Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

Pull s390 updates from Heiko Carstens:
 "The main thing in this merge is the defense for the Spectre
  vulnerabilities. But there are other updates as well, the changes in
  more detail:

   - An s390 specific implementation of the array_index_mask_nospec
     function to the defense against spectre v1

   - Two patches to utilize the new PPA-12/PPA-13 instructions to run
     the kernel and/or user space with reduced branch predicton.

   - The s390 variant of the 'retpoline' spectre v2 defense called
     'expoline'. There is no return instruction for s390, instead an
     indirect branch is used for function return

     The s390 defense mechanism for indirect branches works by using an
     execute-type instruction with the indirect branch as the target of
     the execute. In effect that turns off the prediction for the
     indirect branch.

   - Scrub registers in entry.S that contain user controlled values to
     prevent the speculative use of these values.

   - Re-add the second parameter for the s390 specific runtime
     instrumentation system call and move the header file to uapi. The
     second parameter will continue to do nothing but older kernel
     versions only accepted valid real-time signal numbers. The details
     will be documented in the man-page for the system call.

   - Corrections and improvements for the s390 specific documentation

   - Add a line to /proc/sysinfo to display the CPU model dependent
     license-internal-code identifier

   - A header file include fix for eadm.

   - An error message fix in the kprobes code.

   - The removal of an outdated ARCH_xxx select statement"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/kconfig: Remove ARCH_WANTS_PROT_NUMA_PROT_NONE select
  s390: introduce execute-trampolines for branches
  s390: run user space and KVM guests with modified branch prediction
  s390: add options to change branch prediction behaviour for the kernel
  s390/alternative: use a copy of the facility bit mask
  s390: add optimized array_index_mask_nospec
  s390: scrub registers on kernel entry and KVM exit
  s390/cio: fix kernel-doc usage
  s390/runtime_instrumentation: re-add signum system call parameter
  s390/cpum_cf: correct counter number of LAST_HOST_TRANSLATIONS
  s390/kprobes: Fix %p uses in error messages
  s390/runtime instrumentation: provide uapi header file
  s390/sysinfo: add and display licensed internal code identifier
  s390/docs: reword airq section
  s390/docs: mention subchannel types
  s390/cmf: fix kerneldoc
  s390/eadm: fix CONFIG_BLOCK include dependency

1 files changed, 45 insertions, 1 deletions

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0105ce28e246..eaee7087886f 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -112,7 +112,6 @@ config S390
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
-	select ARCH_WANTS_PROT_NUMA_PROT_NONE
 	select ARCH_WANTS_UBSAN_NO_NULL
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select BUILDTIME_EXTABLE_SORT
@@ -540,6 +539,51 @@ config ARCH_RANDOM
 
 	  If unsure, say Y.
 
+config KERNEL_NOBP
+	def_bool n
+	prompt "Enable modified branch prediction for the kernel by default"
+	help
+	  If this option is selected the kernel will switch to a modified
+	  branch prediction mode if the firmware interface is available.
+	  The modified branch prediction mode improves the behaviour in
+	  regard to speculative execution.
+
+	  With the option enabled the kernel parameter "nobp=0" or "nospec"
+	  can be used to run the kernel in the normal branch prediction mode.
+
+	  With the option disabled the modified branch prediction mode is
+	  enabled with the "nobp=1" kernel parameter.
+
+	  If unsure, say N.
+
+config EXPOLINE
+	def_bool n
+	prompt "Avoid speculative indirect branches in the kernel"
+	help
+	  Compile the kernel with the expoline compiler options to guard
+	  against kernel-to-user data leaks by avoiding speculative indirect
+	  branches.
+	  Requires a compiler with -mindirect-branch=thunk support for full
+	  protection. The kernel may run slower.
+
+	  If unsure, say N.
+
+choice
+	prompt "Expoline default"
+	depends on EXPOLINE
+	default EXPOLINE_FULL
+
+config EXPOLINE_OFF
+	bool "spectre_v2=off"
+
+config EXPOLINE_MEDIUM
+	bool "spectre_v2=auto"
+
+config EXPOLINE_FULL
+	bool "spectre_v2=on"
+
+endchoice
+
 endmenu
 
 menu "Memory setup"