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Posted: **Mon Aug 29, 2022 3:02 pm**

Hello, guys!

I have problem with passing arguments to user mode process. If i do this:

int *stack = (int *)fr->usersp+4;

All works fine, but if i try to add something to the allocated stack, the stack are brokes:

frame->usersp = (isUser ? ((int)pmml_alloc(true)+4096) : 0);

The first poping from stack are zero, i use this code for checking valid of stack:

pop eax
    ; Check if argument exists
    cmp eax,0
    je .exit

And program always jumps to exit label, this means that after the poping from stack done, the register eax are zero.
What i am doing wrong?

Posted: **Mon Aug 29, 2022 3:38 pm**

Where is your code to add something to the allocated stack?

Posted: **Mon Aug 29, 2022 3:43 pm**

Octocontrabass wrote:Where is your code to add something to the allocated stack?

Here is:

*(--stack) = (int)argv;

Posted: **Mon Aug 29, 2022 3:58 pm**

That looks fine.

After you add that value to the user stack, do you put the user stack pointer back into the stack frame?

Posted: **Mon Aug 29, 2022 4:03 pm**

Octocontrabass wrote:That looks fine.

After you add that value to the user stack, do you put the user stack pointer back into the stack frame?

Ah, yeah i don't update the pointer of stack. Thank now all works fine!

Argument passing