */
+#endif /* _PPC64_PHYP_DUMP_H */