[Crash-utility] [PATCH 2/3] arm64: read pagesize

[Dave Anderson]

----- Original Message -----
> 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 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/arm64.c b/arm64.c
> index 8cfb863d1bfe2..6187b96d25a4d 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__)
>  
> @@ -98,6 +99,35 @@ arm64_init(int when)
>  
>  	case PRE_GDB:
>  		if (!machdep->pagesize &&
> +		    kernel_symbol_exists("_kernel_flags_le")) {
> +
> +			/*
> +			 * Kerneldoc Documentation/arm64/booting.txt describes
> +			 * the kernel image header flags field.
> +			 */
> +
> +			value = le64toh(symbol_value("_kernel_flags_le"));
> +			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")) {
>  			value = symbol_value("swapper_pg_dir") -
> --
> 2.4.3

So yeah, let's not keep "_kernel_flags_le" as a kernel symbol, but stash
it aside as a variable, say in the arm64_machine_specific structure, so that
it can be displayed later by arm64_dump_machdep_table().

Dave