| #!/usr/bin/env python3 |
| |
| # 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 filecmp |
| import glob |
| import re |
| import shutil |
| import stat |
| import string |
| import sys |
| import tempfile |
| |
| |
| SupportedArchitectures = [ "arm", "arm64", "riscv64", "x86", "x86_64" ] |
| |
| syscall_stub_header = \ |
| """ |
| 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 template 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) |
| """ |
| |
| |
| # |
| # RISC-V64 assembler templates for each syscall stub |
| # |
| |
| riscv64_call = syscall_stub_header + """\ |
| li a7, %(__NR_name)s |
| ecall |
| |
| li a7, -MAX_ERRNO |
| bgeu a0, a7, 1f |
| |
| ret |
| 1: |
| neg a0, a0 |
| tail __set_errno_internal |
| 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 template 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"]) |
| 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 riscv64_genstub(syscall): |
| return riscv64_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 |
| self.errors = False |
| |
| def E(self, msg): |
| print("%d: %s" % (self.lineno, msg)) |
| self.errors = True |
| |
| 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 = ' '.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 = alias_list.split(',') |
| else: |
| syscall_aliases = [] |
| |
| if pos_rparen > pos_lparen+1: |
| syscall_params = line[pos_lparen+1:pos_rparen].split(',') |
| params = ','.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 SupportedArchitectures: |
| t[arch] = True |
| else: |
| for arch in arch_list.split(','): |
| if arch == "lp32": |
| for arch in SupportedArchitectures: |
| if "64" not in arch: |
| t[arch] = True |
| elif arch == "lp64": |
| for arch in SupportedArchitectures: |
| if "64" in arch: |
| t[arch] = True |
| elif arch in SupportedArchitectures: |
| t[arch] = True |
| else: |
| E("invalid syscall architecture '%s' in '%s'" % (arch, line)) |
| return |
| |
| self.syscalls.append(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) |
| if self.errors: |
| sys.exit(1) |
| |
| def parse_file(self, file_path): |
| with open(file_path) as fp: |
| self.parse_open_file(fp) |
| |
| |
| def main(arch, syscall_file): |
| parser = SysCallsTxtParser() |
| parser.parse_file(syscall_file) |
| |
| for syscall in parser.syscalls: |
| syscall["__NR_name"] = make__NR_name(syscall["name"]) |
| |
| if "arm" in syscall: |
| syscall["asm-arm"] = add_footer(32, arm_eabi_genstub(syscall), syscall) |
| |
| if "arm64" in syscall: |
| syscall["asm-arm64"] = add_footer(64, arm64_genstub(syscall), syscall) |
| |
| if "riscv64" in syscall: |
| syscall["asm-riscv64"] = add_footer(64, riscv64_genstub(syscall), syscall) |
| |
| if "x86" in syscall: |
| 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 "x86_64" in syscall: |
| syscall["asm-x86_64"] = add_footer(64, x86_64_genstub(syscall), syscall) |
| |
| print("/* Generated by gensyscalls.py. Do not edit. */\n") |
| print("#include <private/bionic_asm.h>\n") |
| for syscall in parser.syscalls: |
| if ("asm-%s" % arch) in syscall: |
| print(syscall["asm-%s" % arch]) |
| |
| if arch == 'arm64': |
| print('\nNOTE_GNU_PROPERTY()\n') |
| |
| if __name__ == "__main__": |
| if len(sys.argv) < 2: |
| print("Usage: gensyscalls.py ARCH SOURCE_FILE") |
| sys.exit(1) |
| |
| arch = sys.argv[1] |
| syscall_file = sys.argv[2] |
| main(arch, syscall_file) |
