Page-align offset before calculating virtual addresses for ELF

This mimics what `ld.so` does by aligning the virtual addresses to
the current page size, and fixes:
- Existing issues with DSOs produced by LLD which, unlike gold or BFD,
  doesn't align p_vaddr to p_align (the previous overflow prevention
  wasn't sufficient here).
- Systems w/ configurable page sizes, where just using p_align isn't
  enough.

Cargo.toml

@@ -27,6 +27,7 @@ log = "0.4"
 lru = "0.10"
 regex = ">=1.6.0"
 tempfile = "3.6.0"
+page_size = "0.6.0"
 proc-maps = "0.3.2"
 memmap = "0.7.0"
 cpp_demangle = "0.4"

src/binary_parser.rs

@@ -124,9 +124,10 @@ pub fn parse_binary(filename: &Path, addr: u64, size: u64) -> Result<BinaryInfo,
                     )
                 })?;
 
-            // p_vaddr may be larger than the map address in case when the header has an offset and
-            // the map address is relatively small. In this case we can default to 0.
-            let offset = offset.saturating_sub(program_header.p_vaddr);
+            // Align the virtual address offset, then subtract it from the offset
+            // to get real offset for symbol addresses in the file.
+            let aligned_vaddr = program_header.p_vaddr - (program_header.p_vaddr % page_size::get() as u64);
+            let offset = offset - aligned_vaddr;
 
             for sym in elf.syms.iter() {
                 let name = elf.strtab[sym.st_name].to_string();