ELF: Don't check DT_NEEDED for symbols defined by linker scriptusers/hjl/pr22471

Linker shouldn't use any shared objects, including those from DT_NEEDED,
to resolve references of symbols which will be defined by linker script.
gld${EMULATION_NAME}_get_script is called to get default linker script,
which is updated to set link_info.linker_script to type_${SCRIPT_NAME}.
In gld${EMULATION_NAME}_after_open, we set ldscript_def to 1 for symbols
which will be defined by default linker script derived from elf.sc so
that elf_link_add_object_symbols can avoid checking DT_NEEDED if symbols
are defined by linker script.

bfd/

	PR ld/22471
	* elflink.c (elf_link_add_object_symbols)): Don't check DT_NEEDED
	for symbols defined by linker script.

include/

	PR ld/22471
	* bfdlink.h (linker_script_type): New enum.
	(bfd_link_info): Add linker_script.

ld/

	PR ld/22471
	* emultempl/elf32.em (ETEXT_NAME): Set to ${USER_LABEL_PREFIX}etext
	if not set.
	(SCRIPT_TYPE): New.
	(gld${EMULATION_NAME}_after_open): Set ldscript_def on referenced
	symbols defined by default linker script.
	(gld${EMULATION_NAME}_get_script): Set link_info.linker_script to
	${SCRIPT_TYPE}.
	* ldmain.c (main): Initialize link_info.linker_script to
	type_unknown.
	* testsuite/ld-elf/pr22471.t: New file.
	* testsuite/ld-elf/pr22471a.s: Likewise.
	* testsuite/ld-elf/pr22471b.s: Likewise.
	* testsuite/ld-elf/shared.exp (ASFLAGS): Define UNDERSCORE for
	underscore targets.
	Run PR ld/22471 tests.

8 files changed, 150 insertions, 0 deletions

diff --git a/bfd/elflink.c b/bfd/elflink.c
index 99f867dc75c..ae2c31237a7 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -4887,6 +4887,7 @@ error_free_dyn:
 	  if (!add_needed
 	      && matched
 	      && definition
+	      && !h->root.ldscript_def
 	      && ((dynsym
 		   && h->ref_regular_nonweak
 		   && (old_bfd == NULL
diff --git a/include/bfdlink.h b/include/bfdlink.h
index 2370c0d45a3..7a83e45365a 100644
--- a/include/bfdlink.h
+++ b/include/bfdlink.h
@@ -296,6 +296,45 @@ enum output_type
   type_dll,
 };
 
+/* Types of linker script.  */
+enum linker_script_type
+{
+  type_unknown,
+  type_armbpabi,	/* From armbpabi.sc.  */
+  type_arclinux,	/* From arclinux.sc.  */
+  type_avr,		/* From avr.sc.  */
+  type_elf,		/* From elf.sc.  */
+  type_elf_chaos,	/* From elf_chaos.sc.  */
+  type_elf32crx,	/* From elf32crx.sc.  */
+  type_elfarc,		/* From elfarc.sc.  */
+  type_elfarcv2,	/* From elfarcv2.sc.  */
+  type_elf32cr16,	/* From elf32cr16.sc.  */
+  type_elf32cr16c,	/* From elf32cr16c.sc.  */
+  type_elf32sh_symbian,	/* From elf32sh-symbian.sc.  */
+  type_elf32xc16x,	/* From elf32xc16x.sc.  */
+  type_elf32xc16xl,	/* From elf32xc16xl.sc.  */
+  type_elf32xc16xs,	/* From elf32xc16xs.sc.  */
+  type_elf64hppa,	/* From elf64hppa.sc.  */
+  type_elfd10v,		/* From elfd10v.sc.  */
+  type_elfi370,		/* From elfi370.sc.  */
+  type_elfm68hc11,	/* From elfm68hc11.sc.  */
+  type_elfm68hc12,	/* From elfm68hc12.sc.  */
+  type_elfmicroblaze,	/* From elfmicroblaze.sc.  */
+  type_elfxgate,	/* From elfxgate.sc.  */
+  type_elfxtensa,	/* From elfxtensa.sc.  */
+  type_epiphany_4x4,	/* From epiphany_4x4.sc.  */
+  type_hppaelf,		/* From hppaelf.sc.  */
+  type_mep,		/* From mep.sc.  */
+  type_nds32elf,	/* From nds32elf.sc.  */
+  type_nw,		/* From nw.sc.  */
+  type_pru,		/* From pru.sc.  */
+  type_psos,		/* From psos.sc.  */
+  type_v850,		/* From v850.sc.  */
+  type_v850_rh850,	/* From v850_rh850.sc.  */
+  type_visium,		/* From visium.sc.  */
+  type_xstormy16	/* From xstormy16.sc.  */
+};
+
 #define bfd_link_pde(info)	   ((info)->type == type_pde)
 #define bfd_link_dll(info)	   ((info)->type == type_dll)
 #define bfd_link_relocatable(info) ((info)->type == type_relocatable)
@@ -492,6 +531,9 @@ struct bfd_link_info
   /* TRUE if common symbols should be treated as undefined.  */
   unsigned int inhibit_common_definition : 1;
 
