Re: [kvm-unit-tests PATCH 3/8] lib: s390x: Print addressing related exception information

[Janosch Frank <frankja@linux.ibm.com>]

On 8/13/21 10:40 AM, Claudio Imbrenda wrote:
> On Fri, 13 Aug 2021 07:36:10 +0000
> Janosch Frank <frankja@linux.ibm.com> wrote:
> 
>> Right now we only get told the kind of program exception as well as
>> the PSW at the point where it happened.
>>
>> For addressing exceptions the PSW is not always enough so let's print
>> the TEID which contains the failing address and flags that tell us
>> more about the kind of address exception.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>  lib/s390x/asm/arch_def.h |  4 +++
>>  lib/s390x/interrupt.c    | 72
>> ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 76
>> insertions(+)
>>
>> diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
>> index 4ca02c1d..39c5ba99 100644
>> --- a/lib/s390x/asm/arch_def.h
>> +++ b/lib/s390x/asm/arch_def.h
>> @@ -41,6 +41,10 @@ struct psw {
>>  	uint64_t	addr;
>>  };
>>  
>> +/* Let's ignore spaces we don't expect to use for now. */
>> +#define AS_PRIM				0
>> +#define AS_HOME				3
>> +
>>  #define PSW_MASK_EXT			0x0100000000000000UL
>>  #define PSW_MASK_IO			0x0200000000000000UL
>>  #define PSW_MASK_DAT			0x0400000000000000UL
>> diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
>> index 01ded49d..1248bceb 100644
>> --- a/lib/s390x/interrupt.c
>> +++ b/lib/s390x/interrupt.c
>> @@ -12,6 +12,7 @@
>>  #include <sclp.h>
>>  #include <interrupt.h>
>>  #include <sie.h>
>> +#include <asm/page.h>
>>  
>>  static bool pgm_int_expected;
>>  static bool ext_int_expected;
>> @@ -126,6 +127,73 @@ static void fixup_pgm_int(struct stack_frame_int
>> *stack) /* suppressed/terminated/completed point already at the next
>> address */ }
>>  
>> +static void decode_pgm_prot(uint64_t teid)
> 
> it is actually more complicated than this.

I know it hurts to look at the spec :)

> 
> if you don't want to add all the possibilities because they are
> unlikely and/or not relevant, maybe add a comment

Will do!

> 
>> +{
>> +	/* Low-address protection exception, 100 */
>> +	if (test_bit_inv(56, &teid) && !test_bit_inv(60, &teid) &&
>> !test_bit_inv(61, &teid)) {
>> +		printf("Type: LAP\n");
>> +		return;
>> +	}
>> +
>> +	/* Instruction execution prevention, i.e. no-execute, 101 */
>> +	if (test_bit_inv(56, &teid) && !test_bit_inv(60, &teid) &&
>> test_bit_inv(61, &teid)) {
>> +		printf("Type: IEP\n");
>> +		return;
>> +	}
>> +
>> +	/* Standard DAT exception, 001 */
>> +	if (!test_bit_inv(56, &teid) && !test_bit_inv(60, &teid) &&
>> test_bit_inv(61, &teid)) {
>> +		printf("Type: DAT\n");
>> +		return;
>> +	}
>> +}
>> +
>> +static void decode_teid(uint64_t teid)
>> +{
>> +	int asce_id = lc->trans_exc_id & 3;
>> +	bool dat = lc->pgm_old_psw.mask & PSW_MASK_DAT;
>> +
>> +	printf("Memory exception information:\n");
>> +	printf("TEID: %lx\n", teid);
>> +	printf("DAT: %s\n", dat ? "on" : "off");
>> +	printf("AS: %s\n", asce_id == AS_PRIM ? "Primary" : "Home");
>> +
>> +	if (lc->pgm_int_code == PGM_INT_CODE_PROTECTION)
>> +		decode_pgm_prot(teid);
>> +
>> +	/*
>> +	 * If teid bit 61 is off for these two exception the reported
>> +	 * address is unpredictable.
>> +	 */
>> +	if ((lc->pgm_int_code == PGM_INT_CODE_SECURE_STOR_ACCESS ||
>> +	     lc->pgm_int_code == PGM_INT_CODE_SECURE_STOR_VIOLATION)
>> &&
>> +	    !test_bit_inv(61, &teid)) {
>> +		printf("Address: %lx, unpredictable\n ", teid &
>> PAGE_MASK);
>> +		return;
>> +	}
>> +	printf("Address: %lx\n\n", teid & PAGE_MASK);
>> +}
>> +
>> +static void print_storage_exception_information(void)
>> +{
>> +	switch (lc->pgm_int_code) {
>> +	case PGM_INT_CODE_PROTECTION:
>> +	case PGM_INT_CODE_PAGE_TRANSLATION:
>> +	case PGM_INT_CODE_SEGMENT_TRANSLATION:
>> +	case PGM_INT_CODE_ASCE_TYPE:
>> +	case PGM_INT_CODE_REGION_FIRST_TRANS:
>> +	case PGM_INT_CODE_REGION_SECOND_TRANS:
>> +	case PGM_INT_CODE_REGION_THIRD_TRANS:
>> +	case PGM_INT_CODE_SECURE_STOR_ACCESS:
>> +	case PGM_INT_CODE_NON_SECURE_STOR_ACCESS:
>> +	case PGM_INT_CODE_SECURE_STOR_VIOLATION:
>> +		decode_teid(lc->trans_exc_id);
>> +		break;
>> +	default:
>> +		return;
>> +	}
>> +}
>> +
>>  static void print_int_regs(struct stack_frame_int *stack)
>>  {
>>  	printf("\n");
>> @@ -155,6 +223,10 @@ static void print_pgm_info(struct
>> stack_frame_int *stack) lc->pgm_int_code, stap(),
>> lc->pgm_old_psw.addr, lc->pgm_int_id); print_int_regs(stack);
>>  	dump_stack();
>> +
>> +	/* Dump stack doesn't end with a \n so we add it here
>> instead */
>> +	printf("\n");
>> +	print_storage_exception_information();
>>  	report_summary();
>>  	abort();
>>  }
>