binutils-gdb/gdb/testsuite/gdb.arch/aarch64-mte-core.exp
Luis Machado 68cffbbd44 [AArch64] MTE corefile support
Teach GDB how to dump memory tags for AArch64 when using the gcore command
and how to read memory tag data back from a core file generated by GDB
(via gcore) or by the Linux kernel.

The format is documented in the Linux Kernel documentation [1].

Each tagged memory range (listed in /proc/<pid>/smaps) gets dumped to its
own PT_AARCH64_MEMTAG_MTE segment. A section named ".memtag" is created for each
of those segments when reading the core file back.

To save a little bit of space, given MTE tags only take 4 bits, the memory tags
are stored packed as 2 tags per byte.

When reading the data back, the tags are unpacked.

I've added a new testcase to exercise the feature.

Build-tested with --enable-targets=all and regression tested on aarch64-linux
Ubuntu 20.04.

[1] Documentation/arm64/memory-tagging-extension.rst (Core Dump Support)
2022-07-19 15:24:31 +01:00

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# Copyright (C) 2018-2022 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 generating and reading a core file with MTE memory tags.
proc test_mte_core_file { core_filename mode } {
# Load the core file and make sure we see the tag violation fault
# information.
if {$mode == "sync"} {
gdb_test "core $core_filename" \
[multi_line \
"Core was generated by.*\." \
"Program terminated with signal SIGSEGV, Segmentation fault" \
"Memory tag violation while accessing address ${::hex}" \
"Allocation tag ${::hex}" \
"Logical tag ${::hex}\." \
"#0.*${::hex} in main \\(.*\\) at .*" \
".*mmap_pointers\\\[0\\\] = 0x4;"] \
"core file shows $mode memory tag violation"
} else {
gdb_test "core $core_filename" \
[multi_line \
"Core was generated by.*\." \
"Program terminated with signal SIGSEGV, Segmentation fault" \
"Memory tag violation" \
"Fault address unavailable\." \
"#0 ${::hex} in .* from .*"] \
"core file shows $mode memory tag violation"
}
# Make sure we have the tag_ctl register.
gdb_test "info register tag_ctl" \
"tag_ctl.*${::hex}.*${::decimal}" \
"tag_ctl is available"
# In ASYNC mode, there is nothing left to test, as the program stops at
# a place where further source code inspection is not possible.
if {$mode == "async"} {
return
}
# First, figure out the page size.
set page_size [get_valueof "" "page_sz" "0" \
"fetch value of page size"]
# Get the number of maps for the test
set nmaps [get_valueof "" "NMAPS" "0" \
"fetch number of maps"]
set tag 1
# Iterate over all of the MTE-protected memory mappings and make sure
# GDB retrieves the correct allocation tags for each one. If the tag
# has the expected value, that means the core file was generated correctly
# and that GDB read the contents correctly.
for {set i 0} {$i < $nmaps} {incr i} {
for {set offset 0} {$offset < $page_size} {set offset [expr $offset + 16]} {
set hex_tag [format "%x" $tag]
gdb_test "memory-tag print-allocation-tag mmap_pointers\[$i\] + $offset" \
"= 0x$hex_tag" \
"mmap_ponters\[$i\] + $offset contains expected tag"
# Update the expected tag. The test writes tags in sequential
# order.
set tag [expr ($tag + 1) % 16]
}
}
}
# Exercise MTE corefile support using mode MODE (Async or Sync)
proc test_mode { mode } {
set compile_flags {"debug" "macros" "additional_flags=-march=armv8.5-a+memtag"}
# If we are testing async mode, we need to force the testcase to use
# such mode.
if {$mode == "async"} {
lappend compile_flags "additional_flags=-DASYNC"
}
standard_testfile
set executable "${::testfile}-${mode}"
if {[prepare_for_testing "failed to prepare" ${executable} ${::srcfile} ${compile_flags}]} {
return -1
}
set binfile [standard_output_file ${executable}]
if ![runto_main] {
untested "could not run to main"
return -1
}
# Targets that don't support memory tagging should not execute the
# runtime memory tagging tests.
if {![supports_memtag]} {
unsupported "memory tagging unsupported"
return -1
}
# Run until a crash and confirm GDB displays memory tag violation
# information.
if {$mode == "sync"} {
gdb_test "continue" \
[multi_line \
"Program received signal SIGSEGV, Segmentation fault" \
"Memory tag violation while accessing address ${::hex}" \
"Allocation tag 0x1" \
"Logical tag 0x0\." \
"${::hex} in main \\(.*\\) at .*" \
".*mmap_pointers\\\[0\\\] = 0x4;"] \
"run to memory $mode tag violation"
} else {
gdb_test "continue" \
[multi_line \
"Program received signal SIGSEGV, Segmentation fault" \
"Memory tag violation" \
"Fault address unavailable\." \
"${::hex} in .* from .*"] \
"run to memory $mode tag violation"
}
# Generate the gcore core file.
set gcore_filename [standard_output_file "${executable}.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 ${binfile}
with_test_prefix "gcore corefile" {
test_mte_core_file $gcore_filename $mode
}
} else {
fail "gcore corefile not generated"
}
if {$core_generated} {
clean_restart ${binfile}
with_test_prefix "native corefile" {
test_mte_core_file $core_filename $mode
}
} else {
untested "native corefile not generated"
}
}
if {![is_aarch64_target]} {
verbose "Skipping ${gdb_test_file_name}."
return
}
# Run tests
foreach_with_prefix mode {"sync" "async"} {
test_mode $mode
}