Add "-z call-nop=PADDING" option to ld

The ld linker can transform indirect call to a locally defined function,
foo, via its GOT slot, to either "NOP call foo" or "call foo NOP" where
NOP is a 1-byte NOP padding.  This patch adds a "-z call-nop=PADDING"
option to x86 ld to control 1-byte NOP padding for x86 call instruction.
PADDING is one of prefix-addr, prefix-nop, suffix-nop, prefix-NUMBER or
suffix-NUMBER.

bfd/

	* elf32-i386.c (elf_i386_convert_load): Use call_nop_byte and
	check call_nop_as_suffix for 1-byte NOP padding to pad call.
	* elf64-x86-64.c (elf_x86_64_convert_load): Likewise.

include/

	* bfdlink.h (bfd_link_info): Add call_nop_as_suffix and
	call_nop_byte.

ld/

	* ld/ld.texinfo: Document "-z call-nop=PADDING" option.
	* emulparams/call_nop.sh: New file.
	* emulparams/elf_i386_be.sh: Source
	${srcdir}/emulparams/call_nop.sh.
	* emulparams/elf_i386_chaos.sh: Likewise.
	* emulparams/elf_i386_ldso.sh: Likewise.
	* emulparams/elf_i386_vxworks.sh: Likewise.
	* emulparams/elf_iamcu.sh: Likewise.
	* emulparams/elf_k1om.sh: Likewise.
	* emulparams/elf_l1om.sh: Likewise.
	* emulparams/elf_x86_64.sh: Likewise.
	* emultempl/elf32.em (gld${EMULATION_NAME}_before_parse): Set
	link_info.call_nop_byte if $CALL_NOP_BYTE isn't empty.

ld/testsuite/

	* ld-i386/call3.s: New file.
	* ld-i386/call3a.d: Likewise.
	* ld-i386/call3b.d: Likewise.
	* ld-i386/call3c.d: Likewise.
	* ld-i386/call3d.d: Likewise.
	* ld-i386/call3e.d: Likewise.
	* ld-i386/call3f.d: Likewise.
	* ld-i386/call3g.d: Likewise.
	* ld-i386/call3h.d: Likewise.
	* ld-i386/load1-nacl.d: Likewise.
	* ld-x86-64/call1.s: Likewise.
	* ld-x86-64/call1a.d: Likewise.
	* ld-x86-64/call1b.d: Likewise.
	* ld-x86-64/call1c.d: Likewise.
	* ld-x86-64/call1d.d: Likewise.
	* ld-x86-64/call1e.d: Likewise.
	* ld-x86-64/call1f.d: Likewise.
	* ld-x86-64/call1g.d: Likewise.
	* ld-x86-64/call1h.d: Likewise.
	* ld-x86-64/call1i.d: Likewise.
	* ld-x86-64/load1a-nacl.d: Likewise.
	* ld-x86-64/load1b-nacl.d: Likewise.
	* ld-x86-64/load1c-nacl.d: Likewise.
	* ld-x86-64/load1d-nacl.d: Likewise.

