missing_syscall: verify our fallback numbers when possible

Instead of defining the numbers only as fallback, always define our fallback
number, and if we have the real __NR_foo define, assert that our number matches
the real one.

This will result in warnings when our fallback number is not defined, even if
the kernel headers are new enough to define __NR_foo. This will probably annoy
people compiling for seldom-used architectures, but hopefully it'll provide
motivation to add the missing fallback defines.

The upside is that we have a higher chance of catching the cases where we got
the number wrong. Calling the wrong syscall is quite problematic, and with some
back luck, it might take us a long time to notice that we got the number wrong
on some rarely used architecture.

Also, rework some of the fallback wrappers to not call the syscall with a
negative number (that'd fail, but we'd got to the kernel and back). It seems
nicer to let the compiler know that this can never succeed.

diff --git a/src/basic/missing_syscall.h b/src/basic/missing_syscall.h
index b633ea4541f7adda86b7395b0eca6cfa8057d020..21f470d96b287f7313c0833f0971ac21dec24541 100644 (file)
--- a/src/basic/missing_syscall.h
+++ b/src/basic/missing_syscall.h
@@ -33,39 +33,47 @@ static inline int missing_pivot_root(const char *new_root, const char *put_old)
 
 /* ======================================================================= */
 
-#if !HAVE_MEMFD_CREATE
+#if defined __x86_64__
+#  define systemd_NR_memfd_create 319
+#elif defined __arm__
+#  define systemd_NR_memfd_create 385
+#elif defined __aarch64__
+#  define systemd_NR_memfd_create 279
+#elif defined __s390__
+#  define systemd_NR_memfd_create 350
+#elif defined _MIPS_SIM
+#  if _MIPS_SIM == _MIPS_SIM_ABI32
+#    define systemd_NR_memfd_create 4354
+#  endif
+#  if _MIPS_SIM == _MIPS_SIM_NABI32
+#    define systemd_NR_memfd_create 6318
+#  endif
+#  if _MIPS_SIM == _MIPS_SIM_ABI64
+#    define systemd_NR_memfd_create 5314
+#  endif
+#elif defined __i386__
+#  define systemd_NR_memfd_create 356
+#elif defined __arc__
+#  define systemd_NR_memfd_create 279
+#else
+#  warning "memfd_create() syscall number unknown for your architecture"
+#endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_memfd_create && __NR_memfd_create >= 0)
-#    if defined __NR_memfd_create
-#      undef __NR_memfd_create
-#    endif
-#    if defined __x86_64__
-#      define __NR_memfd_create 319
-#    elif defined __arm__
-#      define __NR_memfd_create 385
-#    elif defined __aarch64__
-#      define __NR_memfd_create 279
-#    elif defined __s390__
-#      define __NR_memfd_create 350
-#    elif defined _MIPS_SIM
-#      if _MIPS_SIM == _MIPS_SIM_ABI32
-#        define __NR_memfd_create 4354
-#      endif
-#      if _MIPS_SIM == _MIPS_SIM_NABI32
-#        define __NR_memfd_create 6318
-#      endif
-#      if _MIPS_SIM == _MIPS_SIM_ABI64
-#        define __NR_memfd_create 5314
-#      endif
-#    elif defined __i386__
-#      define __NR_memfd_create 356
-#    elif defined __arc__
-#      define __NR_memfd_create 279
-#    else
-#      warning "__NR_memfd_create unknown for your architecture"
-#    endif
+#if defined __NR_memfd_create && __NR_memfd_create >= 0
+#  if defined systemd_NR_memfd_create
+assert_cc(__NR_memfd_create == systemd_NR_memfd_create);
+#  endif
+#else
+#  if defined __NR_memfd_create
+#    undef __NR_memfd_create
+#  endif
+#  if defined systemd_NR_memfd_create
+#    define __NR_memfd_create systemd_NR_memfd_create
 #  endif
+#endif
 
+#if !HAVE_MEMFD_CREATE
 static inline int missing_memfd_create(const char *name, unsigned int flags) {
 #  ifdef __NR_memfd_create
         return syscall(__NR_memfd_create, name, flags);
@@ -80,45 +88,53 @@ static inline int missing_memfd_create(const char *name, unsigned int flags) {
 
