tree c4463379feb70dc26874b71a26be912cad2018d1
parent a44c3426879b58b20bb74bec39cc46126346bd9c
author Boyan Karatotev <boyan.karatotev@arm.com> 1675163154 +0000
committer Sona Mathew <SonaRebecca.Mathew@arm.com> 1691166764 -0500

refactor(cpus): convert the Cortex-A77 to use the bit set helpers

This makes the implementation itself much more readable. At this point
all errata have been tested with a script [1] to make sure the migration
kept everything the same. It reported 1508412, 1946167, and
CVE_2022_23960 as having some mismatch. The first has a small
non-trivial change that results in identical behaviour. The second is
non-trivial to compare, but manual inspection shows it is identical. The
CVE had no workaround function previously, however, the instructions are
indeed identical. All errata have been checked that they get invoked.

The script's commandline looks like:
  ./script.py cortex_a77 /path/to/tf-a-with-changes /path/to/tf-a-clean/

[1]: the script:
import re
import subprocess
import sys

def full_cpu_name():
    return sys.argv[1]

def old_cpu_name():
    return sys.argv[1].split('_')[1]

def new_build():
    return sys.argv[2]

def old_build():
    return sys.argv[3]

def get_dump(root_dir, symbol):
    # bl31 includes more stuff
    raw_dump = subprocess.run([
            'aarch64-none-elf-objdump', f'--disassemble={symbol}',
            root_dir + '/build/fvp/release/bl31/bl31.elf'
        ], capture_output=True, encoding='ascii'
    ).stdout

    # get rid of objdump verbosity
    raw_dump = raw_dump.split('\n')[7:-1]
    # split arguments and remove addresses at the start
    return [line.split('\t')[2:] for line in raw_dump]

def check_identical(new, old):
    if old and old[-1][0] == 'isb':
        old = old[:-1]
        print('    NOTE: dropped trailing isb (ok on reset)')

    if not new or not old or len(new) != len(old):
        return False

    for newi, oldi in zip(new, old):
        if newi[0] == oldi[0] == 'b':
            # ignore the address, compare just the name
            if newi[1].split(' ')[1] != newi[1].split(' ')[1]:
                return False
            continue # identical, proceed

        if newi != oldi:
            return False
    return True

FLAG_RE = r'report_errata (.*?), '
cpu_path = old_build() + '/lib/cpus/aarch64/' + full_cpu_name() + '.S'
with open(cpu_path) as cpu_src:
    errata_flags = re.findall(FLAG_RE, cpu_src.read())
    errata_ids = [flg.split('_')[-1] for flg in errata_flags]

print('List of flags to build with:')
print(' '.join([flg + '=1' for flg in errata_flags]))
input((
    'Press enter when your patch in argv[2] and '
    'the top of master in argv[3] are both built for release...'
))

for id in errata_ids:
    new_check = get_dump(new_build(),
        f'check_erratum_{full_cpu_name()}_{id}')
    old_check = get_dump(old_build(), f'check_errata_{id}')
    new_wa = get_dump(new_build(), f'erratum_{full_cpu_name()}_{id}_wa')
    old_wa = get_dump(old_build(), f'errata_{old_cpu_name()}_{id}_wa')

    # remove the boilerplate for each (mov, bl, cbz, ret)
    new_wa = new_wa[4:-3]
    old_wa = old_wa[3:-1]

    print(f'Checking {id} . . .')
    if not check_identical(new_check, old_check):
        print(f'  Check {id} check function manually!')
    if not check_identical(new_wa, old_wa):
        print(f'  Check {id} workaround manually!')

print('All previous errata checked against their migrations')

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: I987ded7962f3449344feda47e314994f400e85b8