Re: [kvm-unit-tests PATCH v1] s390x: spec_ex: Add test for misaligned load

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On Wed,  1 Mar 2023 14:26:38 +0100
Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx> wrote:

> The operand of LOAD RELATIVE LONG must be word aligned, otherwise a
> specification exception occurs. Test that this exception occurs.

you're only testing halfword misalignment; would it make sense to test
all possible misalignments? (it's only 3 of them after all)

> 
> Signed-off-by: Nina Schoetterl-Glausch <nsg@xxxxxxxxxxxxx>
> ---
> 
> 
> Noticed while writing another test that TCG fails this requirement,
> so thought it best do document this in the form of a test.
> 
> 
>  s390x/spec_ex.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/s390x/spec_ex.c b/s390x/spec_ex.c
> index 42ecaed3..42e86070 100644
> --- a/s390x/spec_ex.c
> +++ b/s390x/spec_ex.c
> @@ -136,7 +136,7 @@ static int short_psw_bit_12_is_0(void)
>  	return 0;
>  }
>  
> -static int bad_alignment(void)
> +static int bad_alignment_lqp(void)
>  {
>  	uint32_t words[5] __attribute__((aligned(16)));
>  	uint32_t (*bad_aligned)[4] = (uint32_t (*)[4])&words[1];
> @@ -149,6 +149,22 @@ static int bad_alignment(void)
>  	return 0;
>  }
>  
> +static int bad_alignment_lrl(void)
> +{
> +	uint64_t r;
> +
> +	asm volatile ( ".pushsection .rodata\n"

why not declare this as a local array?

uint8_t stuff[8] __attribute__((aligned(8)));

> +		"	.balign	4\n"
> +		"	. = . + 2\n"
> +		"0:	.fill	4\n"
> +		"	.popsection\n"
> +
> +		"	lrl	%0,0b\n"
> +		: "=d" (r)

and here pass stuff + 1 or something like that?

less asm = more readable

> +	);
> +	return 0;
> +}
> +
>  static int not_even(void)
>  {
>  	uint64_t quad[2] __attribute__((aligned(16))) = {0};
> @@ -176,7 +192,8 @@ struct spec_ex_trigger {
>  static const struct spec_ex_trigger spec_ex_triggers[] = {
>  	{ "psw_bit_12_is_1", &psw_bit_12_is_1, false, &fixup_invalid_psw },
>  	{ "short_psw_bit_12_is_0", &short_psw_bit_12_is_0, false, &fixup_invalid_psw },
> -	{ "bad_alignment", &bad_alignment, true, NULL },
> +	{ "bad_alignment_lqp", &bad_alignment_lqp, true, NULL },
> +	{ "bad_alignment_lrl", &bad_alignment_lrl, true, NULL },
>  	{ "not_even", &not_even, true, NULL },
>  	{ NULL, NULL, false, NULL },
>  };
> 
> base-commit: e3c5c3ef2524c58023073c0fadde2e8ae3c04ec6




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