+  /* Type of linker script used.  */
+  ENUM_BITFIELD (linker_script_type) linker_script : 6;
+
   /* The 1-byte NOP for x86 call instruction.  */
   char call_nop_byte;
 
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em
index edd8944f042..e6db53fbff1 100644
--- a/ld/emultempl/elf32.em
+++ b/ld/emultempl/elf32.em
@@ -3,6 +3,8 @@
 # This file is now misnamed, because it supports both 32 bit and 64 bit
 # ELF emulations.
 test -z "${ELFSIZE}" && ELFSIZE=32
+test -z "${ETEXT_NAME}" && ETEXT_NAME=${USER_LABEL_PREFIX}etext
+SCRIPT_TYPE=`echo "type_${SCRIPT_NAME}" | sed -e "s/-/_/g"`
 if [ -z "$MACHINE" ]; then
   OUTPUT_ARCH=${ARCH}
 else
@@ -1284,6 +1286,49 @@ gld${EMULATION_NAME}_after_open (void)
       return;
     }
 
+EOF
+
+# FIXME: Update for other ${SCRIPT_NAME} if PR ld/22471 tests failed.
+case ${SCRIPT_NAME} in
+  arclinux | elf | elf64hppa | elfxtensa | nds32elf)
+    fragment <<EOF
+  if (link_info.linker_script == ${SCRIPT_TYPE})
+    {
+      struct bfd_link_hash_entry *h;
+      const char *symbols[] =
+	{
+	  "__${ETEXT_NAME}",
+	  "_${ETEXT_NAME}",
+	  "${ETEXT_NAME}",
+	  "${USER_LABEL_PREFIX}" "__bss_start",
+	  "${USER_LABEL_PREFIX}" "_edata",
+	  "${USER_LABEL_PREFIX}" "edata",
+	  "${USER_LABEL_PREFIX}" "_end",
+	  "${USER_LABEL_PREFIX}" "end",
+	  NULL
+	};
+      const char **p;
+
+      /* These symbols will be defined by default linker script.  Set
+	 ldscript_def if they are referenced.  */
+      for (p = symbols; *p != NULL; p++)
+	{
+	  h = bfd_link_hash_lookup (link_info.hash, *p, FALSE, FALSE,
+				    FALSE);
+	  if (h != NULL
+	      && (h->type == bfd_link_hash_new
+		  || h->type == bfd_link_hash_undefined
+		  || h->type == bfd_link_hash_undefweak
+		  || h->type == bfd_link_hash_common))
+	    h->ldscript_def = 1;
+	}
+    }
+
+EOF
+    ;;
+esac
+
+fragment <<EOF
   if (!link_info.traditional_format)
     {
       bfd *elfbfd = NULL;
@@ -2350,7 +2395,11 @@ sc="-f stringify.sed"
 fragment <<EOF
 {
   *isfile = 0;
+EOF
 
