Mips exercise

.gitignore

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+.vscode
+.idea
+*.o
+*.swp
+*.objdump
+*~
+tags
+hello

Makefile

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+ENDIAN                  := EL
+
+QEMU                    := qemu-system-mipsel
+CROSS_COMPILE           := mips-linux-gnu-
+CC                      := $(CROSS_COMPILE)gcc
+CFLAGS                  += --std=gnu99 -$(ENDIAN) -G 0 -mno-abicalls -fno-pic \
+                        -ffreestanding -fno-stack-protector -fno-builtin \
+                        -Wa,-xgot -Wall -mxgot -mno-fix-r4000 -march=4kc -g -ggdb
+LD                      := $(CROSS_COMPILE)ld
+LDFLAGS                 += -EL -G 0 -static -n -nostdlib --fatal-warnings
+INCLUDES                := -I./include/
+target                  := hello
+objects                 := hello.o output.o start.o
+qemu_files              += hello
+qemu_flags              += -cpu 4Kc -m 64 -nographic -M malta -no-reboot
+
+%.o: %.c
+	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
+
+%.o: %.S
+	$(CC) $(CFLAGS) $(INCLUDES) -c -o $@ $<
+
+.PHONY: all clean dbg
+
+all:    hello
+
+hello:  linker.lds $(objects)
+	$(LD) $(LDFLAGS) -o hello -N -T linker.lds $(objects)
+
+clean:
+	rm -rf *~ *.o hello *.objdump
+
+dbg_run: qemu_flags += -s -S
+dbg_run: run
+
+dbg:
+	make dbg_run >/dev/null 2>&1 &
+	gdb-multiarch $(target) -ex "target remote localhost:1234"
+	killall $(QEMU)
+
+run:
+	$(QEMU) $(qemu_flags)  -kernel $(qemu_files)
+
+objdump:
+	$(CROSS_COMPILE)objdump $(target) -aldS > hello.objdump

hello.c

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+#include "output.h"
+#include <stddef.h>
+
+void hello(int a, int b, int c, int d, int e, int f) {
+	print_num(a);
+	print_str("\n");
+	print_num(b);
+	print_str("\n");
+	print_num(c);
+	print_str("\n");
+	print_num(d);
+	print_str("\n");
+	print_num(e);
+	print_str("\n");
+	print_num(f);
+	print_str("\n");
+	halt();
+}

include/asm/asm.h

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+#include <asm/cp0regdef.h>
+#include <asm/regdef.h>
+
+/*
+ * LEAF - declare leaf routine
+ */
+#define LEAF(symbol)                                                                               \
+	.globl symbol;                                                                             \
+	.align 2;                                                                                  \
+	.type symbol, @function;                                                                   \
+	.ent symbol;                                                                               \
+	symbol:                                                                                    \
+	.frame sp, 0, ra
+
+/*
+ * NESTED - declare nested routine entry point
+ */
+#define NESTED(symbol, framesize, rpc)                                                             \
+	.globl symbol;                                                                             \
+	.align 2;                                                                                  \
+	.type symbol, @function;                                                                   \
+	.ent symbol;                                                                               \
+	symbol:                                                                                    \
+	.frame sp, framesize, rpc
+
+/*
+ * END - mark end of function
+ */
+#define END(function)                                                                              \
+	.end function;                                                                             \
+	.size function, .- function
+
+#define EXPORT(symbol)                                                                             \
+	.globl symbol;                                                                             \
+	symbol:
+
+#define FEXPORT(symbol)                                                                            \
+	.globl symbol;                                                                             \
+	.type symbol, @function;                                                                   \
+	symbol:

include/asm/cp0regdef.h

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+#ifndef _cp0regdef_h_
+#define _cp0regdef_h_
+
+#define CP0_INDEX $0
+#define CP0_RANDOM $1
+#define CP0_ENTRYLO0 $2
+#define CP0_ENTRYLO1 $3
+#define CP0_CONTEXT $4
+#define CP0_PAGEMASK $5
+#define CP0_WIRED $6
+#define CP0_BADVADDR $8
+#define CP0_COUNT $9
+#define CP0_ENTRYHI $10
+#define CP0_COMPARE $11
+#define CP0_STATUS $12
+#define CP0_CAUSE $13
+#define CP0_EPC $14
+#define CP0_PRID $15
+#define CP0_CONFIG $16
+#define CP0_LLADDR $17
+#define CP0_WATCHLO $18
+#define CP0_WATCHHI $19
+#define CP0_XCONTEXT $20
+#define CP0_FRAMEMASK $21
+#define CP0_DIAGNOSTIC $22
+#define CP0_PERFORMANCE $25
+#define CP0_ECC $26
+#define CP0_CACHEERR $27
+#define CP0_TAGLO $28
+#define CP0_TAGHI $29
+#define CP0_ERROREPC $30
+
+#define STATUS_CU0 0x10000000
+#define STATUS_IM4 0x1000
+#define STATUS_KUp 0x8
+#define STATUS_IEp 0x4
+#define STATUS_KUc 0x2
+#define STATUS_IEc 0x1
+#endif

