x86: warn about insns exceeding the 15-byte limit

Such insns will cause #UD when an attempt to execute them is made.

See also http://www.sandpile.org/x86/opc_enc.htm.

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 91c4d494ea8a00617f43580d57e1751302202165..b4bf405b98a96e5e92d50cc65663685cd82fd2d8 100644 (file)
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,13 @@
+2019-07-01  Jan Beulich  <jbeulich@suse.com>
+
+       * tc-i386.c (encoding_length): New.
+       (output_insn): Use it.
+       * testsuite/gas/i386/oversized16.l,
+       testsuite/gas/i386/oversized16.s,
+       testsuite/gas/i386/oversized64.l,
+       testsuite/gas/i386/oversized64.s: New.
+       * testsuite/gas/i386/i386.exp: Run new tests.
+
 2019-06-27  H.J. Lu  <hongjiu.lu@intel.com>
 
        PR binutils/24719

diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 4e5518816a4bc06632c243619786c223dc73f1e8..84c4bc5020a3a52deea881efe74fd142a73d474e 100644 (file)
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -8123,6 +8123,25 @@ x86_cleanup (void)
 }
 #endif
 
+static unsigned int
+encoding_length (const fragS *start_frag, offsetT start_off,
+                const char *frag_now_ptr)
+{
+  unsigned int len = 0;
+
+  if (start_frag != frag_now)
+    {
+      const fragS *fr = start_frag;
+
+      do {
+       len += fr->fr_fix;
+       fr = fr->fr_next;
+      } while (fr && fr != frag_now);
+    }
+
+  return len - start_off + (frag_now_ptr - frag_now->fr_literal);
+}
+
 static void
 output_insn (void)
 {
@@ -8400,6 +8419,19 @@ output_insn (void)
 
       if (i.imm_operands)
        output_imm (insn_start_frag, insn_start_off);
+
+      /*
+       * frag_now_fix () returning plain abs_section_offset when we're in the
+       * absolute section, and abs_section_offset not getting updated as data
+       * gets added to the frag breaks the logic below.
+       */
+      if (now_seg != absolute_section)
+       {
+         j = encoding_length (insn_start_frag, insn_start_off, frag_more (0));
+         if (j > 15)
+           as_warn (_("instruction length of %u bytes exceeds the limit of 15"),
+                    j);
+       }
     }
 
 #ifdef DEBUG386

diff --git a/gas/testsuite/gas/i386/i386.exp b/gas/testsuite/gas/i386/i386.exp
index 09f5dec2d2a71bdfd62a823f12d0a186312bda20..1b4fcb6200b2897bb33075ac4b010b04770a1543 100644 (file)
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -130,6 +130,7 @@ if [expr ([istarget "i*86-*-*"] ||  [istarget "x86_64-*-*"]) && [gas_32_check]]
     run_dump_test "nops-7"
     run_dump_test "addr16"
     run_dump_test "addr32"
+    run_list_test "oversized16" "-al"
     run_dump_test "sse4_1"
     run_dump_test "sse4_1-intel"
     run_dump_test "sse4_2"
@@ -722,6 +723,7 @@ if [expr ([istarget "i*86-*-*"] || [istarget "x86_64-*-*"]) && [gas_64_check]] t
     run_list_test "x86-64-suffix-bad"
     run_list_test "unspec64" ""
     run_list_test "prefix64" "-al"
+    run_list_test "oversized64" "-al"
     run_dump_test "x86-64-fxsave"
     run_dump_test "x86-64-fxsave-intel"
     run_dump_test "x86-64-arch-1"

diff --git a/gas/testsuite/gas/i386/oversized16.l b/gas/testsuite/gas/i386/oversized16.l
new file mode 100644 (file)
index 0000000..3bf7e1d
--- /dev/null
+++ b/gas/testsuite/gas/i386/oversized16.l
@@ -0,0 +1,41 @@
+.*: Assembler messages:
+.*:6: Warning: instruction length.*
+.*:7: Warning: instruction length.*
+.*:8: Warning: instruction length.*
+.*:10: Warning: instruction length.*
+.*:11: Warning: instruction length.*
+GAS LISTING .*
+
+
+[      ]*1[    ]+\.text
+[      ]*2[    ]+\.intel_syntax noprefix
+[      ]*3[    ]+\.code16
+[      ]*4[    ]+
+[      ]*5[    ]+long16:
+[      ]*6[    ]+0000 26678FEA[        ]+lwpins        eax, es:\[eax\*8\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*6[    ]+781204C5[     ]*
+[      ]*6[    ]+00000000[     ]*
+[      ]*6[    ]+44332211[     ]*
+[      ]*7[    ]+0010 26678FEA[        ]+lwpval        eax, es:\[eax\*4\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*7[    ]+78120C85[     ]*
+[      ]*7[    ]+00000000[     ]*
+[      ]*7[    ]+44332211[     ]*
+[      ]*8[    ]+0020 26678FEA[        ]+bextr eax, es:\[eax\*2\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*8[    ]+78100445[     ]*
+[      ]*8[    ]+00000000[     ]*
+[      ]*8[    ]+44332211[     ]*
+[      ]*9[    ]+
+[      ]*10[   ]+0030 266766F2[        ]+xacquire lock add dword ptr es:\[eax\*2\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*10[   ]+F0810445[     ]*
+[      ]*10[   ]+00000000[     ]*
+[      ]*10[   ]+44332211[     ]*
+[      ]*11[   ]+0040 266766F3[        ]+xrelease lock sub dword ptr es:\[eax\*2\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*11[   ]+F0812C45[     ]*
+[      ]*11[   ]+00000000[     ]*
+[      ]*11[   ]+44332211[     ]*
+#pass