 /* ======================================================================= */
 
-#if !HAVE_GETRANDOM
+#if defined __x86_64__
+#  define systemd_NR_getrandom 318
+#elif defined(__i386__)
+#  define systemd_NR_getrandom 355
+#elif defined(__arm__)
+#  define systemd_NR_getrandom 384
+#elif defined(__aarch64__)
+#  define systemd_NR_getrandom 278
+#elif defined(__ia64__)
+#  define systemd_NR_getrandom 1339
+#elif defined(__m68k__)
+#  define systemd_NR_getrandom 352
+#elif defined(__s390x__)
+#  define systemd_NR_getrandom 349
+#elif defined(__powerpc__)
+#  define systemd_NR_getrandom 359
+#elif defined _MIPS_SIM
+#  if _MIPS_SIM == _MIPS_SIM_ABI32
+#    define systemd_NR_getrandom 4353
+#  endif
+#  if _MIPS_SIM == _MIPS_SIM_NABI32
+#    define systemd_NR_getrandom 6317
+#  endif
+#  if _MIPS_SIM == _MIPS_SIM_ABI64
+#    define systemd_NR_getrandom 5313
+#  endif
+#elif defined(__arc__)
+#  define systemd_NR_getrandom 278
+#else
+#  warning "getrandom() syscall number unknown for your architecture"
+#endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_getrandom && __NR_getrandom >= 0)
-#    if defined __NR_getrandom
-#      undef __NR_getrandom
-#    endif
-#    if defined __x86_64__
-#      define __NR_getrandom 318
-#    elif defined(__i386__)
-#      define __NR_getrandom 355
-#    elif defined(__arm__)
-#      define __NR_getrandom 384
-#   elif defined(__aarch64__)
-#      define __NR_getrandom 278
-#    elif defined(__ia64__)
-#      define __NR_getrandom 1339
-#    elif defined(__m68k__)
-#      define __NR_getrandom 352
-#    elif defined(__s390x__)
-#      define __NR_getrandom 349
-#    elif defined(__powerpc__)
-#      define __NR_getrandom 359
-#    elif defined _MIPS_SIM
-#      if _MIPS_SIM == _MIPS_SIM_ABI32
-#        define __NR_getrandom 4353
-#      endif
-#      if _MIPS_SIM == _MIPS_SIM_NABI32
-#        define __NR_getrandom 6317
-#      endif
-#      if _MIPS_SIM == _MIPS_SIM_ABI64
-#        define __NR_getrandom 5313
-#      endif
-#    elif defined(__arc__)
-#      define __NR_getrandom 278
-#    else
-#      warning "__NR_getrandom unknown for your architecture"
-#    endif
+#if defined __NR_getrandom && __NR_getrandom >= 0
+#  if defined systemd_NR_getrandom
+assert_cc(__NR_getrandom == systemd_NR_getrandom);
+#  endif
+#else
+#  if defined __NR_getrandom
+#    undef __NR_getrandom
 #  endif
+#  if defined systemd_NR_getrandom
+#    define __NR_getrandom systemd_NR_getrandom
+#  endif
+#endif
 
+#if !HAVE_GETRANDOM
 static inline int missing_getrandom(void *buffer, size_t count, unsigned flags) {
 #  ifdef __NR_getrandom
         return syscall(__NR_getrandom, buffer, count, flags);
@@ -133,9 +149,14 @@ static inline int missing_getrandom(void *buffer, size_t count, unsigned flags)
 
 /* ======================================================================= */
 
+/* The syscall has been defined since forever, but the glibc wrapper was missing. */
 #if !HAVE_GETTID
 static inline pid_t missing_gettid(void) {
+#  if defined __NR_gettid && __NR_gettid >= 0
         return (pid_t) syscall(__NR_gettid);
+#  else
+#    error "__NR_gettid not defined"
+#  endif
 }
 
