[rtems commit] score: Allow interrupts during thread dispatch
Sebastian Huber
sebh at rtems.org
Fri Nov 18 07:02:48 UTC 2016
Module: rtems
Branch: master
Commit: d5e073cde70211b2471e4366be397370e9f6ce48
Changeset: http://git.rtems.org/rtems/commit/?id=d5e073cde70211b2471e4366be397370e9f6ce48
Author: Sebastian Huber <sebastian.huber at embedded-brains.de>
Date: Fri Nov 11 14:37:51 2016 +0100
score: Allow interrupts during thread dispatch
Use a processor-specific interrupt frame during context switches in case
the executing thread is longer executes on the processor and the heir
thread is about to start execution. During this period we must not use
a thread stack for interrupt processing.
Update #2809.
---
c/src/lib/libbsp/sparc/shared/irq_asm.S | 19 +++++++++------
c/src/lib/libcpu/powerpc/new-exceptions/cpu_asm.S | 29 +++++++++++++----------
cpukit/score/cpu/arm/cpu_asm.S | 10 +++++---
cpukit/score/include/rtems/score/userextimpl.h | 13 +++++++++-
cpukit/score/src/threaddispatch.c | 17 +------------
cpukit/score/src/threadhandler.c | 3 ---
cpukit/score/src/threadloadenv.c | 16 +------------
7 files changed, 50 insertions(+), 57 deletions(-)
diff --git a/c/src/lib/libbsp/sparc/shared/irq_asm.S b/c/src/lib/libbsp/sparc/shared/irq_asm.S
index 7a595d1..a842a62 100644
--- a/c/src/lib/libbsp/sparc/shared/irq_asm.S
+++ b/c/src/lib/libbsp/sparc/shared/irq_asm.S
@@ -178,17 +178,22 @@ done_flushing:
mov %g4, %wim
#if defined(RTEMS_SMP)
- ! The executing context no longer executes on this processor
+ /*
+ * The executing thread no longer executes on this processor. Switch
+ * the stack to the temporary interrupt stack of this processor. Mark
+ * the context of the executing thread as not executing.
+ */
+ add %g6, PER_CPU_INTERRUPT_FRAME_AREA + CPU_INTERRUPT_FRAME_SIZE, %sp
st %g0, [%o0 + SPARC_CONTEXT_CONTROL_IS_EXECUTING_OFFSET]
! Try to update the is executing indicator of the heir context
mov 1, %g1
-try_update_is_executing:
+.Ltry_update_is_executing:
swap [%o1 + SPARC_CONTEXT_CONTROL_IS_EXECUTING_OFFSET], %g1
cmp %g1, 0
- bne check_is_executing
+ bne .Lcheck_is_executing
! The next load is in a delay slot, which is all right
#endif
@@ -225,12 +230,12 @@ try_update_is_executing:
nop ! delay slot
#if defined(RTEMS_SMP)
-check_is_executing:
+.Lcheck_is_executing:
! Check the is executing indicator of the heir context
ld [%o1 + SPARC_CONTEXT_CONTROL_IS_EXECUTING_OFFSET], %g1
cmp %g1, 0
- beq try_update_is_executing
+ beq .Ltry_update_is_executing
mov 1, %g1
! We may have a new heir
@@ -242,7 +247,7 @@ check_is_executing:
! Update the executing only if necessary to avoid cache line
! monopolization.
cmp %g2, %g4
- beq try_update_is_executing
+ beq .Ltry_update_is_executing
mov 1, %g1
! Calculate the heir context pointer
@@ -252,7 +257,7 @@ check_is_executing:
! Update the executing
st %g4, [%g6 + PER_CPU_OFFSET_EXECUTING]
- ba try_update_is_executing
+ ba .Ltry_update_is_executing
mov 1, %g1
#endif
diff --git a/c/src/lib/libcpu/powerpc/new-exceptions/cpu_asm.S b/c/src/lib/libcpu/powerpc/new-exceptions/cpu_asm.S
index 7f3c036..e5b4fcd 100644
--- a/c/src/lib/libcpu/powerpc/new-exceptions/cpu_asm.S
+++ b/c/src/lib/libcpu/powerpc/new-exceptions/cpu_asm.S
@@ -402,23 +402,30 @@ PROC (_CPU_Context_switch):
#endif
#ifdef RTEMS_SMP
- /* The executing context no longer executes on this processor */
+ /*
+ * The executing thread no longer executes on this processor. Switch
+ * the stack to the temporary interrupt stack of this processor. Mark
+ * the context of the executing thread as not executing.
