Treat `start_stop` symbols as having section size

There is special handling to ensure that symbols which look like they
are supposed to point at the start of a section are given a size to span
that entire section.

GNU ld has special `start_stop` symbols which are automatically provided
by the linker for sections where the output section and input section
share a name and that name is representable as a C identifier.
(see commit cbd0eecf2)

These special symbols represent the start and end address of the output
section.  These special symbols are used in much the same way in source
code as section-start symbols provided by the linker script.  Glibc uses
these for the __libc_atexit section containing pointers for functions to
run at exit.

This change accounts for these `start_stop` symbols by giving them the
size of the "remaining" range of the output section in the same way as
linker script defined symbols.  This means that the `start` symbols get
section-spanning bounds and the `stop` symbols get bounds of zero.

N.b. We will have to also account for these symbols in the
`resize_sections` function, but that's not done yet.

diff --git a/bfd/elfnn-aarch64.c b/bfd/elfnn-aarch64.c
index 5e7f0324dd89838a56eda2b87cd2b439ba52b796..c31e707a4fb8870522d2eb5a624e13fcaabf84bf 100644 (file)
--- a/bfd/elfnn-aarch64.c
+++ b/bfd/elfnn-aarch64.c
@@ -6456,6 +6456,15 @@ c64_symbol_section_adjustment (struct elf_link_hash_entry *h, bfd_vma value,
        }
       return C64_SYM_LDSCRIPT_DEF;
     }
+
+  if (h->start_stop)
+    {
+      asection *s = h->u2.start_stop_section->output_section;
+      BFD_ASSERT (s != NULL);
+      *ret_sec = s;
+      return C64_SYM_LDSCRIPT_DEF;
+    }
+
   return C64_SYM_STANDARD;
 }
 

diff --git a/ld/testsuite/ld-aarch64/aarch64-elf.exp b/ld/testsuite/ld-aarch64/aarch64-elf.exp
index 49b2e70adca947b61294bf1d589ce366b81da569..f0d2048efc37c2df3f4dfea304c7f93f8fe3a169 100644 (file)
--- a/ld/testsuite/ld-aarch64/aarch64-elf.exp
+++ b/ld/testsuite/ld-aarch64/aarch64-elf.exp
@@ -271,6 +271,7 @@ run_dump_test_lp64 "morello-sec-round-include-relro"
 run_dump_test_lp64 "morello-pcc-bounds-include-readonly"
 run_dump_test_lp64 "morello-sec-round-choose-linker-syms"
 run_dump_test_lp64 "morello-entry-point"
+run_dump_test_lp64 "morello-sec-start_stop-round"
 run_dump_test_lp64 "morello-tlsdesc"
 run_dump_test_lp64 "morello-tlsdesc-static"
 run_dump_test_lp64 "morello-tlsdesc-staticpie"

diff --git a/ld/testsuite/ld-aarch64/morello-sec-start_stop-round.d b/ld/testsuite/ld-aarch64/morello-sec-start_stop-round.d
new file mode 100644 (file)
index 0000000..3987696
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/morello-sec-start_stop-round.d
@@ -0,0 +1,26 @@
+#as: -march=morello+c64
+#ld: -static
+#objdump: -d -j .data -j __libc_atexit
+
+.*:     file format .*
+
+
+Disassembly of section \.data:
+
+[0-9a-f]+ <__data_start>:
+#record: START_LIBC_ADDR
+.*:    ([0-9a-f]+)     .*
+.*:    00000000        .*
+.*:    00000008        .*
+.*:    02000000        .*
+
+Disassembly of section __libc_atexit:
+
+# Use `string tolower` because we know we only have a number so it won't change
+# anything.  That's needed because the current record/check implementation
+# doesn't have a way to define a replacement which is just the existing
+# variable.
+#check: START_LIBC string tolower $START_LIBC_ADDR
+00000000START_LIBC <__start___libc_atexit>:
+.*:    0000002a        .*
+.*:    00000000        .*

diff --git a/ld/testsuite/ld-aarch64/morello-sec-start_stop-round.s b/ld/testsuite/ld-aarch64/morello-sec-start_stop-round.s
new file mode 100644 (file)
index 0000000..b89273e
--- /dev/null
+++ b/ld/testsuite/ld-aarch64/morello-sec-start_stop-round.s
@@ -0,0 +1,10 @@
+.section __libc_atexit,"aw"
+       .xword 42
+.data
+atexit_location:
+       .chericap __start___libc_atexit
+.text
+.globl _start
+.type _start STT_FUNC
+_start:
+       add c0, c0, :lo12:atexit_location