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Add support for PowerPC 32-bit
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@mebeim
mebeim committed Mar 19, 2024
1 parent 2c4d54d commit 66e75de
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Showing 2 changed files with 139 additions and 32 deletions.
7 changes: 4 additions & 3 deletions src/systrack/arch/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@
'mips64' : lambda v: ArchMips(v, abi='n64'),
'mips64-n32' : lambda v: ArchMips(v, abi='n32'),
'mips64-o32' : lambda v: ArchMips(v, abi='o32'),
# 'powerpc' : lambda v: ArchPowerPC(v, abi='ppc32', bits32=True), # "32" ABI TODO
'powerpc' : lambda v: ArchPowerPC(v, abi='ppc32', bits32=True), # "32" ABI
'powerpc64' : lambda v: ArchPowerPC(v, abi='ppc64'), # "64" ABI
'powerpc64-32' : lambda v: ArchPowerPC(v, abi='ppc32'), # "32" ABI
'powerpc64-spu': lambda v: ArchPowerPC(v, abi='spu'),
Expand All @@ -45,8 +45,8 @@
('mips64' , 'n64' ),
('mips64-n32' , 'n32' ),
('mips64-o32' , 'o32-64' ),
# ('powerpc' , 'ppc' ), TODO
# ('powerpc' , 'ppc32' ), TODO
('powerpc' , 'ppc' ),
('powerpc' , 'ppc32' ),
('powerpc64' , 'ppc64' ),
('powerpc64-32' , 'ppc64-32' ),
('powerpc64-spu', 'ppc64-spu' ),
Expand Down Expand Up @@ -76,6 +76,7 @@
mips64-n32 n32 MIPS 64-bit 64-bit N32 ip27_defconfig [1]
mips64-o32 o32-64 MIPS 64-bit 32-bit O32 ip27_defconfig [1]
-----------------------------------------------------------------------------------------
powerpc ppc, ppc32 PowerPC 32-bit 32-bit PPC32 ppc64_defconfig
powerpc64 ppc64 PowerPC 64-bit 64-bit PPC64 ppc64_defconfig [1]
powerpc64-32 ppc64-32 PowerPC 64-bit 32-bit PPC32 ppc64_defconfig [1]
powerpc64-spu ppc64-spu, spu PowerPC 64-bit 64-bit "SPU" ppc64_defconfig [1,5]
Expand Down
164 changes: 135 additions & 29 deletions src/systrack/arch/powerpc.py
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,8 @@ class ArchPowerPC(Arch):
# (v5.0) explains, they can only use a subset of the syscalls defined for
# the "64" ABI.

# NOTE: we are assuming to have PPC_BOOK3S=y
# NOTE: we are assuming to have PPC_BOOK3S=y (and therefore PPC_BOOK3S_32=y
# for 32-bit or PPC_BOOK3S_64=y for 64-bit)
kconfig = VersionedDict((
# These are needed for RELOCATABLE=n, we do not really need to list
# dependencies since we are disabling them.
Expand All @@ -33,19 +34,20 @@ class ArchPowerPC(Arch):
((3,4) , VERSION_INF, 'FA_DUMP=n' , []),
# Needs to be set here too because arch-specific kconfigs are applied
# after those listed in KCONFIG_DEBUGGING (kconfig_options.py)
(VERSION_ZERO, VERSION_INF, 'RELOCATABLE=n' , ['PPC_OF_BOOT_TRAMPOLINE=n', 'CRASH_DUMP=n', 'FA_DUMP=n']),
(VERSION_ZERO, VERSION_INF, 'RELOCATABLE=n', ['PPC_OF_BOOT_TRAMPOLINE=n', 'CRASH_DUMP=n', 'FA_DUMP=n']),
# kexec_load
((2,6,15) , (3,9) , 'KEXEC=y' , ['PPC_BOOK3S=y']),
((3,9) , VERSION_INF, 'KEXEC=y' , ['PPC_BOOK3S=y', 'EXPERIMENTAL=y']),
((2,6,15) , (3,9) , 'KEXEC=y', ['PPC_BOOK3S=y', 'EXPERIMENTAL=y']),
((3,9) , VERSION_INF, 'KEXEC=y', ['PPC_BOOK3S=y']),
# seccomp
((2,6,15) , (5,10) , 'SECCOMP=y' , ['PROC_FS=y']),
((2,6,15) , (5,10) , 'SECCOMP=y', ['PROC_FS=y']),
# rtas
((2,6,15) , VERSION_INF, 'PPC_RTAS=y' , []),
# spu_run, spu_create
((2,6,16) , VERSION_INF, 'SPU_FS=y' , ['PPC_CELL=y', 'COREDUMP=y']),
((2,6,18) , VERSION_INF, 'SPU_BASE=y' , []),
((2,6,15) , VERSION_INF, 'PPC_RTAS=y', []),
))

