* [PATCH 1/2] riscv: Support irq_work via self IPIs
2020-06-23 13:28 [PATCH 0/2] riscv: Add context tracker support Greentime Hu
@ 2020-06-23 13:28 ` Greentime Hu
2020-06-23 16:19 ` kernel test robot
2020-06-23 13:28 ` [PATCH 2/2] riscv: Enable context tracking Greentime Hu
1 sibling, 1 reply; 4+ messages in thread
From: Greentime Hu @ 2020-06-23 13:28 UTC (permalink / raw)
To: greentime.hu, linux-riscv, linux-kernel, aou, palmer,
paul.walmsley, guoren
Support for arch_irq_work_raise() and arch_irq_work_has_interrupt() was
missing from riscv (a prerequisite for FULL_NOHZ).
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
---
arch/riscv/include/asm/irq_work.h | 10 ++++++++++
arch/riscv/kernel/smp.c | 15 +++++++++++++++
2 files changed, 25 insertions(+)
create mode 100644 arch/riscv/include/asm/irq_work.h
diff --git a/arch/riscv/include/asm/irq_work.h b/arch/riscv/include/asm/irq_work.h
new file mode 100644
index 000000000000..eb9f3d9b15ed
--- /dev/null
+++ b/arch/riscv/include/asm/irq_work.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_IRQ_WORK_H
+#define _ASM_RISCV_IRQ_WORK_H
+
+static inline bool arch_irq_work_has_interrupt(void)
+{
+ return true;
+}
+
+#endif /* _ASM_RISCV_IRQ_WORK_H */
diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
index b1d4f452f843..554b0fb47060 100644
--- a/arch/riscv/kernel/smp.c
+++ b/arch/riscv/kernel/smp.c
@@ -16,6 +16,7 @@
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/delay.h>
+#include <linux/irq_work.h>
#include <asm/clint.h>
#include <asm/sbi.h>
@@ -26,6 +27,7 @@ enum ipi_message_type {
IPI_RESCHEDULE,
IPI_CALL_FUNC,
IPI_CPU_STOP,
+ IPI_IRQ_WORK,
IPI_MAX
};
@@ -123,6 +125,13 @@ static inline void clear_ipi(void)
clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
}
+#ifdef CONFIG_IRQ_WORK
+void arch_irq_work_raise(void)
+{
+ send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
+}
+#endif
+
void handle_IPI(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
@@ -158,6 +167,11 @@ void handle_IPI(struct pt_regs *regs)
ipi_stop();
}
+ if (ops & (1 << IPI_IRQ_WORK)) {
+ stats[IPI_IRQ_WORK]++;
+ irq_work_run();
+ }
+
BUG_ON((ops >> IPI_MAX) != 0);
/* Order data access and bit testing. */
@@ -173,6 +187,7 @@ static const char * const ipi_names[] = {
[IPI_RESCHEDULE] = "Rescheduling interrupts",
[IPI_CALL_FUNC] = "Function call interrupts",
[IPI_CPU_STOP] = "CPU stop interrupts",
+ [IPI_IRQ_WORK] = "IRQ work interrupts",
};
void show_ipi_stats(struct seq_file *p, int prec)
--
2.27.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH 2/2] riscv: Enable context tracking
2020-06-23 13:28 [PATCH 0/2] riscv: Add context tracker support Greentime Hu
2020-06-23 13:28 ` [PATCH 1/2] riscv: Support irq_work via self IPIs Greentime Hu
@ 2020-06-23 13:28 ` Greentime Hu
1 sibling, 0 replies; 4+ messages in thread
From: Greentime Hu @ 2020-06-23 13:28 UTC (permalink / raw)
To: greentime.hu, linux-riscv, linux-kernel, aou, palmer,
paul.walmsley, guoren
This patch implements and enables context tracking for riscv (which is a
prerequisite for CONFIG_NO_HZ_FULL support)
It adds checking for previous state in the entry that all excepttions and
interrupts goes to and calls context_tracking_user_exit() if it comes from
user space. It also calls context_tracking_user_enter() if it will return
to user space before restore_all.
This patch is tested with the dynticks-testing testcase in
qemu-system-riscv64 virt machine and Unleashed board.
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/dynticks-testing.git
We can see the log here. The tick got mostly stopped during the execution
of the user loop.
