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, 30 insertions, 6 deletions

diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index fcfa1939ac41..06f02f6aecd2 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -22,6 +22,7 @@
 #include <linux/stacktrace.h>
 #include <linux/dma-debug.h>
 #include <linux/spinlock.h>
+#include <linux/vmalloc.h>
 #include <linux/debugfs.h>
 #include <linux/uaccess.h>
 #include <linux/export.h>
@@ -1164,11 +1165,32 @@ static void check_unmap(struct dma_debug_entry *ref)
         put_hash_bucket(bucket, &flags);
 }
 
-static void check_for_stack(struct device *dev, void *addr)
+static void check_for_stack(struct device *dev,
+                            struct page *page, size_t offset)
 {
-        if (object_is_on_stack(addr))
-                err_printk(dev, NULL, "DMA-API: device driver maps memory from "
-                                "stack [addr=%p]\n", addr);
+        void *addr;
+        struct vm_struct *stack_vm_area = task_stack_vm_area(current);
+
+        if (!stack_vm_area) {
+                /* Stack is direct-mapped. */
+                if (PageHighMem(page))
+                        return;
+                addr = page_address(page) + offset;
+                if (object_is_on_stack(addr))
+                        err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [addr=%p]\n", addr);
+        } else {
+                /* Stack is vmalloced. */
+                int i;
+
+                for (i = 0; i < stack_vm_area->nr_pages; i++) {
+                        if (page != stack_vm_area->pages[i])
+                                continue;
+
+                        addr = (u8 *)current->stack + i * PAGE_SIZE + offset;
+                        err_printk(dev, NULL, "DMA-API: device driver maps memory from stack [probable addr=%p]\n", addr);
+                        break;
+                }
+        }
 }
 
 static inline bool overlap(void *addr, unsigned long len, void *start, void *end)
@@ -1291,10 +1313,11 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
         if (map_single)
                 entry->type = dma_debug_single;
 
+        check_for_stack(dev, page, offset);
+
         if (!PageHighMem(page)) {
                 void *addr = page_address(page) + offset;
 
-                check_for_stack(dev, addr);
                 check_for_illegal_area(dev, addr, size);
         }
 
@@ -1386,8 +1409,9 @@ void debug_dma_map_sg(struct device *dev, struct scatterlist *sg,
                 entry->sg_call_ents   = nents;
                 entry->sg_mapped_ents = mapped_ents;
 
+                check_for_stack(dev, sg_page(s), s->offset);
+
                 if (!PageHighMem(sg_page(s))) {
-                        check_for_stack(dev, sg_virt(s));
                         check_for_illegal_area(dev, sg_virt(s), sg_dma_len(s));
                 }