Please revert the accident pull request and use this if you want.

Documentation/kbuild/makefiles.txt

@@ -45,7 +45,7 @@ This document describes the Linux kernel Makefiles.
 
 	=== 7 Kbuild syntax for exported headers
 		--- 7.1 header-y
-		--- 7.2 objhdr-y
+		--- 7.2 genhdr-y
 		--- 7.3 destination-y
 		--- 7.4 generic-y
 
@@ -1282,15 +1282,15 @@ See subsequent chapter for the syntax of the Kbuild file.
 
 	Subdirectories are visited before their parent directories.
 
-	--- 7.2 objhdr-y
+	--- 7.2 genhdr-y
 
-	objhdr-y specifies generated files to be exported.
+	genhdr-y specifies generated files to be exported.
 	Generated files are special as they need to be looked
 	up in another directory when doing 'make O=...' builds.
 
 		Example:
 			#include/linux/Kbuild
-			objhdr-y += version.h
+			genhdr-y += version.h
 
 	--- 7.3 destination-y
 

Documentation/siphash.txt

@@ -0,0 +1,100 @@
+         SipHash - a short input PRF
+-----------------------------------------------
+Written by Jason A. Donenfeld <[email protected]>
+
+SipHash is a cryptographically secure PRF -- a keyed hash function -- that
+performs very well for short inputs, hence the name. It was designed by
+cryptographers Daniel J. Bernstein and Jean-Philippe Aumasson. It is intended
+as a replacement for some uses of: `jhash`, `md5_transform`, `sha_transform`,
+and so forth.
+
+SipHash takes a secret key filled with randomly generated numbers and either
+an input buffer or several input integers. It spits out an integer that is
+indistinguishable from random. You may then use that integer as part of secure
+sequence numbers, secure cookies, or mask it off for use in a hash table.
+
+1. Generating a key
+
+Keys should always be generated from a cryptographically secure source of
+random numbers, either using get_random_bytes or get_random_once:
+
+siphash_key_t key;
+get_random_bytes(&key, sizeof(key));
+
+If you're not deriving your key from here, you're doing it wrong.
+
+2. Using the functions
+
+There are two variants of the function, one that takes a list of integers, and
+one that takes a buffer:
+
+u64 siphash(const void *data, size_t len, const siphash_key_t *key);
+
+And:
+
+u64 siphash_1u64(u64, const siphash_key_t *key);
+u64 siphash_2u64(u64, u64, const siphash_key_t *key);
+u64 siphash_3u64(u64, u64, u64, const siphash_key_t *key);
+u64 siphash_4u64(u64, u64, u64, u64, const siphash_key_t *key);
+u64 siphash_1u32(u32, const siphash_key_t *key);
+u64 siphash_2u32(u32, u32, const siphash_key_t *key);
+u64 siphash_3u32(u32, u32, u32, const siphash_key_t *key);
+u64 siphash_4u32(u32, u32, u32, u32, const siphash_key_t *key);
+
+If you pass the generic siphash function something of a constant length, it
+will constant fold at compile-time and automatically choose one of the
+optimized functions.
+
+3. Hashtable key function usage:
+
+struct some_hashtable {
+	DECLARE_HASHTABLE(hashtable, 8);
+	siphash_key_t key;
+};
+
+void init_hashtable(struct some_hashtable *table)
+{
+	get_random_bytes(&table->key, sizeof(table->key));
+}
+
+static inline hlist_head *some_hashtable_bucket(struct some_hashtable *table, struct interesting_input *input)
+{
+	return &table->hashtable[siphash(input, sizeof(*input), &table->key) & (HASH_SIZE(table->hashtable) - 1)];
+}
+
+You may then iterate like usual over the returned hash bucket.
+
+4. Security
+
+SipHash has a very high security margin, with its 128-bit key. So long as the
+key is kept secret, it is impossible for an attacker to guess the outputs of
+the function, even if being able to observe many outputs, since 2^128 outputs
+is significant.
+
+Linux implements the "2-4" variant of SipHash.
+
+5. Struct-passing Pitfalls
+
+Often times the XuY functions will not be large enough, and instead you'll
+want to pass a pre-filled struct to siphash. When doing this, it's important
+to always ensure the struct has no padding holes. The easiest way to do this
+is to simply arrange the members of the struct in descending order of size,
+and to use offsetendof() instead of sizeof() for getting the size. For
+performance reasons, if possible, it's probably a good thing to align the
+struct to the right boundary. Here's an example:
+
+const struct {
+	struct in6_addr saddr;
+	u32 counter;
+	u16 dport;
+} __aligned(SIPHASH_ALIGNMENT) combined = {
+	.saddr = *(struct in6_addr *)saddr,
+	.counter = counter,
+	.dport = dport
+};
+u64 h = siphash(&combined, offsetofend(typeof(combined), dport), &secret);
+
+6. Resources
+
+Read the SipHash paper if you're interested in learning more:
+https://131002.net/siphash/siphash.pdf

MAINTAINERS

@@ -6096,6 +6096,13 @@ F:	arch/arm/mach-s3c2410/mach-bast.c
 F:	arch/arm/mach-s3c2410/bast-ide.c
 F:	arch/arm/mach-s3c2410/bast-irq.c
 
