| From d0bab0c39e32d39a8c5cddca72e5b4a3059fe050 Mon Sep 17 00:00:00 2001 |
| From: Cristian Marussi <cristian.marussi@arm.com> |
| Date: Wed, 11 Mar 2020 17:12:44 +0000 |
| Subject: arm64: smp: fix smp_send_stop() behaviour |
| |
| From: Cristian Marussi <cristian.marussi@arm.com> |
| |
| commit d0bab0c39e32d39a8c5cddca72e5b4a3059fe050 upstream. |
| |
| On a system with only one CPU online, when another one CPU panics while |
| starting-up, smp_send_stop() will fail to send any STOP message to the |
| other already online core, resulting in a system still responsive and |
| alive at the end of the panic procedure. |
| |
| [ 186.700083] CPU3: shutdown |
| [ 187.075462] CPU2: shutdown |
| [ 187.162869] CPU1: shutdown |
| [ 188.689998] ------------[ cut here ]------------ |
| [ 188.691645] kernel BUG at arch/arm64/kernel/cpufeature.c:886! |
| [ 188.692079] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP |
| [ 188.692444] Modules linked in: |
| [ 188.693031] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.6.0-rc4-00001-g338d25c35a98 #104 |
| [ 188.693175] Hardware name: Foundation-v8A (DT) |
| [ 188.693492] pstate: 200001c5 (nzCv dAIF -PAN -UAO) |
| [ 188.694183] pc : has_cpuid_feature+0xf0/0x348 |
| [ 188.694311] lr : verify_local_elf_hwcaps+0x84/0xe8 |
| [ 188.694410] sp : ffff800011b1bf60 |
| [ 188.694536] x29: ffff800011b1bf60 x28: 0000000000000000 |
| [ 188.694707] x27: 0000000000000000 x26: 0000000000000000 |
| [ 188.694801] x25: 0000000000000000 x24: ffff80001189a25c |
| [ 188.694905] x23: 0000000000000000 x22: 0000000000000000 |
| [ 188.694996] x21: ffff8000114aa018 x20: ffff800011156a38 |
| [ 188.695089] x19: ffff800010c944a0 x18: 0000000000000004 |
| [ 188.695187] x17: 0000000000000000 x16: 0000000000000000 |
| [ 188.695280] x15: 0000249dbde5431e x14: 0262cbe497efa1fa |
| [ 188.695371] x13: 0000000000000002 x12: 0000000000002592 |
| [ 188.695472] x11: 0000000000000080 x10: 00400032b5503510 |
| [ 188.695572] x9 : 0000000000000000 x8 : ffff800010c80204 |
| [ 188.695659] x7 : 00000000410fd0f0 x6 : 0000000000000001 |
| [ 188.695750] x5 : 00000000410fd0f0 x4 : 0000000000000000 |
| [ 188.695836] x3 : 0000000000000000 x2 : ffff8000100939d8 |
| [ 188.695919] x1 : 0000000000180420 x0 : 0000000000180480 |
| [ 188.696253] Call trace: |
| [ 188.696410] has_cpuid_feature+0xf0/0x348 |
| [ 188.696504] verify_local_elf_hwcaps+0x84/0xe8 |
| [ 188.696591] check_local_cpu_capabilities+0x44/0x128 |
| [ 188.696666] secondary_start_kernel+0xf4/0x188 |
| [ 188.697150] Code: 52805001 72a00301 6b01001f 54000ec0 (d4210000) |
| [ 188.698639] ---[ end trace 3f12ca47652f7b72 ]--- |
| [ 188.699160] Kernel panic - not syncing: Attempted to kill the idle task! |
| [ 188.699546] Kernel Offset: disabled |
| [ 188.699828] CPU features: 0x00004,20c02008 |
| [ 188.700012] Memory Limit: none |
| [ 188.700538] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]--- |
| |
| [root@arch ~]# echo Helo |
| Helo |
| [root@arch ~]# cat /proc/cpuinfo | grep proce |
| processor : 0 |
| |
| Make smp_send_stop() account also for the online status of the calling CPU |
| while evaluating how many CPUs are effectively online: this way, the right |
| number of STOPs is sent, so enforcing a proper freeze of the system at the |
| end of panic even under the above conditions. |
| |
| Fixes: 08e875c16a16c ("arm64: SMP support") |
| Reported-by: Dave Martin <Dave.Martin@arm.com> |
| Acked-by: Mark Rutland <mark.rutland@arm.com> |
| Signed-off-by: Cristian Marussi <cristian.marussi@arm.com> |
| Signed-off-by: Will Deacon <will@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/arm64/kernel/smp.c | 17 ++++++++++++++--- |
| 1 file changed, 14 insertions(+), 3 deletions(-) |
| |
| --- a/arch/arm64/kernel/smp.c |
| +++ b/arch/arm64/kernel/smp.c |
| @@ -769,11 +769,22 @@ void tick_broadcast(const struct cpumask |
| } |
| #endif |
| |
| +/* |
| + * The number of CPUs online, not counting this CPU (which may not be |
| + * fully online and so not counted in num_online_cpus()). |
| + */ |
| +static inline unsigned int num_other_online_cpus(void) |
| +{ |
| + unsigned int this_cpu_online = cpu_online(smp_processor_id()); |
| + |
| + return num_online_cpus() - this_cpu_online; |
| +} |
| + |
| void smp_send_stop(void) |
| { |
| unsigned long timeout; |
| |
| - if (num_online_cpus() > 1) { |
| + if (num_other_online_cpus()) { |
| cpumask_t mask; |
| |
| cpumask_copy(&mask, cpu_online_mask); |
| @@ -784,10 +795,10 @@ void smp_send_stop(void) |
| |
| /* Wait up to one second for other CPUs to stop */ |
| timeout = USEC_PER_SEC; |
| - while (num_online_cpus() > 1 && timeout--) |
| + while (num_other_online_cpus() && timeout--) |
| udelay(1); |
| |
| - if (num_online_cpus() > 1) |
| + if (num_other_online_cpus()) |
| pr_warning("SMP: failed to stop secondary CPUs\n"); |
| } |
| |