From 1a36a39e225d3558fb3776a3d3d7736cf1ec9f60 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Thu, 29 Oct 2015 10:28:26 +0100 Subject: s390/dump: rework CPU register dump code To collect the CPU registers of the crashed system allocated a single page with memblock_alloc_base and use it as a copy buffer. Replace the stop-and-store-status sigp with a store-status-at-address sigp in smp_save_dump_cpus() and smp_store_status(). In both cases the target CPU is already stopped and store-status-at-address avoids the detour via the absolute zero page. For kexec simplify s390_reset_system and call store_status() before the prefix register of the boot CPU has been set to zero. Use STPX to store the prefix register and remove dump_prefix_page. Acked-by: Michael Holzheu Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/machine_kexec.c | 104 +++++++++++++++++++++++---------------- 1 file changed, 61 insertions(+), 43 deletions(-) (limited to 'arch/s390/kernel/machine_kexec.c') diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c index bf2cd69..2f1b721 100644 --- a/arch/s390/kernel/machine_kexec.c +++ b/arch/s390/kernel/machine_kexec.c @@ -35,40 +35,6 @@ extern const unsigned long long relocate_kernel_len; #ifdef CONFIG_CRASH_DUMP /* - * Initialize CPU ELF notes - */ -static void setup_regs(void) -{ - struct save_area *sa, *sa_0; - unsigned long prefix; - int cpu, this_cpu; - - /* setup_regs is called with the prefix register = 0 */ - sa_0 = (struct save_area *) __LC_FPREGS_SAVE_AREA; - - /* Get status of this CPU out of absolute zero */ - prefix = (unsigned long) S390_lowcore.prefixreg_save_area; - sa = (struct save_area *)(prefix + __LC_FPREGS_SAVE_AREA); - memcpy(sa, sa_0, sizeof(struct save_area)); - if (MACHINE_HAS_VX) { - struct _lowcore *lc = (struct _lowcore *) prefix; - save_vx_regs_safe((void *) lc->vector_save_area_addr); - } - - /* Get status of the other CPUs */ - this_cpu = smp_find_processor_id(stap()); - for_each_online_cpu(cpu) { - if (cpu == this_cpu) - continue; - if (smp_store_status(cpu)) - continue; - prefix = (unsigned long) S390_lowcore.prefixreg_save_area; - sa = (struct save_area *)(prefix + __LC_FPREGS_SAVE_AREA); - memcpy(sa, sa_0, sizeof(struct save_area)); - } -} - -/* * PM notifier callback for kdump */ static int machine_kdump_pm_cb(struct notifier_block *nb, unsigned long action, @@ -99,14 +65,66 @@ static int __init machine_kdump_pm_init(void) arch_initcall(machine_kdump_pm_init); /* - * Start kdump: We expect here that a store status has been done on our CPU + * Reset the system, copy boot CPU registers to absolute zero, + * and jump to the kdump image */ static void __do_machine_kdump(void *image) { - int (*start_kdump)(int) = (void *)((struct kimage *) image)->start; + int (*start_kdump)(int); + unsigned long prefix; + + /* store_status() saved the prefix register to lowcore */ + prefix = (unsigned long) S390_lowcore.prefixreg_save_area; + + /* Now do the reset */ + s390_reset_system(); + + /* + * Copy dump CPU store status info to absolute zero. + * This need to be done *after* s390_reset_system set the + * prefix register of this CPU to zero + */ + memcpy((void *) __LC_FPREGS_SAVE_AREA, + (void *)(prefix + __LC_FPREGS_SAVE_AREA), 512); __load_psw_mask(PSW_MASK_BASE | PSW_DEFAULT_KEY | PSW_MASK_EA | PSW_MASK_BA); + start_kdump = (void *)((struct kimage *) image)->start; start_kdump(1); + + /* Die if start_kdump returns */ + disabled_wait((unsigned long) __builtin_return_address(0)); +} + +/* + * Start kdump: create a LGR log entry, store status of all CPUs and + * branch to __do_machine_kdump. + */ +static noinline void __machine_kdump(void *image) +{ + int this_cpu, cpu; + + lgr_info_log(); + /* Get status of the other CPUs */ + this_cpu = smp_find_processor_id(stap()); + for_each_online_cpu(cpu) { + if (cpu == this_cpu) + continue; + if (smp_store_status(cpu)) + continue; + } + /* Store status of the boot CPU */ + if (MACHINE_HAS_VX) + save_vx_regs((void *) &S390_lowcore.vector_save_area); + /* + * To create a good backchain for this CPU in the dump store_status + * is passed the address of a function. The address is saved into + * the PSW save area of the boot CPU and the function is invoked as + * a tail call of store_status. The backchain in the dump will look + * like this: + * restart_int_handler -> __machine_kexec -> __do_machine_kdump + * The call to store_status() will not return. + */ + store_status(__do_machine_kdump, image); } #endif @@ -229,10 +247,14 @@ static void __do_machine_kexec(void *data) relocate_kernel_t data_mover; struct kimage *image = data; + s390_reset_system(); data_mover = (relocate_kernel_t) page_to_phys(image->control_code_page); /* Call the moving routine */ (*data_mover)(&image->head, image->start); + + /* Die if kexec returns */ + disabled_wait((unsigned long) __builtin_return_address(0)); } /* @@ -245,14 +267,10 @@ static void __machine_kexec(void *data) tracing_off(); debug_locks_off(); #ifdef CONFIG_CRASH_DUMP - if (((struct kimage *) data)->type == KEXEC_TYPE_CRASH) { - - lgr_info_log(); - s390_reset_system(setup_regs, __do_machine_kdump, data); - } else + if (((struct kimage *) data)->type == KEXEC_TYPE_CRASH) + __machine_kdump(data); #endif - s390_reset_system(NULL, __do_machine_kexec, data); - disabled_wait((unsigned long) __builtin_return_address(0)); + __do_machine_kexec(data); } /* -- cgit v1.1