Why doesn't assembly make output from input? [closed]
I have been coding assembly language on my MacOS 10.14. I am using the nasm assembler I got from brew, I am using Macho64, and I coded this script using Linux 32 bit syscalls, but putting 0x200000 before each syscall. I am using the 64 bit registers, %rax, %rdi, %rsi, and %rdx for each syscall and three variables. I have compiled and linked the script, but it does not work, asking for input, but not responding. Here is my code:
global start
section.data
section.bss
var: resb 8
section.text
start:
mov rax, 0x2000003
mov rdi, 0
mov rsi, var
mov rdx, 4
syscall
mov rax, 0x2000004
mov rdi, 1
mov rsi, var
mov rdx, 4
syscall
mov rax, 0x2000001
mov rdi, 0
syscall
I have been unable to find an answer, I have seen this question, but I did not understand the push and pull, and also I am using a pure 64 bit syntax and the question seems to be mainly about matching x86 and x64.
macos assembly nasm x86-64 mach-o
edited Jan 20 at 9:38
Michael Petch
25.5k556102
asked Jan 20 at 4:01
Murpha SchneeMurpha Schnee
494
closed as off-topic by sideshowbarker, M-M, Mike M., Vega, Machavity Jan 30 at 1:13
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting." – sideshowbarker, M-M, Mike M., Vega, Machavity
If this question can be reworded to fit the rules in the help center, please edit the question.
|
show 4 more comments
I have been coding assembly language on my MacOS 10.14. I am using the nasm assembler I got from brew, I am using Macho64, and I coded this script using Linux 32 bit syscalls, but putting 0x200000 before each syscall. I am using the 64 bit registers, %rax, %rdi, %rsi, and %rdx for each syscall and three variables. I have compiled and linked the script, but it does not work, asking for input, but not responding. Here is my code:
global start
section.data
section.bss
var: resb 8
section.text
start:
mov rax, 0x2000003
mov rdi, 0
mov rsi, var
mov rdx, 4
syscall
mov rax, 0x2000004
mov rdi, 1
mov rsi, var
mov rdx, 4
syscall
mov rax, 0x2000001
mov rdi, 0
syscall
I have been unable to find an answer, I have seen this question, but I did not understand the push and pull, and also I am using a pure 64 bit syntax and the question seems to be mainly about matching x86 and x64.
macos assembly nasm x86-64 mach-o
edited Jan 20 at 9:38
Michael Petch
25.5k556102
asked Jan 20 at 4:01
Murpha SchneeMurpha Schnee
494
closed as off-topic by sideshowbarker, M-M, Mike M., Vega, Machavity Jan 30 at 1:13
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting." – sideshowbarker, M-M, Mike M., Vega, Machavity
If this question can be reworded to fit the rules in the help center, please edit the question.
1
Do you get warnings when you assemble this?I ask because after the wordsectionyou need a space.
– Michael Petch
Jan 20 at 8:55
The x64 syscalls are completely different than the 32bit int80 calls. So themov eax, 0x3to signify "read a character" to int80 does something entirely different when passed in rax to syscall. And I'm not sure what you think putting 0x2000000 in front of everything is supposed to do, but it's not helping.
– David Wohlferd
Jan 20 at 9:22
2
@DavidWohlferd : because this is for MacOS (BSD) and the system call numbers for 64-bit are the 32-bit MacOS calls with0x2000000added.
– Michael Petch
Jan 20 at 9:33
1
Doh! My bad. I'll leave it to show my shame.
– David Wohlferd
Jan 20 at 10:04
1
@MichaelPetch You're actually right, that was the problem, though, it did not return an error, thank you.
– Murpha Schnee
Jan 20 at 10:31
|
show 4 more comments
I have been coding assembly language on my MacOS 10.14. I am using the nasm assembler I got from brew, I am using Macho64, and I coded this script using Linux 32 bit syscalls, but putting 0x200000 before each syscall. I am using the 64 bit registers, %rax, %rdi, %rsi, and %rdx for each syscall and three variables. I have compiled and linked the script, but it does not work, asking for input, but not responding. Here is my code:
global start
section.data
section.bss
var: resb 8
section.text
start:
mov rax, 0x2000003
mov rdi, 0
mov rsi, var
mov rdx, 4
syscall
mov rax, 0x2000004
mov rdi, 1
mov rsi, var
mov rdx, 4
syscall
mov rax, 0x2000001
mov rdi, 0
syscall
I have been unable to find an answer, I have seen this question, but I did not understand the push and pull, and also I am using a pure 64 bit syntax and the question seems to be mainly about matching x86 and x64.
