interrupt: filter out reserved int number by decoding risc-v JAL instruction

components/hal/interrupt_controller_hal.c

@@ -14,11 +14,27 @@
 
 #include "hal/interrupt_controller_hal.h"
 
+#if __riscv
+#include "riscv/instruction_decode.h"
+
+static bool is_interrupt_number_reserved(int interrupt_number)
+{
+    extern int _vector_table;
+    extern int _interrupt_handler;
+    const intptr_t pc = (intptr_t)(&_vector_table + interrupt_number);
+
+    /* JAL instructions are relative to the PC there are executed from. */
+    const intptr_t destination = pc + riscv_decode_offset_from_jal_instruction(pc);
+
+    return destination != (intptr_t)&_interrupt_handler;
+}
+#endif
+
 int_type_t interrupt_controller_hal_desc_type(int interrupt_number)
 {
 #ifndef SOC_CPU_HAS_FLEXIBLE_INTC
     const int_desc_t *int_desc = interrupt_controller_hal_desc_table();
-    return(int_desc[interrupt_number].type);
+    return (int_desc[interrupt_number].type);
 #else
     return (INTTP_NA);
 #endif
@@ -28,7 +44,7 @@ int interrupt_controller_hal_desc_level(int interrupt_number)
 {
 #ifndef SOC_CPU_HAS_FLEXIBLE_INTC
     const int_desc_t *int_desc = interrupt_controller_hal_desc_table();
-    return(int_desc[interrupt_number].level);
+    return (int_desc[interrupt_number].level);
 #else
     return 1;
 #endif
@@ -38,8 +54,12 @@ int_desc_flag_t interrupt_controller_hal_desc_flags(int interrupt_number, int cp
 {
 #ifndef SOC_CPU_HAS_FLEXIBLE_INTC
     const int_desc_t *int_desc = interrupt_controller_hal_desc_table();
-    return(int_desc[interrupt_number].cpuflags[cpu_number]);
+    return (int_desc[interrupt_number].cpuflags[cpu_number]);
+#else
+#if __riscv
+    return is_interrupt_number_reserved(interrupt_number) ? INTDESC_RESVD : INTDESC_NORMAL;
 #else
     return INTDESC_NORMAL;
 #endif
+#endif
 }

components/riscv/CMakeLists.txt

@@ -7,10 +7,11 @@ if(BOOTLOADER_BUILD)
 else()
     set(priv_requires soc freertos)
     set(srcs
-        "interrupt.c"
-        "stdatomic.c"
         "expression_with_stack_riscv.c"
         "expression_with_stack_riscv_asm.S"
+        "instruction_decode.c"
+        "interrupt.c"
+        "stdatomic.c"
         "vectors.S")
 endif()
 

components/riscv/include/riscv/instruction_decode.h

@@ -3,7 +3,7 @@
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
-
+//
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
@@ -14,12 +14,20 @@
 
 #pragma once
 
+#include <stdint.h>
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#define SOC_INTERRUPT_LEVEL_CAN_SET (1)
-#define SOC_INTERRUPT_TYPE_CAN_SET  (1)
+/**
+ * @brief Decode the offset value from a RISC-V JAL instruction
+ * @note This API will abort if the instruction is not JAL formatted.
+ *
+ * @param inst_addr Address of JAL instruction
+ * @return int offset value
+ */
+int riscv_decode_offset_from_jal_instruction(const intptr_t inst_addr);
 
 #ifdef __cplusplus
 }

components/riscv/instruction_decode.c

@@ -0,0 +1,38 @@
+// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <stdlib.h>
+#include "riscv/instruction_decode.h"
+
+typedef union {
+    struct {
+        unsigned int opcode: 7;
+        unsigned int rd: 5;
+        int imm_19_12: 8;
+        int imm_11: 1;
+        int imm_10_1: 10;
+        int imm20: 1;
+    };
+    unsigned int inst;
+} riscv_jal_intruction_t;
+
+int riscv_decode_offset_from_jal_instruction(const intptr_t inst_addr)
+{
+    riscv_jal_intruction_t *jal_inst = (riscv_jal_intruction_t *)inst_addr;
+    // check if it's a valid JAL instruction
+    if (jal_inst->opcode != 0x6f && jal_inst->rd != 0) {
+        abort();
+    }
+    return (jal_inst->imm_10_1 | jal_inst->imm_11 << 10 | jal_inst->imm_19_12 << 11 | jal_inst->imm20 << 19) << 1;
+}