#!/usr/bin/python
# This tool is used to generate the assembler system call stubs,
# the header files listing all available system calls, and the
# makefiles used to build all the stubs.
import atexit
import commands
import filecmp
import glob
import logging
import os.path
import re
import shutil
import stat
import string
import sys
import tempfile
all_arches = [ "arm", "arm64", "mips", "mips64", "x86", "x86_64" ]
# temp directory where we store all intermediate files
bionic_temp = tempfile.mkdtemp(prefix="bionic_gensyscalls");
# Make sure the directory is deleted when the script exits.
atexit.register(shutil.rmtree, bionic_temp)
bionic_libc_root = os.path.join(os.environ["ANDROID_BUILD_TOP"], "bionic/libc")
warning = "Generated by gensyscalls.py. Do not edit."
DRY_RUN = False
def make_dir(path):
path = os.path.abspath(path)
if not os.path.exists(path):
parent = os.path.dirname(path)
if parent:
make_dir(parent)
os.mkdir(path)
def create_file(relpath):
full_path = os.path.join(bionic_temp, relpath)
dir = os.path.dirname(full_path)
make_dir(dir)
return open(full_path, "w")
syscall_stub_header = "/* " + warning + " */\n" + \
"""
#include <private/bionic_asm.h>
ENTRY(%(func)s)
"""
#
# ARM assembler templates for each syscall stub
#
arm_eabi_call_default = syscall_stub_header + """\
mov ip, r7
.cfi_register r7, ip
ldr r7, =%(__NR_name)s
swi #0
mov r7, ip
.cfi_restore r7
cmn r0, #(MAX_ERRNO + 1)
bxls lr
neg r0, r0
b __set_errno_internal
END(%(func)s)
"""
arm_eabi_call_long = syscall_stub_header + """\
mov ip, sp
stmfd sp!, {r4, r5, r6, r7}
.cfi_def_cfa_offset 16
.cfi_rel_offset r4, 0
.cfi_rel_offset r5, 4
.cfi_rel_offset r6, 8
.cfi_rel_offset r7, 12
ldmfd ip, {r4, r5, r6}
ldr r7, =%(__NR_name)s
swi #0
ldmfd sp!, {r4, r5, r6, r7}
.cfi_def_cfa_offset 0
cmn r0, #(MAX_ERRNO + 1)
bxls lr
neg r0, r0
b __set_errno_internal
END(%(func)s)
"""
#
# Arm64 assembler templates for each syscall stub
#
arm64_call = syscall_stub_header + """\
mov x8, %(__NR_name)s
svc #0
cmn x0, #(MAX_ERRNO + 1)
cneg x0, x0, hi
b.hi __set_errno_internal
ret
END(%(func)s)
"""
#
# MIPS assembler templates for each syscall stub
#
mips_call = syscall_stub_header + """\
.set noreorder
.cpload t9
li v0, %(__NR_name)s
syscall
bnez a3, 1f
move a0, v0
j ra
nop
1:
la t9,__set_errno_internal
j t9
nop
.set reorder
END(%(func)s)
"""
#
# MIPS64 assembler templates for each syscall stub
#
mips64_call = syscall_stub_header + """\
.set push
.set noreorder
li v0, %(__NR_name)s
syscall
bnez a3, 1f
move a0, v0
j ra
nop
1:
move t0, ra
bal 2f
nop
2:
.cpsetup ra, t1, 2b
LA t9,__set_errno_internal
.cpreturn
j t9
move ra, t0
.set pop
END(%(func)s)
"""
#
# x86 assembler templates for each syscall stub
#
x86_registers = [ "ebx", "ecx", "edx", "esi", "edi", "ebp" ]
x86_call_prepare = """\
call __kernel_syscall
pushl %eax
.cfi_adjust_cfa_offset 4
.cfi_rel_offset eax, 0
"""
x86_call = """\
movl $%(__NR_name)s, %%eax
call *(%%esp)
addl $4, %%esp
cmpl $-MAX_ERRNO, %%eax
jb 1f
negl %%eax
pushl %%eax
call __set_errno_internal
addl $4, %%esp
1:
"""
x86_return = """\
ret
END(%(func)s)
"""
#
# x86_64 assembler templates for each syscall stub
#
x86_64_call = """\
movl $%(__NR_name)s, %%eax
syscall
cmpq $-MAX_ERRNO, %%rax
jb 1f
negl %%eax
movl %%eax, %%edi
call __set_errno_internal
1:
ret
END(%(func)s)
"""
def param_uses_64bits(param):
"""Returns True iff a syscall parameter description corresponds
to a 64-bit type."""
param = param.strip()
# First, check that the param type begins with one of the known
# 64-bit types.
if not ( \
param.startswith("int64_t") or param.startswith("uint64_t") or \
param.startswith("loff_t") or param.startswith("off64_t") or \
param.startswith("long long") or param.startswith("unsigned long long") or
param.startswith("signed long long") ):
return False
# Second, check that there is no pointer type here
if param.find("*") >= 0:
return False
# Ok
return True
def count_arm_param_registers(params):
"""This function is used to count the number of register used
to pass parameters when invoking an ARM system call.
