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author | Ashwin Chaugule <ashwin.chaugule@linaro.org> | 2014-05-07 10:18:36 -0400 |
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committer | Ashwin Chaugule <ashwin.chaugule@linaro.org> | 2014-05-15 10:16:30 -0400 |
commit | c814ca029e1015bb0ecec312f4bb9751ba1a711a (patch) | |
tree | 75ff2a914c476700b4a2272c523416d7d4cb3328 /arch/arm64/kernel/psci.c | |
parent | e1cd3b361a4f1dd323252543f40d43509d80affa (diff) | |
download | linux-c814ca029e1015bb0ecec312f4bb9751ba1a711a.tar.bz2 |
ARM: Check if a CPU has gone offline
PSCIv0.2 adds a new function called AFFINITY_INFO, which
can be used to query if a specified CPU has actually gone
offline. Calling this function via cpu_kill ensures that
a CPU has quiesced after a call to cpu_die. This helps
prevent the CPU from doing arbitrary bad things when data
or instructions are clobbered (as happens with kexec)
in the window between a CPU announcing that it is dead
and said CPU leaving the kernel.
Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/psci.c')
-rw-r--r-- | arch/arm64/kernel/psci.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c index 90df6e641227..9e9798f91172 100644 --- a/arch/arm64/kernel/psci.c +++ b/arch/arm64/kernel/psci.c @@ -20,6 +20,7 @@ #include <linux/smp.h> #include <linux/reboot.h> #include <linux/pm.h> +#include <linux/delay.h> #include <uapi/linux/psci.h> #include <asm/compiler.h> @@ -403,6 +404,35 @@ static void cpu_psci_cpu_die(unsigned int cpu) pr_crit("unable to power off CPU%u (%d)\n", cpu, ret); } + +static int cpu_psci_cpu_kill(unsigned int cpu) +{ + int err, i; + + if (!psci_ops.affinity_info) + return 1; + /* + * cpu_kill could race with cpu_die and we can + * potentially end up declaring this cpu undead + * while it is dying. So, try again a few times. + */ + + for (i = 0; i < 10; i++) { + err = psci_ops.affinity_info(cpu_logical_map(cpu), 0); + if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) { + pr_info("CPU%d killed.\n", cpu); + return 1; + } + + msleep(10); + pr_info("Retrying again to check for CPU kill\n"); + } + + pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n", + cpu, err); + /* Make op_cpu_kill() fail. */ + return 0; +} #endif const struct cpu_operations cpu_psci_ops = { @@ -413,6 +443,7 @@ const struct cpu_operations cpu_psci_ops = { #ifdef CONFIG_HOTPLUG_CPU .cpu_disable = cpu_psci_cpu_disable, .cpu_die = cpu_psci_cpu_die, + .cpu_kill = cpu_psci_cpu_kill, #endif }; |