diff --git a/gas/testsuite/gas/i386/oversized16.s b/gas/testsuite/gas/i386/oversized16.s
new file mode 100644 (file)
index 0000000..8b250d0
--- /dev/null
+++ b/gas/testsuite/gas/i386/oversized16.s
@@ -0,0 +1,11 @@
+       .text
+       .intel_syntax noprefix
+       .code16
+
+long16:
+       lwpins  eax, es:[eax*8], 0x11223344
+       lwpval  eax, es:[eax*4], 0x11223344
+       bextr   eax, es:[eax*2], 0x11223344
+
+       xacquire lock add dword ptr es:[eax*2], 0x11223344
+       xrelease lock sub dword ptr es:[eax*2], 0x11223344

diff --git a/gas/testsuite/gas/i386/oversized64.l b/gas/testsuite/gas/i386/oversized64.l
new file mode 100644 (file)
index 0000000..dc63fb5
--- /dev/null
+++ b/gas/testsuite/gas/i386/oversized64.l
@@ -0,0 +1,40 @@
+.*: Assembler messages:
+.*:5: Warning: instruction length.*
+.*:6: Warning: instruction length.*
+.*:7: Warning: instruction length.*
+.*:9: Warning: instruction length.*
+.*:10: Warning: instruction length.*
+GAS LISTING .*
+
+
+[      ]*1[    ]+\.text
+[      ]*2[    ]+\.intel_syntax noprefix
+[      ]*3[    ]+
+[      ]*4[    ]+long64:
+[      ]*5[    ]+0000 64678FEA[        ]+lwpins        rax, fs:\[eax\*8\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*5[    ]+F81204C5[     ]*
+[      ]*5[    ]+00000000[     ]*
+[      ]*5[    ]+44332211[     ]*
+[      ]*6[    ]+0010 64678FEA[        ]+lwpval        eax, fs:\[eax\*4\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*6[    ]+78120C85[     ]*
+[      ]*6[    ]+00000000[     ]*
+[      ]*6[    ]+44332211[     ]*
+[      ]*7[    ]+0020 64678FEA[        ]+bextr rax, fs:\[eax\*2\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*7[    ]+F8100445[     ]*
+[      ]*7[    ]+00000000[     ]*
+[      ]*7[    ]+44332211[     ]*
+[      ]*8[    ]+
+[      ]*9[    ]+0030 6567F2F0[        ]+xacquire lock add qword ptr gs:\[eax\*8\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*9[    ]+488104C5[     ]*
+[      ]*9[    ]+00000000[     ]*
+[      ]*9[    ]+44332211[     ]*
+[      ]*10[   ]+0040 6567F3F0[        ]+xrelease lock sub qword ptr gs:\[eax\*8\], 0x11223344
+\*\*\*\*  Warning: instruction length of 16 bytes exceeds the limit of 15
+[      ]*10[   ]+48812CC5[     ]*
+[      ]*10[   ]+00000000[     ]*
+[      ]*10[   ]+44332211[     ]*
+#pass

diff --git a/gas/testsuite/gas/i386/oversized64.s b/gas/testsuite/gas/i386/oversized64.s
new file mode 100644 (file)
index 0000000..9db09af
--- /dev/null
+++ b/gas/testsuite/gas/i386/oversized64.s
@@ -0,0 +1,10 @@
+       .text
+       .intel_syntax noprefix
+
+long64:
+       lwpins  rax, fs:[eax*8], 0x11223344
+       lwpval  eax, fs:[eax*4], 0x11223344
+       bextr   rax, fs:[eax*2], 0x11223344
+
+       xacquire lock add qword ptr gs:[eax*8], 0x11223344
+       xrelease lock sub qword ptr gs:[eax*8], 0x11223344