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riscv: Add SMP context switch support

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Update #3433.
This commit is contained in:
Sebastian Huber
2018-06-29 08:07:02 +02:00
parent 52352387cc
commit 109bc1c74b
1 changed files with 47 additions and 0 deletions
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47
cpukit/score/cpu/riscv/riscv-context-switch.S
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@@ -80,7 +80,25 @@ SYM(_CPU_Context_switch):
sw a3, RISCV_CONTEXT_ISR_DISPATCH_DISABLE(a0)
#ifdef RTEMS_SMP
/*
* 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.
*/
addi sp, a2, PER_CPU_INTERRUPT_FRAME_AREA + CPU_INTERRUPT_FRAME_SIZE
amoswap.w.rl zero, zero, RISCV_CONTEXT_IS_EXECUTING(a0)
.Ltry_update_is_executing:
/* Try to update the is executing indicator of the heir context */
li a3, 1
amoswap.w.aq a3, a3, RISCV_CONTEXT_IS_EXECUTING(a1)
bnez a3, .Lcheck_is_executing
#endif
.Lrestore:
lw a3, RISCV_CONTEXT_ISR_DISPATCH_DISABLE(a1)
LREG ra, RISCV_CONTEXT_RA(a1)
@@ -124,3 +142,32 @@ SYM(_CPU_Context_restore):
mv a1, a0
GET_SELF_CPU_CONTROL a2
j .Lrestore
#ifdef RTEMS_SMP
.Lcheck_is_executing:
/* Check the is executing indicator of the heir context */
lw a3, RISCV_CONTEXT_IS_EXECUTING(a1)
beqz a3, .Ltry_update_is_executing
/* We may have a new heir */
/* Read the executing and heir */
lw a4, PER_CPU_OFFSET_EXECUTING(a2)
lw a5, PER_CPU_OFFSET_HEIR(a2)
/*
* Update the executing only if necessary to avoid cache line
* monopolization.
*/
beq a4, a5, .Ltry_update_is_executing
/* Calculate the heir context pointer */
sub a4, a1, a4
add a1, a5, a4
/* Update the executing */
sw a5, PER_CPU_OFFSET_EXECUTING(a2)
j .Ltry_update_is_executing
#endif