Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull low-level x86 updates from Ingo Molnar:
 "In this cycle this topic tree has become one of those 'super topics'
  that accumulated a lot of changes:

   - Add CONFIG_VMAP_STACK=y support to the core kernel and enable it on
     x86 - preceded by an array of changes. v4.8 saw preparatory changes
     in this area already - this is the rest of the work. Includes the
     thread stack caching performance optimization. (Andy Lutomirski)

   - switch_to() cleanups and all around enhancements. (Brian Gerst)

   - A large number of dumpstack infrastructure enhancements and an
     unwinder abstraction. The secret long term plan is safe(r) live
     patching plus maybe another attempt at debuginfo based unwinding -
     but all these current bits are standalone enhancements in a frame
     pointer based debug environment as well. (Josh Poimboeuf)

   - More __ro_after_init and const annotations. (Kees Cook)

   - Enable KASLR for the vmemmap memory region. (Thomas Garnier)"

[ The virtually mapped stack changes are pretty fundamental, and not
  x86-specific per se, even if they are only used on x86 right now. ]

* 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (70 commits)
  x86/asm: Get rid of __read_cr4_safe()
  thread_info: Use unsigned long for flags
  x86/alternatives: Add stack frame dependency to alternative_call_2()
  x86/dumpstack: Fix show_stack() task pointer regression
  x86/dumpstack: Remove dump_trace() and related callbacks
  x86/dumpstack: Convert show_trace_log_lvl() to use the new unwinder
  oprofile/x86: Convert x86_backtrace() to use the new unwinder
  x86/stacktrace: Convert save_stack_trace_*() to use the new unwinder
  perf/x86: Convert perf_callchain_kernel() to use the new unwinder
  x86/unwind: Add new unwind interface and implementations
  x86/dumpstack: Remove NULL task pointer convention
  fork: Optimize task creation by caching two thread stacks per CPU if CONFIG_VMAP_STACK=y
  sched/core: Free the stack early if CONFIG_THREAD_INFO_IN_TASK
  lib/syscall: Pin the task stack in collect_syscall()
  x86/process: Pin the target stack in get_wchan()
  x86/dumpstack: Pin the target stack when dumping it
  kthread: Pin the stack via try_get_task_stack()/put_task_stack() in to_live_kthread() function
  sched/core: Add try_get_task_stack() and put_task_stack()
  x86/entry/64: Fix a minor comment rebase error
  iommu/amd: Don't put completion-wait semaphore on stack
  ...

1 files changed, 24 insertions, 2 deletions

diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c
index bda8d5eef04d..ddd2661c4502 100644
--- a/arch/x86/mm/kaslr.c
+++ b/arch/x86/mm/kaslr.c
@@ -40,17 +40,26 @@
  * You need to add an if/def entry if you introduce a new memory region
  * compatible with KASLR. Your entry must be in logical order with memory
  * layout. For example, ESPFIX is before EFI because its virtual address is
- * before. You also need to add a BUILD_BUG_ON in kernel_randomize_memory to
+ * before. You also need to add a BUILD_BUG_ON() in kernel_randomize_memory() to
  * ensure that this order is correct and won't be changed.
  */
 static const unsigned long vaddr_start = __PAGE_OFFSET_BASE;
-static const unsigned long vaddr_end = VMEMMAP_START;
+
+#if defined(CONFIG_X86_ESPFIX64)
+static const unsigned long vaddr_end = ESPFIX_BASE_ADDR;
+#elif defined(CONFIG_EFI)
+static const unsigned long vaddr_end = EFI_VA_START;
+#else
+static const unsigned long vaddr_end = __START_KERNEL_map;
+#endif
 
 /* Default values */
 unsigned long page_offset_base = __PAGE_OFFSET_BASE;
 EXPORT_SYMBOL(page_offset_base);
 unsigned long vmalloc_base = __VMALLOC_BASE;
 EXPORT_SYMBOL(vmalloc_base);
+unsigned long vmemmap_base = __VMEMMAP_BASE;
+EXPORT_SYMBOL(vmemmap_base);
 
 /*
  * Memory regions randomized by KASLR (except modules that use a separate logic
@@ -63,6 +72,7 @@ static __initdata struct kaslr_memory_region {
 } kaslr_regions[] = {
 	{ &page_offset_base, 64/* Maximum */ },
 	{ &vmalloc_base, VMALLOC_SIZE_TB },
+	{ &vmemmap_base, 1 },
 };
 
 /* Get size in bytes used by the memory region */
@@ -89,6 +99,18 @@ void __init kernel_randomize_memory(void)
 	struct rnd_state rand_state;
 	unsigned long remain_entropy;
 
+	/*
+	 * All these BUILD_BUG_ON checks ensures the memory layout is
+	 * consistent with the vaddr_start/vaddr_end variables.
+	 */
+	BUILD_BUG_ON(vaddr_start >= vaddr_end);
+	BUILD_BUG_ON(config_enabled(CONFIG_X86_ESPFIX64) &&
+		     vaddr_end >= EFI_VA_START);
+	BUILD_BUG_ON((config_enabled(CONFIG_X86_ESPFIX64) ||
+		      config_enabled(CONFIG_EFI)) &&
+		     vaddr_end >= __START_KERNEL_map);
+	BUILD_BUG_ON(vaddr_end > __START_KERNEL_map);
+
 	if (!kaslr_memory_enabled())
 		return;