Merge tag 'llvmlinux-for-v3.15' of git://git.linuxfoundation.org/llvmlinux/kernel

Pull llvm patches from Behan Webster:
 "These are some initial updates to support compiling the kernel with
  clang.

  These patches have been through the proper reviews to the best of my
  ability, and have been soaking in linux-next for a few weeks.  These
  patches by themselves still do not completely allow clang to be used
  with the kernel code, but lay the foundation for other patches which
  are still under review.

  Several other of the LLVMLinux patches have been already added via
  maintainer trees"

* tag 'llvmlinux-for-v3.15' of git://git.linuxfoundation.org/llvmlinux/kernel:
  x86: LLVMLinux: Fix "incomplete type const struct x86cpu_device_id"
  x86 kbuild: LLVMLinux: More cc-options added for clang
  x86, acpi: LLVMLinux: Remove nested functions from Thinkpad ACPI
  LLVMLinux: Add support for clang to compiler.h and new compiler-clang.h
  LLVMLinux: Remove warning about returning an uninitialized variable
  kbuild: LLVMLinux: Fix LINUX_COMPILER definition script for compilation with clang
  Documentation: LLVMLinux: Update Documentation/dontdiff
  kbuild: LLVMLinux: Adapt warnings for compilation with clang
  kbuild: LLVMLinux: Add Kbuild support for building kernel with Clang

diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index b89a739a32761db0f9100395fd6426352ad9167c..9de9813d0ec5df101a48428d40cfc9b9d2df6142 100644 (file)
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -1,5 +1,6 @@
 *.a
 *.aux
+*.bc
 *.bin
 *.bz2
 *.cis
@@ -21,6 +22,7 @@
 *.i
 *.jpeg
 *.ko
+*.ll
 *.log
 *.lst
 *.lzma
@@ -35,6 +37,7 @@
 *.out
 *.patch
 *.pdf
+*.plist
 *.png
 *.pot
 *.ps

diff --git a/Makefile b/Makefile
index cf3e07516a043192576af45ab07fc3ee1bfdcaed..10812e495e8df7e3fcbf976e3dfd59dcee3a22a2 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -248,6 +248,11 @@ HOSTCXX      = g++
 HOSTCFLAGS   = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer
 HOSTCXXFLAGS = -O2
 
+ifeq ($(shell $(HOSTCC) -v 2>&1 | grep -c "clang version"), 1)
+HOSTCFLAGS  += -Wno-unused-value -Wno-unused-parameter \
+               -Wno-missing-field-initializers -fno-delete-null-pointer-checks
+endif
+
 # Decide whether to build built-in, modular, or both.
 # Normally, just do built-in.
 
@@ -324,6 +329,14 @@ endif
 
 export quiet Q KBUILD_VERBOSE
 
+ifneq ($(CC),)
+ifeq ($(shell $(CC) -v 2>&1 | grep -c "clang version"), 1)
+COMPILER := clang
+else
+COMPILER := gcc
+endif
+export COMPILER
+endif
 
 # Look for make include files relative to root of kernel src
 MAKEFLAGS += --include-dir=$(srctree)
@@ -383,7 +396,7 @@ KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
                   -fno-strict-aliasing -fno-common \
                   -Werror-implicit-function-declaration \
                   -Wno-format-security \
-                  -fno-delete-null-pointer-checks
+                  $(call cc-option,-fno-delete-null-pointer-checks,)
 KBUILD_AFLAGS_KERNEL :=
 KBUILD_CFLAGS_KERNEL :=
 KBUILD_AFLAGS   := -D__ASSEMBLY__
@@ -623,9 +636,24 @@ endif
 endif
 KBUILD_CFLAGS += $(stackp-flag)
 
+ifeq ($(COMPILER),clang)
+KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
+KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-variable)
+KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier)
+KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
+# Quiet clang warning: comparison of unsigned expression < 0 is always false
+KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
+# CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the
+# source of a reference will be _MergedGlobals and not on of the whitelisted names.
+# See modpost pattern 2
+KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
+else
+
 # This warning generated too much noise in a regular build.
 # Use make W=1 to enable this warning (see scripts/Makefile.build)
 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
+endif
 
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS  += -fno-omit-frame-pointer -fno-optimize-sibling-calls

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 3b9348a0c1a496244575dced7f89303ae78b168d..602f57e590b57fafd8dcf461c9a5468842d9c29e 100644 (file)
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -108,7 +108,7 @@ else
 
         # this works around some issues with generating unwind tables in older gccs
         # newer gccs do it by default
-        KBUILD_CFLAGS += -maccumulate-outgoing-args
+        KBUILD_CFLAGS += $(call cc-option,-maccumulate-outgoing-args)
 endif
 
