[binutils-gdb] ld: Issue an error for GC on __patchable_function_entries section

[H.J.Lu]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5242a0a000ad7d3f2fa1cd0023f692d53261b302

commit 5242a0a000ad7d3f2fa1cd0023f692d53261b302
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Thu Feb 6 19:37:54 2020 -0800

    ld: Issue an error for GC on __patchable_function_entries section
    
    __patchable_function_entries section is generated by a compiler with
    -fpatchable-function-entry=XX.  The assembly code looks like this:
    
    ---
    	.text
    	.globl	_start
    	.type	_start, %function
    _start:
    	.section __patchable_function_entries,"aw",%progbits
    	.dc.a	.LPFE1
    	.text
    .LPFE1:
    	.byte 0
    ---
    
    But --gc-sections will silently remove __patchable_function_entries
    section and generate corrupt result.  This patch disallows garbage
    collection on __patchable_function_entries section without linked-to
    section.
    
    bfd/
    
    	PR ld/25490
    	* elflink.c (_bfd_elf_gc_mark_extra_sections): Issue an error
    	for garbage collection on __patchable_function_entries section
    	without linked-to section.
    
    ld/
    
    	PR ld/25490
    	* testsuite/ld-elf/pr25490-1.d: New file.
    	* testsuite/ld-elf/pr25490-1.s: Likewise.

Diff:
---
 bfd/ChangeLog                   | 7 +++++++
 bfd/elflink.c                   | 7 +++++++
 ld/ChangeLog                    | 6 ++++++
 ld/testsuite/ld-elf/pr25490-1.d | 3 +++
 ld/testsuite/ld-elf/pr25490-1.s | 9 +++++++++
 5 files changed, 32 insertions(+)

diff --git a/bfd/ChangeLog b/bfd/ChangeLog
index 9971885..e1a8412 100644
--- a/bfd/ChangeLog
+++ b/bfd/ChangeLog
@@ -1,5 +1,12 @@
 2020-02-06  H.J. Lu  <hongjiu.lu@intel.com>
 
+	PR ld/25490
+	* elflink.c (_bfd_elf_gc_mark_extra_sections): Issue an error
+	for garbage collection on __patchable_function_entries section
+	without linked-to section.
+
+2020-02-06  H.J. Lu  <hongjiu.lu@intel.com>
+
 	PR gas/25381
 	* bfd-in2.h: Regenerated.
 	* elflink.c (_bfd_elf_gc_mark_extra_sections): Call mark_hook
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 30a572d..3add9f1 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -13365,6 +13365,13 @@ _bfd_elf_gc_mark_extra_sections (struct bfd_link_info *info,
 	      && (isec->flags & SEC_DEBUGGING)
 	      && CONST_STRNEQ (isec->name, ".debug_line."))
 	    debug_frag_seen = TRUE;
+	  else if (strcmp (bfd_section_name (isec),
+			   "__patchable_function_entries") == 0
+		   && elf_linked_to_section (isec) == NULL)
+	      info->callbacks->einfo (_("%F%P: %pB(%pA): error: "
+					"need linked-to section "
+					"for --gc-sections\n"),
+				      isec->owner, isec);
 	}
 
       /* If no non-note alloc section in this file will be kept, then
diff --git a/ld/ChangeLog b/ld/ChangeLog
index b5c8326..3ad571f 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,5 +1,11 @@
 2020-02-06  H.J. Lu  <hongjiu.lu@intel.com>
 
+	PR ld/25490
+	* testsuite/ld-elf/pr25490-1.d: New file.
+	* testsuite/ld-elf/pr25490-1.s: Likewise.
+
+2020-02-06  H.J. Lu  <hongjiu.lu@intel.com>
+
 	PR ld/24526
 	PR ld/25021
 	PR ld/25490
diff --git a/ld/testsuite/ld-elf/pr25490-1.d b/ld/testsuite/ld-elf/pr25490-1.d
new file mode 100644
index 0000000..3f58264
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr25490-1.d
@@ -0,0 +1,3 @@
+#ld: --gc-sections -e _start
+#target: [check_gc_sections_available]
+#error: .*\(__patchable_function_entries\): error: need linked-to section for --gc-sections
diff --git a/ld/testsuite/ld-elf/pr25490-1.s b/ld/testsuite/ld-elf/pr25490-1.s
new file mode 100644
index 0000000..51ba1ea
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr25490-1.s
@@ -0,0 +1,9 @@
+	.text
+	.globl	_start
+	.type	_start, %function
+_start:
+	.section	__patchable_function_entries,"aw",%progbits
+	.dc.a	.LPFE1
+	.text
+.LPFE1:
+	.byte 0