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

Claudio Imbrenda
2021-08-13T08:50:42Z

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.

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

> +{
> + /* 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();
> }