[RFC PATCH v3 1/8] arm64: Introduce cpu_die_early

Suzuki K. Poulose
2015-12-09T09:57:42Z

Or in other words, make fail_incapable_cpu() reusable.

We use fail_incapable_cpu() to kill a secondary CPU early during the
bringup, which doesn't have the system advertised capabilities.
This patch makes the routine more generic, to kill a secondary
booting CPU, getting rid of the dependency on capability struct.
This can be used by checks which are not necessarily attached to
a capability struct (e.g, cpu ASIDBits).

In that process, renames the function to cpu_die_early() to better
match its functionality. This will be later moved to arch/arm64/kernel/smp.c.

Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
arch/arm64/kernel/cpufeature.c | 33 ++++++++++++++++++++-------------
1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 0669c63..581b779 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -826,25 +826,26 @@ static u64 __raw_read_system_reg(u32 sys_id)
}

/*
- * Park the CPU which doesn't have the capability as advertised
- * by the system.
+ * Kill the calling secondary CPU, early in bringup before it is turned
+ * online.
*/
-static void fail_incapable_cpu(char *cap_type,
- const struct arm64_cpu_capabilities *cap)
+void cpu_die_early(void)
{
int cpu = smp_processor_id();

- pr_crit("CPU%d: missing %s : %s\n", cpu, cap_type, cap->desc);
+ pr_crit("CPU%d: will not boot\n", cpu);
+
/* Mark this CPU absent */
set_cpu_present(cpu, 0);

/* Check if we can park ourselves */
if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_die)
cpu_ops[cpu]->cpu_die(cpu);
- asm(
- "1: wfe\n"
- " wfi\n"
- " b 1b");
+
+ for (;;) {
+ wfe();
+ wfi();
+ }
}

/*
@@ -875,8 +876,11 @@ void verify_local_cpu_capabilities(void)
* If the new CPU misses an advertised feature, we cannot proceed
* further, park the cpu.
*/
- if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i]))
- fail_incapable_cpu("arm64_features", &caps[i]);
+ if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i])) {
+ pr_crit("CPU%d: missing feature: %s\n",
+ smp_processor_id(), caps[i].desc);
+ cpu_die_early();
+ }
if (caps[i].enable)
caps[i].enable(NULL);
}
@@ -884,8 +888,11 @@ void verify_local_cpu_capabilities(void)
for (i = 0, caps = arm64_hwcaps; caps[i].desc; i++) {
if (!cpus_have_hwcap(&caps[i]))
continue;
- if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i]))
- fail_incapable_cpu("arm64_hwcaps", &caps[i]);
+ if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i])) {
+ pr_crit("CPU%d: missing HWCAP: %s\n",
+ smp_processor_id(), caps[i].desc);
+ cpu_die_early();
+ }
}
}

--
1.7.9.5