4.20-stable review patch. If anyone has any objections, please let me know.
------------------
[ Upstream commit d8797b125711f23d83f5a71e908d34dfcd1fc3e9 ]
__install_bp_hardening_cb() is called via stop_machine() as part
of the cpu_enable callback. To force each CPU to take its turn
when allocating slots, they take a spinlock.
With the RT patches applied, the spinlock becomes a mutex,
and we get warnings about sleeping while in stop_machine():
| [ 0.319176] CPU features: detected: RAS Extension Support
| [ 0.319950] BUG: scheduling while atomic: migration/3/36/0x00000002
| [ 0.319955] Modules linked in:
| [ 0.319958] Preemption disabled at:
| [ 0.319969] [<ffff000008181ae4>] cpu_stopper_thread+0x7c/0x108
| [ 0.319973] CPU: 3 PID: 36 Comm: migration/3 Not tainted 4.19.1-rt3-00250-g330fc2c2a880 #2
| [ 0.319975] Hardware name: linux,dummy-virt (DT)
| [ 0.319976] Call trace:
| [ 0.319981] dump_backtrace+0x0/0x148
| [ 0.319983] show_stack+0x14/0x20
| [ 0.319987] dump_stack+0x80/0xa4
| [ 0.319989] __schedule_bug+0x94/0xb0
| [ 0.319991] __schedule+0x510/0x560
| [ 0.319992] schedule+0x38/0xe8
| [ 0.319994] rt_spin_lock_slowlock_locked+0xf0/0x278
| [ 0.319996] rt_spin_lock_slowlock+0x5c/0x90
| [ 0.319998] rt_spin_lock+0x54/0x58
| [ 0.320000] enable_smccc_arch_workaround_1+0xdc/0x260
| [ 0.320001] __enable_cpu_capability+0x10/0x20
| [ 0.320003] multi_cpu_stop+0x84/0x108
| [ 0.320004] cpu_stopper_thread+0x84/0x108
| [ 0.320008] smpboot_thread_fn+0x1e8/0x2b0
| [ 0.320009] kthread+0x124/0x128
| [ 0.320010] ret_from_fork+0x10/0x18
Switch this to a raw spinlock, as we know this is only called with
IRQs masked.
Signed-off-by: James Morse <james.morse@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/arm64/kernel/cpu_errata.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index 6ad715d67df8..99622e5ad21b 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -135,7 +135,7 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn,
const char *hyp_vecs_start,
const char *hyp_vecs_end)
{
- static DEFINE_SPINLOCK(bp_lock);
+ static DEFINE_RAW_SPINLOCK(bp_lock);
int cpu, slot = -1;
/*
@@ -147,7 +147,7 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn,
return;
}
- spin_lock(&bp_lock);
+ raw_spin_lock(&bp_lock);
for_each_possible_cpu(cpu) {
if (per_cpu(bp_hardening_data.fn, cpu) == fn) {
slot = per_cpu(bp_hardening_data.hyp_vectors_slot, cpu);
@@ -163,7 +163,7 @@ static void __install_bp_hardening_cb(bp_hardening_cb_t fn,
__this_cpu_write(bp_hardening_data.hyp_vectors_slot, slot);
__this_cpu_write(bp_hardening_data.fn, fn);
- spin_unlock(&bp_lock);
+ raw_spin_unlock(&bp_lock);
}
#else
#define __smccc_workaround_1_smc_start NULL
--
2.19.1
