Merge tag 'x86-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull core x86 updates from Ingo Molnar:

 - The biggest change is the rework of the percpu code, to support the
   'Named Address Spaces' GCC feature, by Uros Bizjak:

      - This allows C code to access GS and FS segment relative memory
        via variables declared with such attributes, which allows the
        compiler to better optimize those accesses than the previous
        inline assembly code.

      - The series also includes a number of micro-optimizations for
        various percpu access methods, plus a number of cleanups of %gs
        accesses in assembly code.

      - These changes have been exposed to linux-next testing for the
        last ~5 months, with no known regressions in this area.

 - Fix/clean up __switch_to()'s broken but accidentally working handling
   of FPU switching - which also generates better code

 - Propagate more RIP-relative addressing in assembly code, to generate
   slightly better code

 - Rework the CPU mitigations Kconfig space to be less idiosyncratic, to
   make it easier for distros to follow & maintain these options

 - Rework the x86 idle code to cure RCU violations and to clean up the
   logic

 - Clean up the vDSO Makefile logic

 - Misc cleanups and fixes

* tag 'x86-core-2024-03-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (52 commits)
  x86/idle: Select idle routine only once
  x86/idle: Let prefer_mwait_c1_over_halt() return bool
  x86/idle: Cleanup idle_setup()
  x86/idle: Clean up idle selection
  x86/idle: Sanitize X86_BUG_AMD_E400 handling
  sched/idle: Conditionally handle tick broadcast in default_idle_call()
  x86: Increase brk randomness entropy for 64-bit systems
  x86/vdso: Move vDSO to mmap region
  x86/vdso/kbuild: Group non-standard build attributes and primary object file rules together
  x86/vdso: Fix rethunk patching for vdso-image-{32,64}.o
  x86/retpoline: Ensure default return thunk isn't used at runtime
  x86/vdso: Use CONFIG_COMPAT_32 to specify vdso32
  x86/vdso: Use $(addprefix ) instead of $(foreach )
  x86/vdso: Simplify obj-y addition
  x86/vdso: Consolidate targets and clean-files
  x86/bugs: Rename CONFIG_RETHUNK              => CONFIG_MITIGATION_RETHUNK
  x86/bugs: Rename CONFIG_CPU_SRSO             => CONFIG_MITIGATION_SRSO
  x86/bugs: Rename CONFIG_CPU_IBRS_ENTRY       => CONFIG_MITIGATION_IBRS_ENTRY
  x86/bugs: Rename CONFIG_CPU_UNRET_ENTRY      => CONFIG_MITIGATION_UNRET_ENTRY
  x86/bugs: Rename CONFIG_SLS                  => CONFIG_MITIGATION_SLS
  ...

1 files changed, 29 insertions, 16 deletions

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0f869c4785b8..8f7271d9f1d7 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -147,6 +147,7 @@ config X86
 	select EDAC_ATOMIC_SCRUB
 	select EDAC_SUPPORT
 	select GENERIC_CLOCKEVENTS_BROADCAST	if X86_64 || (X86_32 && X86_LOCAL_APIC)
+	select GENERIC_CLOCKEVENTS_BROADCAST_IDLE	if GENERIC_CLOCKEVENTS_BROADCAST
 	select GENERIC_CLOCKEVENTS_MIN_ADJUST
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_CPU_AUTOPROBE
@@ -2430,6 +2431,18 @@ source "kernel/livepatch/Kconfig"
 
 endmenu
 
+config CC_HAS_NAMED_AS
+	def_bool CC_IS_GCC && GCC_VERSION >= 120100
+
+config USE_X86_SEG_SUPPORT
+	def_bool y
+	depends on CC_HAS_NAMED_AS
+	#
+	# -fsanitize=kernel-address (KASAN) is at the moment incompatible
+	# with named address spaces - see GCC PR sanitizer/111736.
+	#
+	depends on !KASAN
+
 config CC_HAS_SLS
 	def_bool $(cc-option,-mharden-sls=all)
 
@@ -2461,12 +2474,12 @@ config CALL_PADDING
 
 config FINEIBT
 	def_bool y
-	depends on X86_KERNEL_IBT && CFI_CLANG && RETPOLINE
+	depends on X86_KERNEL_IBT && CFI_CLANG && MITIGATION_RETPOLINE
 	select CALL_PADDING
 
 config HAVE_CALL_THUNKS
 	def_bool y
-	depends on CC_HAS_ENTRY_PADDING && RETHUNK && OBJTOOL
+	depends on CC_HAS_ENTRY_PADDING && MITIGATION_RETHUNK && OBJTOOL
 
 config CALL_THUNKS
 	def_bool n
@@ -2488,7 +2501,7 @@ menuconfig SPECULATION_MITIGATIONS
 
 if SPECULATION_MITIGATIONS
 
-config PAGE_TABLE_ISOLATION
+config MITIGATION_PAGE_TABLE_ISOLATION
 	bool "Remove the kernel mapping in user mode"
 	default y
 	depends on (X86_64 || X86_PAE)
@@ -2499,7 +2512,7 @@ config PAGE_TABLE_ISOLATION
 
 	  See Documentation/arch/x86/pti.rst for more details.
 
