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coredump: enable coredump generation on arm
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Add relevant elf header constants and notes for the arm platform
to enable coredump generation.

Signed-off-by: समीर सिंह Sameer Singh <lumarzeli30@gmail.com>
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@ss141309 @rst0git
ss141309 authored and rst0git committed Mar 3, 2025
1 parent 6f94888 commit da7f5b7
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Showing 4 changed files with 288 additions and 30 deletions.
2 changes: 1 addition & 1 deletion coredump/coredump
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ import sys

import criu_coredump

PLATFORMS = ["aarch64", "x86_64"]
PLATFORMS = ["aarch64", "armv7l", "x86_64"]


def coredump(opts):
Expand Down
124 changes: 102 additions & 22 deletions coredump/criu_coredump/coredump.py
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Original file line number Diff line number Diff line change
Expand Up @@ -95,8 +95,13 @@ def write(self, f):
buf.write(b"\0" * (8 - len(note.owner)))
buf.write(note.data)

offset = ctypes.sizeof(elf.Elf64_Ehdr())
offset += (len(self.vmas) + 1) * ctypes.sizeof(elf.Elf64_Phdr())
bits = platform.architecture()[0] # 32 or 64 bits

ehdr = {"32bit": elf.Elf32_Ehdr, "64bit": elf.Elf64_Ehdr}
phdr = {"32bit": elf.Elf32_Phdr, "64bit": elf.Elf64_Phdr}

offset = ctypes.sizeof(ehdr[bits]())
offset += (len(self.vmas) + 1) * ctypes.sizeof(phdr[bits]())

filesz = 0
for note in self.notes:
Expand Down Expand Up @@ -132,9 +137,18 @@ class coredump_generator:
pagemaps = {} # pagemap by pid;

# thread info key based on the current arch
thread_info_key = {"aarch64": "ti_aarch64", "x86_64": "thread_info"}
thread_info_key = {
"aarch64": "ti_aarch64",
"armv7l": "ti_arm",
"x86_64": "thread_info",
}

machine = platform.machine() # current arch
bits = platform.architecture()[0] # 32 or 64 bits

ehdr = {"32bit": elf.Elf32_Ehdr, "64bit": elf.Elf64_Ehdr} # 32 or 64 bits Ehdr
nhdr = {"32bit": elf.Elf32_Nhdr, "64bit": elf.Elf64_Nhdr} # 32 or 64 bits Nhdr
phdr = {"32bit": elf.Elf32_Phdr, "64bit": elf.Elf64_Phdr} # 32 or 64 bits Phdr

def _img_open_and_strip(self, name, single=False, pid=None):
"""
Expand Down Expand Up @@ -207,23 +221,30 @@ def _gen_ehdr(self, pid, phdrs):
"""
Generate elf header for process pid with program headers phdrs.
"""
ehdr = elf.Elf64_Ehdr()
ei_class = {"32bit": elf.ELFCLASS32, "64bit": elf.ELFCLASS64}

ehdr = self.ehdr[self.bits]()

ctypes.memset(ctypes.addressof(ehdr), 0, ctypes.sizeof(ehdr))
ehdr.e_ident[elf.EI_MAG0] = elf.ELFMAG0
ehdr.e_ident[elf.EI_MAG1] = elf.ELFMAG1
ehdr.e_ident[elf.EI_MAG2] = elf.ELFMAG2
ehdr.e_ident[elf.EI_MAG3] = elf.ELFMAG3
ehdr.e_ident[elf.EI_CLASS] = elf.ELFCLASS64
ehdr.e_ident[elf.EI_CLASS] = ei_class[self.bits]
ehdr.e_ident[elf.EI_DATA] = elf.ELFDATA2LSB
ehdr.e_ident[elf.EI_VERSION] = elf.EV_CURRENT

if self.machine == "armv7l":
ehdr.e_ident[elf.EI_OSABI] = elf.ELFOSABI_ARM
else:
ehdr.e_ident[elf.EI_OSABI] = elf.ELFOSABI_NONE