+ */
msync
+
+ GET_SELF_CPU_CONTROL r12
+ addi r1, r12, PER_CPU_INTERRUPT_FRAME_AREA + CPU_INTERRUPT_FRAME_SIZE
li r6, 0
stw r6, PPC_CONTEXT_OFFSET_IS_EXECUTING(r3)
-check_is_executing:
+.Lcheck_is_executing:
/* Check the is executing indicator of the heir context */
addi r6, r5, PPC_CONTEXT_OFFSET_IS_EXECUTING
lwarx r7, r0, r6
cmpwi r7, 0
- bne get_potential_new_heir
+ bne .Lget_potential_new_heir
/* Try to update the is executing indicator of the heir context */
li r7, 1
stwcx. r7, r0, r6
- bne get_potential_new_heir
+ bne .Lget_potential_new_heir
isync
#endif
@@ -537,22 +544,20 @@ PROC (_CPU_Context_restore):
b restore_context
#ifdef RTEMS_SMP
-get_potential_new_heir:
-
- GET_SELF_CPU_CONTROL r6
+.Lget_potential_new_heir:
/* We may have a new heir */
/* Read the executing and heir */
- lwz r7, PER_CPU_OFFSET_EXECUTING(r6)
- lwz r8, PER_CPU_OFFSET_HEIR(r6)
+ lwz r7, PER_CPU_OFFSET_EXECUTING(r12)
+ lwz r8, PER_CPU_OFFSET_HEIR(r12)
/*
* Update the executing only if necessary to avoid cache line
* monopolization.
*/
cmpw r7, r8
- beq check_is_executing
+ beq .Lcheck_is_executing
/* Calculate the heir context pointer */
sub r7, r4, r7
@@ -560,7 +565,7 @@ get_potential_new_heir:
clrrwi r5, r4, PPC_DEFAULT_CACHE_LINE_POWER
/* Update the executing */
- stw r8, PER_CPU_OFFSET_EXECUTING(r6)
+ stw r8, PER_CPU_OFFSET_EXECUTING(r12)
- b check_is_executing
+ b .Lcheck_is_executing
#endif
diff --git a/cpukit/score/cpu/arm/cpu_asm.S b/cpukit/score/cpu/arm/cpu_asm.S
index cf94822..1ad3a51 100644
--- a/cpukit/score/cpu/arm/cpu_asm.S
+++ b/cpukit/score/cpu/arm/cpu_asm.S
@@ -69,8 +69,14 @@ DEFINE_FUNCTION_ARM(_CPU_Context_switch)
#endif
#ifdef RTEMS_SMP
- /* The executing context no longer executes on this processor */
+ /*
+ * The executing thread no longer executes on this processor. Switch
+ * the stack to the temporary interrupt stack of this processor. Mark
+ * the context of the executing thread as not executing.