# FIXME: more like a curiosity, but why the hell do migrate_pages and
# move_pages look like they depend on MIGRATION and not necessarily on NUMA,
# but then aren't available for PPC 32-bit which has NUMA=n???

kconfig_syscall_deps = VersionedDict((
(VERSION_ZERO, VERSION_INF, 'pkey_alloc' , 'PPC_MEM_KEYS'),
(VERSION_ZERO, VERSION_INF, 'pkey_free' , 'PPC_MEM_KEYS'),
Expand All @@ -56,17 +58,14 @@ def __init__(self, kernel_version: KernelVersion, abi: str, bits32: bool = False
super().__init__(kernel_version, abi, bits32)
assert self.abi in ('ppc32', 'ppc64', 'spu')

# TODO
assert not self.bits32, 'PPC 32-bit not supported yet'

# The "powerpc" directory was added under arch in v2.6.15 and it weirdly
# coexisted with "ppc" until v2.6.27, when the latter was removed.
assert self.kernel_version >= (2,6,15), 'kernel too old, sorry!'

if self.abi == 'spu':
# spu_syscall_table only exists since v2.6.16, I have no idea how
# things were handled before then. This is a rather old kernel
# version, we'll worry about it in the future.
# version, we'll worry about it in the future (if ever).
assert self.kernel_version >= (2,6,16), 'kernel too old, sorry!'

if self.abi == 'ppc32':
Expand All @@ -77,14 +76,27 @@ def __init__(self, kernel_version: KernelVersion, abi: str, bits32: bool = False
self.abi_bits32 = False

if self.bits32:
# TODO: which one?
self.config_target = None
self.compat = False
else:
self.uses_function_descriptors = True
self.uses_function_descriptors = False
self.syscall_table_name = 'sys_call_table'

# PPC_BOOK3S_32 was introduced in v2.6.31. We'll worry about
# older kernels in the future (if ever).
assert self.kernel_version >= (2,6,31), 'kernel too old, sorry!'

# Apparently there isn't a nice 32-bit defconfig and one needs
# to manually disable 64-bit??? What in tarnation >:( lame!
# There's ppc_defconfig from v5.2, which also takes half the time to
# build so it'd be nice to use... but using it as is without tweaks
# compiles a kernel without memfd_create.
self.config_target = 'ppc64_defconfig'
self.abi_bits32 = self.abi == 'ppc32'
self.kconfig.add(VERSION_ZERO, VERSION_INF, 'PPC64=n', [])
self.kconfig.add(VERSION_ZERO, VERSION_INF, 'PPC_BOOK3S_32=y', [])
else:
self.compat = self.abi != 'ppc64'
self.abi_bits32 = self.abi == 'ppc32'
self.config_target = 'ppc64_defconfig'
self.uses_function_descriptors = True

if self.abi == 'spu':
self.syscall_table_name = 'spu_syscall_table'
Expand All @@ -96,29 +108,32 @@ def __init__(self, kernel_version: KernelVersion, abi: str, bits32: bool = False

# PowerPC64 supports all ABIs: 64, 32, "spu". Enable all of them, we
# will be able to extract the right syscall table regardless.
self.kconfig.add((2,6,15), (5,7) , 'COMPAT=y' , ['PPC64=y'])
self.kconfig.add((5,7) , VERSION_INF, 'COMPAT=y' , ['PPC64=y', 'CPU_LITTLE_ENDIAN=n', 'CC_IS_CLANG=n'])
self.kconfig.add((2,6,15), (5,7) , 'COMPAT=y', ['PPC64=y'])
self.kconfig.add((5,7) , VERSION_INF, 'COMPAT=y', ['PPC64=y', 'CPU_LITTLE_ENDIAN=n', 'CC_IS_CLANG=n'])

