[PATCH v15 15/20] arm64: kdump: reserve memory for crash dump kernel

Geoff Levand
2016-03-14T17:48:01Z

From: AKASHI Takahiro <takahiro.akashi@linaro.org>

On the startup of primary kernel, the memory region used by crash dump
kernel must be specified by "crashkernel=" kernel parameter.
reserve_crashkernel() will allocate and reserve the region for later use.

User space tools, like kexec-tools, will be able to find that region marked
as "Crash kernel" in /proc/iomem.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Pratyush Anand <panand@redhat.com>
---
arch/arm64/kernel/setup.c | 7 +++++-
arch/arm64/mm/init.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 8119479..293cee2 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>
@@ -221,6 +220,12 @@ 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
}

#ifdef CONFIG_BLK_DEV_INITRD
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 7802f21..4edf181 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -34,6 +34,7 @@
#include <linux/dma-contiguous.h>
#include <linux/efi.h>
#include <linux/swiotlb.h>
+#include <linux/kexec.h>

#include <asm/fixmap.h>
#include <asm/memory.h>
@@ -66,6 +67,63 @@ static int __init early_initrd(char *p)
early_param("initrd", early_initrd);
#endif

+#ifdef CONFIG_KEXEC_CORE
+/*
+ * 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)
+{
+ unsigned long long crash_size = 0, crash_base = 0;
+ int ret;
+
+ ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
+ &crash_size, &crash_base);
+ if (ret)
+ return;
+
+ if (crash_base == 0) {
+ crash_base = memblock_find_in_range(0,
+ MEMBLOCK_ALLOC_ACCESSIBLE, crash_size, 1 << 21);
+ if (crash_base == 0) {
+ pr_warn("Unable to allocate crashkernel (size:%llx)\n",
+ crash_size);
+ return;
+ }
+ memblock_reserve(crash_base, crash_size);
+
+ } 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 (crash_base & ((1 << 21) - 1)) {
+ pr_warn("crashkernel base address is not 2MB aligned\n");
+ return;
+ }
+
+ memblock_reserve(crash_base, crash_size);
+ }
+
+ pr_info("Reserving %lldMB of memory@%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
@@ -171,6 +229,8 @@ void __init arm64_memblock_init(void)
memblock_reserve(__virt_to_phys(initrd_start), initrd_end - initrd_start);
#endif

+ reserve_crashkernel();
+
early_init_fdt_scan_reserved_mem();

/* 4GB maximum for 32-bit only capable devices */
--
2.5.0