Hi Mikhail,
Your patch is queued for crash-7.2.8:
https://github.com/crash-utility/crash/commit/6664cb3f4ea2eac1b6d482e541b56d7792a4be04
Note that I made the s390x_lc_kaslr check gated upon a successful return from
readmem(),
just for the highly unlikely case of a failed read.
Thanks,
Dave
----- Original Message -----
> If the kernel crashes before vmcoreinfo initialization, there is
> no way to extract KASLR offset for such early s390 dumps. With a new s390
> kernel patch, the KASLR offset will be stored in the lowcore memory during
> early boot and then overwritten after vmcoreinfo is initialized.
> This patch allows crash to identify the KASLR offset stored in the lowcore
> memory for s390 dumps.
>
> Signed-off-by: Mikhail Zaslonko <[email protected]>
> ---
> s390x.c | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/s390x.c b/s390x.c
> index 4a1a466..5e28ea4 100644
> --- a/s390x.c
> +++ b/s390x.c
> @@ -46,6 +46,8 @@
>
> #define S390X_PSW_MASK_PSTATE 0x0001000000000000UL
>
> +#define S390X_LC_VMCORE_INFO 0xe0c
> +
> /*
> * Flags for Region and Segment table entries.
> */
> @@ -460,6 +462,8 @@ static void s390x_check_live(void)
> void
> s390x_init(int when)
> {
> + ulong s390x_lc_kaslr;
> +
> switch (when)
> {
> case SETUP_ENV:
> @@ -486,6 +490,23 @@ s390x_init(int when)
> machdep->verify_paddr = generic_verify_paddr;
> machdep->get_kvaddr_ranges = s390x_get_kvaddr_ranges;
> machdep->ptrs_per_pgd = PTRS_PER_PGD;
> + if (DUMPFILE() && !(kt->flags & RELOC_SET)) {
> + /* Read the value from well-known lowcore location*/
> + readmem(S390X_LC_VMCORE_INFO, PHYSADDR, &s390x_lc_kaslr,
> + sizeof(s390x_lc_kaslr), "s390x_lc_kaslr",
> + QUIET|RETURN_ON_ERROR);
> + /* Check for explicit kaslr offset flag */
> + if (s390x_lc_kaslr & 0x1UL) {
> + /* Drop the last bit to get an offset value */
> + s390x_lc_kaslr &= ~(0x1UL);
> + /* Make sure the offset is aligned by 0x1000 */
> + if (s390x_lc_kaslr && !(s390x_lc_kaslr &
> 0xfff)) {
> + kt->relocate = s390x_lc_kaslr * (-1);
> + kt->flags |= RELOC_SET;
> + kt->flags2 |= KASLR;
> + }
> + }
> + }
> break;
>
> case PRE_GDB:
> --
> 2.17.1
>
>
--
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