課程影片連結：
6.S081 Fall 2020 Lecture 5: RISC-V Calling Convention and Stack Frames 這篇文章目的在於整理這個影片的重點，主要有以下的重點
如何用 GDB 追蹤 user program RISC-V 的 Calling Convention RISC-V 的 register (Caller and Callee saved) RISC-V 的 Stack Frame 影片中的範例程式並沒有附在 lab 中，要自己新增：
新增影片中的範例程式 kernel/defs.h // demos.c void demo1(void); void demo2(void); void demo3(void); void demo4(void); void demo5(void); void demo6(void); void demo7(void); // asmdemo.S int sum_to(int); int sum_then_double(int); kernel/demos.c #include "types.h" #include "riscv.h" #include "defs.h" #include "date.h" #include "param.h" #include "memlayout.h" #include "spinlock.h" #include "proc.h" #include "sysinfo.h" void demo1() { printf("Result: %d\n", sum_to(5)); } void demo2() { printf("Tesult: %d\n", sum_ten_double(5)); } void _demo3(char a, char b, char c, char d, char e, char f, char g, char h, char i, char j) { printf("%d, %d, %d, %d, %d, %d, %d, %d, %d, %d\n", a, b, c, d, e, f, g, h, i, j); } void demo3() { _demo3('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'); } int dummymain(int argc, char *argv[]) { int i = 0; for (; i < argc; i++) { printf("Argument %d: %s\n", i, argv[i]); } return 0; } void demo4() { char *args[] = {"foo", "bar", "baz"}; int result = dummymain(sizeof(args)/sizeof(args[0]), args); if (result < 0) panic("Demo 4"); } int _dummy(int n) { int div = 5; int sum = 0; for (int i=0; i < n; i++) { if (i % div == 0) sum += i; } return sum; } void demo5() { printf("Demo\n"); int top = 50; int result = _dummy(top); printf("Result: %d\n", result); } void demo6() { int sum = 0; for (int i = 1; i < 10; i++) { sum += 3 *i; printf("%d\n", sum_to(i)); } printf("Sum: %d\n", sum); } struct Person { int id; int age; // char *name; }; void printPerson(struct Person *p) { printf("Person %d (%d)\n", p->id, p->age); // printf("Name:%s: %d (%d)\n", p->name, p->id, p->age); } void demo7() { // Structs struct Person p; p.id = 1215; p.age = 22; // p.name = "Nick"; printPerson(&p); } kernel/asmdemo.S .section .text .global sum_to /* int sum_to() { int acc = 0; for (int i = 0; i <= n; i++) { acc += i; } return acc; } */ sum_to: mv t0, a0 # t0 <- a0 li a0, 0 # a0 <- 0 loop: add a0, a0, t0 # a0 <- a0 + t0 addi t0, t0, -1 # t0 <- t0 - 1 bnez t0, loop # if t0 != 0: pc <- loop ret .global sum_then_double sum_then_double: addi sp, sp, -16 sd ra, 0(sp) call sum_to li t0, 2 mul a0, a0, t0 ld ra, 0(sp) addi sp, sp, 16 ret Makefile OBJS = \ $K/entry.o \ $K/kalloc.o \ $K/string.o \ ... $K/plic.o \ $K/virtio_disk.o \ $K/demos.o \ $K/asmdemo.o 新增 system call demo() user/usys.pl 加上 entry(demo);
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