 #  define gettid missing_gettid
@@ -143,27 +164,35 @@ static inline pid_t missing_gettid(void) {
 
 /* ======================================================================= */
 
-#if !HAVE_NAME_TO_HANDLE_AT
+#if defined(__x86_64__)
+#  define systemd_NR_name_to_handle_at 303
+#elif defined(__i386__)
+#  define systemd_NR_name_to_handle_at 341
+#elif defined(__arm__)
+#  define systemd_NR_name_to_handle_at 370
+#elif defined(__powerpc__)
+#  define systemd_NR_name_to_handle_at 345
+#elif defined(__arc__)
+#  define systemd_NR_name_to_handle_at 264
+#else
+#  warning "name_to_handle_at number is not defined"
+#endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_name_to_handle_at && __NR_name_to_handle_at >= 0)
-#    if defined __NR_name_to_handle_at
-#      undef __NR_name_to_handle_at
-#    endif
-#    if defined(__x86_64__)
-#      define __NR_name_to_handle_at 303
-#    elif defined(__i386__)
-#      define __NR_name_to_handle_at 341
-#    elif defined(__arm__)
-#      define __NR_name_to_handle_at 370
-#    elif defined(__powerpc__)
-#      define __NR_name_to_handle_at 345
-#    elif defined(__arc__)
-#      define __NR_name_to_handle_at 264
-#    else
-#      error "__NR_name_to_handle_at is not defined"
-#    endif
+#if defined __NR_name_to_handle_at && __NR_name_to_handle_at >= 0
+#  if defined systemd_NR_name_to_handle_at
+assert_cc(__NR_name_to_handle_at == systemd_NR_name_to_handle_at);
+#  endif
+#else
+#  if defined __NR_name_to_handle_at
+#    undef __NR_name_to_handle_at
+#  endif
+#  if defined systemd_NR_name_to_handle_at
+#    define __NR_name_to_handle_at systemd_NR_name_to_handle_at
 #  endif
+#endif
 
+#if !HAVE_NAME_TO_HANDLE_AT
 struct file_handle {
         unsigned int handle_bytes;
         int handle_type;
@@ -184,23 +213,31 @@ static inline int missing_name_to_handle_at(int fd, const char *name, struct fil
 
 /* ======================================================================= */
 
-#if !HAVE_SETNS
+#if defined(__x86_64__)
+#  define systemd_NR_setns 308
+#elif defined(__i386__)
+#  define systemd_NR_setns 346
+#elif defined(__arc__)
+#  define systemd_NR_setns 268
+#else
+#  warning "setns() syscall number unknown for your architecture"
+#endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_setns && __NR_setns >= 0)
-#    if defined __NR_setns
-#      undef __NR_setns
-#    endif
-#    if defined(__x86_64__)
-#      define __NR_setns 308
-#    elif defined(__i386__)
-#      define __NR_setns 346
-#    elif defined(__arc__)
-#      define __NR_setns 268
-#    else
-#      error "__NR_setns is not defined"
-#    endif
+#if defined __NR_setns && __NR_setns >= 0
+#  if defined systemd_NR_setns
+assert_cc(__NR_setns == systemd_NR_setns);
+#  endif
+#else
+#  if defined __NR_setns
+#    undef __NR_setns
 #  endif
+#  if defined systemd_NR_setns
+#    define __NR_setns systemd_NR_setns
+#  endif
+#endif
 
+#if !HAVE_SETNS
 static inline int missing_setns(int fd, int nstype) {
 #  ifdef __NR_setns
         return syscall(__NR_setns, fd, nstype);
@@ -225,41 +262,49 @@ static inline pid_t raw_getpid(void) {
 
