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Revert "ANDROID: arm64: Disallow offlining the last aarch32 cpu"

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This reverts commit d4313b326c.

Bug: 178507149
Signed-off-by: Will Deacon <willdeacon@google.com>
Change-Id: I5ea1946c496211536840de9525a71901ad60a348
This commit is contained in:
Will Deacon 2021-01-25 15:00:58 +00:00
parent edde5dfd5d
commit d7ea8ab496
2 changed files with 3 additions and 57 deletions
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6
arch/arm64/Kconfig
View File

@ -1904,10 +1904,8 @@ config ASYMMETRIC_AARCH32
CPU configurations. Once the AArch32 EL0 support is detected
on a CPU, the feature is made available to user space to allow
the execution of 32-bit (compat) applications by migrating
them to the capable CPUs. You will not be able to offline all
such CPUs to prevent any running 32-bit application from being
killed. I.e: we guarantee there will always be at least one
32-bit capable CPU online.
them to the capable CPUs. Offlining such CPUs leads to 32-bit
applications being killed.
If unsure say N.

54
arch/arm64/kernel/smp.c
View File

@ -98,54 +98,6 @@ static inline int op_cpu_kill(unsigned int cpu)
}
#endif
#ifdef CONFIG_ASYMMETRIC_AARCH32
static int last_aarch32_cpu = -1;
static cpumask_t aarch32_online;
static void asym_aarch32_online(void)
{
/*
* Since we onlined another cpu, restore the hotpluggability of
* the last AAarch32 cpu if it was disabled.
*/
cpumask_and(&aarch32_online, &aarch32_el0_mask, cpu_online_mask);
if (last_aarch32_cpu >= 0 &&
cpumask_weight(&aarch32_online) > 1) {
struct device *dev;
dev = get_cpu_device(last_aarch32_cpu);
dev->offline_disabled = 0;
last_aarch32_cpu = -1;
}
}
static void asym_aarch32_offline(void)
{
/* Don't let the last AArch32-compatible CPU go down */
if (!cpumask_empty(&aarch32_el0_mask)) {
cpumask_and(&aarch32_online, &aarch32_el0_mask, cpu_online_mask);
/*
* If we're left with only one AAarch32 cpu, prevent it from
* being offlined.
*/
if (cpumask_weight(&aarch32_online) == 1) {
struct device *dev;
last_aarch32_cpu = cpumask_first(&aarch32_online);
dev = get_cpu_device(last_aarch32_cpu);
dev->offline_disabled = 1;
}
}
}
#else
static void asym_aarch32_online(void) {}
static void asym_aarch32_offline(void) {}
#endif
/*
* Boot a secondary CPU, and assign it the specified idle task.
@ -190,10 +142,8 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
*/
wait_for_completion_timeout(&cpu_running,
msecs_to_jiffies(5000));
if (cpu_online(cpu)) {
asym_aarch32_online();
if (cpu_online(cpu))
return 0;
}
pr_crit("CPU%u: failed to come online\n", cpu);
secondary_data.task = NULL;
@ -371,8 +321,6 @@ int __cpu_disable(void)
set_cpu_online(cpu, false);
ipi_teardown(cpu);
asym_aarch32_offline();
/*
* OK - migrate IRQs away from this CPU
*/