[2/2] ARC: Add new compiler define to indicate @pcl relocation support

Submitted by Andrew Burgess on July 28, 2016, 6:20 p.m.


Message ID 1469730034-8068-1-git-send-email-andrew.burgess@embecosm.com
State New
Headers show

Commit Message

Andrew Burgess July 28, 2016, 6:20 p.m.
Some old versions of binutils did not support @pcl relocations.  This
commit adds a new flag to the uClibc configuration system that detects
if the toolchain supports @pcl relocations or not.

If this relocation is supported then the define ARC_HAS_AT_PCL_RELOC
will be passed to the compiler, which is then used in the arc ldso to
choose between generating old or new style code.

This commit addresses and issue that was worked around in commit
181d410ad00cddd1d6c9f4835e129136b74c5187 (ARC: Conditionalise certain
relocations as provided by TLS tools only).  In this commit the choice
between old or new style relocations was made based on whether uClibc
was configured with native threads or not.  The problem is that a user
of a new toolchain might choose to configure without native threads.
 Rules.mak                  | 2 ++
 ldso/ldso/arc/dl-startup.h | 2 +-
 ldso/ldso/arc/dl-sysdep.h  | 4 ++++
 3 files changed, 7 insertions(+), 1 deletion(-)

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diff --git a/Rules.mak b/Rules.mak
index 3c80016..04ff02f 100644
--- a/Rules.mak
+++ b/Rules.mak
@@ -507,9 +507,11 @@  ifeq ($(TARGET_ARCH),c6x)
 ifeq ($(TARGET_ARCH),arc)
+	ARC_HAS_AT_PCL_RELOC:=$(shell echo -e "\t.text\n\tadd r0,pcl,_symbol@pcl" | $(CC) -c -x assembler -o /dev/null -  2> /dev/null && echo -n y || echo -n n)
 	CPU_CFLAGS-y += -mlock -mswape
 	CPU_CFLAGS-$(CONFIG_ARC_CPU_HS) += -mcpu=archs
 	CPU_LDFLAGS-y += $(CPU_CFLAGS) -marclinux
diff --git a/ldso/ldso/arc/dl-startup.h b/ldso/ldso/arc/dl-startup.h
index ef89b53..80ffd79 100644
--- a/ldso/ldso/arc/dl-startup.h
+++ b/ldso/ldso/arc/dl-startup.h
@@ -34,7 +34,7 @@  __asm__(
     "   ; skip the extra args calc by dl_start()                \n"
     "   ld_s    r1, [sp]       ; orig argc from aux-vec Tbl     \n"
     "   ld      r12, [pcl, _dl_skip_args@pcl]                   \n"
     "   add     r2, pcl, _dl_fini@pcl       ; finalizer         \n"
diff --git a/ldso/ldso/arc/dl-sysdep.h b/ldso/ldso/arc/dl-sysdep.h
index caece99..27463f0 100644
--- a/ldso/ldso/arc/dl-sysdep.h
+++ b/ldso/ldso/arc/dl-sysdep.h
@@ -154,7 +154,11 @@  static __always_inline Elf32_Addr elf_machine_load_address(void)
 	Elf32_Addr addr, tmp;
 	__asm__ (
         "ld  %1, [pcl, _dl_start@gotpc] ;build addr of _dl_start   \n"
+        "add %0, pcl, _dl_start@pcl     ;runtime addr of _dl_start \n"
         "add %0, pcl, _dl_start-.+(.&2) ;runtime addr of _dl_start \n"
+#endif /* ARC_HAS_AT_PCL_RELOC */
         "sub %0, %0, %1                 ;delta                     \n"
          : "=&r" (addr), "=r"(tmp)