ehdr.e_type = elf.ET_CORE
ehdr.e_machine = self._get_e_machine()
ehdr.e_version = elf.EV_CURRENT
ehdr.e_phoff = ctypes.sizeof(elf.Elf64_Ehdr())
ehdr.e_ehsize = ctypes.sizeof(elf.Elf64_Ehdr())
ehdr.e_phentsize = ctypes.sizeof(elf.Elf64_Phdr())
ehdr.e_phoff = ctypes.sizeof(self.ehdr[self.bits]())
ehdr.e_ehsize = ctypes.sizeof(self.ehdr[self.bits]())
ehdr.e_phentsize = ctypes.sizeof(self.phdr[self.bits]())
# FIXME Case len(phdrs) > PN_XNUM should be handled properly.
# See fs/binfmt_elf.c from linux kernel.
ehdr.e_phnum = len(phdrs)
Expand All @@ -234,7 +255,11 @@ def _get_e_machine(self):
"""
Get the e_machine field based on the current architecture.
"""
e_machine_dict = {"aarch64": elf.EM_AARCH64, "x86_64": elf.EM_X86_64}
e_machine_dict = {
"aarch64": elf.EM_AARCH64,
"armv7l": elf.EM_ARM,
"x86_64": elf.EM_X86_64,
}
return e_machine_dict[self.machine]

def _gen_phdrs(self, pid, notes, vmas):
Expand All @@ -243,15 +268,15 @@ def _gen_phdrs(self, pid, notes, vmas):
"""
phdrs = []

offset = ctypes.sizeof(elf.Elf64_Ehdr())
offset += (len(vmas) + 1) * ctypes.sizeof(elf.Elf64_Phdr())
offset = ctypes.sizeof(self.ehdr[self.bits]())
offset += (len(vmas) + 1) * ctypes.sizeof(self.phdr[self.bits]())

filesz = 0
for note in notes:
filesz += ctypes.sizeof(note.nhdr) + ctypes.sizeof(note.data) + 8

# PT_NOTE
phdr = elf.Elf64_Phdr()
phdr = self.phdr[self.bits]()
ctypes.memset(ctypes.addressof(phdr), 0, ctypes.sizeof(phdr))
phdr.p_type = elf.PT_NOTE
phdr.p_offset = offset
Expand All @@ -271,7 +296,7 @@ def _gen_phdrs(self, pid, notes, vmas):
for vma in vmas:
offset += filesz
filesz = vma.filesz
phdr = elf.Elf64_Phdr()
phdr = self.phdr[self.bits]()
ctypes.memset(ctypes.addressof(phdr), 0, ctypes.sizeof(phdr))
phdr.p_type = elf.PT_LOAD
phdr.p_align = PAGESIZE
Expand Down Expand Up @@ -328,7 +353,7 @@ def _gen_prpsinfo(self, pid):
prpsinfo.pr_psargs = self._gen_cmdline(pid)[:80]
prpsinfo.pr_fname = core["tc"]["comm"].encode()

nhdr = elf.Elf64_Nhdr()
nhdr = self.nhdr[self.bits]()
nhdr.n_namesz = 5
nhdr.n_descsz = ctypes.sizeof(elf.elf_prpsinfo())
nhdr.n_type = elf.NT_PRPSINFO
Expand Down Expand Up @@ -360,7 +385,7 @@ def _gen_prstatus(self, pid, tid):

self._set_pr_regset(prstatus.pr_reg, regs)

nhdr = elf.Elf64_Nhdr()
nhdr = self.nhdr[self.bits]()
nhdr.n_namesz = 5
nhdr.n_descsz = ctypes.sizeof(elf.elf_prstatus())
nhdr.n_type = elf.NT_PRSTATUS
Expand Down Expand Up @@ -390,6 +415,25 @@ def _set_pr_regset(self, pr_reg, regs):
pr_reg.sp = regs["sp"]
pr_reg.pc = regs["pc"]
pr_reg.pstate = regs["pstate"]
elif self.machine == "armv7l":
pr_reg.r0 = regs["r0"]
pr_reg.r1 = regs["r1"]
pr_reg.r2 = regs["r2"]
pr_reg.r3 = regs["r3"]
pr_reg.r4 = regs["r4"]
pr_reg.r5 = regs["r5"]
pr_reg.r6 = regs["r6"]
pr_reg.r7 = regs["r7"]
pr_reg.r8 = regs["r8"]
pr_reg.r9 = regs["r9"]
pr_reg.r10 = regs["r10"]
pr_reg.fp = regs["fp"]
pr_reg.ip = regs["ip"]
pr_reg.sp = regs["sp"]
pr_reg.lr = regs["lr"]
pr_reg.pc = regs["pc"]
pr_reg.cpsr = regs["cpsr"]
pr_reg.orig_r0 = regs["orig_r0"]
elif self.machine == "x86_64":
pr_reg.r15 = regs["r15"]
pr_reg.r14 = regs["r14"]
Expand Down Expand Up @@ -495,6 +539,34 @@ def _gen_arm_tls(self, tid):

