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s390/dump: rework CPU register dump code

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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 <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2015-10-29 10:28:26 +01:00
parent f08b841463
commit 1a36a39e22
12 changed files with 158 additions and 145 deletions
Download patch file Download diff file Expand all files Collapse all files

104
arch/s390/kernel/machine_kexec.c
View file

@ -34,40 +34,6 @@ 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
*/
@ -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);
}
/*