Revert "Generate segment padding from ELF-internal offsets"

src/convert.rs

@@ -549,18 +549,32 @@ pub fn elf_to_tbf(
         if let Some(last_segment_address_end) = last_segment_address_end {
             // We have a previous segment. Now, check if there is any padding
             // between the segments in the .elf.
-            let padding = (segment.p_offset as usize)
-                .checked_sub(last_segment_address_end)
-                .expect("Invariant violated: expect to iterate over ELF sections in order");
+            let chk_padding = (segment.p_paddr as usize).checked_sub(last_segment_address_end);
 
-            if padding > 0 {
-                if verbose {
-                    println!("  Including padding between segments size={}", padding);
-                }
+            if let Some(padding) = chk_padding {
+                if padding > 0 {
+                    if verbose {
+                        println!("  Including padding between segments size={}", padding);
+                    }
 
-                // Insert the padding into the generated binary.
-                binary.extend(vec![0; padding]);
-                binary_index += padding;
+                    if padding >= 4096 {
+                        // Warn the user that we're inserting a large amount of
+                        // padding (>= 4096, which is the ELF file segment padding)
+                        // into the binary. This can be a sign of an incorrect /
+                        // broken ELF file (where not all LOADed non-zero sized
+                        // sections are marked to be loaded from flash).
+                        println!("  Warning! Inserting a large amount of padding.");
+                    }
+
+                    // Insert the padding into the generated binary.
+                    binary.extend(vec![0; padding]);
+                    binary_index += padding;
+                }
+            } else {
+                println!(
+                    "  Warning! Expecting ELF sections to be in physical (load) address order."
+                );
+                println!("           Not inserting padding, the resulting TBF may be broken.");
             }
         }
 
@@ -582,7 +596,6 @@ pub fn elf_to_tbf(
 
         let start_segment = segment.p_paddr;
         let end_segment = segment.p_paddr + segment.p_filesz;
-        let end_offset = segment.p_offset + segment.p_filesz;
 
         // Check if this segment contains the entry point, and calculate the
         // offset we need to store in the TBF header if so.
@@ -684,9 +697,9 @@ pub fn elf_to_tbf(
             }
         }
 
-        // Save the end-offset of this segment within the ELF file, so we can
-        // check if padding is required between segments.
-        last_segment_address_end = Some(end_offset as usize);
+        // Save the end of this segment so we can check if padding is required
+        // between segments.
+        last_segment_address_end = Some(end_segment as usize);
 
         binary.extend(content);
         binary_index += segment.p_filesz as usize;