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Posted to commits@nuttx.apache.org by GitBox <gi...@apache.org> on 2022/03/13 13:01:34 UTC
[GitHub] [incubator-nuttx] xiaoxiang781216 commented on a change in pull request #5731: arch/risc-v: Improve speed of context switch
xiaoxiang781216 commented on a change in pull request #5731:
URL: https://github.com/apache/incubator-nuttx/pull/5731#discussion_r825443766
##########
File path: arch/risc-v/src/qemu-rv/qemu_rv_head.S
##########
@@ -77,9 +77,9 @@ __start:
ld sp, 0(t0)
#endif
- /* sp (stack top) = sp + idle stack size */
+ /* sp (stack top) = sp + idle stack size - XCPTCONTEXT_SIZE */
- li t0, CONFIG_IDLETHREAD_STACKSIZE
+ li t0, CONFIG_IDLETHREAD_STACKSIZE - XCPTCONTEXT_SIZE
Review comment:
don't need reserve xcpt for idle thread
##########
File path: arch/risc-v/src/k210/k210_head.S
##########
@@ -73,9 +73,9 @@ __start:
ld sp, 0(t0)
- /* sp (stack top) = sp + idle stack size */
+ /* sp (stack top) = sp + idle stack size - XCPTCONTEXT_SIZE */
- li t0, CONFIG_IDLETHREAD_STACKSIZE
+ li t0, CONFIG_IDLETHREAD_STACKSIZE - XCPTCONTEXT_SIZE
Review comment:
don't preserve
##########
File path: arch/risc-v/src/common/riscv_schedulesigaction.c
##########
@@ -267,20 +258,34 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
* been delivered.
*/
- tcb->xcp.sigdeliver = (void *)sigdeliver;
- tcb->xcp.saved_epc = tcb->xcp.regs[REG_EPC];
- tcb->xcp.saved_int_ctx = tcb->xcp.regs[REG_INT_CTX];
+ tcb->xcp.sigdeliver = sigdeliver;
/* Then set up vector to the trampoline with interrupts
* disabled. We must already be in privileged thread mode
* to be here.
*/
- tcb->xcp.regs[REG_EPC] = (uintptr_t)riscv_sigdeliver;
+ /* Save the current register context location */
+
+ tcb->xcp.saved_regs = tcb->xcp.regs;
+
+ /* Duplicate the register context. These will be
+ * restored by the signal trampoline after the signal has
+ * been delivered.
+ */
+
+ tcb->xcp.regs = (uintptr_t *)STACK_ALIGN_DOWN(
+ (uintptr_t)tcb->xcp.regs -
+ XCPTCONTEXT_SIZE);
Review comment:
merge to line 278
##########
File path: arch/risc-v/src/common/riscv_schedulesigaction.c
##########
@@ -172,26 +162,27 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
* been delivered.
*/
- tcb->xcp.sigdeliver = sigdeliver;
- tcb->xcp.saved_epc = tcb->xcp.regs[REG_EPC];
- tcb->xcp.saved_int_ctx = tcb->xcp.regs[REG_INT_CTX];
+ tcb->xcp.sigdeliver = sigdeliver;
Review comment:
remove the extra space before =
##########
File path: arch/risc-v/src/common/riscv_schedulesigaction.c
##########
@@ -353,8 +370,22 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
*/
tcb->xcp.sigdeliver = (void *)sigdeliver;
- tcb->xcp.saved_epc = tcb->xcp.regs[REG_EPC];
- tcb->xcp.saved_int_ctx = tcb->xcp.regs[REG_INT_CTX];
+
+ /* Save the current register context location */
+
+ tcb->xcp.saved_regs = tcb->xcp.regs;
+
+ /* Duplicate the register context. These will be
+ * restored by the signal trampoline after the signal has been
+ * delivered.
+ */
+
+ tcb->xcp.regs = (uintptr_t *)STACK_ALIGN_DOWN(
+ (uintptr_t)tcb->xcp.regs -
+ XCPTCONTEXT_SIZE);
Review comment:
merge to line 384
##########
File path: arch/risc-v/src/common/riscv_schedulesigaction.c
##########
@@ -293,8 +298,26 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
*/
tcb->xcp.sigdeliver = (void *)sigdeliver;
- tcb->xcp.saved_epc = CURRENT_REGS[REG_EPC];
- tcb->xcp.saved_int_ctx = CURRENT_REGS[REG_INT_CTX];
+
+ /* And make sure that the saved context in the TCB is the
+ * same as the interrupt return context.
+ */
+
+ riscv_savestate(tcb->xcp.saved_regs);
+
+ /* Duplicate the register context. These will be
+ * restored by the signal trampoline after the signal has
+ * been delivered.
+ */
+
+ CURRENT_REGS = (uintptr_t *)STACK_ALIGN_DOWN(
+ (uintptr_t)CURRENT_REGS -
+ XCPTCONTEXT_SIZE);
Review comment:
align with line 314
##########
File path: arch/risc-v/src/common/riscv_schedulesigaction.c
##########
@@ -172,26 +162,27 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
* been delivered.
