From 506faa5b9b4f05e667b39252a28dace17a5017a1 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Mon, 28 Nov 2022 14:16:33 +0100 Subject: s390/nmi: print machine check interruption code before stopping system In case a system will be stopped because of e.g. missing validity bits print the machine check interruption code before the system is stopped. This is helpful, since up to now no message was printed in such a case. Only a disabled wait PSW was loaded, which doesn't give a hint of what went wrong. Improve this by printing a message with debug information. Reviewed-by: Peter Oberparleiter Reviewed-by: Alexander Gordeev Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev --- arch/s390/kernel/nmi.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) (limited to 'arch/s390') diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c index 3518ba638a85..b1579c85b869 100644 --- a/arch/s390/kernel/nmi.c +++ b/arch/s390/kernel/nmi.c @@ -114,9 +114,61 @@ void nmi_free_mcesa(u64 *mcesad) kmem_cache_free(mcesa_cache, __va(*mcesad & MCESA_ORIGIN_MASK)); } +static __always_inline char *nmi_puts(char *dest, const char *src) +{ + while (*src) + *dest++ = *src++; + *dest = 0; + return dest; +} + +static __always_inline char *u64_to_hex(char *dest, u64 val) +{ + int i, num; + + for (i = 1; i <= 16; i++) { + num = (val >> (64 - 4 * i)) & 0xf; + if (num >= 10) + *dest++ = 'A' + num - 10; + else + *dest++ = '0' + num; + } + *dest = 0; + return dest; +} + static notrace void s390_handle_damage(void) { + union ctlreg0 cr0, cr0_new; + char message[100]; + psw_t psw_save; + char *ptr; + smp_emergency_stop(); + diag_amode31_ops.diag308_reset(); + ptr = nmi_puts(message, "System stopped due to unrecoverable machine check, code: 0x"); + u64_to_hex(ptr, S390_lowcore.mcck_interruption_code); + + /* + * Disable low address protection and make machine check new PSW a + * disabled wait PSW. Any additional machine check cannot be handled. + */ + __ctl_store(cr0.val, 0, 0); + cr0_new = cr0; + cr0_new.lap = 0; + __ctl_load(cr0_new.val, 0, 0); + psw_save = S390_lowcore.mcck_new_psw; + psw_bits(S390_lowcore.mcck_new_psw).io = 0; + psw_bits(S390_lowcore.mcck_new_psw).ext = 0; + psw_bits(S390_lowcore.mcck_new_psw).wait = 1; + sclp_emergency_printk(message); + + /* + * Restore machine check new PSW and control register 0 to original + * values. This makes possible system dump analysis easier. + */ + S390_lowcore.mcck_new_psw = psw_save; + __ctl_load(cr0.val, 0, 0); disabled_wait(); while (1); } -- cgit v1.2.3