Add build option to disable usage of scv on powerpc

Commit 68ab82f56690ada86ac1e0c46bad06ba189a10ef added support for the scv
syscall ABI on powerpc.  Since then systems that have kernel and processor
support started using scv.  However adding the proper support for a new syscall
ABI requires changes to several other projects (e.g. qemu, valgrind, strace,
kernel), which are gradually receiving support.

Meanwhile, having a way to disable scv on glibc at build time can be useful for
distros that may encounter conflicts with projects that still do not support the
scv ABI, buying time until proper support is added.

This commit adds a --disable-scv option that disables scv support and uses sc
for all syscalls, like before commit 68ab82f56690ada86ac1e0c46bad06ba189a10ef.

Reviewed-by: Raphael M Zinsly <rzinsly@linux.ibm.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/configure b/configure
index a86bcf7..9619c10 100755
--- a/configure
+++ b/configure
@@ -791,6 +791,7 @@ enable_pt_chown
 enable_tunables
 enable_mathvec
 enable_cet
+enable_scv
 with_cpu
 '
       ac_precious_vars='build_alias
@@ -1463,6 +1464,8 @@ Optional Features:
                           depends on architecture]
   --enable-cet            enable Intel Control-flow Enforcement Technology
                           (CET), x86 only
+  --disable-scv           syscalls will not use scv instruction, even if the
+                          kernel supports it, powerpc only
 
 Optional Packages:
   --with-PACKAGE[=ARG]    use PACKAGE [ARG=yes]
@@ -3814,6 +3817,19 @@ else
 fi
 
 
+# Check whether --enable-scv was given.
+if test "${enable_scv+set}" = set; then :
+  enableval=$enable_scv; use_scv=$enableval
+else
+  use_scv=yes
+fi
+
+
+if test "$use_scv" != "no"; then :
+  $as_echo "#define USE_PPC_SCV 1" >>confdefs.h
+
+fi
+
 # We keep the original values in `$config_*' and never modify them, so we
 # can write them unchanged into config.make.  Everything else uses
 # $machine, $vendor, and $os, and changes them whenever convenient.