macos assembly nasm x86-64 mach-o
edited Jan 20 at 9:38
Michael Petch
25.5k556102
asked Jan 20 at 4:01
Murpha SchneeMurpha Schnee
494
I have been coding assembly language on my MacOS 10.14. I am using the nasm assembler I got from brew, I am using Macho64, and I coded this script using Linux 32 bit syscalls, but putting 0x200000 before each syscall. I am using the 64 bit registers, %rax, %rdi, %rsi, and %rdx for each syscall and three variables. I have compiled and linked the script, but it does not work, asking for input, but not responding. Here is my code:
global start
section.data
section.bss
var: resb 8
section.text
start:
mov rax, 0x2000003
mov rdi, 0
mov rsi, var
mov rdx, 4
syscall
mov rax, 0x2000004
mov rdi, 1
mov rsi, var
mov rdx, 4
syscall
mov rax, 0x2000001
mov rdi, 0
syscall
I have been unable to find an answer, I have seen this question, but I did not understand the push and pull, and also I am using a pure 64 bit syntax and the question seems to be mainly about matching x86 and x64.
macos assembly nasm x86-64 mach-o
macos assembly nasm x86-64 mach-o
edited Jan 20 at 9:38
Michael Petch
25.5k556102
asked Jan 20 at 4:01
Murpha SchneeMurpha Schnee
494
edited Jan 20 at 9:38
Michael Petch
25.5k556102
asked Jan 20 at 4:01
Murpha SchneeMurpha Schnee
494
edited Jan 20 at 9:38
Michael Petch
25.5k556102
edited Jan 20 at 9:38
Michael Petch
25.5k556102
edited Jan 20 at 9:38
Michael Petch
25.5k556102
25.5k556102
asked Jan 20 at 4:01
Murpha SchneeMurpha Schnee
494
asked Jan 20 at 4:01
Murpha SchneeMurpha Schnee
494
asked Jan 20 at 4:01
Murpha SchneeMurpha Schnee
494
494
closed as off-topic by sideshowbarker, M-M, Mike M., Vega, Machavity Jan 30 at 1:13
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting." – sideshowbarker, M-M, Mike M., Vega, Machavity
If this question can be reworded to fit the rules in the help center, please edit the question.
closed as off-topic by sideshowbarker, M-M, Mike M., Vega, Machavity Jan 30 at 1:13
This question appears to be off-topic. The users who voted to close gave this specific reason:
- "This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting." – sideshowbarker, M-M, Mike M., Vega, Machavity
If this question can be reworded to fit the rules in the help center, please edit the question.
1
Do you get warnings when you assemble this?I ask because after the wordsectionyou need a space.
– Michael Petch
Jan 20 at 8:55
The x64 syscalls are completely different than the 32bit int80 calls. So themov eax, 0x3to signify "read a character" to int80 does something entirely different when passed in rax to syscall. And I'm not sure what you think putting 0x2000000 in front of everything is supposed to do, but it's not helping.
– David Wohlferd
Jan 20 at 9:22
2
@DavidWohlferd : because this is for MacOS (BSD) and the system call numbers for 64-bit are the 32-bit MacOS calls with0x2000000added.
– Michael Petch
Jan 20 at 9:33
1
Doh! My bad. I'll leave it to show my shame.
– David Wohlferd
Jan 20 at 10:04
1
@MichaelPetch You're actually right, that was the problem, though, it did not return an error, thank you.
– Murpha Schnee
Jan 20 at 10:31
|
show 4 more comments
1
Do you get warnings when you assemble this?I ask because after the wordsectionyou need a space.
– Michael Petch
Jan 20 at 8:55
The x64 syscalls are completely different than the 32bit int80 calls. So themov eax, 0x3to signify "read a character" to int80 does something entirely different when passed in rax to syscall. And I'm not sure what you think putting 0x2000000 in front of everything is supposed to do, but it's not helping.
– David Wohlferd
Jan 20 at 9:22
2
@DavidWohlferd : because this is for MacOS (BSD) and the system call numbers for 64-bit are the 32-bit MacOS calls with0x2000000added.
– Michael Petch
Jan 20 at 9:33
1
Doh! My bad. I'll leave it to show my shame.
– David Wohlferd
Jan 20 at 10:04
1
@MichaelPetch You're actually right, that was the problem, though, it did not return an error, thank you.
