REL section alignment fixes

- Honor section alignment from splits.txt when writing RELs
- Better heuristic for determining REL section alignment on initial analysis

src/cmd/dol.rs

@@ -48,7 +48,7 @@ use crate::{
         file::{buf_reader, buf_writer, map_file, touch, verify_hash, FileIterator},
         lcf::{asm_path_for_unit, generate_ldscript, obj_path_for_unit},
         map::apply_map_file,
-        rel::{process_rel, process_rel_header},
+        rel::{process_rel, process_rel_header, update_rel_section_alignment},
         rso::{process_rso, DOL_SECTION_ABS, DOL_SECTION_NAMES},
         split::{is_linker_generated_object, split_obj, update_splits},
         IntoCow, ToCow,
@@ -856,7 +856,7 @@ fn load_analyze_rel(config: &ProjectConfig, module_config: &ModuleConfig) -> Res
     if let Some(hash_str) = &module_config.hash {
         verify_hash(file.as_slice(), hash_str)?;
     }
-    let (_, mut module_obj) =
+    let (header, mut module_obj) =
         process_rel(&mut Cursor::new(file.as_slice()), module_config.name().as_ref())?;
 
     if let Some(comment_version) = config.mw_comment_version {
@@ -895,6 +895,9 @@ fn load_analyze_rel(config: &ProjectConfig, module_config: &ModuleConfig) -> Res
     // Create _ctors and _dtors symbols if missing
     update_ctors_dtors(&mut module_obj)?;
 
+    // Determine REL section alignment
+    update_rel_section_alignment(&mut module_obj, &header)?;
+
     Ok((module_obj, dep))
 }
 

src/cmd/rel.rs

@@ -30,7 +30,7 @@ use crate::{
     cmd::dol::{ModuleConfig, ProjectConfig},
     obj::{ObjInfo, ObjReloc, ObjRelocKind, ObjSection, ObjSectionKind, ObjSymbol},
     util::{
-        config::is_auto_symbol,
+        config::{is_auto_symbol, read_splits_sections, SectionDef},
         dol::process_dol,
         elf::{to_obj_reloc_kind, write_elf},
         file::{buf_reader, buf_writer, map_file, process_rsp, verify_hash, FileIterator},
@@ -153,7 +153,7 @@ fn match_section_index(
     //     })
 }
 
-fn load_rel(module_config: &ModuleConfig) -> Result<(RelHeader, Vec<RelSectionHeader>)> {
+fn load_rel(module_config: &ModuleConfig) -> Result<RelInfo> {
     let file = map_file(&module_config.object)?;
     if let Some(hash_str) = &module_config.hash {
         verify_hash(file.as_slice(), hash_str)?;
@@ -161,12 +161,17 @@ fn load_rel(module_config: &ModuleConfig) -> Result<(RelHeader, Vec<RelSectionHe
     let mut reader = file.as_reader();
     let header = process_rel_header(&mut reader)?;
     let sections = process_rel_sections(&mut reader, &header)?;
-    Ok((header, sections))
+    let section_defs = if let Some(splits_path) = &module_config.splits {
+        read_splits_sections(splits_path)?
+    } else {
+        None
+    };
+    Ok((header, sections, section_defs))
 }
 
 fn resolve_relocations(
     module: &File,
-    existing_headers: &BTreeMap<u32, (RelHeader, Vec<RelSectionHeader>)>,
+    existing_headers: &BTreeMap<u32, RelInfo>,
     module_id: usize,
     symbol_map: &FxHashMap<&[u8], (usize, SymbolIndex)>,
     modules: &[(File, PathBuf)],
@@ -177,11 +182,12 @@ fn resolve_relocations(
         if !matches!(section.name(), Ok(name) if PERMITTED_SECTIONS.contains(&name)) {
             continue;
         }
-        let section_index = if let Some((_, sections)) = existing_headers.get(&(module_id as u32)) {
-            match_section_index(module, section.index(), sections)?
-        } else {
-            section.index().0
-        } as u8;
+        let section_index =
+            if let Some((_, sections, _)) = existing_headers.get(&(module_id as u32)) {
+                match_section_index(module, section.index(), sections)?
+            } else {
+                section.index().0
+            } as u8;
         for (address, reloc) in section.relocations() {
             let reloc_target = match reloc.target() {
                 RelocationTarget::Symbol(idx) => {
@@ -208,7 +214,7 @@ fn resolve_relocations(
                 (module_id, reloc_target)
             };
             let target_section_index = target_symbol.section_index().unwrap();
-            let target_section = if let Some((_, sections)) =
+            let target_section = if let Some((_, sections, _)) =
                 existing_headers.get(&(target_module_id as u32))
             {
                 match_section_index(&modules[target_module_id].0, target_section_index, sections)?
@@ -231,19 +237,21 @@ fn resolve_relocations(
     Ok(resolved)
 }
 
+type RelInfo = (RelHeader, Vec<RelSectionHeader>, Option<Vec<SectionDef>>);
+
 fn make(args: MakeArgs) -> Result<()> {
     let total = Instant::now();
 
     // Load existing REL headers (if specified)
-    let mut existing_headers = BTreeMap::<u32, (RelHeader, Vec<RelSectionHeader>)>::new();
+    let mut existing_headers = BTreeMap::<u32, RelInfo>::new();
     if let Some(config_path) = &args.config {
         let config: ProjectConfig = serde_yaml::from_reader(&mut buf_reader(config_path)?)?;
         for module_config in &config.modules {
             let _span = info_span!("module", name = %module_config.name()).entered();
-            let (header, sections) = load_rel(module_config).with_context(|| {
+            let info = load_rel(module_config).with_context(|| {
                 format!("While loading REL '{}'", module_config.object.display())
             })?;
-            existing_headers.insert(header.module_id, (header, sections));
+            existing_headers.insert(info.0.module_id, info);
         }
     }
 
@@ -316,14 +324,19 @@ fn make(args: MakeArgs) -> Result<()> {
             bss_align: None,
             section_count: None,
             quiet: args.no_warn,
+            section_align: None,
         };
-        if let Some((header, _)) = existing_headers.get(&(module_id as u32)) {
+        if let Some((header, _, section_defs)) = existing_headers.get(&(module_id as u32)) {
             info.version = header.version;
             info.name_offset = Some(header.name_offset);
             info.name_size = Some(header.name_size);
             info.align = header.align;
             info.bss_align = header.bss_align;
             info.section_count = Some(header.num_sections as usize);
+            info.section_align = section_defs
+                .as_ref()
+                .map(|defs| defs.iter().map(|def| def.align).collect())
+                .unwrap_or_default();
         }
         let rel_path = path.with_extension("rel");
         let mut w = buf_writer(&rel_path)?;