libdrgn: x86_64: allow phys_base to be 0 #457
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Mark reported recursive address translation errors when debugging a QEMU guest memory dump. We're supposed to be handling this in linux_kernel_pgtable_iterator_next_x86_64() by translating swapper_pg_dir to a physical address. However, it decides whether phys_base was present in the VMCOREINFO by comparing phys_base to 0, and this dump legitimately had a phys_base of 0. Add a separate flag so we can distinguish missing vs 0. Reported-and-tested-by: Mark Harmstone <[email protected]> Fixes: 5b39bfb ("libdrgn: x86_64: avoid recursive address translation for swapper_pg_dir") Signed-off-by: Omar Sandoval <[email protected]>
brenns10
approved these changes
Dec 18, 2024
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| // this if phys_base is 0, since that likely means it | ||
| // was not present in the vmcoreinfo. It has been |
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I wonder who was lazy enough to do it that way? :P
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Mark reported recursive address translation errors when debugging a QEMU guest memory dump. We're supposed to be handling this in
linux_kernel_pgtable_iterator_next_x86_64()by translatingswapper_pg_dirto a physical address. However, it decides whetherphys_basewas present in the VMCOREINFO by comparingphys_baseto 0, and this dump legitimately had aphys_baseof 0. Add a separate flag so we can distinguish missing vs 0.@brenns10, mind sanity checking this?