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score: Allow interrupts during thread dispatch

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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.
This commit is contained in:
Sebastian Huber
2016-11-11 14:37:51 +01:00
parent f9aa34ddd9
commit d5e073cde7
7 changed files with 50 additions and 57 deletions
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29
c/src/lib/libcpu/powerpc/new-exceptions/cpu_asm.S
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@@ -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