@@ -35,15 +35,59 @@
* (src/internal/syscall_ret.c) and glibc (sysdeps/unix/sysv/linux/sysdep.h)
*/
-static __inline__ __attribute__((unused, always_inline))
-long __sysret(unsigned long ret)
-{
- if (ret >= (unsigned long)-MAX_ERRNO) {
- SET_ERRNO(-(long)ret);
- return -1;
- }
- return ret;
-}
+/*
+ * Whether 'type' is a signed type or an unsigned type. Supports scalar types,
+ * bool and also pointer types. (from include/linux/compiler.h)
+ */
+#define __is_signed_type(type) (((type)(-1)) < (type)1)
+
+/* __auto_type is used instead of __typeof__ to workaround the build error
+ * 'error: assignment of read-only variable' when the argument has 'const' in
+ * the type, but __auto_type is a new feature from newer gcc version and it
+ * only works with 'const' from gcc 11.0 (__GXX_ABI_VERSION = 1016)
+ * https://gcc.gnu.org/legacy-ml/gcc-patches/2013-11/msg01378.html
+ */
+
+#if __GXX_ABI_VERSION >= 1016
+#define __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT
+#endif
+
+#ifdef __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT
+#define __sysret(arg) \
+({ \
+ __auto_type __ret = (arg); \
+ if (__is_signed_type(__typeof__(arg))) { \
+ if ((long)__ret < 0) { \
+ SET_ERRNO(-(long)__ret); \
+ __ret = (__typeof__(arg))(-1L); \
+ } \
+ } else { \
+ if ((unsigned long)__ret >= (unsigned long)-MAX_ERRNO) { \
+ SET_ERRNO(-(long)__ret); \
+ __ret = (__typeof__(arg))(-1L); \
+ } \
+ } \
+ __ret; \
+})
+
+#else /* ! __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT */
+#define __sysret(arg) \
+({ \
+ long __ret = (long)(arg); \
+ if (__is_signed_type(__typeof__(arg))) { \
+ if (__ret < 0) { \
+ SET_ERRNO(-__ret); \
+ __ret = -1L; \
+ } \
+ } else { \
+ if ((unsigned long)__ret >= (unsigned long)-MAX_ERRNO) { \
+ SET_ERRNO(-__ret); \
+ __ret = -1L; \
+ } \
+ } \
+ (__typeof__(arg))__ret; \
+})
+#endif /* ! __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT */
/* Functions in this file only describe syscalls. They're declared static so
* that the compiler usually decides to inline them while still being allowed
@@ -94,7 +138,7 @@ void *sbrk(intptr_t inc)
if (ret && sys_brk(ret + inc) == ret + inc)
return ret + inc;
- return (void *)__sysret(-ENOMEM);
+ return __sysret((void *)-ENOMEM);
}
@@ -682,7 +726,7 @@ void *sys_mmap(void *addr, size_t length, int prot, int flags, int fd,
static __attribute__((unused))
void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
{
- return (void *)__sysret((unsigned long)sys_mmap(addr, length, prot, flags, fd, offset));
+ return __sysret(sys_mmap(addr, length, prot, flags, fd, offset));
}
static __attribute__((unused))
As reported and suggested by Willy, the inline __sysret() helper introduces three types of conversions and increases the size: (1) the "unsigned long" argument to __sysret() forces a sign extension from all sys_* functions that used to return 'int' (2) the comparison with the error range now has to be performed on a 'unsigned long' instead of an 'int' (3) the return value from __sysret() is a 'long' (note, a signed long) which then has to be turned back to an 'int' before being returned by the caller to satisfy the caller's prototype. To fix up this, firstly, let's use macro instead of inline function to preserves the input type and avoids these useless conversions (1), (3). Secondly, comparison to -MAX_ERRNO inflicts on all integer returns where we could previously keep a simple sign comparison, let's use a new is_signed_type() macro from include/linux/compiler.h to limit the comparision to -MAX_ERRNO (2) only on demand and preserves a simple sign comparision for most of the cases as before. Thirdly, fix up the following warning by an explicit conversion and let __sysret() be able to accept the (void *) type of argument: sysroot/powerpc/include/sys.h: In function 'sbrk': sysroot/powerpc/include/sys.h:104:16: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 104 | return (void *)__sysret(-ENOMEM); Fourthly, to further workaround the argument type with 'const', must use __auto_type in a new enough version or use 'long' as before. Here reports the size testing result of nolibc-test with gcc 13.2.0: before: // ppc64le with powerpc64-linux-gcc $ size nolibc-test text data bss dec hex filename 28004 8 80 28092 6dbc nolibc-test // mips with mips64-linux-gcc (CFLAGS="-mabi=32 -EL") $ size nolibc-test text data bss dec hex filename 23164 64 64 23292 5afc nolibc-test after: // ppc64le with powerpc64-linux-gcc $ size nolibc-test text data bss dec hex filename 27828 8 80 27916 6d0c nolibc-test // mips with mips64-linux-gcc (CFLAGS="-mabi=32 -EL") $ size nolibc-test text data bss dec hex filename 22924 64 64 23052 5a0c nolibc-test Suggested-by: Willy Tarreau <w@1wt.eu> Link: https://lore.kernel.org/lkml/20230806095846.GB10627@1wt.eu/ Link: https://lore.kernel.org/lkml/20230806134348.GA19145@1wt.eu/ Signed-off-by: Zhangjin Wu <falcon@tinylab.org> --- Hi, Willy v4 rebases on latest 20230806-for-6.6-1 and fixes up a warning reported by the new -Wall -Wextra options. Changes from v3 --> v4: * fix up a new warning about 'ret < 0' when the input arg type is (void *) Changes from v2 --> v3: * define a __GXX_HAS_AUTO_TYPE_WITH_CONST_SUPPORT for gcc >= 11.0 (ABI_VERSION >= 1016) * split __sysret() to two versions by the macro instead of a mixed unified and unreadable version * use shorter __ret instead of __sysret_arg Changes from v1 --> v2: * fix up argument with 'const' in the type * support "void *" argument v2: https://lore.kernel.org/lkml/95fe3e732f455fab653fe1427118d905e4d04257.1691339836.git.falcon@tinylab.org/ v1: https://lore.kernel.org/lkml/20230806131921.52453-1-falcon@tinylab.org/ --- tools/include/nolibc/sys.h | 66 +++++++++++++++++++++++++++++++------- 1 file changed, 55 insertions(+), 11 deletions(-)