Root/arch/s390/kernel/switch_cpu.S

1/*
2 * 31-bit switch cpu code
3 *
4 * Copyright IBM Corp. 2009
5 *
6 */
7
8#include <asm/asm-offsets.h>
9#include <asm/ptrace.h>
10
11# smp_switch_to_cpu switches to destination cpu and executes the passed function
12# Parameter: %r2 - function to call
13# %r3 - function parameter
14# %r4 - stack poiner
15# %r5 - current cpu
16# %r6 - destination cpu
17
18    .section .text
19    .align 4
20    .globl smp_switch_to_cpu
21smp_switch_to_cpu:
22    stm %r6,%r15,__SF_GPRS(%r15)
23    lr %r1,%r15
24    ahi %r15,-STACK_FRAME_OVERHEAD
25    st %r1,__SF_BACKCHAIN(%r15)
26    basr %r13,0
270: la %r1,.gprregs_addr-0b(%r13)
28    l %r1,0(%r1)
29    stm %r0,%r15,0(%r1)
301: sigp %r0,%r6,__SIGP_RESTART /* start destination CPU */
31    brc 2,1b /* busy, try again */
322: sigp %r0,%r5,__SIGP_STOP /* stop current CPU */
33    brc 2,2b /* busy, try again */
343: j 3b
35
36    .globl smp_restart_cpu
37smp_restart_cpu:
38    basr %r13,0
390: la %r1,.gprregs_addr-0b(%r13)
40    l %r1,0(%r1)
41    lm %r0,%r15,0(%r1)
421: sigp %r0,%r5,__SIGP_SENSE /* Wait for calling CPU */
43    brc 10,1b /* busy, accepted (status 0), running */
44    tmll %r0,0x40 /* Test if calling CPU is stopped */
45    jz 1b
46    ltr %r4,%r4 /* New stack ? */
47    jz 1f
48    lr %r15,%r4
491: basr %r14,%r2
50
51.gprregs_addr:
52    .long .gprregs
53
54    .section .data,"aw",@progbits
55.gprregs:
56    .rept 16
57    .long 0
58    .endr
59

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