4.20-stable review patch. If anyone has any objections, please let me know.
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[ 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@arm.com Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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