11 files changed, 58 insertions, 0 deletions

diff --git a/ld/emulparams/call_nop.sh b/ld/emulparams/call_nop.sh
new file mode 100644
index 0000000..fee4a81
--- /dev/null
+++ b/ld/emulparams/call_nop.sh
@@ -0,0 +1,48 @@
+PARSE_AND_LIST_OPTIONS_CALL_NOP='
+  fprintf (file, _("\
+  -z call-nop=PADDING         Use PADDING as 1-byte NOP for branch\n"));
+'
+PARSE_AND_LIST_ARGS_CASE_Z_CALL_NOP='
+      else if (strncmp (optarg, "call-nop=", 9) == 0)
+	{
+	  if (strcmp (optarg + 9, "prefix-addr") == 0)
+	    {
+	      link_info.call_nop_as_suffix = FALSE;
+	      link_info.call_nop_byte = 0x67;
+	    }
+	  else if (strcmp (optarg + 9, "prefix-nop") == 0)
+	    {
+	      link_info.call_nop_as_suffix = FALSE;
+	      link_info.call_nop_byte = 0x90;
+	    }
+	  else if (strcmp (optarg + 9, "suffix-nop") == 0)
+	    {
+	      link_info.call_nop_as_suffix = TRUE;
+	      link_info.call_nop_byte = 0x90;
+	    }
+	  else if (strncmp (optarg + 9, "prefix-", 7) == 0)
+	    {
+	      char *end;
+	      link_info.call_nop_byte = strtoul (optarg + 16 , &end, 0);
+	      if (*end)
+	        einfo (_("%P%F: invalid number for -z call-nop=prefix-: %s\n"),
+		       optarg + 16);
+	      link_info.call_nop_as_suffix = FALSE;
+	    }
+	  else if (strncmp (optarg + 9, "suffix-", 7) == 0)
+	    {
+	      char *end;
+	      link_info.call_nop_byte = strtoul (optarg + 16, &end, 0);
+	      if (*end)
+	        einfo (_("%P%F: invalid number for -z call-nop=suffix-: %s\n"),
+		       optarg + 16);
+	      link_info.call_nop_as_suffix = TRUE;
+	    }
+	  else
+	    einfo (_("%P%F: unsupported option: -z %s\n"), optarg);
+	}
+'
+
+PARSE_AND_LIST_OPTIONS="$PARSE_AND_LIST_OPTIONS $PARSE_AND_LIST_OPTIONS_CALL_NOP"
+PARSE_AND_LIST_ARGS_CASE_Z="$PARSE_AND_LIST_ARGS_CASE_Z $PARSE_AND_LIST_ARGS_CASE_Z_CALL_NOP"
+CALL_NOP_BYTE=0x67
diff --git a/ld/emulparams/elf32_x86_64.sh b/ld/emulparams/elf32_x86_64.sh
index 8fd96fb..0a03548 100644
--- a/ld/emulparams/elf32_x86_64.sh
+++ b/ld/emulparams/elf32_x86_64.sh
@@ -1,5 +1,6 @@
 . ${srcdir}/emulparams/plt_unwind.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf
 ELFSIZE=32
 OUTPUT_FORMAT="elf32-x86-64"
diff --git a/ld/emulparams/elf_i386.sh b/ld/emulparams/elf_i386.sh
index ae87f6b..7dceea9 100644
--- a/ld/emulparams/elf_i386.sh
+++ b/ld/emulparams/elf_i386.sh
@@ -1,5 +1,6 @@
 . ${srcdir}/emulparams/plt_unwind.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf
 OUTPUT_FORMAT="elf32-i386"
 NO_RELA_RELOCS=yes
diff --git a/ld/emulparams/elf_i386_be.sh b/ld/emulparams/elf_i386_be.sh
index 06a80c7..40ed8c6 100644
--- a/ld/emulparams/elf_i386_be.sh
+++ b/ld/emulparams/elf_i386_be.sh
@@ -1,4 +1,5 @@
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf
 OUTPUT_FORMAT="elf32-i386"
 NO_RELA_RELOCS=yes
diff --git a/ld/emulparams/elf_i386_chaos.sh b/ld/emulparams/elf_i386_chaos.sh
index c59dbce..33757bf 100644
--- a/ld/emulparams/elf_i386_chaos.sh
+++ b/ld/emulparams/elf_i386_chaos.sh
@@ -1,5 +1,6 @@
 . ${srcdir}/emulparams/plt_unwind.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf_chaos
 OUTPUT_FORMAT="elf32-i386"
 TEXT_START_ADDR=0x40000000
diff --git a/ld/emulparams/elf_i386_ldso.sh b/ld/emulparams/elf_i386_ldso.sh
index 7fd08fe..f780581 100644
--- a/ld/emulparams/elf_i386_ldso.sh
+++ b/ld/emulparams/elf_i386_ldso.sh
@@ -1,5 +1,6 @@
 . ${srcdir}/emulparams/plt_unwind.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf
 OUTPUT_FORMAT="elf32-i386"
 NO_RELA_RELOCS=yes
diff --git a/ld/emulparams/elf_i386_vxworks.sh b/ld/emulparams/elf_i386_vxworks.sh
index 306e8d3..cb289e6 100644
--- a/ld/emulparams/elf_i386_vxworks.sh
+++ b/ld/emulparams/elf_i386_vxworks.sh
@@ -12,3 +12,4 @@ GENERATE_PIE_SCRIPT=yes
 NO_SMALL_DATA=yes
 . ${srcdir}/emulparams/vxworks.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
diff --git a/ld/emulparams/elf_iamcu.sh b/ld/emulparams/elf_iamcu.sh
index 39c7a57..5fae651 100644
--- a/ld/emulparams/elf_iamcu.sh
+++ b/ld/emulparams/elf_iamcu.sh
@@ -1,5 +1,6 @@
 . ${srcdir}/emulparams/plt_unwind.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf
 OUTPUT_FORMAT="elf32-iamcu"
 NO_RELA_RELOCS=yes
diff --git a/ld/emulparams/elf_k1om.sh b/ld/emulparams/elf_k1om.sh
index 0cd606a..289274d 100644
--- a/ld/emulparams/elf_k1om.sh
+++ b/ld/emulparams/elf_k1om.sh
@@ -1,5 +1,6 @@
 . ${srcdir}/emulparams/plt_unwind.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf
 ELFSIZE=64
 OUTPUT_FORMAT="elf64-k1om"
diff --git a/ld/emulparams/elf_l1om.sh b/ld/emulparams/elf_l1om.sh
index 1964e85..17fa8e2 100644
--- a/ld/emulparams/elf_l1om.sh
+++ b/ld/emulparams/elf_l1om.sh
@@ -1,5 +1,6 @@
 . ${srcdir}/emulparams/plt_unwind.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf
 ELFSIZE=64
 OUTPUT_FORMAT="elf64-l1om"
diff --git a/ld/emulparams/elf_x86_64.sh b/ld/emulparams/elf_x86_64.sh
index a304771..5d31da1 100644
--- a/ld/emulparams/elf_x86_64.sh
+++ b/ld/emulparams/elf_x86_64.sh
@@ -1,5 +1,6 @@
 . ${srcdir}/emulparams/plt_unwind.sh
 . ${srcdir}/emulparams/extern_protected_data.sh
+. ${srcdir}/emulparams/call_nop.sh
 SCRIPT_NAME=elf
 ELFSIZE=64
 OUTPUT_FORMAT="elf64-x86-64"