Use mach_vm_read_overwrite to read image infos for dyld_images
#403
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ianks
reviewed
Oct 31, 2024
ianks
reviewed
Oct 31, 2024
ianks
reviewed
Oct 31, 2024
ianks
reviewed
Oct 31, 2024
samply/src/mac/proc_maps.rs
Outdated
| mach_vm_read_overwrite(task, info_array_elem_addr, size, &mut image_info as *mut MaybeUninit<dyld_image_info> as u64, &mut size).into_result()?; | ||
| } | ||
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| if size != mem::size_of::<dyld_image_info>() as u64 { |
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We should also check that the result of mach_vm_read_overwrite was KERN_SUCCESS, I think
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into_result does it
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I just tried this, and while it now include symbols, they don't quite look correct |
could you try again? I've pushed some new changes that make us of |
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It works now ! ❤️ 
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Thank you @Maaarcocr for the patch, @ianks for the review and @casperisfine for testing! |
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As I've explained in #389 (comment) it seems like the mapped memory that samply relies on to read image infos for dyld_images is no longer kept up to date with the newest version of macOS.
This results in samply not being able to reconcile from where an address is coming from (as it was shown in the issue I already linked) and thus then we get no symbolication whatsover.
I have a simple solution for this (which I understand may not be desirable from a perf POV): for image infos just read them directly from the other process memory using
mach_vm_read_overwrite. This may be slower, but it at least get samply working again when people use dlopen in the application code. Also, even if it is slower, hopefully people are not constantly dlopen-ing new libraries so this code should only be called few times at startup and that should be it hopefully?