_-----=> irqs-off
/ _----=> need-resched
| / _---=> hardirq/softirq
|| / _--=> preempt-depth
||| / delay
TASK-PID CPU# |||| TIMESTAMP FUNCTION
| | | |||| | |
<idle>-0 [001] d..2 604.183512: sched_switch: prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=taskset next_pid=273 next_prio=120
user_loop-273 [001] d.h1 604.184788: hrtimer_expire_entry: hrtimer=000000002eda5fab function=tick_sched_timer now=604176096300
user_loop-273 [001] d.s2 604.184897: workqueue_queue_work: work struct=00000000383402c2 function=vmstat_update workqueue=00000000f36d35d4 req_cpu=1 cpu=1
user_loop-273 [001] dns2 604.185039: tick_stop: success=0 dependency=SCHED
user_loop-273 [001] dn.1 604.185103: tick_stop: success=0 dependency=SCHED
user_loop-273 [001] d..2 604.185154: sched_switch: prev_comm=taskset prev_pid=273 prev_prio=120 prev_state=R+ ==> next_comm=kworker/1:1 next_pid=46 next_prio=120
<...>-46 [001] .... 604.185194: workqueue_execute_start: work struct 00000000383402c2: function vmstat_update
<...>-46 [001] d..2 604.185266: sched_switch: prev_comm=kworker/1:1 prev_pid=46 prev_prio=120 prev_state=I ==> next_comm=taskset next_pid=273 next_prio=120
user_loop-273 [001] d.h1 604.188812: hrtimer_expire_entry: hrtimer=000000002eda5fab function=tick_sched_timer now=604180133400
user_loop-273 [001] d..1 604.189050: tick_stop: success=1 dependency=NONE
user_loop-273 [001] d..2 614.251386: sched_switch: prev_comm=user_loop prev_pid=273 prev_prio=120 prev_state=X ==> next_comm=swapper/1 next_pid=0 next_prio=120
<idle>-0 [001] d..2 614.315391: sched_switch: prev_comm=swapper/1 prev_pid=0 prev_prio=120 prev_state=R ==> next_comm=taskset next_pid=276 next_prio=120
Signed-off-by: Greentime Hu <greentime.hu@sifive.com>
---
arch/riscv/Kconfig | 1 +
arch/riscv/kernel/entry.S | 23 +++++++++++++++++++++++
2 files changed, 24 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 128192e14ff2..17520e11815b 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -52,6 +52,7 @@ config RISCV
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_ASM_MODVERSIONS
+ select HAVE_CONTEXT_TRACKING
select HAVE_COPY_THREAD_TLS
select HAVE_DMA_CONTIGUOUS if MMU
select HAVE_EBPF_JIT if MMU
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index cae7e6d4c7ef..6ed579fc1073 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -97,6 +97,14 @@ _save_context:
la gp, __global_pointer$
.option pop
+#ifdef CONFIG_CONTEXT_TRACKING
+ /* If previous state is in user mode, call context_tracking_user_exit. */
+ andi a0, s1, SR_SPP
+ bnez a0, skip_context_tracking
+ call context_tracking_user_exit
+
+skip_context_tracking:
+#endif
la ra, ret_from_exception
/*
* MSB of cause differentiates between
@@ -137,6 +145,17 @@ _save_context:
tail do_trap_unknown
handle_syscall:
+#ifdef CONFIG_CONTEXT_TRACKING
+ /* Recover a0 - a7 for system calls */
+ REG_L x10, PT_A0(sp)
+ REG_L x11, PT_A1(sp)
+ REG_L x12, PT_A2(sp)
+ REG_L x13, PT_A3(sp)
+ REG_L x14, PT_A4(sp)
+ REG_L x15, PT_A5(sp)
+ REG_L x16, PT_A6(sp)
+ REG_L x17, PT_A7(sp)
+#endif
/* save the initial A0 value (needed in signal handlers) */
REG_S a0, PT_ORIG_A0(sp)
/*
@@ -205,6 +224,10 @@ resume_userspace:
andi s1, s0, _TIF_WORK_MASK
bnez s1, work_pending
+#ifdef CONFIG_CONTEXT_TRACKING
+ call context_tracking_user_enter
+#endif
+
/* Save unwound kernel stack pointer in thread_info */
addi s0, sp, PT_SIZE_ON_STACK
REG_S s0, TASK_TI_KERNEL_SP(tp)
--
2.27.0
^ permalink raw reply related [flat|nested] 4+ messages in thread