 # Make sure compiler does not have buggy stack-protector support.

diff --git a/include/asm-generic/cmpxchg-local.h b/include/asm-generic/cmpxchg-local.h
index d8d4c898c1bbabbaa1a13387d9818a2331b0ee85..70bef78912b796171fb03cc00fe912ded7da1785 100644 (file)
--- a/include/asm-generic/cmpxchg-local.h
+++ b/include/asm-generic/cmpxchg-local.h
@@ -4,7 +4,8 @@
 #include <linux/types.h>
 #include <linux/irqflags.h>
 
-extern unsigned long wrong_size_cmpxchg(volatile void *ptr);
+extern unsigned long wrong_size_cmpxchg(volatile void *ptr)
+       __noreturn;
 
 /*
  * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
new file mode 100644 (file)
index 0000000..d1e49d5
--- /dev/null
+++ b/include/linux/compiler-clang.h
@@ -0,0 +1,12 @@
+#ifndef __LINUX_COMPILER_H
+#error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead."
+#endif
+
+/* Some compiler specific definitions are overwritten here
+ * for Clang compiler
+ */
+
+#ifdef uninitialized_var
+#undef uninitialized_var
+#define uninitialized_var(x) x = *(&(x))
+#endif

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 2472740d7ab2201f58d68ce864448b3def30cdaf..ee7239ea1583482b16bfa0b46ebd45714c7babd6 100644 (file)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -63,6 +63,13 @@ extern void __chk_io_ptr(const volatile void __iomem *);
 # include <linux/compiler-intel.h>
 #endif
 
+/* Clang compiler defines __GNUC__. So we will overwrite implementations
+ * coming from above header files here
+ */
+#ifdef __clang__
+#include <linux/compiler-clang.h>
+#endif
+
 /*
  * Generic compiler-dependent macros required for kernel
  * build go below this comment. Actual compiler/compiler version

diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 9a165a213d9320fa79d088ebe8aaa80408c7fb71..44eeef0da186b20b0ab32c8d81103afa8e57cf56 100644 (file)
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -556,6 +556,11 @@ struct amba_id {
  * See documentation of "x86_match_cpu" for details.
  */
 
+/*
+ * MODULE_DEVICE_TABLE expects this struct to be called x86cpu_device_id.
+ * Although gcc seems to ignore this error, clang fails without this define.
+ */
+#define x86cpu_device_id x86_cpu_id
 struct x86_cpu_id {
        __u16 vendor;
        __u16 family;

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9f0ee22b914f3c8e83ea58ab71278e98b8c03e89..003bc263105ae3fc5a92e671faa8654ac6809fa5 100644 (file)
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -65,12 +65,22 @@ warning-  := $(empty)
 warning-1 := -Wextra -Wunused -Wno-unused-parameter
 warning-1 += -Wmissing-declarations
 warning-1 += -Wmissing-format-attribute
-warning-1 += -Wmissing-prototypes
+warning-1 += $(call cc-option, -Wmissing-prototypes)
 warning-1 += -Wold-style-definition
 warning-1 += $(call cc-option, -Wmissing-include-dirs)
 warning-1 += $(call cc-option, -Wunused-but-set-variable)
 warning-1 += $(call cc-disable-warning, missing-field-initializers)
 
+# Clang
+warning-1 += $(call cc-disable-warning, initializer-overrides)
+warning-1 += $(call cc-disable-warning, unused-value)
+warning-1 += $(call cc-disable-warning, format)
+warning-1 += $(call cc-disable-warning, unknown-warning-option)
+warning-1 += $(call cc-disable-warning, sign-compare)
+warning-1 += $(call cc-disable-warning, format-zero-length)
+warning-1 += $(call cc-disable-warning, uninitialized)
+warning-1 += $(call cc-option, -fcatch-undefined-behavior)
+
 warning-2 := -Waggregate-return
 warning-2 += -Wcast-align
 warning-2 += -Wdisabled-optimization

diff --git a/scripts/mkcompile_h b/scripts/mkcompile_h
index f221ddf69080402a60ad612a4ce63f05be671a6e..cfb8440cc0b2cf5611db59014d4b83fd27af2e9d 100755 (executable)
--- a/scripts/mkcompile_h
+++ b/scripts/mkcompile_h
@@ -76,7 +76,7 @@ UTS_TRUNCATE="cut -b -$UTS_LEN"
   echo \#define LINUX_COMPILE_BY \"`echo $LINUX_COMPILE_BY | $UTS_TRUNCATE`\"
   echo \#define LINUX_COMPILE_HOST \"`echo $LINUX_COMPILE_HOST | $UTS_TRUNCATE`\"
 
-  echo \#define LINUX_COMPILER \"`$CC -v 2>&1 | tail -n 1`\"
+  echo \#define LINUX_COMPILER \"`$CC -v 2>&1 | grep ' version '`\"
 ) > .tmpcompile
 
 # Only replace the real compile.h if the new one is different,