[PATCH v13 2/7] linux: Introduce INTERNAL_VSYSCALL

[Evan Green]

Add an INTERNAL_VSYSCALL() macro that makes a vDSO call, falling back to
a regular syscall, but without setting errno. Instead, the return value
is plumbed straight out of the macro.

Signed-off-by: Evan Green <evan@rivosinc.com>
---

Changes in v13:
 - Remove label, use -ENOSYS and return value directly (Florian)

Changes in v10:
 - Introduced INTERNAL_VSYSCALL patch

 sysdeps/unix/sysv/linux/sysdep-vdso.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/sysdeps/unix/sysv/linux/sysdep-vdso.h b/sysdeps/unix/sysv/linux/sysdep-vdso.h
index 189319ad98..2f53ada6e5 100644
--- a/sysdeps/unix/sysv/linux/sysdep-vdso.h
+++ b/sysdeps/unix/sysv/linux/sysdep-vdso.h
@@ -53,4 +53,16 @@
     sc_ret;								      \
   })
 
+#define INTERNAL_VSYSCALL(name, nr, args...)				      \
+  ({									      \
+    long int sc_ret = -ENOSYS;						      \
+									      \
+    __typeof (GLRO(dl_vdso_##name)) vdsop = GLRO(dl_vdso_##name);	      \
+    if (vdsop != NULL)							      \
+	sc_ret = INTERNAL_VSYSCALL_CALL (vdsop, nr, ##args);		      \
+    if (sc_ret == -ENOSYS)						      \
+	sc_ret = INTERNAL_SYSCALL_CALL (name, ##args);			      \
+    sc_ret;								      \
+  })
+
 #endif /* SYSDEP_VDSO_LINUX_H  */
-- 
2.34.1