Implement Read/Write constraints on system registers on AArch64

This patch adds constraints for read and write only system registers with the
msr and mrs instructions.  The code will treat having both flags set and none
set as the same.  These flags add constraints that must be matched up. e.g. a
system register with a READ only flag set, can only be used with mrs.  If The
constraint fails a warning is emitted.

Examples of the warnings generated:

test.s: Assembler messages:
test.s:5: Warning: specified register cannot be written to at operand 1 -- `msr dbgdtrrx_el0,x3'
test.s:7: Warning: specified register cannot be read from at operand 2 -- `mrs x3,dbgdtrtx_el0'
test.s:8: Warning: specified register cannot be written to at operand 1 -- `msr midr_el1,x3'

and disassembly notes:

0000000000000000 <main>:
   0:	d5130503 	msr	dbgdtrtx_el0, x3
   4:	d5130503 	msr	dbgdtrtx_el0, x3
   8:	d5330503 	mrs	x3, dbgdtrrx_el0
   c:	d5330503 	mrs	x3, dbgdtrrx_el0
  10:	d5180003 	msr	midr_el1, x3	; note: writing to a read-only register.

Note that because dbgdtrrx_el0 and dbgdtrtx_el0 have the same encoding, during
disassembly the constraints are use to disambiguate between the two.  An exact
constraint match is always prefered over partial ones if available.

As always the warnings can be suppressed with -w and also be made errors using
warnings as errors.

binutils/

	PR binutils/21446
	* doc/binutils.texi (-M): Document AArch64 options.

gas/

	PR binutils/21446
	* testsuite/gas/aarch64/illegal-sysreg-2.s: Fix pmbidr_el1 test.
	* testsuite/gas/aarch64/illegal-sysreg-2.l: Likewise.
	* testsuite/gas/aarch64/illegal-sysreg-2.d: Likewise.
	* testsuite/gas/aarch64/sysreg-diagnostic.s: New.
	* testsuite/gas/aarch64/sysreg-diagnostic.l: New.
	* testsuite/gas/aarch64/sysreg-diagnostic.d: New.

include/

	PR binutils/21446
	* opcode/aarch64.h (F_SYS_READ, F_SYS_WRITE): New.

opcodes/

	PR binutils/21446
	* aarch64-asm.c (opintl.h): Include.
	(aarch64_ins_sysreg): Enforce read/write constraints.
	* aarch64-dis.c (aarch64_ext_sysreg): Likewise.
	* aarch64-opc.h (F_DEPRECATED, F_ARCHEXT, F_HASXT): Moved here.
	(F_REG_READ, F_REG_WRITE): New.
	* aarch64-opc.c (aarch64_print_operand): Generate notes for
	AARCH64_OPND_SYSREG.
	(F_DEPRECATED, F_ARCHEXT, F_HASXT): Move to aarch64-opc.h.
	(aarch64_sys_regs): Add constraints to currentel, midr_el1, ctr_el0,
	mpidr_el1, revidr_el1, aidr_el1, dczid_el0, id_dfr0_el1, id_pfr0_el1,
	id_pfr1_el1, id_afr0_el1, id_mmfr0_el1, id_mmfr1_el1, id_mmfr2_el1,
	id_mmfr3_el1, id_mmfr4_el1, id_isar0_el1, id_isar1_el1, id_isar2_el1,
	id_isar3_el1, id_isar4_el1, id_isar5_el1, mvfr0_el1, mvfr1_el1,
	mvfr2_el1, ccsidr_el1, id_aa64pfr0_el1, id_aa64pfr1_el1,
	id_aa64dfr0_el1, id_aa64dfr1_el1, id_aa64isar0_el1, id_aa64isar1_el1,
	id_aa64mmfr0_el1, id_aa64mmfr1_el1, id_aa64mmfr2_el1, id_aa64afr0_el1,
	id_aa64afr0_el1, id_aa64afr1_el1, id_aa64zfr0_el1, clidr_el1,
	csselr_el1, vsesr_el2, erridr_el1, erxfr_el1, rvbar_el1, rvbar_el2,
	rvbar_el3, isr_el1, tpidrro_el0, cntfrq_el0, cntpct_el0, cntvct_el0,
	mdccsr_el0, dbgdtrrx_el0, dbgdtrtx_el0, osdtrrx_el1, osdtrtx_el1,
	mdrar_el1, oslar_el1, oslsr_el1, dbgauthstatus_el1, pmbidr_el1,
	pmsidr_el1, pmswinc_el0, pmceid0_el0, pmceid1_el0.
	* aarch64-tbl.h (aarch64_opcode_table): Add constraints to
	msr (F_SYS_WRITE), mrs (F_SYS_READ).

