[PATCH v2 5/5] gdb/aarch64: Tests for fpmr

[<Ezra.Sitorus@arm.com>]

From: Ezra Sitorus <ezra.sitorus@arm.com>

Add tests for FPMR support in gdb/gdbserver. These tests check
availability of FPMR, reading/writing to FPMR, core file generation and
preservation under sighandler frame unwinding.

A run of the full gdb testsuite has been done on aarch64-none-linux-gnu
without FPMR support. I have run the gdb.arch tests on Shrinkwrap with
FPMR support.
---
Changes from v1->v2:
* Removed fpmr modification functions to make the tests easier to
  follow.
* Test writing to fpmr in aarch64-fpmr.exp from outside the inferior
  program.
* Rewrite allow_aarch64_fpmr_tests to follow allow_aarch64_sve_tests.

Ezra

 gdb/testsuite/gdb.arch/aarch64-fpmr-core.c    |  40 ++++++
 gdb/testsuite/gdb.arch/aarch64-fpmr-core.exp  |  97 +++++++++++++++
 .../gdb.arch/aarch64-fpmr-sighandler.c        |  55 ++++++++
 .../gdb.arch/aarch64-fpmr-sighandler.exp      |  77 ++++++++++++
 gdb/testsuite/gdb.arch/aarch64-fpmr.c         | 117 ++++++++++++++++++
 gdb/testsuite/gdb.arch/aarch64-fpmr.exp       |  72 +++++++++++
 gdb/testsuite/lib/gdb.exp                     |  66 ++++++++++
 7 files changed, 524 insertions(+)
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-fpmr-core.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-fpmr-core.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-fpmr-sighandler.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-fpmr-sighandler.exp
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-fpmr.c
 create mode 100644 gdb/testsuite/gdb.arch/aarch64-fpmr.exp

diff --git a/gdb/testsuite/gdb.arch/aarch64-fpmr-core.c b/gdb/testsuite/gdb.arch/aarch64-fpmr-core.c
new file mode 100644
index 00000000000..785fbd42d5c
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-fpmr-core.c
@@ -0,0 +1,40 @@
+/* This file is part of GDB, the GNU debugger.
+
+   Copyright 2008-2025 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <stdint.h>
+
+uint64_t crash_address = 0;
+
+void
+set_fpmr (uint64_t value)
+{
+  register uint64_t x0_val asm ("x0") = value;
+  /* msr	fpmr, x0 */
+  __asm__ volatile (".inst	0xd51b4440" : : );
+}
+
+int
+main (void)
+{
+  set_fpmr (0x3fff7fc049);
+
+  /* Check FPMR */
+
+  *((uint64_t *) crash_address) = 0xDEAD; /* crash point */
+
+  return 1;
+}
diff --git a/gdb/testsuite/gdb.arch/aarch64-fpmr-core.exp b/gdb/testsuite/gdb.arch/aarch64-fpmr-core.exp
new file mode 100644
index 00000000000..6f8ee996d27
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-fpmr-core.exp
@@ -0,0 +1,97 @@
+# Copyright (C) 2018-2025 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This file is part of the gdb testsuite.
+
+# Test generating and reading a core file with FPMR.
+
+proc check_fpmr_core_file { core_filename } {
+    # Load the core file.
+    if [gdb_test "core $core_filename" \
+    [multi_line \
+	    "Core was generated by .*" \
+	    "Program terminated with signal SIGSEGV, Segmentation fault\\." \
+	    "#0  ${::hex} in main \\(.*\\) at .*" \
+	    ".* \\*\\(\\(uint64_t \\*\\) crash_address\\) = 0xDEAD.*"] \
+	    "load core file"] {
+	untested "failed to generate core file"
+	return -1
+	}
+
+    # Check the value of FPMR in the core file.