– Murpha Schnee
Jan 20 at 10:31
1
1
Do you get warnings when you assemble this?I ask because after the word
section you need a space.– Michael Petch
Jan 20 at 8:55
Do you get warnings when you assemble this?I ask because after the word
section you need a space.– Michael Petch
Jan 20 at 8:55
The x64 syscalls are completely different than the 32bit int80 calls. So the
mov eax, 0x3 to signify "read a character" to int80 does something entirely different when passed in rax to syscall. And I'm not sure what you think putting 0x2000000 in front of everything is supposed to do, but it's not helping.– David Wohlferd
Jan 20 at 9:22
The x64 syscalls are completely different than the 32bit int80 calls. So the
mov eax, 0x3 to signify "read a character" to int80 does something entirely different when passed in rax to syscall. And I'm not sure what you think putting 0x2000000 in front of everything is supposed to do, but it's not helping.– David Wohlferd
Jan 20 at 9:22
2
2
@DavidWohlferd : because this is for MacOS (BSD) and the system call numbers for 64-bit are the 32-bit MacOS calls with
0x2000000 added.– Michael Petch
Jan 20 at 9:33
@DavidWohlferd : because this is for MacOS (BSD) and the system call numbers for 64-bit are the 32-bit MacOS calls with
0x2000000 added.– Michael Petch
Jan 20 at 9:33
1
1
Doh! My bad. I'll leave it to show my shame.
– David Wohlferd
Jan 20 at 10:04
Doh! My bad. I'll leave it to show my shame.
– David Wohlferd
Jan 20 at 10:04
1
1
@MichaelPetch You're actually right, that was the problem, though, it did not return an error, thank you.
– Murpha Schnee
Jan 20 at 10:31
@MichaelPetch You're actually right, that was the problem, though, it did not return an error, thank you.
– Murpha Schnee
Jan 20 at 10:31
|
show 4 more comments
1 Answer
1
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oldest
votes
I was actually mistaken about the problem, it wasn't a syscall error, but rather a syntax error that did not return the error. The mistake I found out was I had to put a blank space after section, which I didn't. Thank you @Michael Petch for solving this.
answered Jan 20 at 10:33
Murpha SchneeMurpha Schnee
494
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
I was actually mistaken about the problem, it wasn't a syscall error, but rather a syntax error that did not return the error. The mistake I found out was I had to put a blank space after section, which I didn't. Thank you @Michael Petch for solving this.
answered Jan 20 at 10:33
Murpha SchneeMurpha Schnee
494
add a comment |
I was actually mistaken about the problem, it wasn't a syscall error, but rather a syntax error that did not return the error. The mistake I found out was I had to put a blank space after section, which I didn't. Thank you @Michael Petch for solving this.
answered Jan 20 at 10:33
Murpha SchneeMurpha Schnee
494
add a comment |
I was actually mistaken about the problem, it wasn't a syscall error, but rather a syntax error that did not return the error. The mistake I found out was I had to put a blank space after section, which I didn't. Thank you @Michael Petch for solving this.
answered Jan 20 at 10:33
Murpha SchneeMurpha Schnee
494
I was actually mistaken about the problem, it wasn't a syscall error, but rather a syntax error that did not return the error. The mistake I found out was I had to put a blank space after section, which I didn't. Thank you @Michael Petch for solving this.
answered Jan 20 at 10:33
Murpha SchneeMurpha Schnee
494
answered Jan 20 at 10:33
Murpha SchneeMurpha Schnee
494
answered Jan 20 at 10:33
Murpha SchneeMurpha Schnee
494
answered Jan 20 at 10:33
Murpha SchneeMurpha Schnee
494
494
add a comment |
add a comment |
1
Do you get warnings when you assemble this?I ask because after the word
sectionyou need a space.– Michael Petch
Jan 20 at 8:55
The x64 syscalls are completely different than the 32bit int80 calls. So the
mov eax, 0x3to signify "read a character" to int80 does something entirely different when passed in rax to syscall. And I'm not sure what you think putting 0x2000000 in front of everything is supposed to do, but it's not helping.– David Wohlferd
Jan 20 at 9:22
2
@DavidWohlferd : because this is for MacOS (BSD) and the system call numbers for 64-bit are the 32-bit MacOS calls with
0x2000000added.– Michael Petch
Jan 20 at 9:33
1
Doh! My bad. I'll leave it to show my shame.
– David Wohlferd
Jan 20 at 10:04
1
@MichaelPetch You're actually right, that was the problem, though, it did not return an error, thank you.
– Murpha Schnee
Jan 20 at 10:31