mirror of https://gitee.com/openkylin/linux.git
xtensa: SMP: fix secondary CPU initialization
- add missing memory barriers to the secondary CPU synchronization spin loops; add comment to the matching memory barrier in the boot_secondary and __cpu_die functions; - use READ_ONCE/WRITE_ONCE to access cpu_start_id/cpu_start_ccount instead of reading/writing them directly; - re-initialize cpu_running every time before starting secondary CPU to flush possible previous CPU startup results. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
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@ -276,12 +276,13 @@ should_never_return:
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movi a2, cpu_start_ccount
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1:
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memw
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l32i a3, a2, 0
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beqi a3, 0, 1b
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movi a3, 0
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s32i a3, a2, 0
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memw
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1:
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memw
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l32i a3, a2, 0
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beqi a3, 0, 1b
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wsr a3, ccount
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@ -317,11 +318,13 @@ ENTRY(cpu_restart)
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rsr a0, prid
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neg a2, a0
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movi a3, cpu_start_id
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memw
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s32i a2, a3, 0
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#if XCHAL_DCACHE_IS_WRITEBACK
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dhwbi a3, 0
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#endif
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1:
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memw
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l32i a2, a3, 0
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dhi a3, 0
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bne a2, a0, 1b
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@ -195,9 +195,11 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts)
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int i;
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#ifdef CONFIG_HOTPLUG_CPU
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cpu_start_id = cpu;
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system_flush_invalidate_dcache_range(
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(unsigned long)&cpu_start_id, sizeof(cpu_start_id));
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WRITE_ONCE(cpu_start_id, cpu);
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/* Pairs with the third memw in the cpu_restart */
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mb();
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system_flush_invalidate_dcache_range((unsigned long)&cpu_start_id,
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sizeof(cpu_start_id));
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#endif
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smp_call_function_single(0, mx_cpu_start, (void *)cpu, 1);
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@ -206,18 +208,21 @@ static int boot_secondary(unsigned int cpu, struct task_struct *ts)
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ccount = get_ccount();
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while (!ccount);
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cpu_start_ccount = ccount;
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WRITE_ONCE(cpu_start_ccount, ccount);
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while (time_before(jiffies, timeout)) {
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do {
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/*
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* Pairs with the first two memws in the
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* .Lboot_secondary.
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*/
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mb();
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if (!cpu_start_ccount)
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break;
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}
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ccount = READ_ONCE(cpu_start_ccount);
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} while (ccount && time_before(jiffies, timeout));
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if (cpu_start_ccount) {
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if (ccount) {
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smp_call_function_single(0, mx_cpu_stop,
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(void *)cpu, 1);
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cpu_start_ccount = 0;
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(void *)cpu, 1);
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WRITE_ONCE(cpu_start_ccount, 0);
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return -EIO;
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}
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}
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@ -237,6 +242,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
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pr_debug("%s: Calling wakeup_secondary(cpu:%d, idle:%p, sp: %08lx)\n",
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__func__, cpu, idle, start_info.stack);
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init_completion(&cpu_running);
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ret = boot_secondary(cpu, idle);
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if (ret == 0) {
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wait_for_completion_timeout(&cpu_running,
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@ -298,8 +304,10 @@ void __cpu_die(unsigned int cpu)
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unsigned long timeout = jiffies + msecs_to_jiffies(1000);
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while (time_before(jiffies, timeout)) {
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system_invalidate_dcache_range((unsigned long)&cpu_start_id,
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sizeof(cpu_start_id));
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if (cpu_start_id == -cpu) {
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sizeof(cpu_start_id));
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/* Pairs with the second memw in the cpu_restart */
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mb();
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if (READ_ONCE(cpu_start_id) == -cpu) {
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platform_cpu_kill(cpu);
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return;
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}
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