+echo "  link_info.linker_script = ${SCRIPT_TYPE};" >> e${EMULATION_NAME}.c
+
+fragment <<EOF
   if (bfd_link_relocatable (&link_info) && config.build_constructors)
     return
 EOF
@@ -2409,7 +2458,11 @@ else
 fragment <<EOF
 {
   *isfile = 1;
+EOF
 
+echo "  link_info.linker_script = ${SCRIPT_TYPE};" >> e${EMULATION_NAME}.c
+
+fragment <<EOF
   if (bfd_link_relocatable (&link_info) && config.build_constructors)
     return "ldscripts/${EMULATION_NAME}.xu";
   else if (bfd_link_relocatable (&link_info))
diff --git a/ld/ldmain.c b/ld/ldmain.c
index 9e8f3304fe9..a1560eb0cd4 100644
--- a/ld/ldmain.c
+++ b/ld/ldmain.c
@@ -287,6 +287,7 @@ main (int argc, char **argv)
   link_info.pei386_auto_import = -1;
   link_info.spare_dynamic_tags = 5;
   link_info.path_separator = ':';
+  link_info.linker_script = type_unknown;
 #ifdef DEFAULT_FLAG_COMPRESS_DEBUG
   link_info.compress_debug = COMPRESS_DEBUG_GABI_ZLIB;
 #endif
diff --git a/ld/testsuite/ld-elf/pr22471.t b/ld/testsuite/ld-elf/pr22471.t
new file mode 100644
index 00000000000..8862dc291df
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr22471.t
@@ -0,0 +1 @@
+{ local: *; };
diff --git a/ld/testsuite/ld-elf/pr22471a.s b/ld/testsuite/ld-elf/pr22471a.s
new file mode 100644
index 00000000000..3bb6a92bdbd
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr22471a.s
@@ -0,0 +1 @@
+# Empty input.
diff --git a/ld/testsuite/ld-elf/pr22471b.s b/ld/testsuite/ld-elf/pr22471b.s
new file mode 100644
index 00000000000..f4edad04648
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr22471b.s
@@ -0,0 +1,17 @@
+	.type start,"function"
+	.global start
+start:
+	.type _start,"function"
+	.global _start
+_start:
+	.type __start,"function"
+	.global __start
+__start:
+	.type main,"function"
+	.global main
+main:
+  .ifdef UNDERSCORE
+	.dc.a ___bss_start
+  .else
+	.dc.a __bss_start
+  .endif
diff --git a/ld/testsuite/ld-elf/shared.exp b/ld/testsuite/ld-elf/shared.exp
index a40f8e0f59d..7514eb116bb 100644
--- a/ld/testsuite/ld-elf/shared.exp
+++ b/ld/testsuite/ld-elf/shared.exp
@@ -47,6 +47,40 @@ if [istarget "tic6x-*-*"] {
     append LFLAGS " -melf32_tic6x_le"
 }
 
+if [is_underscore_target] {
+    set ASFLAGS "$ASFLAGS --defsym UNDERSCORE=1"
+}
+
+run_ld_link_tests [list \
+    [list \
+	"Build pr22471a.so" \
+	"$LFLAGS -shared" \
+	"" \
+	"$AFLAGS_PIC" \
+	{pr22471a.s} \
+	{} \
+	"pr22471a.so" \
+    ] \
+    [list \
+	"Build pr22471b.so" \
+	"$LFLAGS -shared --version-script pr22471.t" \
+	"tmpdir/pr22471a.so" \
+	"$AFLAGS_PIC" \
+	{pr22471a.s} \
+	{} \
+	"pr22471b.so" \
+    ] \
+    [list \
+	"Build pr22471" \
+	"$LFLAGS -rpath-link ." \
+	"tmpdir/pr22471b.so" \
+	"" \
+	{pr22471b.s} \
+	{} \
+	"pr22471" \
+    ] \
+]
+
 # PR ld/20828 check for correct dynamic symbol table entries where:
 # - symbols have been defined with a linker script,
 # - the same symbols have been seen in shared library used in the link,