Merge tag 'uml-for-linus-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

Pull UML updates from Richard Weinberger:

 - Support for preemption

 - i386 Rust support

 - Huge cleanup by Benjamin Berg

 - UBSAN support

 - Removal of dead code

* tag 'uml-for-linus-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (41 commits)
  um: vector: always reset vp->opened
  um: vector: remove vp->lock
  um: register power-off handler
  um: line: always fill *error_out in setup_one_line()
  um: remove pcap driver from documentation
  um: Enable preemption in UML
  um: refactor TLB update handling
  um: simplify and consolidate TLB updates
  um: remove force_flush_all from fork_handler
  um: Do not flush MM in flush_thread
  um: Delay flushing syscalls until the thread is restarted
  um: remove copy_context_skas0
  um: remove LDT support
  um: compress memory related stub syscalls while adding them
  um: Rework syscall handling
  um: Add generic stub_syscall6 function
  um: Create signal stack memory assignment in stub_data
  um: Remove stub-data.h include from common-offsets.h
  um: time-travel: fix signal blocking race/hang
  um: time-travel: remove time_exit()
  ...

4 files changed, 73 insertions, 17 deletions

diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index f2923c767bb9..a3eaca41ff61 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -7,15 +7,13 @@
 #define __ARCH_UM_MMU_H
 
 #include <mm_id.h>
-#include <asm/mm_context.h>
 
 typedef struct mm_context {
 	struct mm_id id;
-	struct uml_arch_mm_context arch;
-} mm_context_t;
 
-/* Avoid tangled inclusion with asm/ldt.h */
-extern long init_new_ldt(struct mm_context *to_mm, struct mm_context *from_mm);
-extern void free_ldt(struct mm_context *mm);
+	/* Address range in need of a TLB sync */
+	unsigned long sync_tlb_range_from;
+	unsigned long sync_tlb_range_to;
+} mm_context_t;
 
 #endif
diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
index 68e2eb9cfb47..23dcc914d44e 100644
--- a/arch/um/include/asm/mmu_context.h
+++ b/arch/um/include/asm/mmu_context.h
@@ -13,8 +13,6 @@
 #include <asm/mm_hooks.h>
 #include <asm/mmu.h>
 
-extern void force_flush_all(void);
-
 #define activate_mm activate_mm
 static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
 {
diff --git a/arch/um/include/asm/pgtable.h b/arch/um/include/asm/pgtable.h
index e1ece21dbe3f..5bb397b65efb 100644
--- a/arch/um/include/asm/pgtable.h
+++ b/arch/um/include/asm/pgtable.h
@@ -244,6 +244,38 @@ static inline void set_pte(pte_t *pteptr, pte_t pteval)
 
 #define PFN_PTE_SHIFT		PAGE_SHIFT
 
+static inline void um_tlb_mark_sync(struct mm_struct *mm, unsigned long start,
+				    unsigned long end)
+{
+	if (!mm->context.sync_tlb_range_to) {
+		mm->context.sync_tlb_range_from = start;
+		mm->context.sync_tlb_range_to = end;
+	} else {
+		if (start < mm->context.sync_tlb_range_from)
+			mm->context.sync_tlb_range_from = start;
+		if (end > mm->context.sync_tlb_range_to)
+			mm->context.sync_tlb_range_to = end;
+	}
+}
+
+#define set_ptes set_ptes
+static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
+			    pte_t *ptep, pte_t pte, int nr)
+{
+	/* Basically the default implementation */
+	size_t length = nr * PAGE_SIZE;
+
+	for (;;) {
+		set_pte(ptep, pte);
+		if (--nr == 0)
+			break;
+		ptep++;
+		pte = __pte(pte_val(pte) + (nr << PFN_PTE_SHIFT));
+	}
+
+	um_tlb_mark_sync(mm, addr, addr + length);
+}
+
 #define __HAVE_ARCH_PTE_SAME
 static inline int pte_same(pte_t pte_a, pte_t pte_b)
 {
diff --git a/arch/um/include/asm/tlbflush.h b/arch/um/include/asm/tlbflush.h
index a5bda890390d..db997976b6ea 100644
--- a/arch/um/include/asm/tlbflush.h
+++ b/arch/um/include/asm/tlbflush.h
@@ -9,23 +9,51 @@
 #include <linux/mm.h>
 
 /*
- * TLB flushing:
+ * In UML, we need to sync the TLB over by using mmap/munmap/mprotect syscalls
+ * from the process handling the MM (which can be the kernel itself).
+ *
+ * To track updates, we can hook into set_ptes and flush_tlb_*. With set_ptes
+ * we catch all PTE transitions where memory that was unusable becomes usable.
+ * While with flush_tlb_* we can track any memory that becomes unusable and
+ * even if a higher layer of the page table was modified.
+ *
+ * So, we simply track updates using both methods and mark the memory area to
+ * be synced later on. The only special case is that flush_tlb_kern_* needs to
+ * be executed immediately as there is no good synchronization point in that
+ * case. In contrast, in the set_ptes case we can wait for the next kernel
+ * segfault before we do the synchornization.
  *
- *  - flush_tlb() flushes the current mm struct TLBs
  *  - flush_tlb_all() flushes all processes TLBs
  *  - flush_tlb_mm(mm) flushes the specified mm context TLB's
  *  - flush_tlb_page(vma, vmaddr) flushes one page
- *  - flush_tlb_kernel_vm() flushes the kernel vm area
  *  - flush_tlb_range(vma, start, end) flushes a range of pages
+ *  - flush_tlb_kernel_range(start, end) flushes a range of kernel pages
  */
 
+extern int um_tlb_sync(struct mm_struct *mm);
+
 extern void flush_tlb_all(void);
 extern void flush_tlb_mm(struct mm_struct *mm);
-extern void flush_tlb_range(struct vm_area_struct *vma, unsigned long start, 
-			    unsigned long end);
-extern void flush_tlb_page(struct vm_area_struct *vma, unsigned long address);
-extern void flush_tlb_kernel_vm(void);
-extern void flush_tlb_kernel_range(unsigned long start, unsigned long end);
-extern void __flush_tlb_one(unsigned long addr);
+
+static inline void flush_tlb_page(struct vm_area_struct *vma,
+				  unsigned long address)
+{
+	um_tlb_mark_sync(vma->vm_mm, address, address + PAGE_SIZE);
+}
+
+static inline void flush_tlb_range(struct vm_area_struct *vma,
+				   unsigned long start, unsigned long end)
+{
+	um_tlb_mark_sync(vma->vm_mm, start, end);
+}
+
+static inline void flush_tlb_kernel_range(unsigned long start,
+					  unsigned long end)
+{
+	um_tlb_mark_sync(&init_mm, start, end);
+
+	/* Kernel needs to be synced immediately */
+	um_tlb_sync(&init_mm);
+}
 
 #endif