@@ -26,8 +26,12 @@ static __must_check inline bool may_use_simd(void)
/*
* RISCV_KERNEL_MODE_V is only set while preemption is disabled,
* and is clear whenever preemption is enabled.
+ *
+ * Kernel-mode Vector temperarily disables bh. So we must not return
+ * true on irq_disabled(). Otherwise we would fail the lockdep check
+ * calling local_bh_enable()
*/
- return !in_hardirq() && !in_nmi() && !(riscv_v_ctx_cnt() & RISCV_KERNEL_MODE_V_MASK);
+ return !in_hardirq() && !in_nmi() && !irqs_disabled() && !(riscv_v_ctx_cnt() & RISCV_KERNEL_MODE_V_MASK);
}
#else /* ! CONFIG_RISCV_ISA_V */
@@ -23,7 +23,10 @@
*/
void get_cpu_vector_context(void)
{
- preempt_disable();
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ local_bh_disable();
+ else
+ preempt_disable();
WARN_ON(riscv_v_ctx_cnt() & RISCV_KERNEL_MODE_V_MASK);
riscv_v_ctx_cnt_add(RISCV_KERNEL_MODE_V);
@@ -41,7 +44,10 @@ void put_cpu_vector_context(void)
WARN_ON(!(riscv_v_ctx_cnt() & RISCV_KERNEL_MODE_V_MASK));
riscv_v_ctx_cnt_sub(RISCV_KERNEL_MODE_V);
- preempt_enable();
+ if (!IS_ENABLED(CONFIG_PREEMPT_RT))
+ local_bh_enable();
+ else
+ preempt_enable();
}
/*
By disabling bottom halves in active kerne-mode Vector, softirq will not be able to nest on top of any kernel-mode Vector. After this patch, Vector context cannot start with irqs disabled. Otherwise local_bh_enable() may run in a wrong context. Disabling bh is not enough for RT-kernel to prevent preeemption. So we must disable preemption, which also implies disabling bh on RT. Related-to: commit 696207d4258b ("arm64/sve: Make kernel FPU protection RT friendly") Related-to: commit 66c3ec5a7120 ("arm64: neon: Forbid when irqs are disabled") Signed-off-by: Andy Chiu <andy.chiu@sifive.com> --- Changelog v4: - new patch since v4 --- arch/riscv/include/asm/simd.h | 6 +++++- arch/riscv/kernel/kernel_mode_vector.c | 10 ++++++++-- 2 files changed, 13 insertions(+), 3 deletions(-)