Assembly stops at segmentation fault

Posted a question that terminates the program on the assembly
I am writing a program to calculate the bmi (Body Mass Index) in the assembly for practice, but I put out a segmentation fault in the middle and it stops.

Why is that?

OS:ubuntu 16.04 x86_64 Compile as 32-bit with gcc-m32


.data
message:.string "file open error\n"
your_height:.string "Please enter the your height(m):"
your_weight:.string "Please enter the your weight(kg):" 
newline: .string "\n"

.bss
tmp: .skip128,0x00

.text
.global main
main:
    push%ebp
    movl%esp, %ebp
    pushl$your_height
    call print
    call read
    pushl$your_weight
    call print
    call read
    movl%esp,%eax
    movl20(%esp), %ebx
    divl%ebx
    divl%ebx
    pushl%eax
    call print
    call exit


read:
    movl$3,%eax
    movl$0,%ebx
    movl$tmp, %ecx
    movl$64,%edx
    int$0x80
    cmpl$-1,%eax
    je write_error_message
    movl$tmp, %esi
    pushl%esi
    ret

write_error_message:
    movl $4,%eax
    movl$1,%ebx
    movl$emessage, %ecx
    movl $16,%edx
    int$0x80
    call exit

exit:
    movl$1,%eax;
    xorl%ebx,%ebx;
    int$0x80

print:
    movl $4,%eax
    US>movl4(%esp), %ecx
    movl$1,%ebx
    movl$1,%edx
write:
    cmpb$0x00, (%ecx)
    jeret_func
    movl $4,%eax
    int$0x80
    include %ecx
    jmp write


ret_func:
    ret

assembly-language

2022-09-30 17:29

1 Answers

The direct cause is ret while read is destroying stack frames.
I'd like to say that it will be fixed if you correct it, but that won't be what I expected.

A system call read() takes a byte string from a file descriptor.
123<line feed> results from 3132330A.
In addition, atoi and atof are required to enter the height and weight numerical values.
pushl%esi is probably part of the function call instruction string that causes the presentation code to drop
It is estimated that the program itself is dead there because it is incomplete.

c compiler or C Runtime Library is in front of you and ready to use.
The Euler does not want to write the equivalent of atoi strtol directly in the assembler.
(I have written the equivalent function in c.It's only an integer operation, so it's not very difficult.)
atofstrtod I don't want to write the equivalent function even if it's c.What's more, the assembler.
(There are too many things to consider, such as poor accuracy and rounding.)