[Crash-utility] [PATCH v2 1/2] arm64: read pagesize

[Andrew Jones]

On Thu, Nov 19, 2015 at 08:16:37PM -0500, Andrew Jones wrote:
> Thanks to kernel commit 9d372c9fab34 "arm64: Add page size to the
> kernel image header", we don't need a heuristic to determine the
> pagesize on arm64. Keep the heuristic for older kernels, but try
> reading the header first.
> ---
>  arm64.c | 30 ++++++++++++++++++++++++++++++
>  defs.h  |  1 +
>  2 files changed, 31 insertions(+)
> 
> diff --git a/arm64.c b/arm64.c
> index 5f8e2f6852434..d85ad7214dd39 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -19,6 +19,7 @@
>  
>  #include "defs.h"
>  #include <elf.h>
> +#include <endian.h>
>  
>  #define NOT_IMPLEMENTED(X) error((X), "%s: function not implemented\n", __func__)
>  
> @@ -97,6 +98,32 @@ arm64_init(int when)
>  		break;
>  
>  	case PRE_GDB:
> +		if (!machdep->pagesize) {
> +			/*
> +			 * Kerneldoc Documentation/arm64/booting.txt describes
> +			 * the kernel image header flags field.
> +			 */
> +			value = machdep->machspec->kernel_flags;
> +			value = (value >> 1) & 3;
> +
> +			switch(value)
> +			{
> +			case 0:
> +				break;
> +			case 1:
> +				machdep->pagesize = 4096;
> +				break;
> +			case 2:
> +				/* TODO: machdep->pagesize = 16384; */
> +				error(FATAL, "16K pages not supported.");
> +				break;
> +			case 3:
> +				machdep->pagesize = 65536;
> +				break;
> +			}
> +
> +		}
> +
>  		if (!machdep->pagesize &&
>  		    kernel_symbol_exists("swapper_pg_dir") &&
>  		    kernel_symbol_exists("idmap_pg_dir")) {
> @@ -305,6 +332,9 @@ arm64_verify_symbol(const char *name, ulong value, char type)
>  	if (!name || !strlen(name))
>  		return FALSE;
>  
> +	if (STREQ(name, "_kernel_flags_le"))
> +		machdep->machspec->kernel_flags = le64toh(value);

I forgot the 'type == A' here to avoid a bunch of unnecessary strcmps. v3
coming in 2 seconds.

> +
>  	if (((type == 'A') || (type == 'a')) && (highest_bit_long(value) != 63))
>  		return FALSE;
>  
> diff --git a/defs.h b/defs.h
> index 7004619017e41..3e5dbd99942b2 100644
> --- a/defs.h
> +++ b/defs.h
> @@ -2944,6 +2944,7 @@ struct machine_specific {
>  	ulong crash_kexec_end;
>  	ulong crash_save_cpu_start;
>  	ulong crash_save_cpu_end;
> +	ulong kernel_flags;
>  };
>  
>  struct arm64_stackframe {
> -- 
> 2.4.3
> 
> --
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