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linux-next/arch/s390/kernel/swsusp_asm64.S
Heiko Carstens b3dcf3de8e [S390] smp: fix sigp sense handling 
sigp sense only returns the status of a cpu if it is non zero. If the
status of the sensed cpu is all zeros condition code 0 (accpeted) is
set and no status bits are returned.
The current code however assumes that a status was returned and tests
bits in it. This means uninitalized data is accessed with random
results.
Worst case is that the code that checks if cpu is offline on cpu
hotplug assumes that the target cpu is offline while it is still
running. This leads potentially to memory corruption since resources
that are still needed by the target cpu will be freed and could be
resused while still in use.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2009-10-29 15:05:13 +01:00

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/*
* S390 64-bit swsusp implementation
*
* Copyright IBM Corp. 2009
*
* Author(s): Hans-Joachim Picht <hans@linux.vnet.ibm.com>
* Michael Holzheu <holzheu@linux.vnet.ibm.com>
*/
#include <asm/page.h>
#include <asm/ptrace.h>
#include <asm/thread_info.h>
#include <asm/asm-offsets.h>
/*
* Save register context in absolute 0 lowcore and call swsusp_save() to
* create in-memory kernel image. The context is saved in the designated
* "store status" memory locations (see POP).
* We return from this function twice. The first time during the suspend to
* disk process. The second time via the swsusp_arch_resume() function
* (see below) in the resume process.
* This function runs with disabled interrupts.
*/
.section .text
.align 4
.globl swsusp_arch_suspend
swsusp_arch_suspend:
stmg %r6,%r15,__SF_GPRS(%r15)
lgr %r1,%r15
aghi %r15,-STACK_FRAME_OVERHEAD
stg %r1,__SF_BACKCHAIN(%r15)
/* Deactivate DAT */
stnsm __SF_EMPTY(%r15),0xfb
/* Store prefix register on stack */
stpx __SF_EMPTY(%r15)
/* Save prefix register contents for lowcore */
llgf %r4,__SF_EMPTY(%r15)
/* Get pointer to save area */
lghi %r1,0x1000
/* Save CPU address */
stap __LC_CPU_ADDRESS(%r0)
/* Store registers */
mvc 0x318(4,%r1),__SF_EMPTY(%r15) /* move prefix to lowcore */
stfpc 0x31c(%r1) /* store fpu control */
std 0,0x200(%r1) /* store f0 */
std 1,0x208(%r1) /* store f1 */
std 2,0x210(%r1) /* store f2 */
std 3,0x218(%r1) /* store f3 */
std 4,0x220(%r1) /* store f4 */
std 5,0x228(%r1) /* store f5 */
std 6,0x230(%r1) /* store f6 */
std 7,0x238(%r1) /* store f7 */
std 8,0x240(%r1) /* store f8 */
std 9,0x248(%r1) /* store f9 */
std 10,0x250(%r1) /* store f10 */
std 11,0x258(%r1) /* store f11 */
std 12,0x260(%r1) /* store f12 */
std 13,0x268(%r1) /* store f13 */
std 14,0x270(%r1) /* store f14 */
std 15,0x278(%r1) /* store f15 */
stam %a0,%a15,0x340(%r1) /* store access registers */
stctg %c0,%c15,0x380(%r1) /* store control registers */
stmg %r0,%r15,0x280(%r1) /* store general registers */
stpt 0x328(%r1) /* store timer */
stck __SF_EMPTY(%r15) /* store clock */
stckc 0x330(%r1) /* store clock comparator */
/* Update cputime accounting before going to sleep */
lg %r0,__LC_LAST_UPDATE_TIMER
slg %r0,0x328(%r1)
alg %r0,__LC_SYSTEM_TIMER
stg %r0,__LC_SYSTEM_TIMER
mvc __LC_LAST_UPDATE_TIMER(8),0x328(%r1)
lg %r0,__LC_LAST_UPDATE_CLOCK
slg %r0,__SF_EMPTY(%r15)
alg %r0,__LC_STEAL_TIMER
stg %r0,__LC_STEAL_TIMER
mvc __LC_LAST_UPDATE_CLOCK(8),__SF_EMPTY(%r15)
/* Activate DAT */
stosm __SF_EMPTY(%r15),0x04
/* Set prefix page to zero */
xc __SF_EMPTY(4,%r15),__SF_EMPTY(%r15)
spx __SF_EMPTY(%r15)
lghi %r2,0
lghi %r3,2*PAGE_SIZE
lghi %r5,2*PAGE_SIZE
1: mvcle %r2,%r4,0
jo 1b
/* Save image */
brasl %r14,swsusp_save
/* Restore prefix register and return */
lghi %r1,0x1000
spx 0x318(%r1)
lmg %r6,%r15,STACK_FRAME_OVERHEAD + __SF_GPRS(%r15)
lghi %r2,0
br %r14
/*
* Restore saved memory image to correct place and restore register context.