# Needed for NUMA=y
self.kconfig.add((2,6,15), (2,6,22) , 'PPC_PSERIES=y' , ['PPC64=y', 'PPC_MULTIPLATFORM=y']),
self.kconfig.add((2,6,22), VERSION_INF, 'PPC_PSERIES=y' , ['PPC64=y', 'PPC_BOOK3S=y']),
self.kconfig.add((2,6,15), (2,6,22) , 'PPC_PSERIES=y', ['PPC64=y', 'PPC_MULTIPLATFORM=y']),
self.kconfig.add((2,6,22), VERSION_INF, 'PPC_PSERIES=y', ['PPC64=y', 'PPC_BOOK3S=y']),
# mbind, migrate_pages, {get,set}_mempolicy
# NOTE: in theory depends on (PPC_PSERIES || PPC_POWERNV) after
# 5.10, but we are assuming PPC_PSERIES=y
self.kconfig.add((2,6,15), VERSION_INF, 'NUMA=y' , ['PPC64=y', 'SMP=y', 'PPC_PSERIES=y'])
self.kconfig.add((2,6,15), VERSION_INF, 'NUMA=y', ['PPC64=y', 'SMP=y', 'PPC_PSERIES=y'])
# kexec_file_load
self.kconfig.add((4,10) , VERSION_INF, 'KEXEC_FILE=y' , ['PPC64=y', 'CRYPTO=y', 'CRYPTO_SHA256=y'])
self.kconfig.add((4,10) , VERSION_INF, 'KEXEC_FILE=y', ['PPC64=y', 'CRYPTO=y', 'CRYPTO_SHA256=y'])
# Needed for PPC_SUBPAGE_PROT=y
# NOTE: in theory depends on (44x || PPC_BOOK3S_64), but we are
# assuming PPC_BOOK3S_64=y
self.kconfig.add((2,6,15), VERSION_INF, 'PPC_64K_PAGES=y' , ['PPC_BOOK3S_64=y'])
self.kconfig.add((2,6,15), VERSION_INF, 'PPC_64K_PAGES=y', ['PPC_BOOK3S_64=y'])
# subpage_prot (ppc only, 64-bit only)
self.kconfig.add((2,6,25), (5,9) , 'PPC_SUBPAGE_PROT=y', ['PPC_64K_PAGES=y', 'PPC_BOOK3S_64=y'])
self.kconfig.add((5,9) , VERSION_INF, 'PPC_SUBPAGE_PROT=y', ['PPC_64K_PAGES=y', 'PPC_64S_HASH_MMU=y'])
# pkey_alloc, pkey_free, pkey_mprotect
self.kconfig.add((4,16) , VERSION_INF, 'PPC_MEM_KEYS=y' , ['PPC_BOOK3S_64=y', 'PPC_64S_HASH_MMU=y'])
self.kconfig.add((4,16) , VERSION_INF, 'PPC_MEM_KEYS=y', ['PPC_BOOK3S_64=y', 'PPC_64S_HASH_MMU=y'])
# switch_endian (esoteric fast version)
self.kconfig.add((4,15) , VERSION_INF, 'PPC_FAST_ENDIAN_SWITCH=y', []),
# spu_run, spu_create
self.kconfig.add((2,6,16), VERSION_INF, 'SPU_FS=y' , ['PPC_CELL=y', 'COREDUMP=y']),
self.kconfig.add((2,6,18), VERSION_INF, 'SPU_BASE=y', []),

@staticmethod
def match(vmlinux: ELF) -> Optional[Tuple[Type[Arch],bool,List[str]]]:
Expand All @@ -132,15 +147,27 @@ def match(vmlinux: ELF) -> Optional[Tuple[Type[Arch],bool,List[str]]]:
if vmlinux.bits32:
abis = ['ppc32']
else:
# 64-bit PowerPC kernels seem to always include both ABIs.
abis = ['ppc64', 'ppc32']
abis = ['ppc64']

