Re: [GIT PULL] Protection Keys (pkeys) support

[Ingo Molnar <mingo@kernel.org>]

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, Mar 21, 2016 at 12:34 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > Furthermore, I'd reorganize the 'arch settings' section into 4 groups, the
> > following way:
> >
> > 1) Options that are fundamentally only set on x86-32 kernels:
> >
> > 2) Options that are fundamentally only set on x86-64 kernels:
> >
> > 3) Bi-arch options and options that are not yet implemented for both
> >
> > 4) All other options are moved as selects to their respective config entries.
> 
> Yes, that sounds much better than what we have now.

... a late update a few months later:

JFYI, I've pushed out a series of changes that implements all this:

 c763ea2650df x86/kconfig: Sort the 'config X86' selects alphabetically
 953fee1d82f3 x86/kconfig: Clean up 32-bit compat options
 39f88911b9dc x86/kconfig: Clean up IA32_EMULATION select
 52c8e6017c76 x86/kconfig, x86/pkeys: Move pkeys selects to X86_INTEL_MEMORY_PROTECTION_KEYS
 d94e068573f2 x86/kconfig: Move 64-bit only arch Kconfig selects to 'config X86_64'
 341c787e34af x86/kconfig: Move 32-bit only arch Kconfig selects to 'config X86_32'

Combo patch is below. Full tree can be found at:

  git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/build

The remaining 'if X86_64' options are all features that are selected for the 
64-bit kernel but could be used on the 32-bit kernel as well (just nobody bothered 
porting it yet). I kept those in the generic section for the time being.

Thanks,

	Ingo

---
 arch/x86/Kconfig | 68 ++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 41 insertions(+), 27 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index bada636d1065..e01f101d4413 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -9,28 +9,50 @@ config 64BIT
 config X86_32
 	def_bool y
 	depends on !64BIT
+	# Options that are inherently 32-bit kernel only:
+	select ARCH_WANT_IPC_PARSE_VERSION
+	select CLKSRC_I8253
+	select CLONE_BACKWARDS
+	select HAVE_AOUT
+	select HAVE_GENERIC_DMA_COHERENT
+	select MODULES_USE_ELF_REL
+	select OLD_SIGACTION
 
 config X86_64
 	def_bool y
 	depends on 64BIT
+	# Options that are inherently 64-bit kernel only:
+	select ARCH_HAS_GIGANTIC_PAGE
+	select ARCH_SUPPORTS_INT128
+	select ARCH_USE_CMPXCHG_LOCKREF
+	select HAVE_ARCH_SOFT_DIRTY
+	select MODULES_USE_ELF_RELA
+	select X86_DEV_DMA_OPS
 
