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 Post subject: Crash in memmove function
PostPosted: Wed Sep 28, 2022 11:36 pm 
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Joined: Wed Sep 14, 2022 12:42 pm
Posts: 10
Hi everyone,

It ís me again :(.

I have an issue with memmove function. When my OS run into memmove function. Everything works correctly if there is no interrupt happened. If there is interrupt happened, when the memmove's thread back, it raises exception General Protection. The context is saved correctly. Please help

Quote:
void* memmove(void* des, void* src, size_t size)
{
size_t numq = size >> 3;
size_t numb = size & 0b111;
if (des < src)
{
uint64 *qdes = (uint64*)des;
uint64 *qsrc = (uint64*)src;
for (size_t i = 0; i < numq; ++i)
{
qdes[i] = qsrc[i];
// printf(" %d ", i);
}
uint8 *bdes = (uint8*)(des + numq * 8);
uint8 *bsrc = (uint8*)(src + numq * 8);
for (size_t i = 0; i < numb; ++i)
{
bdes[i] = bsrc[i];
}
}
return des;
}


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 Post subject: Re: Crash in memmove function
PostPosted: Thu Sep 29, 2022 1:13 am 
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Joined: Mon Feb 02, 2015 7:11 pm
Posts: 861
zungnguyen wrote:
The context is saved correctly.

Is it restored correctly? Clearly both can't be true.

_________________
https://github.com/kiznit/rainbow-os


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 Post subject: Re: Crash in memmove function
PostPosted: Thu Sep 29, 2022 1:44 am 
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Joined: Wed Sep 14, 2022 12:42 pm
Posts: 10
kzinti wrote:
zungnguyen wrote:
The context is saved correctly.

Is it restored correctly? Clearly both can't be true.


Yep, but i handle interrupt in the same stack, can it change data in function stack? I see that the saved rbp is the same with saved rsp , so that when interruptHanler is call, it change the local in my function


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 Post subject: Re: Crash in memmove function
PostPosted: Thu Sep 29, 2022 3:41 am 
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Joined: Sat Nov 21, 2009 5:11 pm
Posts: 802
If you are using a compiler that uses the SystemV AMD64 ABI, such as GCC, you must remember to disable the red zone for code that runs in kernel mode (-mno-red-zone on GCC), because it will be overwritten on every interrupt.


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 Post subject: Re: Crash in memmove function
PostPosted: Thu Sep 29, 2022 9:51 am 
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Joined: Wed Sep 14, 2022 12:42 pm
Posts: 10
Gigasoft wrote:
If you are using a compiler that uses the SystemV AMD64 ABI, such as GCC, you must remember to disable the red zone for code that runs in kernel mode (-mno-red-zone on GCC), because it will be overwritten on every interrupt.


Thank you. It works!


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