* Then we return to the function that called swsusp_arch_suspend().
* swsusp_arch_resume() runs with disabled interrupts.
*/
.globl swsusp_arch_resume
swsusp_arch_resume:
stmg %r6,%r15,__SF_GPRS(%r15)
lgr %r1,%r15
aghi %r15,-STACK_FRAME_OVERHEAD
stg %r1,__SF_BACKCHAIN(%r15)
/* Make all free pages stable */
lghi %r2,1
brasl %r14,arch_set_page_states
/* Deactivate DAT */
stnsm __SF_EMPTY(%r15),0xfb
/* Set prefix page to zero */
xc __SF_EMPTY(4,%r15),__SF_EMPTY(%r15)
spx __SF_EMPTY(%r15)
/* Restore saved image */
larl %r1,restore_pblist
lg %r1,0(%r1)
ltgr %r1,%r1
jz 2f
0:
lg %r2,8(%r1)
lg %r4,0(%r1)
lghi %r3,PAGE_SIZE
lghi %r5,PAGE_SIZE
1:
mvcle %r2,%r4,0
jo 1b
lg %r1,16(%r1)
ltgr %r1,%r1
jnz 0b
2:
ptlb /* flush tlb */
/* Reset System */
larl %r1,restart_entry
larl %r2,.Lrestart_diag308_psw
og %r1,0(%r2)
stg %r1,0(%r0)
larl %r1,.Lnew_pgm_check_psw
epsw %r2,%r3
stm %r2,%r3,0(%r1)
mvc __LC_PGM_NEW_PSW(16,%r0),0(%r1)
lghi %r0,0
diag %r0,%r0,0x308
restart_entry:
lhi %r1,1
sigp %r1,%r0,0x12
sam64
larl %r1,.Lnew_pgm_check_psw
lpswe 0(%r1)
pgm_check_entry:
/* Switch to original suspend CPU */
larl %r1,.Lresume_cpu /* Resume CPU address: r2 */
stap 0(%r1)
llgh %r2,0(%r1)
llgh %r1,__LC_CPU_ADDRESS(%r0) /* 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 */
brc 2,5b /* busy, try again */
6: j 6b
restart_suspend:
larl %r1,.Lresume_cpu
llgh %r2,0(%r1)
7:
sigp %r9,%r2,__SIGP_SENSE /* Wait for resume CPU */
brc 8,7b /* accepted, status 0, still running */
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 area */
/* Ignore time spent in suspended state. */
llgf %r1,0x318(%r13)
stck __LC_LAST_UPDATE_CLOCK(%r1)
spt 0x328(%r13) /* reprogram timer */
//sckc 0x330(%r13) /* set clock comparator */
lctlg %c0,%c15,0x380(%r13) /* load control registers */
lam %a0,%a15,0x340(%r13) /* load access registers */
lfpc 0x31c(%r13) /* load fpu control */
ld 0,0x200(%r13) /* load f0 */
ld 1,0x208(%r13) /* load f1 */
ld 2,0x210(%r13) /* load f2 */
ld 3,0x218(%r13) /* load f3 */
ld 4,0x220(%r13) /* load f4 */
ld 5,0x228(%r13) /* load f5 */
ld 6,0x230(%r13) /* load f6 */
ld 7,0x238(%r13) /* load f7 */
ld 8,0x240(%r13) /* load f8 */
ld 9,0x248(%r13) /* load f9 */
ld 10,0x250(%r13) /* load f10 */
ld 11,0x258(%r13) /* load f11 */
ld 12,0x260(%r13) /* load f12 */
ld 13,0x268(%r13) /* load f13 */
ld 14,0x270(%r13) /* load f14 */
ld 15,0x278(%r13) /* load f15 */
/* Load old stack */
lg %r15,0x2f8(%r13)
/* Restore prefix register */
spx 0x318(%r13)
/* Activate DAT */
stosm __SF_EMPTY(%r15),0x04
/* Make all free pages unstable */
lghi %r2,0
brasl %r14,arch_set_page_states
/* Return 0 */
lmg %r6,%r15,STACK_FRAME_OVERHEAD + __SF_GPRS(%r15)
lghi %r2,0
br %r14
.section .data.nosave,"aw",@progbits
.align 8
.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
.Lrestart_suspend_psw:
.quad 0x0000000180000000,restart_suspend
.Lnew_pgm_check_psw:
.quad 0,pgm_check_entry
.Lresume_cpu:
.byte 0,0
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