7 files changed, 35 insertions, 5 deletions

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 84bba4b..a89ffe1 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,6 +1,16 @@
 2018-05-15  Tamar Christina  <tamar.christina@arm.com>
 
 	PR binutils/21446
+	* testsuite/gas/aarch64/illegal-sysreg-2.s: Fix pmbidr_el1 test.
+	* testsuite/gas/aarch64/illegal-sysreg-2.l: Likewise.
+	* testsuite/gas/aarch64/illegal-sysreg-2.d: Likewise.
+	* testsuite/gas/aarch64/sysreg-diagnostic.s: New.
+	* testsuite/gas/aarch64/sysreg-diagnostic.l: New.
+	* testsuite/gas/aarch64/sysreg-diagnostic.d: New.
+
+2018-05-15  Tamar Christina  <tamar.christina@arm.com>
+
+	PR binutils/21446
 	* config/tc-aarch64.c (print_operands): Indicate no notes.
 	(output_operand_error_record): Support non-fatal errors.
 	(output_operand_error_report, warn_unpredictable_ldst, md_assemble):
diff --git a/gas/testsuite/gas/aarch64/illegal-sysreg-2.l b/gas/testsuite/gas/aarch64/illegal-sysreg-2.l
index f059611..1204056 100644
--- a/gas/testsuite/gas/aarch64/illegal-sysreg-2.l
+++ b/gas/testsuite/gas/aarch64/illegal-sysreg-2.l
@@ -27,8 +27,6 @@
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'pmbptr_el1'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'pmbsr_el1'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'pmbsr_el1'
-[^:]*:[0-9]+: Error: selected processor does not support system register name 'pmbidr_el1'
-[^:]*:[0-9]+: Error: selected processor does not support system register name 'pmbidr_el1'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'pmscr_el1'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'pmscr_el1'
 [^:]*:[0-9]+: Error: selected processor does not support system register name 'pmsicr_el1'
diff --git a/gas/testsuite/gas/aarch64/sysreg-2.d b/gas/testsuite/gas/aarch64/sysreg-2.d
index a0539db..097f272 100644
--- a/gas/testsuite/gas/aarch64/sysreg-2.d
+++ b/gas/testsuite/gas/aarch64/sysreg-2.d
@@ -38,8 +38,6 @@ Disassembly of section .text:
   [0-9a-f]+:	d5389a27 	mrs	x7, pmbptr_el1
   [0-9a-f]+:	d5189a67 	msr	pmbsr_el1, x7
   [0-9a-f]+:	d5389a67 	mrs	x7, pmbsr_el1
-  [0-9a-f]+:	d5189ae7 	msr	pmbidr_el1, x7
-  [0-9a-f]+:	d5389ae7 	mrs	x7, pmbidr_el1
   [0-9a-f]+:	d5189907 	msr	pmscr_el1, x7
   [0-9a-f]+:	d5389907 	mrs	x7, pmscr_el1
   [0-9a-f]+:	d5189947 	msr	pmsicr_el1, x7
diff --git a/gas/testsuite/gas/aarch64/sysreg-2.s b/gas/testsuite/gas/aarch64/sysreg-2.s
index 2f6ea70..57eb08f 100644
--- a/gas/testsuite/gas/aarch64/sysreg-2.s
+++ b/gas/testsuite/gas/aarch64/sysreg-2.s
@@ -44,7 +44,7 @@
 
 	/* Statistical profiling.  */
 
-	.irp reg, pmblimitr_el1, pmbptr_el1, pmbsr_el1 pmbidr_el1
+	.irp reg, pmblimitr_el1, pmbptr_el1, pmbsr_el1
 	rw_sys_reg sys_reg=\reg xreg=x7 r=1 w=1
 	.endr
 
diff --git a/gas/testsuite/gas/aarch64/sysreg-diagnostic.d b/gas/testsuite/gas/aarch64/sysreg-diagnostic.d
new file mode 100644
index 0000000..2f52f36
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/sysreg-diagnostic.d
@@ -0,0 +1,14 @@
+#objdump: -dr -M notes
+#as: -march=armv8-a
+#error-output: sysreg-diagnostic.l
+
+.*:     file format .*
+
+Disassembly of section \.text:
+
+.* <.*>:
+.*:	d5130503 	msr	dbgdtrtx_el0, x3
+.*:	d5130503 	msr	dbgdtrtx_el0, x3
+.*:	d5330503 	mrs	x3, dbgdtrrx_el0
+.*:	d5330503 	mrs	x3, dbgdtrrx_el0
+.*:	d5180003 	msr	midr_el1, x3	; note: writing to a read-only register\.
diff --git a/gas/testsuite/gas/aarch64/sysreg-diagnostic.l b/gas/testsuite/gas/aarch64/sysreg-diagnostic.l
new file mode 100644
index 0000000..4566652
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/sysreg-diagnostic.l
@@ -0,0 +1,4 @@
+.*: Assembler messages:
+.*:3: Warning: specified register cannot be written to at operand 1 -- `msr dbgdtrrx_el0,x3'
+.*:5: Warning: specified register cannot be read from at operand 2 -- `mrs x3,dbgdtrtx_el0'
+.*:6: Warning: specified register cannot be written to at operand 1 -- `msr midr_el1,x3'
diff --git a/gas/testsuite/gas/aarch64/sysreg-diagnostic.s b/gas/testsuite/gas/aarch64/sysreg-diagnostic.s
new file mode 100644
index 0000000..5f68fe6
--- /dev/null
+++ b/gas/testsuite/gas/aarch64/sysreg-diagnostic.s
@@ -0,0 +1,6 @@
+.text
+	msr     dbgdtrtx_el0, x3
+	msr     dbgdtrrx_el0, x3
+	mrs     x3, dbgdtrrx_el0
+	mrs     x3, dbgdtrtx_el0
+	msr     midr_el1, x3