arm64: kdump: reserve memory for crash dump kernel

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

The memory range will be exposed to userspace as a resource named
"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>
Reviewed-by: James Morse <james.morse@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 42274bda0ccb5aa1690183ab2093de9fa5bb9009..28855ec1be95e113fa53081d57f418a5587badb4 100644 (file)
--- 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>
@@ -226,6 +225,12 @@ static void __init request_standard_resources(void)
                if (kernel_data.start >= res->start &&
                    kernel_data.end <= res->end)
                        request_resource(res, &kernel_data);
+#ifdef CONFIG_KEXEC_CORE
+               /* Userspace will find "Crash kernel" region in /proc/iomem. */
+               if (crashk_res.end && crashk_res.start >= res->start &&
+                   crashk_res.end <= res->end)
+                       request_resource(res, &crashk_res);
+#endif
        }
 }
 

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 290794b1a0f1347cfc74031fdc16f5c281907f08..09d19207362de8026037561459bb121c99a29f3f 100644 (file)
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -30,6 +30,7 @@
 #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>
@@ -37,6 +38,7 @@
 #include <linux/swiotlb.h>
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
+#include <linux/kexec.h>
 
 #include <asm/boot.h>
 #include <asm/fixmap.h>
@@ -77,6 +79,67 @@ 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_base, crash_size;
+       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;
+
+       crash_size = PAGE_ALIGN(crash_size);
+
+       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("cannot allocate crashkernel (size:0x%llx)\n",
+                               crash_size);
+                       return;
+               }
+       } else {
+               /* User specifies base address explicitly. */
+               if (!memblock_is_region_memory(crash_base, crash_size)) {
+                       pr_warn("cannot reserve crashkernel: region is not memory\n");
+                       return;
+               }
+
+               if (memblock_is_region_reserved(crash_base, crash_size)) {
+                       pr_warn("cannot reserve crashkernel: region overlaps reserved memory\n");
+                       return;
+               }
+
+               if (!IS_ALIGNED(crash_base, SZ_2M)) {
+                       pr_warn("cannot reserve crashkernel: base address is not 2MB aligned\n");
+                       return;
+               }
+       }
+       memblock_reserve(crash_base, crash_size);
+
+       pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
+               crash_base, crash_base + crash_size, crash_size >> 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
@@ -332,6 +395,9 @@ 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();