# v5.0+ has a separate compat table and can be built with COMPAT=n.
# Before v5.0 64-bit and 32-bit syscalls share a single table and
# apparently it's always COMPAT=y. If none of these match, we must
# be dealing with a v5.0+ COMPAT=n kernel, which is the only case
# where there's no 32-bit syscall table.
if 'compat_sys_call_table' in vmlinux.symbols \
or 'compat_sys_execve' in vmlinux.symbols \
or '.compat_sys_execve' in vmlinux.symbols:
abis.append('ppc32')

if 'spu_syscall_table' in vmlinux.symbols:
abis.append('spu')

return ArchPowerPC, vmlinux.bits32, abis

def matches(self, vmlinux: ELF) -> bool:
# Linux PPC 32-bit should be big-endian only, and _dummy_syscall_code()
# below also relies on this
assert vmlinux.big_endian, 'Little-endian PowerPC 32-bit kernel? WAT'
return (
vmlinux.e_machine == (E_MACHINE.EM_PPC64, E_MACHINE.EM_PPC)[self.bits32]
and vmlinux.bits32 == self.bits32
Expand Down Expand Up @@ -183,6 +210,85 @@ def translate_syscall_symbol_name(self, sym_name: str) -> str:
def _normalize_syscall_name(self, name: str) -> str:
return noprefix(name, 'ppc64_', 'ppc32_', 'ppc_')

def _dummy_syscall_code(self, sc: Syscall, vmlinux: ELF) -> Optional[bytes]:
# Check for `li r3,-ENOSYS; blr` optionally accompained by some other
# known non-branching instructions along the way:
#
# - {mflr,mtlr} r0
# - {stw,std,lwz,ld} r0,X(r1)
# - matching stwu/stdu and addi on r1 (stack pointer)
# - bl (to call _mcount() or other func, which *has* to return)
# - nop (ori 0,0,0)
#
# Some examples:
#
# <sys_migrate_pages>: (32-bit, v6.8)
# 7c 08 02 a6 mflr r0
# 90 01 00 04 stw r0,4(r1)
# 4b f9 20 11 bl c0039860 <_mcount>
# 94 21 ff f0 stwu r1,-16(r1)
# 38 60 ff da li r3,-38
# 38 21 00 10 addi r1,r1,16
# 4e 80 00 20 blr
#
# <.sys_ni_syscall>: (64-bit, v5.0)
# 7c 08 02 a6 mflr r0
# f8 01 00 10 std r0,16(r1)
# f8 21 ff 91 stdu r1,-112(r1)
# 4b ee 47 45 bl c0000000000707e0 <._mcount>
# 60 00 00 00 nop
# 38 21 00 70 addi r1,r1,112
# 38 60 ff da li r3,-38
# e8 01 00 10 ld r0,16(r1)
# 7c 08 03 a6 mtlr r0
# 4e 80 00 20 blr
# 60 00 00 00 nop
# 60 00 00 00 nop
#
# TODO: relies on the symbol having a valid size (!= 0), improve?
if sc.symbol.size < 8:
return None

code = vmlinux.read_symbol(sc.symbol)
r1_dec = r1_inc = None
insns = []

for insn in map(itemgetter(0), iter_unpack('<>'[vmlinux.big_endian] + 'L', code)):
hi = insn >> 16

# mflr r0 / mtlr r0 / nop (ori 0,0,0)
if insn in (0x7c0802a6, 0x7c0803a6, 0x60000000):
continue
# bl X
if (hi >> 8) == 0x4b:
continue
# stw r0,X(r1) / std r0,X(r1) / lwz r0,X(r1) / ld r0,X(r1)
if hi in (0x9001, 0xf801, 0xe801, 0x8001):
continue
# stwu r1,X(r1) / stdu r1,X(r1)
if hi in (0x9421, 0xf821):
r1_dec = 0x10000 - (insn & 0xffff) + 1
continue
# addi r1,r1,X (after stwu/stdu)
if hi == 0x3821 and r1_dec is not None:
r1_inc = insn & 0xffff
continue

if len(insns) > 2:
return None

insns.append(insn)

# Stack pointer decrement/increment must match
if (r1_dec is not None or r1_inc is not None) and r1_dec != r1_inc:
return None

# li r3,-ENOSYS; blr
if insns == [0x3860ffda, 0x4e800020]:
return code

return None

def adjust_syscall_number(self, number: int) -> int:
if self.bits32 or self.kernel_version >= (5,0):
return number
Expand Down Expand Up @@ -242,5 +348,5 @@ def syscall_def_regexp(self, syscall_name: Optional[str]=None) -> Optional[str]:
return None

if syscall_name is not None:
return rf'^PPC32_SYSCALL_DEFINE\d\({syscall_name}'
return rf'\bPPC32_SYSCALL_DEFINE\d\({syscall_name}'
return r'\bPPC32_SYSCALL_DEFINE\d\s*\('

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