 /* ======================================================================= */
 
-#if !HAVE_RENAMEAT2
+#if defined __x86_64__
+#  define systemd_NR_renameat2 316
+#elif defined __arm__
+#  define systemd_NR_renameat2 382
+#elif defined __aarch64__
+#  define systemd_NR_renameat2 276
+#elif defined _MIPS_SIM
+#  if _MIPS_SIM == _MIPS_SIM_ABI32
+#    define systemd_NR_renameat2 4351
+#  endif
+#  if _MIPS_SIM == _MIPS_SIM_NABI32
+#    define systemd_NR_renameat2 6315
+#  endif
+#  if _MIPS_SIM == _MIPS_SIM_ABI64
+#    define systemd_NR_renameat2 5311
+#  endif
+#elif defined __i386__
+#  define systemd_NR_renameat2 353
+#elif defined __powerpc64__
+#  define systemd_NR_renameat2 357
+#elif defined __s390__ || defined __s390x__
+#  define systemd_NR_renameat2 347
+#elif defined __arc__
+#  define systemd_NR_renameat2 276
+#else
+#  warning "renameat2() syscall number unknown for your architecture"
+#endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_renameat2 && __NR_renameat2 >= 0)
-#    if defined __NR_renameat2
-#      undef __NR_renameat2
-#    endif
-#    if defined __x86_64__
-#      define __NR_renameat2 316
-#    elif defined __arm__
-#      define __NR_renameat2 382
-#    elif defined __aarch64__
-#      define __NR_renameat2 276
-#    elif defined _MIPS_SIM
-#      if _MIPS_SIM == _MIPS_SIM_ABI32
-#        define __NR_renameat2 4351
-#      endif
-#      if _MIPS_SIM == _MIPS_SIM_NABI32
-#        define __NR_renameat2 6315
-#      endif
-#      if _MIPS_SIM == _MIPS_SIM_ABI64
-#        define __NR_renameat2 5311
-#      endif
-#    elif defined __i386__
-#      define __NR_renameat2 353
-#    elif defined __powerpc64__
-#      define __NR_renameat2 357
-#    elif defined __s390__ || defined __s390x__
-#      define __NR_renameat2 347
-#    elif defined __arc__
-#      define __NR_renameat2 276
-#    else
-#      warning "__NR_renameat2 unknown for your architecture"
-#    endif
+#if defined __NR_renameat2 && __NR_renameat2 >= 0
+#  if defined systemd_NR_renameat2
+assert_cc(__NR_renameat2 == systemd_NR_renameat2);
+#  endif
+#else
+#  if defined __NR_renameat2
+#    undef __NR_renameat2
 #  endif
+#  if defined systemd_NR_renameat2
+#    define __NR_renameat2 systemd_NR_renameat2
+#  endif
+#endif
 
+#if !HAVE_RENAMEAT2
 static inline int missing_renameat2(int oldfd, const char *oldname, int newfd, const char *newname, unsigned flags) {
 #  ifdef __NR_renameat2
         return syscall(__NR_renameat2, oldfd, oldname, newfd, newname, flags);
@@ -326,31 +371,39 @@ static inline key_serial_t missing_request_key(const char *type, const char *des
 
 /* ======================================================================= */
 
-#if !HAVE_COPY_FILE_RANGE
+#if defined(__x86_64__)
+#  define systemd_NR_copy_file_range 326
+#elif defined(__i386__)
+#  define systemd_NR_copy_file_range 377
+#elif defined __s390__
+#  define systemd_NR_copy_file_range 375
+#elif defined __arm__
+#  define systemd_NR_copy_file_range 391
+#elif defined __aarch64__
+#  define systemd_NR_copy_file_range 285
+#elif defined __powerpc__
+#  define systemd_NR_copy_file_range 379
+#elif defined __arc__
+#  define systemd_NR_copy_file_range 285
+#else
+#  warning "copy_file_range() syscall number unknown for your architecture"
+#endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_copy_file_range && __NR_copy_file_range >= 0)
-#    if defined __NR_copy_file_range
-#      undef __NR_copy_file_range
-#    endif
-#    if defined(__x86_64__)
-#      define __NR_copy_file_range 326
-#    elif defined(__i386__)
-#      define __NR_copy_file_range 377
-#    elif defined __s390__
-#      define __NR_copy_file_range 375
-#    elif defined __arm__
-#      define __NR_copy_file_range 391
-#    elif defined __aarch64__
-#      define __NR_copy_file_range 285
-#    elif defined __powerpc__
-#      define __NR_copy_file_range 379
-#    elif defined __arc__
-#      define __NR_copy_file_range 285
-#    else
-#      warning "__NR_copy_file_range not defined for your architecture"
-#    endif
+#if defined __NR_copy_file_range && __NR_copy_file_range >= 0
+#  if defined systemd_NR_copy_file_range
+assert_cc(__NR_copy_file_range == systemd_NR_copy_file_range);
 #  endif
+#else
+#  if defined __NR_copy_file_range
+#    undef __NR_copy_file_range
+#  endif
+#  if defined systemd_NR_copy_file_range
+#    define __NR_copy_file_range systemd_NR_copy_file_range
+#  endif
+#endif
 