+    gdb_test "print/x \$fpmr" " = 0x3fff7fc049" \
+	     "fpmr contents from core file"
+}
+
+require is_aarch64_target
+require allow_aarch64_fpmr_tests
+
+standard_testfile
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
+    return -1
+}
+
+set binfile [standard_output_file ${testfile}]
+
+if ![runto_main] {
+    untested "could not run to main"
+    return -1
+}
+
+set crash_breakpoint "crash point"
+gdb_breakpoint [gdb_get_line_number $crash_breakpoint]
+gdb_continue_to_breakpoint $crash_breakpoint
+
+gdb_test "print/x \$fpmr" " = 0x3fff7fc049" \
+	     "fpmr contents from core file"
+
+gdb_test "continue" \
+[multi_line \
+	"Program received signal SIGSEGV, Segmentation fault\\." \
+	"${::hex} in main \\(\\).* at .*" \
+	".* \\*\\(\\(uint64_t \\*\\) crash_address\\) = 0xDEAD.*"] \
+	"run to crash"
+
+# Generate the gcore core file.
+set gcore_filename [standard_output_file "${testfile}.gcore"]
+set gcore_generated [gdb_gcore_cmd "$gcore_filename" "generate gcore file"]
+
+# Generate a native core file.
+set core_filename [core_find ${binfile}]
+set core_generated [expr {$core_filename != ""}]
+
+# At this point we have a couple core files, the gcore one generated by GDB
+# and the native one generated by the Linux Kernel.  Make sure GDB can read
+# both correctly.
+
+if {$gcore_generated} {
+	clean_restart
+	gdb_load ${binfile}
+	with_test_prefix "gcore corefile" {
+		check_fpmr_core_file $gcore_filename
+	}
+} else {
+	fail "gcore corefile not generated"
+}
+
+if {$core_generated} {
+	clean_restart
+	gdb_load ${binfile}
+	with_test_prefix "native corefile" {
+		check_fpmr_core_file $core_filename
+	}
+} else {
+	untested "native corefile not generated"
+}
diff --git a/gdb/testsuite/gdb.arch/aarch64-fpmr-sighandler.c b/gdb/testsuite/gdb.arch/aarch64-fpmr-sighandler.c
new file mode 100644
index 00000000000..bbdfbb0597c
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-fpmr-sighandler.c
@@ -0,0 +1,55 @@
+/* This file is part of GDB, the GNU debugger.
+
+   Copyright 2008-2025 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <stdint.h>
+#include <signal.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+void
+set_fpmr (uint64_t value)
+{
+  register uint64_t x0_val asm ("x0") = value;
+  /* msr	fpmr, x0 */
+  __asm__ volatile (".inst	0xd51b4440" : : );
+}
+
+void
+handler (int sig)
+{
+  set_fpmr (0xff008041);
+  exit(0);
+}
+
+int
+main ()
+{
+  /* Ensure all the signals aren't blocked.  */
+  sigset_t newset;
+  sigemptyset (&newset);
+  sigprocmask (SIG_SETMASK, &newset, NULL);
+
+  signal (SIGILL, handler);
+
+  set_fpmr (0x3fff7fc049);
+
+  /* 0x06000000 : Cause an illegal instruction. Value undefined as per ARM
+     Architecture Reference Manual ARMv8, Section C4.1.  */
+  __asm __volatile (".inst 0x06000000");
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.arch/aarch64-fpmr-sighandler.exp b/gdb/testsuite/gdb.arch/aarch64-fpmr-sighandler.exp
new file mode 100644
index 00000000000..a776976eb7d
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-fpmr-sighandler.exp
@@ -0,0 +1,77 @@
+# Copyright 2018-2025 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# This file is part of the gdb testsuite.
+#
+# Test FPMR register set is properly preserved when unwiding sighandler frames.
