| Message ID | 20190129131223.32505-1-liwei391@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: fix potential deadlock in arm64-provide-pseudo-NMI-with-GICv3 | expand |
Hi Wei, Thanks testing the series. On 29/01/2019 13:12, Wei Li wrote: > In some exception handlers, the interrupt is not reenabled by daifclr at first. > The later process may call local_irq_enable() to enable the interrupt, like > gic_handle_irq(). As we known, function local_irq_enable() just change the pmr now. This is not yet in, so it might be useful to point to the series that adds this: https://lkml.org/lkml/2019/1/21/1060 > The following codes what i found may cause a deadlock or some issues else: > > do_sp_pc_abort <- el0_sp_pc > do_el0_ia_bp_hardening <- el0_ia > kgdb_roundup_cpus <- el1_dbg > > Signed-off-by: Wei Li <liwei391@huawei.com> > --- > arch/arm64/kernel/kgdb.c | 4 ++++ > arch/arm64/mm/fault.c | 6 ++++++ > 2 files changed, 10 insertions(+) > > diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c > index a20de58061a8..119fbf2c0788 100644 > --- a/arch/arm64/kernel/kgdb.c > +++ b/arch/arm64/kernel/kgdb.c > @@ -25,6 +25,7 @@ > #include <linux/kgdb.h> > #include <linux/kprobes.h> > #include <linux/sched/task_stack.h> > +#include <linux/irqchip/arm-gic-v3.h> > > #include <asm/debug-monitors.h> > #include <asm/insn.h> > @@ -291,6 +292,9 @@ static void kgdb_call_nmi_hook(void *ignored) > > void kgdb_roundup_cpus(unsigned long flags) Hmm, I don't see this function defined in arch/arm64/kernel/kgdb.c in v5.0-rc*. Was it removed? or is that something in your local tree. > { > + if (gic_prio_masking_enabled()) > + gic_arch_enable_irqs(); > + > local_irq_enable(); Seeing we introduce the daifflags functions, with the relation described at the top of arch/arm64/include/asm/daifflags.h. I think just calling local_irq_enable() might not comply with this, as PSR.I would be clear while PSR.D is set. Maybe it should be using: local_daif_restore(DAIF_PROCCTX); > smp_call_function(kgdb_call_nmi_hook, NULL, 0); > local_irq_disable(); and here local_daif_mask(); Although I'd like to understand what you are applying the pseudo-NMI series on first. > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index 97ba2ba78aee..f7c39a0b28bc 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -32,6 +32,7 @@ > #include <linux/perf_event.h> > #include <linux/preempt.h> > #include <linux/hugetlb.h> > +#include <linux/irqchip/arm-gic-v3.h> > > #include <asm/bug.h> > #include <asm/cmpxchg.h> > @@ -780,6 +781,8 @@ asmlinkage void __exception do_el0_ia_bp_hardening(unsigned long addr, > if (addr > TASK_SIZE) > arm64_apply_bp_hardening(); > > + if (gic_prio_masking_enabled()) > + gic_arch_enable_irqs(); > local_irq_enable(); This is not in mainline, in v5.0-rc1 there is: local_daif_restore(DAIF_PROCCTX); Which my series updates to modify both DAIF and PMR if needed. So you wouldn't need to have the gic_arch_enable_irqs(). > do_mem_abort(addr, esr, regs); > } > @@ -794,6 +797,9 @@ asmlinkage void __exception do_sp_pc_abort(unsigned long addr, > if (user_mode(regs)) { > if (instruction_pointer(regs) > TASK_SIZE) > arm64_apply_bp_hardening(); > + > + if (gic_prio_masking_enabled()) > + gic_arch_enable_irqs(); > local_irq_enable(); Same here. Thanks,
diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index a20de58061a8..119fbf2c0788 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -25,6 +25,7 @@ #include <linux/kgdb.h> #include <linux/kprobes.h> #include <linux/sched/task_stack.h> +#include <linux/irqchip/arm-gic-v3.h> #include <asm/debug-monitors.h> #include <asm/insn.h> @@ -291,6 +292,9 @@ static void kgdb_call_nmi_hook(void *ignored) void kgdb_roundup_cpus(unsigned long flags) { + if (gic_prio_masking_enabled()) + gic_arch_enable_irqs(); + local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); local_irq_disable(); diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 97ba2ba78aee..f7c39a0b28bc 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -32,6 +32,7 @@ #include <linux/perf_event.h> #include <linux/preempt.h> #include <linux/hugetlb.h> +#include <linux/irqchip/arm-gic-v3.h> #include <asm/bug.h> #include <asm/cmpxchg.h> @@ -780,6 +781,8 @@ asmlinkage void __exception do_el0_ia_bp_hardening(unsigned long addr, if (addr > TASK_SIZE) arm64_apply_bp_hardening(); + if (gic_prio_masking_enabled()) + gic_arch_enable_irqs(); local_irq_enable(); do_mem_abort(addr, esr, regs); } @@ -794,6 +797,9 @@ asmlinkage void __exception do_sp_pc_abort(unsigned long addr, if (user_mode(regs)) { if (instruction_pointer(regs) > TASK_SIZE) arm64_apply_bp_hardening(); + + if (gic_prio_masking_enabled()) + gic_arch_enable_irqs(); local_irq_enable(); }
In some exception handlers, the interrupt is not reenabled by daifclr at first. The later process may call local_irq_enable() to enable the interrupt, like gic_handle_irq(). As we known, function local_irq_enable() just change the pmr now. The following codes what i found may cause a deadlock or some issues else: do_sp_pc_abort <- el0_sp_pc do_el0_ia_bp_hardening <- el0_ia kgdb_roundup_cpus <- el1_dbg Signed-off-by: Wei Li <liwei391@huawei.com> --- arch/arm64/kernel/kgdb.c | 4 ++++ arch/arm64/mm/fault.c | 6 ++++++ 2 files changed, 10 insertions(+)