+#if !HAVE_COPY_FILE_RANGE
 static inline ssize_t missing_copy_file_range(int fd_in, loff_t *off_in,
                                               int fd_out, loff_t *off_out,
                                               size_t len,
@@ -368,31 +421,39 @@ static inline ssize_t missing_copy_file_range(int fd_in, loff_t *off_in,
 
 /* ======================================================================= */
 
-#if !HAVE_BPF
+#if defined __i386__
+#  define systemd_NR_bpf 357
+#elif defined __x86_64__
+#  define systemd_NR_bpf 321
+#elif defined __aarch64__
+#  define systemd_NR_bpf 280
+#elif defined __arm__
+#  define systemd_NR_bpf 386
+#elif defined __sparc__
+#  define systemd_NR_bpf 349
+#elif defined __s390__
+#  define systemd_NR_bpf 351
+#elif defined __tilegx__
+#  define systemd_NR_bpf 280
+#else
+#  warning "bpf() syscall number unknown for your architecture"
+#endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_bpf && __NR_bpf >= 0)
-#    if defined __NR_bpf
-#      undef __NR_bpf
-#    endif
-#    if defined __i386__
-#      define __NR_bpf 357
-#    elif defined __x86_64__
-#      define __NR_bpf 321
-#    elif defined __aarch64__
-#      define __NR_bpf 280
-#    elif defined __arm__
-#      define __NR_bpf 386
-#    elif defined __sparc__
-#      define __NR_bpf 349
-#    elif defined __s390__
-#      define __NR_bpf 351
-#    elif defined __tilegx__
-#      define __NR_bpf 280
-#    else
-#      warning "__NR_bpf not defined for your architecture"
-#    endif
+#if defined __NR_bpf && __NR_bpf >= 0
+#  if defined systemd_NR_bpf
+assert_cc(__NR_bpf == systemd_NR_bpf);
+#  endif
+#else
+#  if defined __NR_bpf
+#    undef __NR_bpf
 #  endif
+#  if defined systemd_NR_bpf
+#    define __NR_bpf systemd_NR_bpf
+#  endif
+#endif
 
+#if !HAVE_BPF
 union bpf_attr;
 
 static inline int missing_bpf(int cmd, union bpf_attr *attr, size_t size) {
@@ -410,69 +471,80 @@ static inline int missing_bpf(int cmd, union bpf_attr *attr, size_t size) {
 /* ======================================================================= */
 