include/asm/readme.md

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+

include/asm/regdef.h

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+#ifndef __ASM_MIPS_REGDEF_H
+#define __ASM_MIPS_REGDEF_H
+
+/*
+ * Symbolic register names for 32 bit ABI
+ */
+#define zero $0 /* wired zero */
+#define AT $1	/* assembler temp  - uppercase because of ".set at" */
+#define v0 $2	/* return value */
+#define v1 $3
+#define a0 $4 /* argument registers */
+#define a1 $5
+#define a2 $6
+#define a3 $7
+#define t0 $8 /* caller saved */
+#define t1 $9
+#define t2 $10
+#define t3 $11
+#define t4 $12
+#define t5 $13
+#define t6 $14
+#define t7 $15
+#define s0 $16 /* callee saved */
+#define s1 $17
+#define s2 $18
+#define s3 $19
+#define s4 $20
+#define s5 $21
+#define s6 $22
+#define s7 $23
+#define t8 $24 /* caller saved */
+#define t9 $25
+#define jp $25 /* PIC jump register */
+#define k0 $26 /* kernel scratch */
+#define k1 $27
+#define gp $28 /* global pointer */
+#define sp $29 /* stack pointer */
+#define fp $30 /* frame pointer */
+#define s8 $30 /* same like fp! */
+#define ra $31 /* return address */
+
+#endif /* __ASM_MIPS_REGDEF_H */

include/machine.h

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+#ifndef _MACHINE_H
+#define _MACHINE_H
+
+// Memory segments (32-bit kernel mode addresses)
+#define KUSEG 0x00000000U
+#define KSEG0 0x80000000U
+#define KSEG1 0xA0000000U
+#define KSEG2 0xC0000000U
+
+/*
+ * QEMU MMIO address definitions.
+ */
+#define MALTA_PCIIO_BASE 0x18000000
+#define MALTA_FPGA_BASE 0x1f000000
+
+/*
+ * 16550 Serial UART device definitions.
+ */
+#define MALTA_SERIAL_BASE (MALTA_PCIIO_BASE + 0x3f8)
+#define MALTA_SERIAL_DATA (MALTA_SERIAL_BASE + 0x0)
+#define MALTA_SERIAL_LSR (MALTA_SERIAL_BASE + 0x5)
+#define MALTA_SERIAL_DATA_READY 0x1
+#define MALTA_SERIAL_THR_EMPTY 0x20
+
+/*
+ * Intel PIIX4 IDE Controller device definitions.
+ * Hardware documentation available at
+ * https://www.intel.com/Assets/PDF/datasheet/290562.pdf
+ */
+#define MALTA_IDE_BASE (MALTA_PCIIO_BASE + 0x01f0)
+#define MALTA_IDE_DATA (MALTA_IDE_BASE + 0x00)
+#define MALTA_IDE_ERR (MALTA_IDE_BASE + 0x01)
+#define MALTA_IDE_NSECT (MALTA_IDE_BASE + 0x02)
+#define MALTA_IDE_LBAL (MALTA_IDE_BASE + 0x03)
+#define MALTA_IDE_LBAM (MALTA_IDE_BASE + 0x04)
+#define MALTA_IDE_LBAH (MALTA_IDE_BASE + 0x05)
+#define MALTA_IDE_DEVICE (MALTA_IDE_BASE + 0x06)
+#define MALTA_IDE_STATUS (MALTA_IDE_BASE + 0x07)
+#define MALTA_IDE_LBA 0xE0
+#define MALTA_IDE_BUSY 0x80
+#define MALTA_IDE_CMD_PIO_READ 0x20  /* Read sectors with retry */
+#define MALTA_IDE_CMD_PIO_WRITE 0x30 /* write sectors with retry */
+
+/*
+ * MALTA Power Management device definitions.
+ */
+#define MALTA_FPGA_HALT (MALTA_FPGA_BASE + 0x500)
+
+
+/* IO function */
+void m_putch(char ch);
+char m_getch(void);
+/* when call this func, gxemul will quit */
+void m_halt(void);
+
+#endif

