[PATCH v22 1/8] arm64: kdump: reserve memory for crash dump kernel

On Tue, Jul 19, 2016 at 08:48:57AM -0400, Mark Salter wrote:

On Tue, 2016-07-19 at 18:41 +0800, Dennis Chen wrote:

quoted

On Tue, Jul 19, 2016 at 07:28:16PM +0900, AKASHI Takahiro wrote:

quoted

On Tue, Jul 19, 2016 at 05:39:07PM +0800, Dennis Chen wrote:

quoted

Hello AKASHI,

On Tue, Jul 12, 2016 at 02:05:07PM +0900, AKASHI Takahiro wrote:

quoted

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 as
????????????- "Crash kernel" in /proc/iomem, or
????????????- "linux,crashkernel-base" and "linux,crashkernel-size" under
????????????????/sys/firmware/devicetree/base/chosen

Signed-off-by: AKASHI Takahiro <redacted>
Signed-off-by: Mark Salter <redacted>
Signed-off-by: Pratyush Anand <redacted>
Reviewed-by: James Morse <james.morse@arm.com>
---
??arch/arm64/kernel/setup.c |??????7 ++-
??arch/arm64/mm/init.c????????????| 115 ++++++++++++++++++++++++++++++++++++++++++++++
??2 files changed, 121 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index c1509e6..cb5eee0 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>

@@ -222,6 +221,12 @@ 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 2ade7a6..51b1302 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -29,11 +29,13 @@

??#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/kexec.h>

??#include <asm/boot.h>
??#include <asm/fixmap.h>

@@ -76,6 +78,117 @@ 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 (!crashk_res.end)
+??????????????????????????return 0;
+
+??????????crash_base = cpu_to_be64(crashk_res.start);
+??????????crash_size = cpu_to_be64(crashk_res.end - crashk_res.start + 1);
+
+??????????/* 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,
+??????????????????????????????????????????????????????????MEMBLOCK_ALLOC_ACCESSIBLE, crash_size, SZ_2M);
+??????????????????????????if (crash_base == 0) {
+??????????????????????????????????????????pr_warn("Unable to allocate crashkernel (size:%llx)\n",
+??????????????????????????????????????????????????????????crash_size);
+??????????????????????????????????????????return;
+??????????????????????????}
+??????????????????????????memblock_reserve(crash_base, crash_size);

I am not pretty sure the context here, but
can we use below code piece instead of the above lines?
????????????????if (crash_base == 0)
????????????????????????????????memblock_alloc(crash_size, SZ_2M);

Either would be fine here.

Hello AKASHI, maybe you can succeed to find the base with memblock_find_in_range(),??
but that doesn't mean you will also succeed to reserve them with memblock_reserve followed.

We avoid memblock_alloc() here because it panics on failure. This could happen

Thank you for pointing this out. I forgot it.

if user asks for an unusually large crashkernel size. Better to print a message
and keep booting. Checking the return value of memblock_reserve() seems like a
good thing to do though.

Yeah, but it is unlikely that the function fails in this context (just
after find_in_range at early boot time) and nobody in arm64/mm/*.c checks
a return value of memblock_reserve() as well.
So I want to keep the code unchanged.

Thanks,
-Takahiro AKASHI

quoted

Thanks,
Dennis

quoted

Thanks,
-Takahiro AKASHI

quoted

Thanks,
Dennis

quoted

+
+??????????} 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

@@ -289,6 +402,8 @@ void __init arm64_memblock_init(void)

????????????}
??#endif

+??????????reserve_crashkernel();
+
????????????early_init_fdt_scan_reserved_mem();

????????????/* 4GB maximum for 32-bit only capable devices */
--
2.9.0


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel