Fixes for pstack module #193
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We generate a single address range for each DSO in the userspace program. However, the method is a bit convoluted: we select the largest "vm_end" value, and we use a start address computed from the start of the executable VMA and its vm_pgoff. The result of this is that, if a DSO file is mapped multiple times in different locations, we may produce an address range that spans other DSO address ranges. This is exactly what happened in osandov/drgn#574. Simplify this by just using the start address of the lowest VMA (the one which has vm_pgoff==0), and computing the end address by taking the file size, or the start of the next DSO address range, whichever is lower. This ensures there are no address range overlaps. It does not provide drgn with any additional information about the file address mappings, but as far as I can tell, that's just fine: drgn can't use multiple address ranges, because it doesn't know which file offsets they correspond to. To ensure this behavior is used by both the "dump" and "pstack" modes, implement factor out the DSO range generation code into a helper and use it in both places. Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
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The pstack module could get drgn stuck in an infinite loop (see osandov/drgn#574). Add a fix for this, as well as one low-priority fix related to unwinding running tasks.