include/output.h

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+#ifndef _OUTPUT_H_
+#define _OUTPUT_H_
+
+void print_str(const char *buf);
+void printcharc(char ch);
+void print_num(unsigned long u);
+void halt(void);
+
+#endif

linker.lds

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+/*
+ * Set the architecture to mips.
+ */
+OUTPUT_ARCH(mips)
+
+/*
+ * Set the ENTRY point of the program to _start_mips.
+ */
+ENTRY(_start_mips)
+
+SECTIONS {
+
+	. = 0x80020000;
+
+	.text : {
+		*(.text)
+	}
+
+	.data : {
+		*(.data)
+	}
+
+	.bss  : {
+		*(.bss)
+	}
+
+	. = 0x80400000;
+	end = . ;
+}

output.c

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+#include <machine.h>
+#include <stddef.h>
+#include <output.h>
+
+void printcharc(char ch) {
+    while (!(*((volatile char *)(KSEG1 + MALTA_SERIAL_LSR)) & MALTA_SERIAL_THR_EMPTY)) {
+    }
+    *((volatile char *)(KSEG1 + MALTA_SERIAL_DATA)) = ch;
+}
+
+void halt(void) {
+    *(volatile char *)(KSEG1 + MALTA_FPGA_HALT) = 0x42;
+}
+
+void print_str(const char *buf) {
+    for (int i = 0; buf[i]; i++) {
+        printcharc(buf[i]);
+    }
+}
+
+void print_num(unsigned long u) {
+    if (u < 0) {
+        printcharc('-');
+        u = -u;
+    }
+    char digit = '0' + u % 10;
+    u /= 10;
+    if (u != 0) {
+        print_num(u);
+    }
+    printcharc(digit);
+}

start.S

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+#include <asm/asm.h>
+.data
+str:
+.asciiz "Hello World\n"  # Null-terminated string "Hello World" stored at label 'str'
+.align 2 # align to 4-byte boundary (2^2)
+var:
+.byte 3 # correctly aligned byte: 3
+/* '<x>' in the comments is the part to be replaced. */
+/* use '.align <x>' to align the following words to 1-byte boundary (disabling word-alignment) */
+/* so that the byte 3 and word 7 is "connected" */
+/* Your code here. (1/6) */
+.align 0
+.word 7, 8, 9
+
+.text
+/* We define '_start_mips' here as the entry of our program. */
+EXPORT(_start_mips)
+.set at
+.set reorder
+	mtc0    zero, CP0_STATUS
+	li      sp, 0x84000000
+	/* Load the address of the string 'str' into the first parameter register. */
+	la      a0, str
+	/* use 'addiu  sp, sp, <x>' to push a proper-sized frame onto the stack for Nonleaf function 'print_str'. */
+	/* Your code here. (2/6) */
+        addiu   sp, sp,-4 
+	jal     print_str
+	/* use 'addiu  sp, sp, <x>' to restore stack pointer. */
+	/* Your code here. (3/6) */
+        addiu   sp, sp,4
+	/* Set the first four parameters. */
+	li      a0, 0
+	li      a1, 1
+	li      a2, 2
+	li      a3, 3
+	/* use 'addiu  sp, sp, <x>' to push a proper-sized frame onto the stack for Nonleaf function 'hello'. */
+	/* Your code here. (4/6) */
+        addiu   sp, sp, -24
+	lw      t1, var	
+	li      t2, 5
+	/* use 'sw  t1, <x>(sp)' to store t1 at the proper place of the stack */
+	/* so that t1 is 5th argument of function hello. */
+	/* Your code here. (5/6) */
+        sw      t1, 16(sp)
+	/* use 'sw  t2, <x>(sp)' to store t2 at the proper place of the stack */
+	/* so that t2 is 6th argument of function hello. */
+	/* Your code here. (6/6) */
+        sw      t2, 20(sp)
+	/* use 'j' to call the function 'hello', we use 'j' instead of 'jal' because 'hello' is 'noreturn' */
+	j       hello