 #ifndef __IGNORE_pkey_mprotect
+#  if defined __i386__
+#    define systemd_NR_pkey_mprotect 380
+#  elif defined __x86_64__
+#    define systemd_NR_pkey_mprotect 329
+#  elif defined __arm__
+#    define systemd_NR_pkey_mprotect 394
+#  elif defined __aarch64__
+#    define systemd_NR_pkey_mprotect 394
+#  elif defined __powerpc__
+#    define systemd_NR_pkey_mprotect 386
+#  elif defined __s390__
+#    define systemd_NR_pkey_mprotect 384
+#  elif defined _MIPS_SIM
+#    if _MIPS_SIM == _MIPS_SIM_ABI32
+#      define systemd_NR_pkey_mprotect 4363
+#    endif
+#    if _MIPS_SIM == _MIPS_SIM_NABI32
+#      define systemd_NR_pkey_mprotect 6327
+#    endif
+#    if _MIPS_SIM == _MIPS_SIM_ABI64
+#      define systemd_NR_pkey_mprotect 5323
+#    endif
+#  else
+#    warning "pkey_mprotect() syscall number unknown for your architecture"
+#  endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_pkey_mprotect && __NR_pkey_mprotect >= 0)
+#  if defined __NR_pkey_mprotect && __NR_pkey_mprotect >= 0
+#    if defined systemd_NR_pkey_mprotect
+assert_cc(__NR_pkey_mprotect == systemd_NR_pkey_mprotect);
+#    endif
+#  else
 #    if defined __NR_pkey_mprotect
 #      undef __NR_pkey_mprotect
 #    endif
-#    if defined __i386__
-#      define __NR_pkey_mprotect 380
-#    elif defined __x86_64__
-#      define __NR_pkey_mprotect 329
-#    elif defined __arm__
-#      define __NR_pkey_mprotect 394
-#    elif defined __aarch64__
-#      define __NR_pkey_mprotect 394
-#    elif defined __powerpc__
-#      define __NR_pkey_mprotect 386
-#    elif defined __s390__
-#      define __NR_pkey_mprotect 384
-#    elif defined _MIPS_SIM
-#      if _MIPS_SIM == _MIPS_SIM_ABI32
-#        define __NR_pkey_mprotect 4363
-#      endif
-#      if _MIPS_SIM == _MIPS_SIM_NABI32
-#        define __NR_pkey_mprotect 6327
-#      endif
-#      if _MIPS_SIM == _MIPS_SIM_ABI64
-#        define __NR_pkey_mprotect 5323
-#      endif
-#    else
-#      warning "__NR_pkey_mprotect not defined for your architecture"
+#    if defined systemd_NR_pkey_mprotect
+#      define __NR_pkey_mprotect systemd_NR_pkey_mprotect
 #    endif
 #  endif
 #endif
 
 /* ======================================================================= */
 
-#if !HAVE_STATX
+#if defined __aarch64__ || defined __arm__
+#  define systemd_NR_statx 397
+#elif defined __alpha__
+#  define systemd_NR_statx 522
+#elif defined __i386__ || defined __powerpc64__
+#  define systemd_NR_statx 383
+#elif defined __sparc__
+#  define systemd_NR_statx 360
+#elif defined __x86_64__
+#  define systemd_NR_statx 332
+#else
+#  warning "statx() syscall number unknown for your architecture"
+#endif
+
 /* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_statx && __NR_statx >= 0)
-#    if defined __NR_statx
-#      undef __NR_statx
-#    endif
-#    if defined __aarch64__ || defined __arm__
-#      define __NR_statx 397
-#    elif defined __alpha__
-#      define __NR_statx 522
-#    elif defined __i386__ || defined __powerpc64__
-#      define __NR_statx 383
-#    elif defined __sparc__
-#      define __NR_statx 360
-#    elif defined __x86_64__
-#      define __NR_statx 332
-#    else
-#      warning "__NR_statx not defined for your architecture"
-#    endif
+#if defined __NR_statx && __NR_statx >= 0
+#  if defined systemd_NR_statx
+assert_cc(__NR_statx == systemd_NR_statx);
+#  endif
+#else
+#  if defined __NR_statx
+#    undef __NR_statx
+#  endif
+#  if defined systemd_NR_statx
+#    define __NR_statx systemd_NR_statx
 #  endif
-
-struct statx;
 #endif
 
-/* This typedef is supposed to be always defined. */
-typedef struct statx struct_statx;
-
 #if !HAVE_STATX
+struct statx;
+
 static inline ssize_t missing_statx(int dfd, const char *filename, unsigned flags, unsigned int mask, struct statx *buffer) {
 #  ifdef __NR_statx
         return syscall(__NR_statx, dfd, filename, flags, mask, buffer);
@@ -481,12 +553,18 @@ static inline ssize_t missing_statx(int dfd, const char *filename, unsigned flag
         return -1;
 #  endif
 }
+#endif
+
+/* This typedef is supposed to be always defined. */
+typedef struct statx struct_statx;
 
+#if !HAVE_STATX
 #  define statx(dfd, filename, flags, mask, buffer) missing_statx(dfd, filename, flags, mask, buffer)
 #endif
 
-#if !HAVE_SET_MEMPOLICY
+/* ======================================================================= */
 
+#if !HAVE_SET_MEMPOLICY
 enum {
         MPOL_DEFAULT,
         MPOL_PREFERRED,
@@ -527,19 +605,28 @@ static inline long missing_get_mempolicy(int *mode, unsigned long *nodemask,
 #  define get_mempolicy missing_get_mempolicy
 #endif
 
