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arch: riscv: pmp: fix IRQ handling of PMP stack guard

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This commit add 2 minor fixes of IRQ handling:

1. Save caller registers before calling z_riscv_configure_stack_guard()
in RISC-V assembly.

2. reschedule and no_reschdule code paths use different interrupt
return path after supporting of CONFIG_PMP_STACK_GUARD. back-to-back
interrupt checking is in the reschedule code path so that it should
jump to interrupt return path of reschedule.

Signed-off-by: Jim Shu <cwshu09@gmail.com>
This commit is contained in:
Jim Shu 2022-01-09 22:01:02 +08:00 • committed by Carles Cufí
commit 5fc5beabe2
1 changed files with 19 additions and 2 deletions
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21
arch/riscv/core/isr.S
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@ -831,7 +831,7 @@ reschedule:
la t0, _kernel
RV_OP_LOADREG t2, _kernel_offset_to_current(t0)
RV_OP_LOADREG t3, _kernel_offset_to_ready_q_cache(t0)
beq t2, t3, no_reschedule
beq t2, t3, no_reschedule_resched
#if CONFIG_INSTRUMENT_THREAD_SWITCHING
call z_thread_mark_switched_out
@ -925,8 +925,16 @@ skip_load_fp_callee_saved:
#ifdef CONFIG_PMP_STACK_GUARD
mv a0, t1 /* kernel current */
/* Save t0/t1 caller registers for function call */
addi sp, sp, -16
RV_OP_STOREREG t0, 0(sp)
RV_OP_STOREREG t1, 8(sp)
jal ra, z_riscv_configure_stack_guard
#endif // CONFIG_PMP_STACK_GUARD
RV_OP_LOADREG t0, 0(sp)
RV_OP_LOADREG t1, 8(sp)
addi sp, sp, 16
#endif /* CONFIG_PMP_STACK_GUARD */
#ifdef CONFIG_USERSPACE
/* t0 still reference to _kernel */
@ -957,6 +965,15 @@ kernel_swap:
call z_thread_mark_switched_in
#endif
/*
* no_reschedule_resched is an another interrupt return path.
*
* When CONFIG_PMP_STACK_GUARD=y, reschedule & no_reschedule
* code paths use different sp and only no_reschedule code path
* needs to switch sp before interrupt return. Thus, we use
* another interrupt return path for reschedule path.
*/
no_reschedule_resched:
#ifdef CONFIG_RISCV_SOC_CONTEXT_SAVE
/* Restore context at SOC level */
addi a0, sp, __z_arch_esf_t_soc_context_OFFSET