[Crash-utility] [PATCH] arm64: fix page size calculation

[Dave Anderson]

----- Original Message -----
> As for v4.16-rc1, crash for arm64 fails to analyze the core dump,
> with a message: cannot determine page size.
> 
> There seems to be a couple of reasons for this:
> [1] splits a 64-bit field of image header, _kernel_flags_le, into two
> 32-bit values and in turn they have got a bit different names.
> 
> [2] and more recent [3] can possibly add extra space between idmap_pg_dir
> and swapper_pg_dir.
> 
> This patch addresses both of changes.
> 
> [1] commit 6ad1fe5d9077 ("arm64: avoid R_AARCH64_ABS64 relocations for
>     Image header fields")
> 
> [2] commit 1e1b8c04fa34 ("arm64: entry: Move the trampoline to be before
> PAN")
> 
> [3] commit 4b65a5db3627 ("arm64: Introduce uaccess_{disable,enable}
>     functionality based on TTBR0_EL1")
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>


Hi Takahiro,

Thanks for investigating and fixing this -- queued for crash-7.2.2:

  https://github.com/crash-utility/crash/commit/764e2d09978bb3f87dfaff4c6a59d4a5cc00f277

Dave



> ---
>  arm64.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/arm64.c b/arm64.c
> index 7904f65..7f87d5b 100644
> --- a/arm64.c
> +++ b/arm64.c
> @@ -172,8 +172,14 @@ arm64_init(int when)
>  		if (!machdep->pagesize &&
>  		    kernel_symbol_exists("swapper_pg_dir") &&
>  		    kernel_symbol_exists("idmap_pg_dir")) {
> -			value = symbol_value("swapper_pg_dir") -
> -				symbol_value("idmap_pg_dir");
> +			if (kernel_symbol_exists("tramp_pg_dir"))
> +				value = symbol_value("tramp_pg_dir");
> +			else if (kernel_symbol_exists("reserved_ttbr0"))
> +				value = symbol_value("reserved_ttbr0");
> +			else
> +				value = symbol_value("swapper_pg_dir");
> +
> +			value -= symbol_value("idmap_pg_dir");
>  			/*
>  			 * idmap_pg_dir is 2 pages prior to 4.1,
>  			 * and 3 pages thereafter.  Only 4K and 64K
> @@ -436,6 +442,12 @@ arm64_verify_symbol(const char *name, ulong value, char
> type)
>  	if ((type == 'A') && STREQ(name, "_kernel_flags_le"))
>  		machdep->machspec->kernel_flags = le64toh(value);
>  
> +	if ((type == 'A') && STREQ(name, "_kernel_flags_le_hi32"))
> +		machdep->machspec->kernel_flags |= (le32toh(value) << 32);
> +
> +	if ((type == 'A') && STREQ(name, "_kernel_flags_le_lo32"))
> +		machdep->machspec->kernel_flags |= le32toh(value);
> +
>  	if (((type == 'A') || (type == 'a')) && (highest_bit_long(value) != 63))
>  		return FALSE;
>  
> --
> 2.15.1
> 
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