-#if !HAVE_PIDFD_SEND_SIGNAL
-/* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_pidfd_send_signal && __NR_pidfd_send_signal >= 0)
-#    if defined __NR_pidfd_send_signal
-#      undef __NR_pidfd_send_signal
-#    endif
+/* ======================================================================= */
+
 /* should be always defined, see kernel 39036cd2727395c3369b1051005da74059a85317 */
-#    if defined(__alpha__)
-#      define __NR_pidfd_send_signal 534
-#    else
-#      define __NR_pidfd_send_signal 424
-#    endif
+#if defined(__alpha__)
+#  define systemd_NR_pidfd_send_signal 534
+#else
+#  define systemd_NR_pidfd_send_signal 424
+#endif
+
+/* may be (invalid) negative number due to libseccomp, see PR 13319 */
+#if defined __NR_pidfd_send_signal && __NR_pidfd_send_signal >= 0
+#  if defined systemd_NR_pidfd_send_signal
+assert_cc(__NR_pidfd_send_signal == systemd_NR_pidfd_send_signal);
 #  endif
+#else
+#  if defined __NR_pidfd_send_signal
+#    undef __NR_pidfd_send_signal
+#  endif
+#  define __NR_pidfd_send_signal systemd_NR_pidfd_send_signal
+#endif
+
+#if !HAVE_PIDFD_SEND_SIGNAL
 static inline int missing_pidfd_send_signal(int fd, int sig, siginfo_t *info, unsigned flags) {
 #  ifdef __NR_pidfd_open
         return syscall(__NR_pidfd_send_signal, fd, sig, info, flags);
@@ -552,19 +639,26 @@ static inline int missing_pidfd_send_signal(int fd, int sig, siginfo_t *info, un
 #  define pidfd_send_signal missing_pidfd_send_signal
 #endif
 
-#if !HAVE_PIDFD_OPEN
-/* may be (invalid) negative number due to libseccomp, see PR 13319 */
-#  if ! (defined __NR_pidfd_open && __NR_pidfd_open >= 0)
-#    if defined __NR_pidfd_open
-#      undef __NR_pidfd_open
-#    endif
 /* should be always defined, see kernel 7615d9e1780e26e0178c93c55b73309a5dc093d7 */
-#    if defined(__alpha__)
-#      define __NR_pidfd_open 544
-#    else
-#      define __NR_pidfd_open 434
-#    endif
+#if defined(__alpha__)
+#  define systemd_NR_pidfd_open 544
+#else
+#  define systemd_NR_pidfd_open 434
+#endif
+
+/* may be (invalid) negative number due to libseccomp, see PR 13319 */
+#if defined __NR_pidfd_open && __NR_pidfd_open >= 0
+#  if defined systemd_NR_pidfd_open
+assert_cc(__NR_pidfd_open == systemd_NR_pidfd_open);
 #  endif
+#else
+#  if defined __NR_pidfd_open
+#    undef __NR_pidfd_open
+#  endif
+#  define __NR_pidfd_open systemd_NR_pidfd_open
+#endif
+
+#if !HAVE_PIDFD_OPEN
 static inline int missing_pidfd_open(pid_t pid, unsigned flags) {
 #  ifdef __NR_pidfd_open
         return syscall(__NR_pidfd_open, pid, flags);
@@ -577,9 +671,15 @@ static inline int missing_pidfd_open(pid_t pid, unsigned flags) {
 #  define pidfd_open missing_pidfd_open
 #endif
 
+/* ======================================================================= */
+
 #if !HAVE_RT_SIGQUEUEINFO
 static inline int missing_rt_sigqueueinfo(pid_t tgid, int sig, siginfo_t *info) {
+#  if defined __NR_rt_sigqueueinfo && __NR_rt_sigqueueinfo >= 0
         return syscall(__NR_rt_sigqueueinfo, tgid, sig, info);
+#  else
+#    error "__NR_rt_sigqueueinfo not defined"
+#  endif
 }
 
 #  define rt_sigqueueinfo missing_rt_sigqueueinfo