+
+require is_aarch64_target
+require allow_aarch64_fpmr_tests
+
+standard_testfile
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
+    return -1
+}
+
+if ![runto_main] {
+    return -1
+}
+
+set reg_main_value "0x3fff7fc049"
+set reg_handler_value "0xff008041"
+
+proc check_fpmr {value} {
+  gdb_test "print /x \$fpmr" \
+    ".* = {?$value}?" \
+    "check register \$fpmr has value $value"
+}
+
+# Run until end of signal handler
+
+gdb_test "continue" \
+    "Continuing.*Program received signal SIGILL.*" \
+    "continue until signal"
+
+gdb_breakpoint [gdb_get_line_number "exit(0)"]
+gdb_continue_to_breakpoint "exit" ".*exit.*"
+
+set handlerframe [get_current_frame_number]
+set mainframe [expr $handlerframe + 2]
+
+# Check register values
+
+with_test_prefix "handler frame 1st" {
+  check_fpmr $reg_handler_value
+}
+
+# Switch to the frame for main(), and check register values
+
+gdb_test "frame $mainframe" \
+      "#$mainframe.*main ().*" \
+      "set to main frame"
+
+with_test_prefix "main frame" {
+  check_fpmr $reg_main_value
+}
+
+# Switch back to the signal handler frame, and check register values
+
+gdb_test "frame $handlerframe" \
+      "#$handlerframe.*handler \\\(sig=4\\\).*" \
+      "set to signal handler frame"
+
+with_test_prefix "handler frame 2nd" {
+  check_fpmr $reg_handler_value
+}
diff --git a/gdb/testsuite/gdb.arch/aarch64-fpmr.c b/gdb/testsuite/gdb.arch/aarch64-fpmr.c
new file mode 100644
index 00000000000..f4bf889c3a8
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-fpmr.c
@@ -0,0 +1,117 @@
+/* This file is part of GDB, the GNU debugger.
+
+   Copyright 2008-2025 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <stdint.h>
+
+enum FPM_FORMAT
+{
+  E5M2,
+  E4M3,
+};
+
+enum FPM_OVERFLOW
+{
+  INFNAN,
+  SATURATE,
+};
+
+void
+set_fpmr (uint64_t value)
+{
+  register uint64_t x0_val asm ("x0") = value;
+  __asm__ volatile (".inst	0xd51b4440" : : );
+}
+
+uint64_t
+modify_src1_fmt (uint64_t fpmr, uint64_t fmt)
+{
+  return (fpmr & ~(0x7)) | (fmt & 0x7);
+}
+
+uint64_t
+modify_src2_fmt (uint64_t fpmr, uint64_t fmt)
+{
+  return (fpmr & ~((0x7) << 3)) | ((fmt & 0x7) << 3);
+}
+
+uint64_t
+modify_dst_fmt (uint64_t fpmr, uint64_t fmt)
+{
+  return (fpmr & ~((0x7) << 6)) | ((fmt & 0x7) << 6);
+}
+
+uint64_t
+modify_osm (uint64_t fpmr, uint64_t overflow)
+{
+  return (fpmr & ~((0x1) << 14)) | ((overflow & 0x1) << 14);
+}
+
+uint64_t
+modify_osc (uint64_t fpmr, uint64_t overflow)
+{
+  return (fpmr & ~((0x1) << 15)) | ((overflow & 0x1) << 15);
+}
+
+uint64_t
+modify_lscale (uint64_t fpmr, uint64_t scale)
+{
+  return (fpmr & ~((0x7f) << 16)) | ((scale & 0x7f) << 16);
+}
+
+uint64_t
+modify_nscale (uint64_t fpmr, uint64_t scale)
+{
+  return (fpmr & ~((0xff) << 24)) | ((scale & 0xff) << 24);
+}
+
+uint64_t
+modify_lscale2 (uint64_t fpmr, uint64_t scale)
+{
