<bits/syscall.h>: Use an arch-independent system call list on Linux

This commit changes the way the list of SYS_* system call macros is
created on Linux.  glibc now contains a list of all known system
calls, and the generated <bits/syscall.h> file defines the SYS_ macro
only if the correspnding __NR_ macro is defined by the kernel headers.

As a result, glibc does not have to be rebuilt to pick up system calls
if the glibc sources already know about them.  This means that glibc
can be built with older kernel headers, and if the installed kernel
headers are upgraded afterwards, additional SYS_ macros become
available as long as glibc has a record for those system calls.

1 files changed, 43 insertions, 68 deletions

diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 9d6a2de870..e571fe2efe 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -52,75 +52,50 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
 tests += tst-clone tst-clone2 tst-clone3 tst-fanotify tst-personality \
 	 tst-quota tst-sync_file_range test-errno-linux
 
-# Generate the list of SYS_* macros for the system calls (__NR_* macros).
-
-# If there is more than one syscall list for different architecture
-# variants, the CPU/Makefile defines abi-variants to be a list of names
-# for those variants (e.g. 32 64), and, for each variant, defines
-# abi-$(variant)-options to be compiler options to cause <asm/unistd.h>
-# to define the desired list of syscalls and abi-$(variant)-condition to
-# be the condition for those options to use in a C #if condition.
-# abi-includes may be defined to a list of headers to include
-# in the generated header, if the default does not suffice.
-#
-# The generated header is compiled with `-ffreestanding' to avoid any
-# circular dependencies against the installed implementation headers.
-# Such a dependency would require the implementation header to be
-# installed before the generated header could be built (See bug 15711).
-# In current practice the generated header dependencies do not include
-# any of the implementation headers removed by the use of `-ffreestanding'.
-
-$(objpfx)bits/syscall%h $(objpfx)bits/syscall%d: ../sysdeps/unix/sysv/linux/sys/syscall.h
+# Generate the list of SYS_* macros for the system calls (__NR_*
+# macros).  The file syscall-names.list contains all possible system
+# call names, and the generated header file produces SYS_* macros for
+# the __NR_* macros which are actually defined.
+
+generated += bits/syscall.h
+$(objpfx)bits/syscall.h: \
+  ../sysdeps/unix/sysv/linux/gen-syscall-h.awk \
+  ../sysdeps/unix/sysv/linux/syscall-names.list
 	$(make-target-directory)
-	{ \
-	 echo '/* Generated at libc build time from kernel syscall list.  */';\
-	 echo ''; \
-	 echo '#ifndef _SYSCALL_H'; \
-	 echo '# error "Never use <bits/syscall.h> directly; include <sys/syscall.h> instead."'; \
-	 echo '#endif'; \
-	 echo ''; \
-	 $(foreach h,$(abi-includes), echo '#include <$(h)>';) \
-	 echo ''; \
-	 $(if $(abi-variants), \
-	 $(foreach v,$(abi-variants),\
-	 $(CC) -ffreestanding -E -MD -MP -MF $(@:.h=.d)-t$(v) -MT '$(@:.d=.h) $(@:.h=.d)' \
-	       -x c $(sysincludes) $< $(abi-$(v)-options) \
-	       -D_LIBC -dM | \
-	 sed -n 's@^#define __NR_\([^ ]*\) .*$$@#define SYS_\1 __NR_\1@p' | \
-	 LC_ALL=C sort > $(@:.d=.h).new$(v); \
-	 $(if $(abi-$(v)-condition),\
-	 echo '#if $(abi-$(v)-condition)';) \
-	 cat $(@:.d=.h).new$(v); \
-	 $(if $(abi-$(v)-condition),echo '#endif';) \
-	 rm -f $(@:.d=.h).new$(v); \
-	 ), \
-	 $(CC) -ffreestanding -E -MD -MP -MF $(@:.h=.d)-t$(v) -MT '$(@:.d=.h) $(@:.h=.d)' \
-	       -x c $(sysincludes) $< \
-	       -D_LIBC -dM | \
-	 sed -n 's@^#define __NR_\([^ ]*\) .*$$@#define SYS_\1 __NR_\1@p' | \
-	 LC_ALL=C sort;) \
-	} > $(@:.d=.h).new
-	mv -f $(@:.d=.h).new $(@:.d=.h)
-ifdef abi-variants
-ifneq (,$(objpfx))
-	sed $(sed-remove-objpfx) \
-	 $(foreach v,$(abi-variants),$(@:.h=.d)-t$(v)) > $(@:.h=.d)-t3
-else
-	cat $(foreach v,$(abi-variants),$(@:.h=.d)-t$(v)) \
-	 > $(@:.h=.d)-t3
-endif
-	rm -f $(foreach v,$(abi-variants),$(@:.h=.d)-t$(v))
-	mv -f $(@:.h=.d)-t3 $(@:.h=.d)
-else
-	mv -f $(@:.h=.d)-t $(@:.h=.d)
-endif
-
-ifndef no_deps
-# Get the generated list of dependencies (probably /usr/include/asm/unistd.h).
--include $(objpfx)bits/syscall.d
-endif
-generated += bits/syscall.h bits/syscall.d
-endif
+	LC_ALL=C $(AWK) -f $^ > $@-tmp
+	$(move-if-change) $@-tmp $@
+before-compile += $(objpfx)bits/syscall.h
+
+# All macros defined by <sys/syscall.h>.  Include <bits/syscall.h>
+# explicitly because <sys/sycall.h> skips it if _LIBC is defined.
+$(objpfx)tst-syscall-list-macros.list: \
+  $(objpfx)bits/syscall.h ../sysdeps/unix/sysv/linux/sys/syscall.h
+	printf '#include <linux/version.h>\n\
+#include <sys/syscall.h>\n#include <bits/syscall.h>\n' | \
+	  $(CC) -E -o $@-tmp $(CFLAGS) $(CPPFLAGS) -x c - -dM
+	$(move-if-change) $@-tmp $@
+
+# __NR_* system call names.  Used by the test below.
+$(objpfx)tst-syscall-list-nr.list: \
+  ../sysdeps/unix/sysv/linux/filter-nr-syscalls.awk \
+  $(objpfx)tst-syscall-list-macros.list
+	LC_ALL=C $(AWK) -f $^ > $@-tmp
+	$(move-if-change) $@-tmp $@
+
+# SYS_* system call names.  Used by the test below.
+$(objpfx)tst-syscall-list-sys.list: $(objpfx)tst-syscall-list-macros.list
+	LC_ALL=C $(AWK) '/^#define SYS_/ { print substr($$2, 5) }' $< > $@-tmp
+	$(move-if-change) $@-tmp $@
+
+tests-special += $(objpfx)tst-syscall-list.out
+$(objpfx)tst-syscall-list.out: \
+  ../sysdeps/unix/sysv/linux/tst-syscall-list.sh \
+  $(objpfx)tst-syscall-list-macros.list \
+  $(objpfx)tst-syscall-list-nr.list \
+  $(objpfx)tst-syscall-list-sys.list
+	$(BASH) $^ $(AWK) > $@; $(evaluate-test)
+
+endif # $(subdir) == misc
 
 ifeq ($(subdir),time)
 sysdep_headers += sys/timex.h bits/timex.h