This is because the ARM EABI mandates that 64-bit quantities
must be passed in an even+odd register pair. So, for example,
something like:
foo(int fd, off64_t pos)
would actually need 4 registers:
r0 -> int
r1 -> unused
r2-r3 -> pos
"""
count = 0
for param in params:
if param_uses_64bits(param):
if (count & 1) != 0:
count += 1
count += 2
else:
count += 1
return count
def count_generic_param_registers(params):
count = 0
for param in params:
if param_uses_64bits(param):
count += 2
else:
count += 1
return count
def count_generic_param_registers64(params):
count = 0
for param in params:
count += 1
return count
# This lets us support regular system calls like __NR_write and also weird
# ones like __ARM_NR_cacheflush, where the NR doesn't come at the start.
def make__NR_name(name):
if name.startswith("__ARM_NR_"):
return name
else:
return "__NR_%s" % (name)
def add_footer(pointer_length, stub, syscall):
# Add any aliases for this syscall.
aliases = syscall["aliases"]
for alias in aliases:
stub += "\nALIAS_SYMBOL(%s, %s)\n" % (alias, syscall["func"])
# Use hidden visibility on LP64 for any functions beginning with underscores.
# Force hidden visibility for any functions which begin with 3 underscores
if (pointer_length == 64 and syscall["func"].startswith("__")) or syscall["func"].startswith("___"):
stub += '.hidden ' + syscall["func"] + '\n'
return stub
def arm_eabi_genstub(syscall):
num_regs = count_arm_param_registers(syscall["params"])
if num_regs > 4:
return arm_eabi_call_long % syscall
return arm_eabi_call_default % syscall
def arm64_genstub(syscall):
return arm64_call % syscall
def mips_genstub(syscall):
return mips_call % syscall
def mips64_genstub(syscall):
return mips64_call % syscall
def x86_genstub(syscall):
result = syscall_stub_header % syscall
numparams = count_generic_param_registers(syscall["params"])
stack_bias = numparams*4 + 8
offset = 0
mov_result = ""
first_push = True
for register in x86_registers[:numparams]:
result += " pushl %%%s\n" % register
if first_push:
result += " .cfi_def_cfa_offset 8\n"
result += " .cfi_rel_offset %s, 0\n" % register
first_push = False
else:
result += " .cfi_adjust_cfa_offset 4\n"
result += " .cfi_rel_offset %s, 0\n" % register
mov_result += " mov %d(%%esp), %%%s\n" % (stack_bias+offset, register)
offset += 4
result += x86_call_prepare
result += mov_result
result += x86_call % syscall
for register in reversed(x86_registers[:numparams]):
result += " popl %%%s\n" % register
result += x86_return % syscall
return result
def x86_genstub_socketcall(syscall):
# %ebx <--- Argument 1 - The call id of the needed vectored
# syscall (socket, bind, recv, etc)
# %ecx <--- Argument 2 - Pointer to the rest of the arguments
# from the original function called (socket())
result = syscall_stub_header % syscall
# save the regs we need
result += " pushl %ebx\n"
result += " .cfi_def_cfa_offset 8\n"
result += " .cfi_rel_offset ebx, 0\n"
result += " pushl %ecx\n"
result += " .cfi_adjust_cfa_offset 4\n"
result += " .cfi_rel_offset ecx, 0\n"
stack_bias = 16
result += x86_call_prepare
# set the call id (%ebx)
result += " mov $%d, %%ebx\n" % syscall["socketcall_id"]
# set the pointer to the rest of the args into %ecx
result += " mov %esp, %ecx\n"
result += " addl $%d, %%ecx\n" % (stack_bias)
# now do the syscall code itself
result += x86_call % syscall
# now restore the saved regs
result += " popl %ecx\n"
result += " popl %ebx\n"
# epilog
result += x86_return % syscall
return result
def x86_64_genstub(syscall):
result = syscall_stub_header % syscall
num_regs = count_generic_param_registers64(syscall["params"])
if (num_regs > 3):
# rcx is used as 4th argument. Kernel wants it at r10.
result += " movq %rcx, %r10\n"
result += x86_64_call % syscall
return result
class SysCallsTxtParser:
def __init__(self):
self.syscalls = []
self.lineno = 0
def E(self, msg):
print "%d: %s" % (self.lineno, msg)
def parse_line(self, line):
""" parse a syscall spec line.