-config RETPOLINE
+config MITIGATION_RETPOLINE
 	bool "Avoid speculative indirect branches in kernel"
 	select OBJTOOL if HAVE_OBJTOOL
 	default y
@@ -2509,9 +2522,9 @@ config RETPOLINE
 	  branches. Requires a compiler with -mindirect-branch=thunk-extern
 	  support for full protection. The kernel may run slower.
 
-config RETHUNK
+config MITIGATION_RETHUNK
 	bool "Enable return-thunks"
-	depends on RETPOLINE && CC_HAS_RETURN_THUNK
+	depends on MITIGATION_RETPOLINE && CC_HAS_RETURN_THUNK
 	select OBJTOOL if HAVE_OBJTOOL
 	default y if X86_64
 	help
@@ -2520,14 +2533,14 @@ config RETHUNK
 	  Requires a compiler with -mfunction-return=thunk-extern
 	  support for full protection. The kernel may run slower.
 
-config CPU_UNRET_ENTRY
+config MITIGATION_UNRET_ENTRY
 	bool "Enable UNRET on kernel entry"
-	depends on CPU_SUP_AMD && RETHUNK && X86_64
+	depends on CPU_SUP_AMD && MITIGATION_RETHUNK && X86_64
 	default y
 	help
 	  Compile the kernel with support for the retbleed=unret mitigation.
 
-config CALL_DEPTH_TRACKING
+config MITIGATION_CALL_DEPTH_TRACKING
 	bool "Mitigate RSB underflow with call depth tracking"
 	depends on CPU_SUP_INTEL && HAVE_CALL_THUNKS
 	select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
@@ -2547,7 +2560,7 @@ config CALL_DEPTH_TRACKING
 
 config CALL_THUNKS_DEBUG
 	bool "Enable call thunks and call depth tracking debugging"
-	depends on CALL_DEPTH_TRACKING
+	depends on MITIGATION_CALL_DEPTH_TRACKING
 	select FUNCTION_ALIGNMENT_32B
 	default n
 	help
@@ -2558,14 +2571,14 @@ config CALL_THUNKS_DEBUG
 	  Only enable this when you are debugging call thunks as this
 	  creates a noticeable runtime overhead. If unsure say N.
 
-config CPU_IBPB_ENTRY
+config MITIGATION_IBPB_ENTRY
 	bool "Enable IBPB on kernel entry"
 	depends on CPU_SUP_AMD && X86_64
 	default y
 	help
 	  Compile the kernel with support for the retbleed=ibpb mitigation.
 
-config CPU_IBRS_ENTRY
+config MITIGATION_IBRS_ENTRY
 	bool "Enable IBRS on kernel entry"
 	depends on CPU_SUP_INTEL && X86_64
 	default y
@@ -2574,14 +2587,14 @@ config CPU_IBRS_ENTRY
 	  This mitigates both spectre_v2 and retbleed at great cost to
 	  performance.
 
-config CPU_SRSO
+config MITIGATION_SRSO
 	bool "Mitigate speculative RAS overflow on AMD"
-	depends on CPU_SUP_AMD && X86_64 && RETHUNK
+	depends on CPU_SUP_AMD && X86_64 && MITIGATION_RETHUNK
 	default y
 	help
 	  Enable the SRSO mitigation needed on AMD Zen1-4 machines.
 
-config SLS
+config MITIGATION_SLS
 	bool "Mitigate Straight-Line-Speculation"
 	depends on CC_HAS_SLS && X86_64
 	select OBJTOOL if HAVE_OBJTOOL
@@ -2591,7 +2604,7 @@ config SLS
 	  against straight line speculation. The kernel image might be slightly
 	  larger.
 
-config GDS_FORCE_MITIGATION
+config MITIGATION_GDS_FORCE
 	bool "Force GDS Mitigation"
 	depends on CPU_SUP_INTEL
 	default n