+SIPHASH PRF ROUTINES
+M:	Jason A. Donenfeld <[email protected]>
+S:	Maintained
+F:	lib/siphash.c
+F:	lib/test_siphash.c
+F:	include/linux/siphash.h
+
 TI DAVINCI MACHINE SUPPORT
 M:	Sekhar Nori <[email protected]>
 M:	Kevin Hilman <[email protected]>

Makefile

@@ -359,13 +359,21 @@ CFLAGS_KERNEL	=-mcpu=cortex-a15 -mtune=cortex-a15 -mfpu=neon-vfpv4
 AFLAGS_KERNEL	=
 CFLAGS_GCOV	= -fprofile-arcs -ftest-coverage
 
+# Use USERINCLUDE when you must reference the UAPI directories only.
+USERINCLUDE    := \
+		-I$(srctree)/arch/$(hdr-arch)/include/uapi \
+		-Iarch/$(hdr-arch)/include/generated/uapi \
+		-I$(srctree)/include/uapi \
+		-Iinclude/generated/uapi \
+                -include $(srctree)/include/linux/kconfig.h
 
 # Use LINUXINCLUDE when you must reference the include/ directory.
 # Needed to be compatible with the O= option
 LINUXINCLUDE    := -I$(srctree)/arch/$(hdr-arch)/include \
                    -Iarch/$(hdr-arch)/include/generated -Iinclude \
                    $(if $(KBUILD_SRC), -I$(srctree)/include) \
-                   -include $(srctree)/include/linux/kconfig.h
+                   -Iinclude \
+                   $(USERINCLUDE)
 
 KBUILD_CPPFLAGS := -D__KERNEL__
 
@@ -445,9 +453,11 @@ asm-generic:
 # Detect when mixed targets is specified, and make a second invocation
 # of make so .config is not included in this case either (for *config).
 
+version_h := include/generated/uapi/linux/version.h
+
 no-dot-config-targets := clean mrproper distclean \
 			 cscope gtags TAGS tags help %docs check% coccicheck \
-			 include/linux/version.h headers_% archheaders archscripts \
+			 $(version_h) headers_% archheaders archscripts \
 			 kernelversion %src-pkg
 
 config-targets := 0
@@ -987,7 +997,7 @@ endif
 # prepare2 creates a makefile if using a separate output directory
 prepare2: prepare3 outputmakefile asm-generic
 
-prepare1: prepare2 include/linux/version.h include/generated/utsrelease.h \
+prepare1: prepare2 $(version_h) include/generated/utsrelease.h \
                    include/config/auto.conf
 	$(cmd_crmodverdir)
 
@@ -1020,7 +1030,7 @@ define filechk_version.h
 	echo '#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))';)
 endef
 
-include/linux/version.h: $(srctree)/Makefile FORCE
+$(version_h): $(srctree)/Makefile FORCE
 	$(call filechk,version.h)
 
 include/generated/utsrelease.h: include/config/kernel.release FORCE
@@ -1065,7 +1075,7 @@ PHONY += archscripts
 archscripts:
 
 PHONY += __headers
-__headers: include/linux/version.h scripts_basic asm-generic archheaders archscripts FORCE
+__headers: $(version_h) scripts_basic asm-generic archheaders archscripts FORCE
 	$(Q)$(MAKE) $(build)=scripts build_unifdef
 
 PHONY += headers_install_all
@@ -1074,19 +1084,19 @@ headers_install_all:
 
 PHONY += headers_install
 headers_install: __headers
-	$(if $(wildcard $(srctree)/arch/$(hdr-arch)/include/asm/Kbuild),, \
-	$(error Headers not exportable for the $(SRCARCH) architecture))
-	$(Q)$(MAKE) $(hdr-inst)=include
-	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/asm $(hdr-dst)
+	$(if $(wildcard $(srctree)/arch/$(hdr-arch)/include/uapi/asm/Kbuild),, \
+	  $(error Headers not exportable for the $(SRCARCH) architecture))
+	$(Q)$(MAKE) $(hdr-inst)=include/uapi
+	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/uapi/asm $(hdr-dst)
 
 PHONY += headers_check_all
 headers_check_all: headers_install_all
 	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/headers.sh check
 
 PHONY += headers_check
 headers_check: headers_install
-	$(Q)$(MAKE) $(hdr-inst)=include HDRCHECK=1
-	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/asm $(hdr-dst) HDRCHECK=1
+	$(Q)$(MAKE) $(hdr-inst)=include/uapi HDRCHECK=1
+	$(Q)$(MAKE) $(hdr-inst)=arch/$(hdr-arch)/include/uapi/asm $(hdr-dst) HDRCHECK=1
 
 # ---------------------------------------------------------------------------
 # Modules
@@ -1177,8 +1187,7 @@ CLEAN_FILES +=	vmlinux System.map \
 # Directories & files removed with 'make mrproper'
 MRPROPER_DIRS  += include/config usr/include include/generated          \
                   arch/*/include/generated
-MRPROPER_FILES += .config .config.old .version .old_version             \
-                  include/linux/version.h                               \
+MRPROPER_FILES += .config .config.old .version .old_version $(version_h) \
 		  Module.symvers tags TAGS cscope* GPATH GTAGS GRTAGS GSYMS
 
 # clean - Delete most, but leave enough to build external modules