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[S390] hibernate: Do real CPU swap at resume time
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Currently, when the physical resume CPU is not equal to the physical suspend
CPU, we swap the CPUs logically, by modifying the logical/physical CPU mapping.
This has two major drawbacks: First the change is visible from user space (e.g.
CPU sysfs files) and second it is hard to ensure that nowhere in the kernel
the physical CPU ID is stored before suspend.
To fix this, we now really swap the physical CPUs, if the resume CPU is not
the pysical suspend CPU. We restart the suspend CPU and stop the resume CPU
using SIGP restart and SIGP stop. If the suspend CPU is no longer available,
we write a message and load a disabled wait PSW.

Signed-off-by: Michael Holzheu <michael.holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Michael Holzheu authored and Martin Schwidefsky committed Sep 22, 2009
1 parent 68d1e5f commit 1aaf179
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Showing 5 changed files with 71 additions and 69 deletions.
1 change: 1 addition & 0 deletions arch/s390/include/asm/lowcore.h
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Original file line number Diff line number Diff line change
Expand Up @@ -86,6 +86,7 @@
#define __LC_PGM_OLD_PSW 0x0150
#define __LC_MCK_OLD_PSW 0x0160
#define __LC_IO_OLD_PSW 0x0170
#define __LC_RESTART_PSW 0x01a0
#define __LC_EXT_NEW_PSW 0x01b0
#define __LC_SVC_NEW_PSW 0x01c0
#define __LC_PGM_NEW_PSW 0x01d0
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7 changes: 6 additions & 1 deletion arch/s390/kernel/asm-offsets.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
#include <linux/sched.h>
#include <linux/kbuild.h>
#include <asm/vdso.h>
#include <asm/sigp.h>

int main(void)
{
Expand Down Expand Up @@ -59,6 +60,10 @@ int main(void)
DEFINE(CLOCK_REALTIME, CLOCK_REALTIME);
DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC);
DEFINE(CLOCK_REALTIME_RES, MONOTONIC_RES_NSEC);

/* constants for SIGP */
DEFINE(__SIGP_STOP, sigp_stop);
DEFINE(__SIGP_RESTART, sigp_restart);
DEFINE(__SIGP_SENSE, sigp_sense);
DEFINE(__SIGP_INITIAL_CPU_RESET, sigp_initial_cpu_reset);
return 0;
}
5 changes: 1 addition & 4 deletions arch/s390/kernel/sclp.S
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Original file line number Diff line number Diff line change
Expand Up @@ -24,8 +24,6 @@ LC_EXT_INT_CODE = 0x86 # addr of ext int code
# R3 = external interruption parameter if R2=0
#

.section ".init.text","ax"

_sclp_wait_int:
stm %r6,%r15,24(%r15) # save registers
basr %r13,0 # get base register
Expand Down Expand Up @@ -318,9 +316,8 @@ _sclp_print_early:
.long _sclp_work_area
.Lascebc:
.long _ascebc
.previous

.section ".init.data","a"
.section .data,"aw",@progbits
.balign 4096
_sclp_work_area:
.fill 4096
Expand Down
36 changes: 0 additions & 36 deletions arch/s390/kernel/smp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1041,42 +1041,6 @@ static ssize_t dispatching_store(struct sysdev_class *dev, const char *buf,
static SYSDEV_CLASS_ATTR(dispatching, 0644, dispatching_show,
dispatching_store);

/*
* If the resume kernel runs on another cpu than the suspended kernel,
* we have to switch the cpu IDs in the logical map.
*/
void smp_switch_boot_cpu_in_resume(u32 resume_phys_cpu_id,
struct _lowcore *suspend_lowcore)
{
int cpu, suspend_cpu_id, resume_cpu_id;
u32 suspend_phys_cpu_id;

suspend_phys_cpu_id = __cpu_logical_map[suspend_lowcore->cpu_nr];
suspend_cpu_id = suspend_lowcore->cpu_nr;

for_each_present_cpu(cpu) {
if (__cpu_logical_map[cpu] == resume_phys_cpu_id) {
resume_cpu_id = cpu;
goto found;
}
}
panic("Could not find resume cpu in logical map.\n");

found:
printk("Resume cpu ID: %i/%i\n", resume_phys_cpu_id, resume_cpu_id);
printk("Suspend cpu ID: %i/%i\n", suspend_phys_cpu_id, suspend_cpu_id);

__cpu_logical_map[resume_cpu_id] = suspend_phys_cpu_id;
__cpu_logical_map[suspend_cpu_id] = resume_phys_cpu_id;

lowcore_ptr[suspend_cpu_id]->cpu_addr = resume_phys_cpu_id;
}

u32 smp_get_phys_cpu_id(void)
{
return __cpu_logical_map[smp_processor_id()];
}

static int __init topology_init(void)
{
int cpu;
Expand Down
91 changes: 63 additions & 28 deletions arch/s390/kernel/swsusp_asm64.S
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@