+ */
dmb
+ GET_SELF_CPU_CONTROL r2
+ add sp, r2, #(PER_CPU_INTERRUPT_FRAME_AREA + CPU_INTERRUPT_FRAME_SIZE)
mov r3, #0
strb r3, [r0, #ARM_CONTEXT_CONTROL_IS_EXECUTING_OFFSET]
@@ -128,8 +134,6 @@ DEFINE_FUNCTION_ARM(_CPU_Context_restore)
#ifdef RTEMS_SMP
.L_get_potential_new_heir:
- GET_SELF_CPU_CONTROL r2
-
/* We may have a new heir */
/* Read the executing and heir */
diff --git a/cpukit/score/include/rtems/score/userextimpl.h b/cpukit/score/include/rtems/score/userextimpl.h
index e175c9f..e6692c8 100644
--- a/cpukit/score/include/rtems/score/userextimpl.h
+++ b/cpukit/score/include/rtems/score/userextimpl.h
@@ -261,8 +261,16 @@ static inline void _User_extensions_Thread_switch(
const Chain_Node *node = _Chain_Immutable_first( chain );
if ( node != tail ) {
- Per_CPU_Control *cpu_self = _Per_CPU_Get();
+ Per_CPU_Control *cpu_self;
+#if defined(RTEMS_SMP)
+ ISR_Level level;
+#endif
+
+ cpu_self = _Per_CPU_Get();
+#if defined(RTEMS_SMP)
+ _ISR_Local_disable( level );
+#endif
_Per_CPU_Acquire( cpu_self );
while ( node != tail ) {
@@ -275,6 +283,9 @@ static inline void _User_extensions_Thread_switch(
}
_Per_CPU_Release( cpu_self );
+#if defined(RTEMS_SMP)
+ _ISR_Local_enable( level );
+#endif
}
}
diff --git a/cpukit/score/src/threaddispatch.c b/cpukit/score/src/threaddispatch.c
index c96299c..f2c2490 100644
--- a/cpukit/score/src/threaddispatch.c
+++ b/cpukit/score/src/threaddispatch.c
@@ -174,14 +174,7 @@ void _Thread_Do_dispatch( Per_CPU_Control *cpu_self, ISR_Level level )
if ( heir->budget_algorithm == THREAD_CPU_BUDGET_ALGORITHM_RESET_TIMESLICE )
heir->cpu_time_budget = rtems_configuration_get_ticks_per_timeslice();
- /*
- * On SMP the complete context switch must be atomic with respect to one
- * processor. See also _Thread_Handler() since _Context_switch() may branch
- * to this function.
- */
-#if !defined( RTEMS_SMP )
_ISR_Local_enable( level );
-#endif
_User_extensions_Thread_switch( executing, heir );
_Thread_Save_fp( executing );
@@ -195,16 +188,8 @@ void _Thread_Do_dispatch( Per_CPU_Control *cpu_self, ISR_Level level )
*/
cpu_self = _Per_CPU_Get();
-#if !defined( RTEMS_SMP )
_ISR_Local_disable( level );
-#endif
- } while (
-#if defined( RTEMS_SMP )
- false
-#else
- cpu_self->dispatch_necessary
-#endif
- );
+ } while ( cpu_self->dispatch_necessary );
post_switch:
_Assert( cpu_self->thread_dispatch_disable_level == 1 );
diff --git a/cpukit/score/src/threadhandler.c b/cpukit/score/src/threadhandler.c
index 397e0cf..a8d6580 100644
--- a/cpukit/score/src/threadhandler.c
+++ b/cpukit/score/src/threadhandler.c
@@ -38,9 +38,6 @@ void _Thread_Handler( void )
_Context_Initialization_at_thread_begin();
executing = _Thread_Executing;
- /* On SMP we enter _Thread_Handler() with interrupts disabled */
- _SMP_Assert( _ISR_Get_level() != 0 );
-
/*
* have to put level into a register for those cpu's that use
* inline asm here
diff --git a/cpukit/score/src/threadloadenv.c b/cpukit/score/src/threadloadenv.c
index 43564af..22606dd 100644
--- a/cpukit/score/src/threadloadenv.c
+++ b/cpukit/score/src/threadloadenv.c
@@ -25,8 +25,6 @@ void _Thread_Load_environment(
Thread_Control *the_thread
)
{
- uint32_t isr_level;
-
#if ( CPU_HARDWARE_FP == TRUE ) || ( CPU_SOFTWARE_FP == TRUE )
if ( the_thread->Start.fp_context ) {
the_thread->fp_context = the_thread->Start.fp_context;
@@ -38,25 +36,13 @@ void _Thread_Load_environment(
the_thread->budget_algorithm = the_thread->Start.budget_algorithm;
the_thread->budget_callout = the_thread->Start.budget_callout;
-#if defined( RTEMS_SMP )
- /*
- * On SMP we have to start the threads with interrupts disabled, see also
- * _Thread_Handler() and _Thread_Dispatch(). In _Thread_Handler() the
- * _ISR_Set_level() is used to set the desired interrupt state of the thread.
- */
- isr_level = CPU_MODES_INTERRUPT_MASK;
-#else
- isr_level = the_thread->Start.isr_level;
-#endif
-
_Context_Initialize(
&the_thread->Registers,
the_thread->Start.Initial_stack.area,
the_thread->Start.Initial_stack.size,
- isr_level,
+ the_thread->Start.isr_level,
_Thread_Handler,
the_thread->is_fp,
the_thread->Start.tls_area
);
-
}
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