+  return (fpmr & ~((uint64_t)(0x3f) << 32)) | ((uint64_t)(scale & 0x3f) << 32);
+}
+
+int
+main (void)
+{
+  uint64_t fpmr = 0;
+
+  fpmr = modify_src1_fmt (fpmr, E4M3);
+  set_fpmr (fpmr); /* MODIFY SRC1 */
+
+  fpmr = modify_src2_fmt (fpmr, E4M3);
+  set_fpmr (fpmr); /* MODIFY SRC2 */
+
+  fpmr = modify_dst_fmt (fpmr, E4M3);
+  set_fpmr (fpmr); /* MODIFY DST */
+
+  fpmr = modify_osm (fpmr, SATURATE);
+  set_fpmr (fpmr); /* MODIFY OSM */
+
+  fpmr = modify_osc (fpmr, SATURATE);
+  set_fpmr (fpmr); /* MODIFY OSC */
+
+  fpmr = modify_lscale (fpmr, -1);
+  set_fpmr (fpmr); /* MODIFY LSCALE */
+
+  fpmr = modify_nscale (fpmr, -1);
+  set_fpmr (fpmr); /* MODIFY NSCALE */
+
+  fpmr = modify_lscale2 (fpmr, -1);
+  set_fpmr (fpmr); /* MODIFY LSCALE2 */
+
+  return 1;
+}
diff --git a/gdb/testsuite/gdb.arch/aarch64-fpmr.exp b/gdb/testsuite/gdb.arch/aarch64-fpmr.exp
new file mode 100644
index 00000000000..947d47e981d
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-fpmr.exp
@@ -0,0 +1,72 @@
+# Copyright 2023-2025 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+# Exercise reading/writing FPMR when it is present.
+
+require is_aarch64_target
+require allow_aarch64_fpmr_tests
+
+standard_testfile
+if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
+    return -1
+}
+
+if ![runto_main] {
+    untested "could not run to main"
+    return -1
+}
+
+gdb_test_multiple "info register \$fpmr" "Test FPMR SRC1 E5M2" {
+    -re ".*\r\n.*\[ F8S1=E5M2 F8S2=E5M2 F8D=E5M2 OSM=Inf OSC=Inf/NaN LSCALE=0 NSCALE=0 LSCALE2=0 \]" {
+        pass "FPMR SRC1 matches E5M2"
+    }
+}
+
+set breakpoints [list "MODIFY SRC1" "MODIFY SRC2" "MODIFY DST" "MODIFY OSM" "MODIFY OSC" "MODIFY LSCALE" "MODIFY NSCALE" "MODIFY LSCALE2"]
+set reg_values [list \
+    ".*\r\n.*\[ F8S1=E4M3 F8S2=E5M2 F8D=E5M2 OSM=Inf OSC=Inf/NaN LSCALE=0 NSCALE=0 LSCALE2=0 \]" \
+    ".*\r\n.*\[ F8S1=E4M3 F8S2=E4M3 F8D=E5M2 OSM=Inf OSC=Inf/NaN LSCALE=0 NSCALE=0 LSCALE2=0 \]" \
+    ".*\r\n.*\[ F8S1=E4M3 F8S2=E4M3 F8D=E4M3 OSM=Inf OSC=Inf/NaN LSCALE=0 NSCALE=0 LSCALE2=0 \]" \
+    ".*\r\n.*\[ F8S1=E4M3 F8S2=E4M3 F8D=E4M3 OSM=MaxNormal OSC=Inf/NaN LSCALE=0 NSCALE=0 LSCALE2=0 \]" \
+    ".*\r\n.*\[ F8S1=E4M3 F8S2=E4M3 F8D=E4M3 OSM=MaxNormal OSC=MaxNormal LSCALE=0 NSCALE=0 LSCALE2=0 \]" \
+    ".*\r\n.*\[ F8S1=E4M3 F8S2=E4M3 F8D=E4M3 OSM=MaxNormal OSC=MaxNormal LSCALE=127 NSCALE=0 LSCALE2=0 \]" \
+    ".*\r\n.*\[ F8S1=E4M3 F8S2=E4M3 F8D=E4M3 OSM=MaxNormal OSC=MaxNormal LSCALE=127 NSCALE=255 LSCALE2=0 \]" \
+    ".*\r\n.*\[ F8S1=E4M3 F8S2=E4M3 F8D=E4M3 OSM=MaxNormal OSC=MaxNormal LSCALE=127 NSCALE=255 LSCALE2=63 \]" \
+]
+set pass_messages [list "FPMR SRC1 matches E4M3" "FPMR SRC2 matches E4M3" "FPMR DST matches E4M3" "FPMR OSM matches MaxNormal" "FPMR OSC matches MaxNormal" "FPMR LSCALE matches" "FPMR NSCALE matches" "FPMR LSCALE2 matches"]
+
