[PATCH v27 3/9] arm64: kdump: reserve memory for crash dump kernel

[AKASHI Takahiro]

"crashkernel=" kernel parameter specifies the size (and optionally
the start address) of the system ram used by crash dump kernel.
reserve_crashkernel() will allocate and reserve the memory at the startup
of primary kernel.

This memory range will be exported to userspace via:
	- an entry named "Crash kernel" in /proc/iomem, and
	- "linux,crashkernel-base" and "linux,crashkernel-size" under
	  /sys/firmware/devicetree/base/chosen

Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
Signed-off-by: Mark Salter <msalter at redhat.com>
Signed-off-by: Pratyush Anand <panand at redhat.com>
Reviewed-by: James Morse <james.morse at arm.com>
---
 arch/arm64/kernel/setup.c |   7 ++-
 arch/arm64/mm/init.c      | 110 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 116 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index f534f49..f012659 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -31,7 +31,6 @@
 #include <linux/screen_info.h>
 #include <linux/init.h>
 #include <linux/kexec.h>
-#include <linux/crash_dump.h>
 #include <linux/root_dev.h>
 #include <linux/cpu.h>
 #include <linux/interrupt.h>
@@ -225,6 +224,12 @@ static void __init request_standard_resources(void)
 		    kernel_data.end <= res->end)
 			request_resource(res, &kernel_data);
 	}
+
+#ifdef CONFIG_KEXEC_CORE
+	/* User space tools will find "Crash kernel" region in /proc/iomem. */
+	if (crashk_res.end)
+		insert_resource(&iomem_resource, &crashk_res);
+#endif
 }
 
 u64 __cpu_logical_map[NR_CPUS] = { [0 ... NR_CPUS-1] = INVALID_HWID };
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 65f1241..1d62bf7 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -30,12 +30,14 @@
 #include <linux/gfp.h>
 #include <linux/memblock.h>
 #include <linux/sort.h>
+#include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/dma-mapping.h>
 #include <linux/dma-contiguous.h>
 #include <linux/efi.h>
 #include <linux/swiotlb.h>
 #include <linux/vmalloc.h>
+#include <linux/kexec.h>
 
 #include <asm/boot.h>
 #include <asm/fixmap.h>
@@ -76,6 +78,111 @@ static int __init early_initrd(char *p)
 early_param("initrd", early_initrd);
 #endif
 
+#ifdef CONFIG_KEXEC_CORE
+static unsigned long long crash_size, crash_base;
+static struct property crash_base_prop = {
+	.name = "linux,crashkernel-base",
+	.length = sizeof(u64),
+	.value = &crash_base
+};
+static struct property crash_size_prop = {
+	.name = "linux,crashkernel-size",
+	.length = sizeof(u64),
+	.value = &crash_size,
+};
+
+static int __init export_crashkernel(void)
+{
+	struct device_node *node;
+	int ret;
+
+	if (!crash_size)
+		return 0;
+
+	/* Add /chosen/linux,crashkernel-* properties */
+	node = of_find_node_by_path("/chosen");
+	if (!node)
+		return -ENOENT;
+
+	/*
+	 * There might be existing crash kernel properties, but we can't
+	 * be sure what's in them, so remove them.
+	 */
+	of_remove_property(node, of_find_property(node,
+				"linux,crashkernel-base", NULL));
+	of_remove_property(node, of_find_property(node,
+				"linux,crashkernel-size", NULL));
+
+	ret = of_add_property(node, &crash_base_prop);
+	if (ret)
+		goto ret_err;
+
+	ret = of_add_property(node, &crash_size_prop);
+	if (ret)
+		goto ret_err;
+
+	return 0;
+
+ret_err:
+	pr_warn("Exporting crashkernel region to device tree failed\n");
+	return ret;
+}
+late_initcall(export_crashkernel);
+
+/*
+ * reserve_crashkernel() - reserves memory for crash kernel
+ *
+ * This function reserves memory area given in "crashkernel=" kernel command
+ * line parameter. The memory reserved is used by dump capture kernel when
+ * primary kernel is crashing.
+ */
+static void __init reserve_crashkernel(void)
+{
+	int ret;
+
+	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
+				&crash_size, &crash_base);
+	/* no crashkernel= or invalid value specified */
+	if (ret || !crash_size)
+		return;
+
+	if (crash_base == 0) {
+		/* Current arm64 boot protocol requires 2MB alignment */
+		crash_base = memblock_find_in_range(0, ARCH_LOW_ADDRESS_LIMIT,
+				crash_size, SZ_2M);
+		if (crash_base == 0) {
+			pr_warn("Unable to allocate crashkernel (size:%llx)\n",
+				crash_size);
+			return;
+		}
+	} else {
+		/* User specifies base address explicitly. */
+		if (!memblock_is_region_memory(crash_base, crash_size) ||
+			memblock_is_region_reserved(crash_base, crash_size)) {
+			pr_warn("crashkernel has wrong address or size\n");
+			return;
+		}
+
+		if (!IS_ALIGNED(crash_base, SZ_2M)) {
+			pr_warn("crashkernel base address is not 2MB aligned\n");
+			return;
+		}
+	}
+	memblock_reserve(crash_base, crash_size);
+
+	pr_info("Reserving %lldMB of memory at %lldMB for crashkernel\n",
+		crash_size >> 20, crash_base >> 20);
+
+	crashk_res.start = crash_base;
+	crashk_res.end = crash_base + crash_size - 1;
+}
+#else
+static void __init reserve_crashkernel(void)
+{
+	;
+}
+#endif /* CONFIG_KEXEC_CORE */
+
 /*
  * Return the maximum physical address for ZONE_DMA (DMA_BIT_MASK(32)). It
  * currently assumes that for memory starting above 4G, 32-bit devices will
@@ -331,6 +438,9 @@ void __init arm64_memblock_init(void)
 		arm64_dma_phys_limit = max_zone_dma_phys();
 	else
 		arm64_dma_phys_limit = PHYS_MASK + 1;
+
+	reserve_crashkernel();
+
 	dma_contiguous_reserve(arm64_dma_phys_limit);
 
 	memblock_allow_resize();
-- 
2.10.0