line processing, format is
return type func_name[|alias_list][:syscall_name[:socketcall_id]] ( [paramlist] ) architecture_list
"""
pos_lparen = line.find('(')
E = self.E
if pos_lparen < 0:
E("missing left parenthesis in '%s'" % line)
return
pos_rparen = line.rfind(')')
if pos_rparen < 0 or pos_rparen <= pos_lparen:
E("missing or misplaced right parenthesis in '%s'" % line)
return
return_type = line[:pos_lparen].strip().split()
if len(return_type) < 2:
E("missing return type in '%s'" % line)
return
syscall_func = return_type[-1]
return_type = string.join(return_type[:-1],' ')
socketcall_id = -1
pos_colon = syscall_func.find(':')
if pos_colon < 0:
syscall_name = syscall_func
else:
if pos_colon == 0 or pos_colon+1 >= len(syscall_func):
E("misplaced colon in '%s'" % line)
return
# now find if there is a socketcall_id for a dispatch-type syscall
# after the optional 2nd colon
pos_colon2 = syscall_func.find(':', pos_colon + 1)
if pos_colon2 < 0:
syscall_name = syscall_func[pos_colon+1:]
syscall_func = syscall_func[:pos_colon]
else:
if pos_colon2+1 >= len(syscall_func):
E("misplaced colon2 in '%s'" % line)
return
syscall_name = syscall_func[(pos_colon+1):pos_colon2]
socketcall_id = int(syscall_func[pos_colon2+1:])
syscall_func = syscall_func[:pos_colon]
alias_delim = syscall_func.find('|')
if alias_delim > 0:
alias_list = syscall_func[alias_delim+1:].strip()
syscall_func = syscall_func[:alias_delim]
alias_delim = syscall_name.find('|')
if alias_delim > 0:
syscall_name = syscall_name[:alias_delim]
syscall_aliases = string.split(alias_list, ',')
else:
syscall_aliases = []
if pos_rparen > pos_lparen+1:
syscall_params = line[pos_lparen+1:pos_rparen].split(',')
params = string.join(syscall_params,',')
else:
syscall_params = []
params = "void"
t = {
"name" : syscall_name,
"func" : syscall_func,
"aliases" : syscall_aliases,
"params" : syscall_params,
"decl" : "%-15s %s (%s);" % (return_type, syscall_func, params),
"socketcall_id" : socketcall_id
}
# Parse the architecture list.
arch_list = line[pos_rparen+1:].strip()
if arch_list == "all":
for arch in all_arches:
t[arch] = True
else:
for arch in string.split(arch_list, ','):
if arch in all_arches:
t[arch] = True
else:
E("invalid syscall architecture '%s' in '%s'" % (arch, line))
return
self.syscalls.append(t)
logging.debug(t)
def parse_open_file(self, fp):
for line in fp:
self.lineno += 1
line = line.strip()
if not line: continue
if line[0] == '#': continue
self.parse_line(line)
def parse_file(self, file_path):
logging.debug("parse_file: %s" % file_path)
with open(file_path) as fp:
parse_open_file(fp)
class State:
def __init__(self):
self.old_stubs = []
self.new_stubs = []
self.other_files = []
self.syscalls = []
def process_file(self, input):
parser = SysCallsTxtParser()
parser.parse_file(input)
self.syscalls = parser.syscalls
parser = None
for syscall in self.syscalls:
syscall["__NR_name"] = make__NR_name(syscall["name"])
if syscall.has_key("arm"):
syscall["asm-arm"] = add_footer(32, arm_eabi_genstub(syscall), syscall)
if syscall.has_key("arm64"):
syscall["asm-arm64"] = add_footer(64, arm64_genstub(syscall), syscall)
if syscall.has_key("x86"):
if syscall["socketcall_id"] >= 0:
syscall["asm-x86"] = add_footer(32, x86_genstub_socketcall(syscall), syscall)
else:
syscall["asm-x86"] = add_footer(32, x86_genstub(syscall), syscall)
elif syscall["socketcall_id"] >= 0:
E("socketcall_id for dispatch syscalls is only supported for x86 in '%s'" % t)
return
if syscall.has_key("mips"):
syscall["asm-mips"] = add_footer(32, mips_genstub(syscall), syscall)
if syscall.has_key("mips64"):
syscall["asm-mips64"] = add_footer(64, mips64_genstub(syscall), syscall)
if syscall.has_key("x86_64"):
syscall["asm-x86_64"] = add_footer(64, x86_64_genstub(syscall), syscall)
