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malloc() and tasks

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Offline alvm

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malloc() and tasks
« on: 17 / September / 2013, 05:57:03 »
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Hi,

How I can get info about which task call malloc()? Is there mapping between tasks and a memory pool which they use through malloc()?

Thanks,
Alex.
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Offline srsa_4c

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Re: malloc() and tasks
« Reply #1 on: 17 / September / 2013, 10:04:37 »
Quote from: alvm on 17 / September / 2013, 05:57:03
Is there mapping between tasks and a memory pool which they use through malloc()?
malloc() allocates from the same memory pool, regardless of which task issued the call (I hope I understood your question correctly).
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How I can get info about which task call malloc()
Well, that isn't so easy. If the pointer returned by malloc() is stored in a static variable (i.e. it's located at a known address), then you could collect these variables and see where they point  :blink:.
Other method is to make cache hacks work, and replace the firmware's memory allocator function with a modified one that logs its callers somewhere.

Maybe someone else will give a better advice.
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Offline alvm

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Re: malloc() and tasks
« Reply #2 on: 17 / September / 2013, 10:19:56 »
Quote from: srsa_4c on 17 / September / 2013, 10:04:37
Other method is to make cache hacks work, and replace the firmware's memory allocator function with a modified one that logs its callers somewhere.

Very interesting! thanks for advice!

Quote from: srsa_4c on 17 / September / 2013, 10:04:37
Well, that isn't so easy. If the pointer returned by malloc() is stored in a static variable (i.e. it's located at a known address), then you could collect these variables and see where they point

drysh meminfo -t should be list of task but STDLIB_MALLOC_USE_LIST is not defined for fw :(

(for a810  meminfo -t  malloc memory info (per task))
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Offline reyalp

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Re: malloc() and tasks
« Reply #3 on: 17 / September / 2013, 13:35:46 »
If you explain what you are trying to do, we might be able to offer better advice.

Modern cameras (including a810) copy DryOS kernel code to RAM. It looks like the actual malloc function is still in ROM, but the underlying functions are in RAM, so you could modify them quite easily using the same approach as the task hook used in recent cameras (e.g. sx160, elph130)
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Offline alvm

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Re: malloc() and tasks
« Reply #4 on: 17 / September / 2013, 15:09:30 »
Quote from: reyalp on 17 / September / 2013, 13:35:46
If you explain what you are trying to do, we might be able to offer better advice.

There is memory leakage when I run my small application based on chdk. I'm trying to find which task is a source of the problem. Task is from Canon fw, not from my application

Quote from: reyalp on 17 / September / 2013, 13:35:46
Modern cameras (including a810) copy DryOS kernel code to RAM. It looks like the actual malloc function is still in ROM, but the underlying functions are in RAM, so you could modify them quite easily using the same approach as the task hook used in recent cameras (e.g. sx160, elph130)

Thanks for advice, I'll try to do this.
« Last Edit: 17 / September / 2013, 15:11:11 by alvm »
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