+for {set i 0} {$i < 8} {incr i} {
+    set bp [lindex $breakpoints $i]
+    gdb_breakpoint [gdb_get_line_number $bp]
+    gdb_continue_to_breakpoint $bp
+
+    gdb_test_multiple "info register \$fpmr" "" {
+        -re [lindex $reg_values $i] {
+            pass [lindex $pass_messages $i]
+        }
+    }
+}
+
+gdb_test_multiple "set \$fpmr=0x0" "" {
+    -re ".*\r\n.*\[ F8S1=E5M2 F8S2=E5M2 F8D=E5M2 OSM=Inf OSC=Inf/NaN LSCALE=0 NSCALE=0 LSCALE2=0 \]" {
+        pass "Reset FPMR to 0 from GDB"
+    }
+}
+
+gdb_test_multiple "set \$fpmr=0x3f007f4008" "" {
+    -re ".*\r\n.*\[ F8S1=E5M2 F8S2=E4M3 F8D=E5M2 OSM=MaxNormal OSC=Inf/NaN LSCALE=127 NSCALE=0 LSCALE2=63 \]" {
+        pass "Write to FPMR from GDB"
+    }
+}
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 930462f63fa..0d0369511bb 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -5201,6 +5201,72 @@ proc aarch64_supports_sme_svl { length } {
     return 1
 }
 
+# Run a test on the target to see if it supports AArch64 FPMR hardware.
+# Return 1 if so, 0 if it does not.  Note this causes a restart of GDB.
+
+gdb_caching_proc allow_aarch64_fpmr_tests {} {
+    global srcdir subdir gdb_prompt inferior_exited_re
+
+    set me "allow_aarch64_fpmr_tests"
+
+    if { ![is_aarch64_target]} {
+	return 0
+    }
+
+    set compile_flags "{additional_flags=-march=armv8-a}"
+
+    # Compile a test program that writes to FPMR.
+    set src {
+	int main() {
+	    asm volatile ("msr x0, fpmr");
+	    return 0;
+	}
+    }
+    if {![gdb_simple_compile $me $src executable $compile_flags]} {
+	# Try again, but with a raw hex instruction so we don't rely on
+	# assembler support for FPMR.
+
+	set compile_flags "{additional_flags=-march=armv8-a}"
+
+	# Compile a test program reading FPMR.
+	set src {
+	    int main() {
+		asm volatile (".word 0xD51B4440");
+		return 0;
+	    }
+	}
+
+	if {![gdb_simple_compile $me $src executable $compile_flags]} {
+	    return 0
+	}
+    }
+
+    # Compilation succeeded so now run it via gdb.
+    clean_restart
+    gdb_load $obj
+    gdb_run_cmd
+
+    gdb_expect {
+        -re ".*Illegal instruction.*${gdb_prompt} $" {
+            verbose -log "\n$me fpmr support not detected"
+            set allow_fpmr_tests 0
+        }
+        -re ".*$inferior_exited_re normally.*${gdb_prompt} $" {
+            verbose -log "\n$me: fpmr support detected"
+            set allow_fpmr_tests 1
+        }
+        default {
+          warning "\n$me: default case taken"
+            set allow_fpmr_tests 0
+        }
+    }
+    gdb_exit
+    remote_file build delete $obj
+
+    verbose "$me:  returning $allow_fpmr_tests" 2
+    return $allow_fpmr_tests
+}
+
 # Run a test on the target to see if it supports AArch64 MOPS (Memory
 # Operations) extensions.  Return 1 if so, 0 if it does not.  Note this
 # causes a restart of GDB.
-- 
2.45.2