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

From: [email-masked] (Dennis Chen)
Date: Tue, 19 Jul 2016 18:41:04 +0800

On Tue, Jul 19, 2016 at 07:28:16PM +0900, AKASHI Takahiro wrote:
> On Tue, Jul 19, 2016 at 05:39:07PM +0800, Dennis Chen wrote:
> > Hello AKASHI,
> > 
> > On Tue, Jul 12, 2016 at 02:05:07PM +0900, AKASHI Takahiro wrote:
> > > 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 <[email-masked]>
> > > Signed-off-by: Mark Salter <[email-masked]>
> > > Signed-off-by: Pratyush Anand <[email-masked]>
> > > Reviewed-by: James Morse <[email-masked]>
> > > ---
> > >  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.

Thanks,
Dennis
> 
> Thanks,
> -Takahiro AKASHI
> 
> > Thanks,
> > Dennis
> > 
> > > +
> > > +     } 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
> > >
>