return note

def _gen_arm_vfp(self, tid):
"""
Generate NT_ARM_VFP note for thread tid of process pid.
"""
core = self.cores[tid]
fpstate = core["ti_arm"]["fpstate"]

data = elf.vfp_hard_struct()
ctypes.memset(ctypes.addressof(data), 0, ctypes.sizeof(data))

data.vfp_regs = (ctypes.c_uint64 * len(fpstate["vfp_regs"]))(*fpstate["vfp_regs"])
data.fpexc = fpstate["fpexc"]
data.fpscr = fpstate["fpscr"]
data.fpinst = fpstate["fpinst"]
data.fpinst2 = fpstate["fpinst2"]

nhdr = elf.Elf32_Nhdr()
nhdr.n_namesz = 6
nhdr.n_descsz = ctypes.sizeof(data)
nhdr.n_type = elf.NT_ARM_VFP

note = elf_note()
note.data = data
note.owner = b"LINUX"
note.nhdr = nhdr

return note

def _gen_x86_xstate(self, pid, tid):
"""
Generate NT_X86_XSTATE note for thread tid of process pid.
Expand Down Expand Up @@ -544,7 +616,7 @@ def _gen_siginfo(self, pid, tid):
# FIXME zeroify everything for now
ctypes.memset(ctypes.addressof(siginfo), 0, ctypes.sizeof(siginfo))

nhdr = elf.Elf64_Nhdr()
nhdr = self.nhdr[self.bits]()
nhdr.n_namesz = 5
nhdr.n_descsz = ctypes.sizeof(elf.siginfo_t())
nhdr.n_type = elf.NT_SIGINFO
Expand All @@ -563,17 +635,22 @@ def _gen_auxv(self, pid):
mm = self.mms[pid]
num_auxv = len(mm["mm_saved_auxv"]) // 2

class elf_auxv(ctypes.Structure):
class elf32_auxv(ctypes.Structure):
_fields_ = [("auxv", elf.Elf32_auxv_t * num_auxv)]

class elf64_auxv(ctypes.Structure):
_fields_ = [("auxv", elf.Elf64_auxv_t * num_auxv)]

auxv = elf_auxv()
elf_auxv = {"32bit": elf32_auxv(), "64bit": elf64_auxv()}

auxv = elf_auxv[self.bits]
for i in range(num_auxv):
auxv.auxv[i].a_type = mm["mm_saved_auxv"][i]
auxv.auxv[i].a_val = mm["mm_saved_auxv"][i + 1]

nhdr = elf.Elf64_Nhdr()
nhdr = self.nhdr[self.bits]()
nhdr.n_namesz = 5
nhdr.n_descsz = ctypes.sizeof(elf_auxv())
nhdr.n_descsz = ctypes.sizeof(elf_auxv[self.bits])
nhdr.n_type = elf.NT_AUXV

note = elf_note()
Expand Down Expand Up @@ -650,7 +727,7 @@ class elf_files(ctypes.Structure):
setattr(data, "file_ofs" + str(i), info.file_ofs)
setattr(data, "name" + str(i), info.name.encode())

nhdr = elf.Elf64_Nhdr()
nhdr = self.nhdr[self.bits]()

nhdr.n_namesz = 5 # strlen + 1
nhdr.n_descsz = ctypes.sizeof(elf_files())
Expand All @@ -667,10 +744,13 @@ def _gen_thread_notes(self, pid, tid):
notes = []

notes.append(self._gen_prstatus(pid, tid))
notes.append(self._gen_fpregset(pid, tid))
if self.machine != "armv7l":
notes.append(self._gen_fpregset(pid, tid))
notes.append(self._gen_siginfo(pid, tid))
if self.machine == "aarch64":
notes.append(self._gen_arm_tls(tid))
elif self.machine == "armv7l":
notes.append(self._gen_arm_vfp(tid))
elif self.machine == "x86_64":
notes.append(self._gen_x86_xstate(pid, tid))

Expand Down
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