# Scan Linux kernel asm/unistd.h files containing __NR_* constants
# and write out equivalent SYS_* constants for glibc source compatibility.
def gen_glibc_syscalls_h(self):
glibc_syscalls_h_path = "include/bits/glibc-syscalls.h"
logging.info("generating " + glibc_syscalls_h_path)
glibc_fp = create_file(glibc_syscalls_h_path)
glibc_fp.write("/* %s */\n" % warning)
glibc_fp.write("#ifndef _BIONIC_BITS_GLIBC_SYSCALLS_H_\n")
glibc_fp.write("#define _BIONIC_BITS_GLIBC_SYSCALLS_H_\n")
# Collect the set of all syscalls for all architectures.
syscalls = set()
pattern = re.compile(r'^\s*#\s*define\s*__NR_([a-z]\S+)')
for unistd_h in ["kernel/uapi/asm-generic/unistd.h",
"kernel/uapi/asm-arm/asm/unistd.h",
"kernel/uapi/asm-arm/asm/unistd-common.h",
"kernel/uapi/asm-arm/asm/unistd-eabi.h",
"kernel/uapi/asm-arm/asm/unistd-oabi.h",
"kernel/uapi/asm-mips/asm/unistd.h",
"kernel/uapi/asm-x86/asm/unistd_32.h",
"kernel/uapi/asm-x86/asm/unistd_64.h"]:
for line in open(os.path.join(bionic_libc_root, unistd_h)):
m = re.search(pattern, line)
if m:
nr_name = m.group(1)
if 'reserved' not in nr_name and 'unused' not in nr_name:
syscalls.add(nr_name)
# Write out a single file listing them all. Note that the input
# files include #if trickery, so even for a single architecture
# we don't know exactly which ones are available.
# https://code.google.com/p/android/issues/detail?id=215853
for syscall in sorted(syscalls):
nr_name = make__NR_name(syscall)
glibc_fp.write("#if defined(%s)\n" % nr_name)
glibc_fp.write(" #define SYS_%s %s\n" % (syscall, nr_name))
glibc_fp.write("#endif\n")
glibc_fp.write("#endif /* _BIONIC_BITS_GLIBC_SYSCALLS_H_ */\n")
glibc_fp.close()
self.other_files.append(glibc_syscalls_h_path)
# Write each syscall stub.
def gen_syscall_stubs(self):
for syscall in self.syscalls:
for arch in all_arches:
if syscall.has_key("asm-%s" % arch):
filename = "arch-%s/syscalls/%s.S" % (arch, syscall["func"])
logging.info(">>> generating " + filename)
fp = create_file(filename)
fp.write(syscall["asm-%s" % arch])
fp.close()
self.new_stubs.append(filename)
def regenerate(self):
logging.info("scanning for existing architecture-specific stub files...")
for arch in all_arches:
arch_dir = "arch-" + arch
logging.info("scanning " + os.path.join(bionic_libc_root, arch_dir))
rel_path = os.path.join(arch_dir, "syscalls")
for file in os.listdir(os.path.join(bionic_libc_root, rel_path)):
if file.endswith(".S"):
self.old_stubs.append(os.path.join(rel_path, file))
logging.info("found %d stub files" % len(self.old_stubs))
if not os.path.exists(bionic_temp):
logging.info("creating %s..." % bionic_temp)
make_dir(bionic_temp)
logging.info("re-generating stubs and support files...")
self.gen_glibc_syscalls_h()
self.gen_syscall_stubs()
logging.info("comparing files...")
adds = []
edits = []
for stub in self.new_stubs + self.other_files:
tmp_file = os.path.join(bionic_temp, stub)
libc_file = os.path.join(bionic_libc_root, stub)
if not os.path.exists(libc_file):
# new file, git add it
logging.info("new file: " + stub)
adds.append(libc_file)
shutil.copyfile(tmp_file, libc_file)
elif not filecmp.cmp(tmp_file, libc_file):
logging.info("changed file: " + stub)
edits.append(stub)
deletes = []
for stub in self.old_stubs:
if not stub in self.new_stubs:
logging.info("deleted file: " + stub)
deletes.append(os.path.join(bionic_libc_root, stub))
if not DRY_RUN:
if adds:
commands.getoutput("git add " + " ".join(adds))
if deletes:
commands.getoutput("git rm " + " ".join(deletes))
if edits:
for file in edits:
shutil.copyfile(os.path.join(bionic_temp, file),
os.path.join(bionic_libc_root, file))
commands.getoutput("git add " + " ".join((os.path.join(bionic_libc_root, file)) for file in edits))
commands.getoutput("git add %s" % (os.path.join(bionic_libc_root, "SYSCALLS.TXT")))
if (not adds) and (not deletes) and (not edits):
logging.info("no changes detected!")
else:
logging.info("ready to go!!")
logging.basicConfig(level=logging.INFO)
if __name__ == "__main__":
state = State()
state.process_file(os.path.join(bionic_libc_root, "SYSCALLS.TXT"))
state.regenerate()