gdb/testsuite/gdb.arch/aarch64-non-address-bits.exp

# Copyright 2022 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 that GDB for AArch64/Linux can properly handle pointers with
# the upper 16 bits (PAC) or 8 bits (Tag) set, as well as the
# VA_RANGE_SELECT bit (55).

if {![is_aarch64_target]} {
    verbose "Skipping ${gdb_test_file_name}."
    return
}

standard_testfile
if { [prepare_for_testing "failed to prepare" ${testfile} ${srcfile}] } {
    return -1
}

if ![runto_main] {
    return -1
}

# We need to iterate over two distinct ranges, separated by a single bit.
# This bit is 55 (VA_RANGE_SELECT) which tells us if we have a kernel-space
# address or a user-space address.

# The tag field has 8 bits.
set tag_bits_count 8

# The pac field has 7 bits.
set pac_bits_count 7

# A couple patterns that we reuse for the tests later.  One is for a successful
# memory read and the other is for a memory read failure.
set memory_read_ok_pattern "$::hex\( <l>\)?:\[ \t\]+$::hex"
set memory_read_fail_pattern "$::hex:\[ \t\]+Cannot access memory at address $::hex"

set pac_enabled 0

# Check if PAC is enabled.
gdb_test_multiple "ptype \$pauth_cmask" "fetch PAC cmask" {
    -re -wrap "type = long" {
	set pac_enabled 1
    }
    -re -wrap "type = void" {
    }
    -re ".*$gdb_prompt $" {
	fail $gdb_test_name
	return 1
    }
}

# Value of the cmask register.
set cmask 0

# If there are PAC registers, GDB uses those to unmask the PAC bits.
if {$pac_enabled} {
    set cmask [get_valueof "" "\$pauth_cmask >> 48" "0" "fetch PAC cmask"]
}

# Cycle through the tag and pac bit ranges and check how GDB
# behaves when trying to access these addresses.
foreach_with_prefix upper_bits {"0x0" "0x1" "0x2" "0x4" "0x8" "0x10" "0x20" "0x40" "0x80"} {
    foreach_with_prefix lower_bits {"0x0" "0x1" "0x2" "0x4" "0x8" "0x10" "0x20" "0x40"} {

	# A successful memory read pattern
	set pattern $memory_read_ok_pattern

	if {!$pac_enabled} {
	    # If PAC is not supported, memory reads will fail if
	    # lower_bits != 0x0
	    if {$lower_bits != "0x0"} {
		set pattern $memory_read_fail_pattern
	    }
	} else {
	    # Otherwise, figure out if the memory read will succeed or not by
	    # checking cmask.
	    gdb_test_multiple "p/x (~${cmask}ULL & (${lower_bits}ULL))" "" {
		-re -wrap "= 0x0" {
		    # Either cmask is 0x7F or lower_bits is 0x0.
		    # Either way, the memory read should succeed.
		}
		-re -wrap "= $::hex" {
		    if {$lower_bits != "0x0"} {
			# cmask doesn't mask off all the PAC bits, which
			# results in a memory read failure, with the actual
			# address being accessed differing from the one we
			# passed.
			set pattern $memory_read_fail_pattern
		    }
		}
	    }
	}

	# Test without the VA_RANGE_SELECT bit set.
	gdb_test "x/gx ((unsigned long) l_ptr | ((${upper_bits}ULL << 56) | (${lower_bits}ULL << 48)))" \
	    $pattern \
	    "user-space memory access"

	# Now test with the VA_RANGE_SELECT bit set.
	gdb_test "x/gx ((unsigned long) l_ptr | ((${upper_bits}ULL << 56) | (${lower_bits}ULL << 48) | (1ULL << 55))) " \
	    $memory_read_fail_pattern \
	    "kernel-space memory access"
    }
}