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s390/boot: fix absolute zero lowcore corruption on boot

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Crash dump always starts on CPU0. In case CPU0 is offline the
prefix page is not installed and the absolute zero lowcore is
used. However, struct lowcore::mcesad is never assigned and
stays zero. That leads to __machine_kdump() -> save_vx_regs()
call silently stores vector registers to the absolute lowcore
at 0x11b0 offset.

Fixes: a62bc0739253 ("s390/kdump: add support for vector extension")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Alexander Gordeev 2022-08-13 19:45:21 +02:00 committed by Vasily Gorbik
parent 7c8d42fdf1
commit 12dd19c159
2 changed files with 2 additions and 1 deletions
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2
arch/s390/kernel/nmi.c
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@ -64,7 +64,7 @@ static inline unsigned long nmi_get_mcesa_size(void)
* structure. The structure is required for machine check happening
* early in the boot process.
*/
static struct mcesa boot_mcesa __initdata __aligned(MCESA_MAX_SIZE);
static struct mcesa boot_mcesa __aligned(MCESA_MAX_SIZE);
void __init nmi_alloc_mcesa_early(u64 *mcesad)
{

1
arch/s390/kernel/setup.c
View File

@ -479,6 +479,7 @@ static void __init setup_lowcore_dat_off(void)
put_abs_lowcore(restart_data, lc->restart_data);
put_abs_lowcore(restart_source, lc->restart_source);
put_abs_lowcore(restart_psw, lc->restart_psw);
put_abs_lowcore(mcesad, lc->mcesad);
mcck_stack = (unsigned long)memblock_alloc(THREAD_SIZE, THREAD_SIZE);
if (!mcck_stack)