*/
- tcb->xcp.sigdeliver = sigdeliver;
- tcb->xcp.saved_epc = tcb->xcp.regs[REG_EPC];
- tcb->xcp.saved_int_ctx = tcb->xcp.regs[REG_INT_CTX];
+ tcb->xcp.sigdeliver = sigdeliver;
- /* Then set up to vector to the trampoline with interrupts
- * disabled. We must already be in privileged thread mode to be
- * here.
+ /* Save the current register context location */
+
+ tcb->xcp.saved_regs = tcb->xcp.regs;
+
+ /* Duplicate the register context. These will be
+ * restored by the signal trampoline after the signal has been
+ * delivered.
*/
- tcb->xcp.regs[REG_EPC] = (uintptr_t)riscv_sigdeliver;
+ tcb->xcp.regs = (uintptr_t *)STACK_ALIGN_DOWN(
+ (uintptr_t)tcb->xcp.regs - XCPTCONTEXT_SIZE);
+ memcpy(tcb->xcp.regs, tcb->xcp.saved_regs, XCPTCONTEXT_SIZE);
+
+ tcb->xcp.regs[REG_SP] = (uintptr_t)tcb->xcp.regs;
Review comment:
keep = at line 180 align with line 182
##########
File path: arch/risc-v/src/common/riscv_schedulesigaction.c
##########
@@ -267,20 +258,34 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
* been delivered.
*/
- tcb->xcp.sigdeliver = (void *)sigdeliver;
- tcb->xcp.saved_epc = tcb->xcp.regs[REG_EPC];
- tcb->xcp.saved_int_ctx = tcb->xcp.regs[REG_INT_CTX];
+ tcb->xcp.sigdeliver = sigdeliver;
/* Then set up vector to the trampoline with interrupts
* disabled. We must already be in privileged thread mode
* to be here.
*/
- tcb->xcp.regs[REG_EPC] = (uintptr_t)riscv_sigdeliver;
+ /* Save the current register context location */
+
+ tcb->xcp.saved_regs = tcb->xcp.regs;
+
+ /* Duplicate the register context. These will be
+ * restored by the signal trampoline after the signal has
+ * been delivered.
+ */
+
+ tcb->xcp.regs = (uintptr_t *)STACK_ALIGN_DOWN(
+ (uintptr_t)tcb->xcp.regs -
+ XCPTCONTEXT_SIZE);
- int_ctx = tcb->xcp.regs[REG_INT_CTX];
- int_ctx &= ~MSTATUS_MPIE;
+ memcpy(tcb->xcp.regs, tcb->xcp.saved_regs,
+ XCPTCONTEXT_SIZE);
Review comment:
merge to line 281
##########
File path: arch/risc-v/src/common/riscv_schedulesigaction.c
##########
@@ -293,8 +298,26 @@ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
*/
tcb->xcp.sigdeliver = (void *)sigdeliver;
- tcb->xcp.saved_epc = CURRENT_REGS[REG_EPC];
- tcb->xcp.saved_int_ctx = CURRENT_REGS[REG_INT_CTX];
+
+ /* And make sure that the saved context in the TCB is the
+ * same as the interrupt return context.
+ */
+
+ riscv_savestate(tcb->xcp.saved_regs);
+
+ /* Duplicate the register context. These will be
+ * restored by the signal trampoline after the signal has
+ * been delivered.
+ */
+
+ CURRENT_REGS = (uintptr_t *)STACK_ALIGN_DOWN(
+ (uintptr_t)CURRENT_REGS -
+ XCPTCONTEXT_SIZE);
+
+ memcpy((uintptr_t *)CURRENT_REGS, tcb->xcp.saved_regs,
+ XCPTCONTEXT_SIZE);
+
+ CURRENT_REGS[REG_SP] = (uintptr_t)CURRENT_REGS;
Review comment:
align = with line 327
##########
File path: arch/risc-v/src/common/riscv_initialstate.c
##########
@@ -74,24 +78,21 @@ void up_initial_state(struct tcb_s *tcb)
riscv_stack_color(tcb->stack_alloc_ptr, 0);
#endif /* CONFIG_STACK_COLORATION */
+ return;
}
- /* Initialize the initial exception register context structure */
-
- memset(xcp, 0, sizeof(struct xcptcontext));
+ xcp->regs = (uintptr_t *)(STACK_ALIGN_DOWN(
+ (uintptr_t)tcb->stack_base_ptr +
+ tcb->adj_stack_size -
+ XCPTCONTEXT_SIZE));
- /* Save the initial stack pointer. Hmmm.. the stack is set to the very
- * beginning of the stack region. Some functions may want to store data on
- * the caller's stack and it might be good to reserve some space. However,
- * only the start function would do that and we have control over that one
- */
+ /* Save the initial stack pointer */
- xcp->regs[REG_SP] = (uintptr_t)tcb->stack_base_ptr +
- tcb->adj_stack_size;
+ xcp->regs[REG_SP] = (uintptr_t)xcp->regs;
/* Save the task entry point */
- xcp->regs[REG_EPC] = (uintptr_t)tcb->start;
+ xcp->regs[REG_EPC] = (uintptr_t)tcb->start;
Review comment:
remove the space at before = at line 100 too
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