Implement sections_allowlist_extra

docs/file_format/settings.md

@@ -104,7 +104,7 @@ A positive integer or `null`.
 
 A list of sections to that should be preserved during linking.
 
-Usually used for keeping debugging sections.
+Usually used to avoid discarding debugging sections.
 
 ### Example
 
@@ -121,6 +121,38 @@ List of strings.
 
 `[]`
 
+## `sections_allowlist_extra`
+
+A list of sections to that should be preserved during linking.
+
+This setting works the same as same as
+[`sections_allowlist`](#sections_allowlist). This option exists as a way to have
+a default list of sections to be preserved that won't be overrided if the user
+wants to specify their own allow list by setting `sections_allowlist`.
+
+These defaults exists because some linkers (like clang's `lld`) complain if the
+`.shstrtab` is not listed explicitly if a wildcard was used on the `/DISCARD/`
+section (see [`discard_wildcard_section`](#discard_wildcard_section)), so to
+avoid issues when wanting to use other linkers we emit the section by default.
+
+### Example
+
+```yaml
+settings:
+  sections_allowlist_extra:
+    - .shstrtab
+    - .strtab
+    - .symtab
+```
+
+### Valid values
+
+List of strings.
+
+### Default value
+
+`[.shstrtab]`
+
 ## `sections_denylist`
 
 List of sections to be discarded.

slinky/src/linker_writer.rs

@@ -62,6 +62,25 @@ impl<'a> LinkerWriter<'a> {
             need_ln = true;
         }
 
+        if !self.settings.sections_allowlist_extra.is_empty() {
+            if need_ln {
+                self.writeln("");
+            }
+
+            let address = " 0";
+
+            for sect in &self.settings.sections_allowlist_extra {
+                self.writeln(&format!("{}{} :", sect, address));
+                self.begin_block();
+
+                self.writeln(&format!("*({});", sect));
+
+                self.end_block();
+            }
+
+            need_ln = true;
+        }
+
         if self.settings.discard_wildcard_section || !self.settings.sections_denylist.is_empty() {
             if need_ln {
                 self.writeln("");

slinky/src/settings.rs

@@ -16,6 +16,7 @@ pub struct Settings {
     pub hardcoded_gp_value: Option<u32>,
 
     pub sections_allowlist: Vec<String>,
+    pub sections_allowlist_extra: Vec<String>,
     pub sections_denylist: Vec<String>,
     pub discard_wildcard_section: bool,
 
@@ -48,7 +49,11 @@ fn settings_default_sections_allowlist() -> Vec<String> {
     vec![]
 }
 
-fn settings_default_section_denylist() -> Vec<String> {
+fn settings_default_sections_allowlist_extra() -> Vec<String> {
+    vec![".shstrtab".into()]
+}
+
+fn settings_default_sections_denylist() -> Vec<String> {
     vec![
         ".reginfo".into(),
         ".MIPS.abiflags".into(),
@@ -102,7 +107,8 @@ impl Default for Settings {
             hardcoded_gp_value: settings_default_hardcoded_gp_value(),
 
             sections_allowlist: settings_default_sections_allowlist(),
-            sections_denylist: settings_default_section_denylist(),
+            sections_allowlist_extra: settings_default_sections_allowlist_extra(),
+            sections_denylist: settings_default_sections_denylist(),
             discard_wildcard_section: settings_default_discard_wildcard_section(),
 
             alloc_sections: settings_default_alloc_sections(),
@@ -131,6 +137,8 @@ pub(crate) struct SettingsSerial {
     #[serde(default)]
     pub sections_allowlist: AbsentNullable<Vec<String>>,
     #[serde(default)]
+    pub sections_allowlist_extra: AbsentNullable<Vec<String>>,
+    #[serde(default)]
     pub sections_denylist: AbsentNullable<Vec<String>>,
     #[serde(default)]
     pub discard_wildcard_section: AbsentNullable<bool>,
@@ -168,9 +176,13 @@ impl SettingsSerial {
         let sections_allowlist = self
             .sections_allowlist
             .get_non_null("sections_allowlist", settings_default_sections_allowlist)?;
+        let sections_allowlist_extra = self.sections_allowlist_extra.get_non_null(
+            "sections_allowlist_extra",
+            settings_default_sections_allowlist_extra,
+        )?;
         let sections_denylist = self
             .sections_denylist
-            .get_non_null("sections_denylist", settings_default_section_denylist)?;
+            .get_non_null("sections_denylist", settings_default_sections_denylist)?;
         let discard_wildcard_section = self.discard_wildcard_section.get_non_null(
             "discard_wildcard_section",
             settings_default_discard_wildcard_section,
@@ -200,6 +212,7 @@ impl SettingsSerial {
             linker_symbols_style,
             hardcoded_gp_value,
             sections_allowlist,
+            sections_allowlist_extra,
             sections_denylist,
             discard_wildcard_section,
             alloc_sections,

tests/linker_scripts/basic_example.ld

@@ -262,6 +262,19 @@ SECTIONS
     boot_ROM_END = __romPos;
     boot_ROM_SIZE = ABSOLUTE(boot_ROM_END - boot_ROM_START);
 
+    .strtab 0 :
+    {
+        *(.strtab);
+    }
+    .symtab 0 :
+    {
+        *(.symtab);
+    }
+    .shstrtab 0 :
+    {
+        *(.shstrtab);
+    }
+
     /DISCARD/ :
     {
         *(.reginfo);

tests/linker_scripts/drmario64.ld

@@ -7624,6 +7624,19 @@ SECTIONS
         *(.comment);
     }
 
+    .strtab 0 :
+    {
+        *(.strtab);
+    }
+    .symtab 0 :
+    {
+        *(.symtab);
+    }
+    .shstrtab 0 :
+    {
+        *(.shstrtab);
+    }
+
     /DISCARD/ :
     {
         *(.reginfo);

tests/linker_scripts/hardcoded_gp.ld

@@ -73,6 +73,19 @@ SECTIONS
     main_ROM_END = __romPos;
     main_ROM_SIZE = ABSOLUTE(main_ROM_END - main_ROM_START);
 
+    .strtab 0 :
+    {
+        *(.strtab);
+    }
+    .symtab 0 :
+    {
+        *(.symtab);
+    }
+    .shstrtab 0 :
+    {
+        *(.shstrtab);
+    }
+
     /DISCARD/ :
     {
         *(.reginfo);

tests/linker_scripts/makerom_zelda_like.ld

@@ -133,6 +133,19 @@ SECTIONS
     _bootSegmentRomEnd = __romPos;
     _bootSegmentRomSize = ABSOLUTE(_bootSegmentRomEnd - _bootSegmentRomStart);
 
+    .strtab 0 :
+    {
+        *(.strtab);
+    }
+    .symtab 0 :
+    {
+        *(.symtab);
+    }
+    .shstrtab 0 :
+    {
+        *(.shstrtab);
+    }
+
     /DISCARD/ :
     {
         *(.reginfo);