[PATCH] aarch64: Fix bogus type punning in parse_barrier() [PR26699]

[Alex Coplan]

Hello,

This patch fixes a bogus use of type punning in parse_barrier() which
was causing an assembly failure on big endian LP64 hosts when attempting
to assemble "isb sy" for AArch64.

The type of the entries in aarch64_barrier_opt_hsh is
aarch64_name_value_pair. We were incorrectly casting this to the
locally-defined asm_barrier_opt which has a wider type (on LP64) for the
second member. This happened to work on little-endian hosts but fails on
LP64 big endian.

The fix is to use the correct type in parse_barrier(). This makes the
locally-defined asm_barrier_opt redundant, so remove it.

Testing:
 * Regression tested natively on aarch64_be-linux-gnu.
 * Regression tested an x86_64 -> aarch64-none-elf cross.

OK for master and backport to binutils-2.35?

Thanks,
Alex

---

gas/ChangeLog:

2020-10-06  Alex Coplan  <alex.coplan@arm.com>

	* config/tc-aarch64.c (asm_barrier_opt): Delete.
	(parse_barrier): Fix bogus type punning.
	* testsuite/gas/aarch64/system.d: Update disassembly.
	* testsuite/gas/aarch64/system.s: Add isb sy test.
-------------- next part --------------
diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index 4bcfa053f75..fac571ea573 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -247,12 +247,6 @@ set_fatal_syntax_error (const char *error)
    present. */
 #define COND_ALWAYS 0x10
 
-typedef struct
-{
-  const char *template;
-  unsigned long value;
-} asm_barrier_opt;
-
 typedef struct
 {
   const char *template;
@@ -3993,7 +3987,7 @@ static int
 parse_barrier (char **str)
 {
   char *p, *q;
-  const asm_barrier_opt *o;
+  const struct aarch64_name_value_pair *o;
 
   p = q = *str;
   while (ISALPHA (*q))
diff --git a/gas/testsuite/gas/aarch64/system.d b/gas/testsuite/gas/aarch64/system.d
index 20d5c204094..c973584af59 100644
--- a/gas/testsuite/gas/aarch64/system.d
+++ b/gas/testsuite/gas/aarch64/system.d
@@ -190,6 +190,7 @@ Disassembly of section \.text:
 .*:	d5033edf 	isb	#0xe
 .*:	d5033fdf 	isb
 .*:	d5033fdf 	isb
+.*:	d5033fdf 	isb
 .*:	d503309f 	ssbb
 .*:	d503349f 	pssbb
 .*:	d8000000 	prfm	pldl1keep, 0 <LABEL1>
diff --git a/gas/testsuite/gas/aarch64/system.s b/gas/testsuite/gas/aarch64/system.s
index 9d86f66806a..6f494f885a6 100644
--- a/gas/testsuite/gas/aarch64/system.s
+++ b/gas/testsuite/gas/aarch64/system.s
@@ -44,6 +44,7 @@
 	all_barriers	op=isb, from=0, to=15
 
 	isb
+	isb sy
 	ssbb
 	pssbb