-### Arch settings
+#
+# Arch settings
+#
+# ( Note that options that are marked 'if X86_64' could in principle be
+#   ported to 32-bit as well. )
+#
 config X86
 	def_bool y
+	#
+	# Note: keep this list sorted alphabetically
+	#
 	select ACPI_LEGACY_TABLES_LOOKUP	if ACPI
 	select ACPI_SYSTEM_POWER_STATES_SUPPORT	if ACPI
 	select ANON_INODES
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_DISCARD_MEMBLOCK
-	select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
+	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FAST_MULTIPLIER
 	select ARCH_HAS_GCOV_PROFILE_ALL
-	select ARCH_HAS_GIGANTIC_PAGE		if X86_64
 	select ARCH_HAS_KCOV			if X86_64
-	select ARCH_HAS_PMEM_API		if X86_64
 	select ARCH_HAS_MMIO_FLUSH
+	select ARCH_HAS_PMEM_API		if X86_64
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
@@ -39,23 +61,17 @@ config X86
 	select ARCH_MIGHT_HAVE_PC_SERIO
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT
-	select ARCH_SUPPORTS_INT128		if X86_64
 	select ARCH_SUPPORTS_NUMA_BALANCING	if X86_64
 	select ARCH_USE_BUILTIN_BSWAP
-	select ARCH_USE_CMPXCHG_LOCKREF		if X86_64
 	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_USE_QUEUED_SPINLOCKS
 	select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH if SMP
-	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 	select ARCH_WANT_FRAME_POINTERS
-	select ARCH_WANT_IPC_PARSE_VERSION	if X86_32
+	select ARCH_WANTS_DYNAMIC_TASK_STRUCT
 	select BUILDTIME_EXTABLE_SORT
 	select CLKEVT_I8253
-	select CLKSRC_I8253			if X86_32
 	select CLOCKSOURCE_VALIDATE_LAST_CYCLE
 	select CLOCKSOURCE_WATCHDOG
-	select CLONE_BACKWARDS			if X86_32
-	select COMPAT_OLD_SIGACTION		if IA32_EMULATION
 	select DCACHE_WORD_ACCESS
 	select EDAC_ATOMIC_SCRUB
 	select EDAC_SUPPORT
@@ -77,7 +93,6 @@ config X86
 	select HAVE_ACPI_APEI			if ACPI
 	select HAVE_ACPI_APEI_NMI		if ACPI
 	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
-	select HAVE_AOUT			if X86_32
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HARDENED_USERCOPY
 	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
@@ -88,12 +103,10 @@ config X86
 	select HAVE_ARCH_MMAP_RND_BITS		if MMU
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
 	select HAVE_ARCH_SECCOMP_FILTER
-	select HAVE_ARCH_SOFT_DIRTY		if X86_64
 	select HAVE_ARCH_TRACEHOOK
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
-	select HAVE_ARCH_WITHIN_STACK_FRAMES
-	select HAVE_EBPF_JIT			if X86_64
 	select HAVE_ARCH_VMAP_STACK		if X86_64
+	select HAVE_ARCH_WITHIN_STACK_FRAMES
 	select HAVE_CC_STACKPROTECTOR
 	select HAVE_CMPXCHG_DOUBLE
 	select HAVE_CMPXCHG_LOCAL
@@ -106,6 +119,7 @@ config X86
 	select HAVE_DMA_CONTIGUOUS
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_DYNAMIC_FTRACE_WITH_REGS
+	select HAVE_EBPF_JIT			if X86_64
 	select HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select HAVE_EXIT_THREAD
 	select HAVE_FENTRY			if X86_64
@@ -113,7 +127,6 @@ config X86
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
 	select HAVE_GCC_PLUGINS
-	select HAVE_GENERIC_DMA_COHERENT	if X86_32
 	select HAVE_HW_BREAKPOINT
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
@@ -142,15 +155,11 @@ config X86
 	select HAVE_PERF_REGS
 	select HAVE_PERF_USER_STACK_DUMP
 	select HAVE_REGS_AND_STACK_ACCESS_API
+	select HAVE_STACK_VALIDATION		if X86_64
 	select HAVE_SYSCALL_TRACEPOINTS
-	select HAVE_UID16			if X86_32 || IA32_EMULATION
 	select HAVE_UNSTABLE_SCHED_CLOCK
 	select HAVE_USER_RETURN_NOTIFIER
 	select IRQ_FORCED_THREADING
-	select MODULES_USE_ELF_RELA		if X86_64
-	select MODULES_USE_ELF_REL		if X86_32
-	select OLD_SIGACTION			if X86_32
-	select OLD_SIGSUSPEND3			if X86_32 || IA32_EMULATION
 	select PERF_EVENTS
 	select RTC_LIB
 	select RTC_MC146818_LIB
@@ -160,11 +169,7 @@ config X86
 	select THREAD_INFO_IN_TASK
 	select USER_STACKTRACE_SUPPORT
 	select VIRT_TO_BUS
-	select X86_DEV_DMA_OPS			if X86_64
 	select X86_FEATURE_NAMES		if PROC_FS
-	select HAVE_STACK_VALIDATION		if X86_64
-	select ARCH_USES_HIGH_VMA_FLAGS		if X86_INTEL_MEMORY_PROTECTION_KEYS
-	select ARCH_HAS_PKEYS			if X86_INTEL_MEMORY_PROTECTION_KEYS
 
 config INSTRUCTION_DECODER
 	def_bool y
@@ -1737,6 +1742,8 @@ config X86_INTEL_MEMORY_PROTECTION_KEYS
 	def_bool y
 	# Note: only available in 64-bit mode
 	depends on CPU_SUP_INTEL && X86_64
+	select ARCH_USES_HIGH_VMA_FLAGS
+	select ARCH_HAS_PKEYS
 	---help---
 	  Memory Protection Keys provides a mechanism for enforcing
 	  page-based protections, but without requiring modification of the
@@ -2092,7 +2099,7 @@ config DEBUG_HOTPLUG_CPU0
 config COMPAT_VDSO
 	def_bool n
 	prompt "Disable the 32-bit vDSO (needed for glibc 2.3.3)"
-	depends on X86_32 || IA32_EMULATION
+	depends on COMPAT_32
 	---help---
 	  Certain buggy versions of glibc will crash if they are
 	  presented with a 32-bit vDSO that is not mapped at the address
@@ -2694,9 +2701,10 @@ source "fs/Kconfig.binfmt"
 config IA32_EMULATION
 	bool "IA32 Emulation"
 	depends on X86_64
+	select ARCH_WANT_OLD_COMPAT_IPC
 	select BINFMT_ELF
 	select COMPAT_BINFMT_ELF
-	select ARCH_WANT_OLD_COMPAT_IPC
+	select COMPAT_OLD_SIGACTION
 	---help---
 	  Include code to run legacy 32-bit programs under a
 	  64-bit kernel. You should likely turn this on, unless you're
@@ -2721,6 +2729,12 @@ config X86_X32
 	  elf32_x86_64 support enabled to compile a kernel with this
 	  option set.
 
+config COMPAT_32
+	def_bool y
+	depends on IA32_EMULATION || X86_32
+	select HAVE_UID16
+	select OLD_SIGSUSPEND3
+
 config COMPAT
 	def_bool y
 	depends on IA32_EMULATION || X86_X32