Merge tag 'arc-4.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel…

…/git/vgupta/arc

Vineet writes:
   "ARC updates for 4.19-rc8
    - Fix clone syscall to update Thread pointer register
    - Make/build updates (needed for AGL/OE builds)   [Alexey]
    - Typo fix [Colin Ian King]"

* tag 'arc-4.19-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: clone syscall to setp r25 as thread pointer
  ARC: build: Don't set CROSS_COMPILE in arch's Makefile
  ARC: fix spelling mistake "entires" -> "entries"
  ARC: build: Get rid of toolchain check
  ARCv2: build: use mcpu=hs38 iso generic mcpu=archs

arch/arc/Kconfig

@@ -149,7 +149,7 @@ config ARC_CPU_770
 	  Support for ARC770 core introduced with Rel 4.10 (Summer 2011)
 	  This core has a bunch of cool new features:
 	  -MMU-v3: Variable Page Sz (4k, 8k, 16k), bigger J-TLB (128x4)
-                   Shared Address Spaces (for sharing TLB entires in MMU)
+                   Shared Address Spaces (for sharing TLB entries in MMU)
 	  -Caches: New Prog Model, Region Flush
 	  -Insns: endian swap, load-locked/store-conditional, time-stamp-ctr
 

arch/arc/Makefile

@@ -6,33 +6,11 @@
 # published by the Free Software Foundation.
 #
 
-ifeq ($(CROSS_COMPILE),)
-ifndef CONFIG_CPU_BIG_ENDIAN
-CROSS_COMPILE := arc-linux-
-else
-CROSS_COMPILE := arceb-linux-
-endif
-endif
-
 KBUILD_DEFCONFIG := nsim_700_defconfig
 
 cflags-y	+= -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__
 cflags-$(CONFIG_ISA_ARCOMPACT)	+= -mA7
-cflags-$(CONFIG_ISA_ARCV2)	+= -mcpu=archs
-
-is_700 = $(shell $(CC) -dM -E - < /dev/null | grep -q "ARC700" && echo 1 || echo 0)
-
-ifdef CONFIG_ISA_ARCOMPACT
-ifeq ($(is_700), 0)
-    $(error Toolchain not configured for ARCompact builds)
-endif
-endif
-
-ifdef CONFIG_ISA_ARCV2
-ifeq ($(is_700), 1)
-    $(error Toolchain not configured for ARCv2 builds)
-endif
-endif
+cflags-$(CONFIG_ISA_ARCV2)	+= -mcpu=hs38
 
 ifdef CONFIG_ARC_CURR_IN_REG
 # For a global register defintion, make sure it gets passed to every file
@@ -79,7 +57,7 @@ cflags-$(disable_small_data)		+= -mno-sdata -fcall-used-gp
 cflags-$(CONFIG_CPU_BIG_ENDIAN)		+= -mbig-endian
 ldflags-$(CONFIG_CPU_BIG_ENDIAN)	+= -EB
 
-LIBGCC	:= $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
+LIBGCC	= $(shell $(CC) $(cflags-y) --print-libgcc-file-name)
 
 # Modules with short calls might break for calls into builtin-kernel
 KBUILD_CFLAGS_MODULE	+= -mlong-calls -mno-millicode

arch/arc/kernel/process.c

@@ -241,6 +241,26 @@ int copy_thread(unsigned long clone_flags,
 		task_thread_info(current)->thr_ptr;
 	}
 
+
+	/*
+	 * setup usermode thread pointer #1:
+	 * when child is picked by scheduler, __switch_to() uses @c_callee to
+	 * populate usermode callee regs: this works (despite being in a kernel
+	 * function) since special return path for child @ret_from_fork()
+	 * ensures those regs are not clobbered all the way to RTIE to usermode
+	 */
+	c_callee->r25 = task_thread_info(p)->thr_ptr;
+
+#ifdef CONFIG_ARC_CURR_IN_REG
+	/*
+	 * setup usermode thread pointer #2:
+	 * however for this special use of r25 in kernel, __switch_to() sets
+	 * r25 for kernel needs and only in the final return path is usermode
+	 * r25 setup, from pt_regs->user_r25. So set that up as well
+	 */
+	c_regs->user_r25 = c_callee->r25;
+#endif
+
 	return 0;
 }