[PATCH] csu: Fix static when PIE is enabled but static PIE is not supported (BZ #29575)

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On architectures where static PIE is not supported, both libc and
static binaries are built still with -fPIE and -DPIC.  It leads to
wrong code for some architectures (for instance sparc).

This patch only enables -DPIC for .o files iff static-pie is also
supported.  Since the same rule is used for both libc.a objects and
installed binaries, the -fno-pie is added if static-pie is not
supported (with a strategy similar to how stack protector is
disabled for some architectures).

Checked on x86_64-linux-gnu (with and without --disable-static-pie)
and I also checked on sparc64-linux-gnu to verify that static binaries
are not broken and both binaries and tests continue to be built
for PIE.
---
 Makeconfig            | 15 +++++++++++++++
 Makerules             |  7 +++++++
 csu/Makefile          |  4 ++++
 stdio-common/Makefile |  4 ++--
 4 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 842f49eb58..4b0d9003cd 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -404,6 +404,9 @@ else
 # for PIE to support exception.
 static-pie-ldflag = -Wl,-pie,--no-dynamic-linker,--eh-frame-hdr,-z,text
 endif # have-static-pie
+else
+no-static-pie = $(no-pie-ccflag)
+no-pic-flag = -UPIC
 endif # enable-static-pie
 endif # build-pie-default
 
@@ -901,6 +904,18 @@ define elide-stack-protector
 $(if $(filter $(@F),$(patsubst %,%$(1),$(2))), $(no-stack-protector))
 endef
 
+# If static-pie is not supported, add the compiler option to avoid building it
+# for pie and to remove the PIC define.  The first argument is the extension
+# (.o, .os, .oS) and the second is a list of routines that this path should be
+# applied to.
+define elide-pie
+$(if $(filter $(@F),$(patsubst %,%$(1),$(2))), $(no-static-pie))
+endef
+# Smae as elide-pie, but remove the PIC flag.
+define elide-pic-flag
+$(if $(filter $(@F),$(patsubst %,%$(1),$(2))), $(no-pic-flag))
+endef
+
 # The program that makes Emacs-style TAGS files.
 ETAGS	:= etags
 
diff --git a/Makerules b/Makerules
index 09c0cf8357..0fcaf565eb 100644
--- a/Makerules
+++ b/Makerules
@@ -1239,6 +1239,13 @@ tests += $(foreach t,$(tests-time64),$(t))
 xtests += $(foreach t,$(xtests-time64),$(t))
 endif
 
+# Disable static-pie for libc.a if target does not support it.
+CFLAGS-.o += $(call elide-pie,.o,$(routines))
+CFLAGS-.op += $(call elide-pie,.op,$(routines))
+# And also remove the PIC flag.
+CPPFLAGS-.o += $(call elide-pic-flag,.o,$(routines))
+CPPFLAGS-.op += $(call elide-pic-flag,.op,$(routines))
+
 # The only difference between MODULE_NAME=testsuite and MODULE_NAME=nonlib is
 # that almost all internal declarations from config.h, libc-symbols.h, and
 # include/*.h are not available to 'testsuite' code, but are to 'nonlib' code.
diff --git a/csu/Makefile b/csu/Makefile
index f71a5eb6c6..62a819608f 100644
--- a/csu/Makefile
+++ b/csu/Makefile
@@ -66,6 +66,10 @@ CFLAGS-.os += $(call elide-stack-protector,.os,$(filter-out \
 						 $(ssp-safe.os), \
 						 $(routines) $(extra-no-ssp)))
 
+# Remove PIC flag for init objects.
+CPPFLAGS-.o += $(call elide-pic-flag,.o,$(basename $(extra-objs)))
+CPPFLAGS-.op += $(call elide-pic-flag,.op,$(basename $(extra-objs)))
+
 ifeq (yes,$(build-shared))
 extra-objs += S$(start-installed-name) gmon-start.os
 ifneq ($(start-installed-name),$(static-start-installed-name))
diff --git a/stdio-common/Makefile b/stdio-common/Makefile
index 9c98c02884..6eee9ba73c 100644
--- a/stdio-common/Makefile
+++ b/stdio-common/Makefile
@@ -265,7 +265,7 @@ $(objpfx)errlist-data-aux-shared.S: errlist-data-gen.c
 
 $(objpfx)errlist-data-aux.S: errlist-data-gen.c
 	$(make-target-directory)
-	$(compile-command.c) $(pie-default) $(no-stack-protector) -S
+	$(compile-command.c) $(pic-cppflags) $(pic-ccflag) $(no-stack-protector) -S
 
 ifndef no_deps
 -include $(objpfx)errlist-data-aux.S.d $(objpfx)errlist-data-aux-shared.S.d
@@ -280,7 +280,7 @@ $(objpfx)siglist-aux-shared.S: siglist-gen.c
 
 $(objpfx)siglist-aux.S: siglist-gen.c
 	$(make-target-directory)
-	$(compile-command.c) $(pie-default) $(no-stack-protector) -S
+	$(compile-command.c) $(pic-cppflags) $(pic-ccflag) $(no-stack-protector) -S
 
 ifndef no_deps
 -include $(objpfx)siglist-aux.S.d $(objpfx)siglist-aux-shared.S.d
-- 
2.34.1