#include <asm/page.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>

/*
Expand Down Expand Up @@ -41,6 +42,9 @@ swsusp_arch_suspend:
/* Get pointer to save area */
lghi %r1,0x1000

/* Save CPU address */
stap __LC_CPU_ADDRESS(%r1)

/* Store registers */
mvc 0x318(4,%r1),__SF_EMPTY(%r15) /* move prefix to lowcore */
stfpc 0x31c(%r1) /* store fpu control */
Expand Down Expand Up @@ -105,12 +109,7 @@ swsusp_arch_resume:
/* Make all free pages stable */
lghi %r2,1
brasl %r14,arch_set_page_states
#ifdef CONFIG_SMP
/* Save boot cpu number */
brasl %r14,smp_get_phys_cpu_id
larl %r1,saved_cpu_id
st %r2,0(%r1)
#endif

/* Deactivate DAT */
stnsm __SF_EMPTY(%r15),0xfb

Expand Down Expand Up @@ -139,12 +138,10 @@ swsusp_arch_resume:

/* Reset System */
larl %r1,restart_entry
larl %r2,restart_psw
larl %r2,.Lrestart_diag308_psw
og %r1,0(%r2)
stg %r1,0(%r0)
larl %r1,saved_pgm_check_psw
mvc 0(16,%r1),__LC_PGM_NEW_PSW(%r0)
larl %r1,new_pgm_check_psw
larl %r1,.Lnew_pgm_check_psw
epsw %r2,%r3
stm %r2,%r3,0(%r1)
mvc __LC_PGM_NEW_PSW(16,%r0),0(%r1)
Expand All @@ -154,12 +151,54 @@ restart_entry:
lhi %r1,1
sigp %r1,%r0,0x12
sam64
larl %r1,new_pgm_check_psw
larl %r1,.Lnew_pgm_check_psw
lpswe 0(%r1)
pgm_check_entry:
larl %r1,saved_pgm_check_psw
mvc __LC_PGM_NEW_PSW(16,%r0),0(%r1)

/* Switch to original suspend CPU */
larl %r1,.Lresume_cpu /* Resume CPU address: r2 */
stap 0(%r1)
llgh %r2,0(%r1)
lghi %r3,0x1000
llgh %r1,__LC_CPU_ADDRESS(%r3) /* Suspend CPU address: r1 */
cgr %r1,%r2
je restore_registers /* r1 = r2 -> nothing to do */
larl %r4,.Lrestart_suspend_psw /* Set new restart PSW */
mvc __LC_RESTART_PSW(16,%r0),0(%r4)
3:
sigp %r9,%r1,__SIGP_INITIAL_CPU_RESET
brc 8,4f /* accepted */
brc 2,3b /* busy, try again */

/* Suspend CPU not available -> panic */
larl %r15,init_thread_union
ahi %r15,1<<(PAGE_SHIFT+THREAD_ORDER)
larl %r2,.Lpanic_string
larl %r3,_sclp_print_early
lghi %r1,0
sam31
sigp %r1,%r0,0x12
basr %r14,%r3
larl %r3,.Ldisabled_wait_31
lpsw 0(%r3)
4:
/* Switch to suspend CPU */
sigp %r9,%r1,__SIGP_RESTART /* start suspend CPU */
brc 2,4b /* busy, try again */
5:
sigp %r9,%r2,__SIGP_STOP /* stop resume (current) CPU */
6: j 6b

restart_suspend:
larl %r1,.Lresume_cpu
llgh %r2,0(%r1)
7:
sigp %r9,%r2,__SIGP_SENSE /* Wait for resume CPU */
brc 2,7b /* busy, try again */
tmll %r9,0x40 /* Test if resume CPU is stopped */
jz 7b

restore_registers:
/* Restore registers */
lghi %r13,0x1000 /* %r1 = pointer to save arae */

Expand Down Expand Up @@ -193,13 +232,6 @@ pgm_check_entry:
/* Pointer to save area */
lghi %r13,0x1000

#ifdef CONFIG_SMP
/* Switch CPUs */
larl %r1,saved_cpu_id
llgf %r2,0(%r1)
llgf %r3,0x318(%r13)
brasl %r14,smp_switch_boot_cpu_in_resume
#endif
/* Restore prefix register */
spx 0x318(%r13)

Expand All @@ -217,13 +249,16 @@ pgm_check_entry:

.section .data.nosave,"aw",@progbits
.align 8
restart_psw:
.Ldisabled_wait_31:
.long 0x000a0000,0x00000000
.Lpanic_string:
.asciz "Resume not possible because suspend CPU is no longer available"
.align 8
.Lrestart_diag308_psw:
.long 0x00080000,0x80000000
new_pgm_check_psw:
.Lrestart_suspend_psw:
.quad 0x0000000180000000,restart_suspend
.Lnew_pgm_check_psw:
.quad 0,pgm_check_entry
saved_pgm_check_psw:
.quad 0,0
#ifdef CONFIG_SMP
saved_cpu_id:
.long 0
#endif
.Lresume_cpu:
.byte 0,0

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