[PATCH 1/2] x86: warn about insns exceeding the 15-byte limit
Jan Beulich
JBeulich@suse.com
Tue Jun 25 14:54:00 GMT 2019
Such insns will cause #UD when an attempt to execute them is made.
See also http://www.sandpile.org/x86/opc_enc.htm.
gas/
2019-06-25 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.
--- 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
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -130,6 +130,7 @@ if [expr ([istarget "i*86-*-*"] || [ist
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-*-*"] || [ista
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"
--- /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
--- /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
--- /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
--- /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
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