linux-kernel - Re: [PATCH] lib/test_hexdump: fix failure on big endian cpu

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Date:   Wed, 08 Aug 2018 15:13:07 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Christophe Leroy <christophe.leroy@....fr>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH] lib/test_hexdump: fix failure on big endian cpu

On Wed, 2018-08-08 at 06:37 +0000, Christophe Leroy wrote:
> On a big endian cpu, test_hexdump fails as follows. The logs show
> that bytes are expected in reversed order.
> 
> [...]
> [   16.643648] test_hexdump: Len: 24 buflen: 130 strlen: 97
> [   16.648681] test_hexdump: Result: 97 'be32db7b 0a1893b2 70bac424
> 7d83349b a69c31ad
> 9c0face9                    .2.{....p..$}.4...1.....'
> [   16.660951] test_hexdump: Expect: 97 '7bdb32be b293180a 24c4ba70
> 9b34837d ad319ca6
> e9ac0f9c                    .2.{....p..$}.4...1.....'
> [   16.673129] test_hexdump: Len: 8 buflen: 130 strlen: 77
> [   16.678113] test_hexdump: Result: 77
> 'be32db7b0a1893b2                                                     
> .2.{....'
> [   16.688660] test_hexdump: Expect: 77
> 'b293180a7bdb32be                                                     
> .2.{....'
> [   16.699170] test_hexdump: Len: 6 buflen: 131 strlen: 87
> [   16.704238] test_hexdump: Result: 87 'be32 db7b
> 0a18                                                                  
>  .2.{..'
> [   16.715511] test_hexdump: Expect: 87 '32be 7bdb
> 180a                                                                  
>  .2.{..'
> [   16.726864] test_hexdump: Len: 24 buflen: 131 strlen: 97
> [   16.731902] test_hexdump: Result: 97 'be32db7b 0a1893b2 70bac424
> 7d83349b a69c31ad
> 9c0face9                    .2.{....p..$}.4...1.....'
> [   16.744175] test_hexdump: Expect: 97 '7bdb32be b293180a 24c4ba70
> 9b34837d ad319ca6
> e9ac0f9c                    .2.{....p..$}.4...1.....'
> [   16.756379] test_hexdump: Len: 32 buflen: 131 strlen: 101
> [   16.761507] test_hexdump: Result: 101 'be32db7b0a1893b2
> 70bac4247d83349b a69c31ad9c0face9
> 4cd1199943b1af0c  .2.{....p..$}.4...1.....L...C...'
> [   16.774212] test_hexdump: Expect: 101 'b293180a7bdb32be
> 9b34837d24c4ba70 e9ac0f9cad319ca6
> 0cafb1439919d14c  .2.{....p..$}.4...1.....L...C...'
> [   16.786763] test_hexdump: failed 801 out of 1184 tests
> 
> This patch fixes it.

I like this approach because in the future we might introduce something
to print be data on le cpu or otherwise and thus test data will be used
independently of cpu endianess.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>

Thanks for adding the BE support.

> 
> Fixes: 64d1d77a44697 ("hexdump: introduce test suite")
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
> ---
>  lib/test_hexdump.c | 28 +++++++++++++++++++++++-----
>  1 file changed, 23 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/test_hexdump.c b/lib/test_hexdump.c
> index 3f415d8101f3..626f580b4ff7 100644
> --- a/lib/test_hexdump.c
> +++ b/lib/test_hexdump.c
> @@ -18,7 +18,7 @@ static const unsigned char data_b[] = {
>  
>  static const unsigned char data_a[] =
> ".2.{....p..$}.4...1.....L...C...";
>  
> -static const char * const test_data_1_le[] __initconst = {
> +static const char * const test_data_1[] __initconst = {
>  	"be", "32", "db", "7b", "0a", "18", "93", "b2",
>  	"70", "ba", "c4", "24", "7d", "83", "34", "9b",
>  	"a6", "9c", "31", "ad", "9c", "0f", "ac", "e9",
> @@ -32,16 +32,33 @@ static const char * const test_data_2_le[]
> __initconst = {
>  	"d14c", "9919", "b143", "0caf",
>  };
>  
> +static const char * const test_data_2_be[] __initconst = {
> +	"be32", "db7b", "0a18", "93b2",
> +	"70ba", "c424", "7d83", "349b",
> +	"a69c", "31ad", "9c0f", "ace9",
> +	"4cd1", "1999", "43b1", "af0c",
> +};
> +
>  static const char * const test_data_4_le[] __initconst = {
>  	"7bdb32be", "b293180a", "24c4ba70", "9b34837d",
>  	"ad319ca6", "e9ac0f9c", "9919d14c", "0cafb143",
>  };
>  
> +static const char * const test_data_4_be[] __initconst = {
> +	"be32db7b", "0a1893b2", "70bac424", "7d83349b",
> +	"a69c31ad", "9c0face9", "4cd11999", "43b1af0c",
> +};
> +
>  static const char * const test_data_8_le[] __initconst = {
>  	"b293180a7bdb32be", "9b34837d24c4ba70",
>  	"e9ac0f9cad319ca6", "0cafb1439919d14c",
>  };
>  
> +static const char * const test_data_8_be[] __initconst = {
> +	"be32db7b0a1893b2", "70bac4247d83349b",
> +	"a69c31ad9c0face9", "4cd1199943b1af0c",
> +};
> +
>  #define FILL_CHAR	'#'
>  
>  static unsigned total_tests __initdata;
> @@ -56,6 +73,7 @@ static void __init test_hexdump_prepare_test(size_t
> len, int rowsize,
>  	size_t l = len;
>  	int gs = groupsize, rs = rowsize;
>  	unsigned int i;
> +	const bool is_be = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN);
>  
>  	if (rs != 16 && rs != 32)
>  		rs = 16;
> @@ -67,13 +85,13 @@ static void __init
> test_hexdump_prepare_test(size_t len, int rowsize,
>  		gs = 1;
>  
>  	if (gs == 8)
> -		result = test_data_8_le;
> +		result = is_be ? test_data_8_be : test_data_8_le;
>  	else if (gs == 4)
> -		result = test_data_4_le;
> +		result = is_be ? test_data_4_be : test_data_4_le;
>  	else if (gs == 2)
> -		result = test_data_2_le;
> +		result = is_be ? test_data_2_be : test_data_2_le;
>  	else
> -		result = test_data_1_le;
> +		result = test_data_1;
>  
>  	/* hex dump */
>  	p = test;

-- 
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy