forked from Minki/linux
s390/kernel: Fix smp_call_ipl_cpu() for offline CPUs
If the IPL CPU is offline, currently the pcpu_delegate() function used by smp_call_ipl_cpu() does not work because pcpu_delegate() modifies the lowcore of the target CPU. In case of an offline IPL CPU currently the prefix register is zero but pcpu->lowcore still points to the old prefix page. Therefore the lowcore changes done by pcpu_delegate() have no effect. With this fix pcpu_delegate() now uses memcpy_absolute() and therefore also prepares the absolute zero lowcore if the target CPU has prefix register zero. Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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@ -297,26 +297,27 @@ static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
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static void pcpu_delegate(struct pcpu *pcpu, void (*func)(void *),
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void *data, unsigned long stack)
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{
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struct _lowcore *lc = pcpu->lowcore;
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unsigned short this_cpu;
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struct _lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];
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struct {
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unsigned long stack;
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void *func;
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void *data;
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unsigned long source;
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} restart = { stack, func, data, stap() };
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__load_psw_mask(psw_kernel_bits);
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this_cpu = stap();
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if (pcpu->address == this_cpu)
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if (pcpu->address == restart.source)
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func(data); /* should not return */
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/* Stop target cpu (if func returns this stops the current cpu). */
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pcpu_sigp_retry(pcpu, sigp_stop, 0);
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/* Restart func on the target cpu and stop the current cpu. */
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lc->restart_stack = stack;
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lc->restart_fn = (unsigned long) func;
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lc->restart_data = (unsigned long) data;
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lc->restart_source = (unsigned long) this_cpu;
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memcpy_absolute(&lc->restart_stack, &restart, sizeof(restart));
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asm volatile(
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"0: sigp 0,%0,6 # sigp restart to target cpu\n"
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" brc 2,0b # busy, try again\n"
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"1: sigp 0,%1,5 # sigp stop to current cpu\n"
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" brc 2,1b # busy, try again\n"
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: : "d" (pcpu->address), "d" (this_cpu) : "0", "1", "cc");
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: : "d" (pcpu->address), "d" (restart.source) : "0", "1", "cc");
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for (;;) ;
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}
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