[PATCH] ld: add READONLY attribute for SECTIONS

[luca.boccassi@gmail.com]

From: Luca Boccassi <luca.boccassi@microsoft.com>

Allows linker scripts to set the SEC_READONLY flag.

Before:

  3 .note.package 0000004c  0000000000000308  0000000000000308  00000308  2**2
                  CONTENTS, ALLOC, LOAD, DATA

After:

  3 .note.package 0000004c  0000000000000308  0000000000000308  00000308  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA

Linker script:

SECTIONS
{
    .note.package (READONLY) : ALIGN(4) {
        BYTE(0x04) BYTE(0x00) BYTE(0x00) BYTE(0x00) /* Length of Owner including NUL */
        BYTE(0x39) BYTE(0x00) BYTE(0x00) BYTE(0x00) /* Length of Value including NUL */
        BYTE(0x7e) BYTE(0x1a) BYTE(0xfe) BYTE(0xca) /* Note ID */
        BYTE(0x46) BYTE(0x44) BYTE(0x4f) BYTE(0x00) /* Owner: 'FDO\x00' */
        BYTE(0x7b) BYTE(0x22) BYTE(0x74) BYTE(0x79)
        BYTE(0x70) BYTE(0x65) BYTE(0x22) BYTE(0x3a)
        BYTE(0x22) BYTE(0x64) BYTE(0x65) BYTE(0x62)
        BYTE(0x22) BYTE(0x2c) BYTE(0x22) BYTE(0x6e)
        BYTE(0x61) BYTE(0x6d) BYTE(0x65) BYTE(0x22)
        BYTE(0x3a) BYTE(0x22) BYTE(0x66) BYTE(0x73)
        BYTE(0x76) BYTE(0x65) BYTE(0x72) BYTE(0x69)
        BYTE(0x74) BYTE(0x79) BYTE(0x2d) BYTE(0x75)
        BYTE(0x74) BYTE(0x69) BYTE(0x6c) BYTE(0x73)
        BYTE(0x22) BYTE(0x2c) BYTE(0x22) BYTE(0x76)
        BYTE(0x65) BYTE(0x72) BYTE(0x73) BYTE(0x69)
        BYTE(0x6f) BYTE(0x6e) BYTE(0x22) BYTE(0x3a)
        BYTE(0x22) BYTE(0x31) BYTE(0x2e) BYTE(0x33)
        BYTE(0x2d) BYTE(0x31) BYTE(0x22) BYTE(0x7d)
        BYTE(0x00) BYTE(0x00) BYTE(0x00) BYTE(0x00)
    }
}
INSERT AFTER .note.gnu.build-id;

---
 ld/ld.texi  | 2 ++
 ld/ldgram.y | 2 ++
 ld/ldlang.c | 6 ++++++
 ld/ldlang.h | 3 ++-
 ld/ldlex.l  | 1 +
 5 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/ld/ld.texi b/ld/ld.texi
index fe653daacd7..a7f2267308d 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -5440,6 +5440,8 @@ parentheses.  The following types are defined:
 @item NOLOAD
 The section should be marked as not loadable, so that it will not be
 loaded into memory when the program is run.
+@item READONLY
+The section should be marked as read-only.
 @item DSECT
 @itemx COPY
 @itemx INFO
diff --git a/ld/ldgram.y b/ld/ldgram.y
index dd911f46169..31e0071c6fc 100644
--- a/ld/ldgram.y
+++ b/ld/ldgram.y
@@ -139,6 +139,7 @@ static int error_index;
 %token REGION_ALIAS
 %token LD_FEATURE
 %token NOLOAD DSECT COPY INFO OVERLAY
+%token READONLY
 %token DEFINED TARGET_K SEARCH_DIR MAP ENTRY
 %token <integer> NEXT
 %token SIZEOF ALIGNOF ADDR LOADADDR MAX_K MIN_K
@@ -1123,6 +1124,7 @@ type:
 	|  COPY    { sectype = noalloc_section; }
 	|  INFO    { sectype = noalloc_section; }
 	|  OVERLAY { sectype = noalloc_section; }
+	|  READONLY { sectype = readonly_section; }
 	;
 
 atype:
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 37b64c89ee1..2610be995ca 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -2639,6 +2639,9 @@ lang_add_section (lang_statement_list_type *ptr,
     case noalloc_section:
       flags &= ~SEC_ALLOC;
       break;
+    case readonly_section:
+      flags |= SEC_READONLY;
+      break;
     case noload_section:
       flags &= ~SEC_LOAD;
       flags |= SEC_NEVER_LOAD;
@@ -4232,6 +4235,9 @@ map_input_to_output_sections
 	    case noalloc_section:
 	      flags = SEC_HAS_CONTENTS;
 	      break;
+	    case readonly_section:
+	      flags |= SEC_READONLY;
+	      break;
 	    case noload_section:
 	      if (bfd_get_flavour (link_info.output_bfd)
 		  == bfd_target_elf_flavour)
diff --git a/ld/ldlang.h b/ld/ldlang.h
index 6fbe16d97d9..f68ae27b409 100644
--- a/ld/ldlang.h
+++ b/ld/ldlang.h
@@ -121,7 +121,8 @@ enum section_type
   first_overlay_section,
   overlay_section,
   noload_section,
-  noalloc_section
+  noalloc_section,
+  readonly_section
 };
 
 /* This structure holds a list of program headers describing
diff --git a/ld/ldlex.l b/ld/ldlex.l
index c1b15263587..25b4bcaae01 100644
--- a/ld/ldlex.l
+++ b/ld/ldlex.l
@@ -294,6 +294,7 @@ V_IDENTIFIER [*?.$_a-zA-Z\[\]\-\!\^\\]([*?.$_a-zA-Z0-9\[\]\-\!\^\\]|::)*
 <BOTH,SCRIPT>"SORT_BY_INIT_PRIORITY"	{ RTOKEN(SORT_BY_INIT_PRIORITY); }
 <BOTH,SCRIPT>"SORT_NONE"		{ RTOKEN(SORT_NONE); }
 <EXPRESSION,BOTH,SCRIPT>"NOLOAD"	{ RTOKEN(NOLOAD);}
+<EXPRESSION,BOTH,SCRIPT>"READONLY"	{ RTOKEN(READONLY);}
 <EXPRESSION,BOTH,SCRIPT>"DSECT"		{ RTOKEN(DSECT);}
 <EXPRESSION,BOTH,SCRIPT>"COPY"		{ RTOKEN(COPY);}
 <EXPRESSION,BOTH,SCRIPT>"INFO"		{ RTOKEN(INFO);}
-- 
2.29.2