Add logic necessary to handler remapping of shared memory on contex switches

6 files changed, 86 insertions, 14 deletions

diff --git a/nuttx/arch/arm/include/arch.h b/nuttx/arch/arm/include/arch.h
index 5b962f3fc..fee37f167 100644
--- a/nuttx/arch/arm/include/arch.h
+++ b/nuttx/arch/arm/include/arch.h
@@ -48,6 +48,7 @@
 #ifndef __ASSEMBLY__
 #  include <stdint.h>
 #  include <nuttx/pgalloc.h>
+#  include <nuttx/addrenv.h>
 #endif
 
 /****************************************************************************
@@ -90,7 +91,7 @@ do { \
   ); \
 } while (0)
 
-#endif
+#endif /* CONFIG_PIC */
 
 #ifdef CONFIG_ARCH_ADDRENV
 #if CONFIG_MM_PGSIZE != 4096
@@ -109,10 +110,14 @@ do { \
 #  define ARCH_DATA_NSECTS    ARCH_PG2SECT(CONFIG_ARCH_DATA_NPAGES)
 #  define ARCH_HEAP_NSECTS    ARCH_PG2SECT(CONFIG_ARCH_HEAP_NPAGES)
 
+#  ifdef CONFIG_MM_SHM
+#    define ARCH_SHM_NSECTS   ARCH_PG2SECT(ARCH_SHM_MAXPAGES)
+#  endif
+
 #  ifdef CONFIG_ARCH_STACK_DYNAMIC
 #    define ARCH_STACK_NSECTS ARCH_PG2SECT(CONFIG_ARCH_STACK_NPAGES)
 #  endif
-#endif
+#endif /* CONFIG_ARCH_ADDRENV */
 
 /****************************************************************************
  * Inline functions
@@ -141,6 +146,9 @@ struct group_addrenv_s
   FAR uintptr_t *data[ARCH_DATA_NSECTS];
 #ifdef CONFIG_BUILD_KERNEL
   FAR uintptr_t *heap[ARCH_HEAP_NSECTS];
+#ifdef CONFIG_MM_SHM
+  FAR uintptr_t *shm[ARCH_SHM_NSECTS];
+#endif
 
   /* Initial heap allocation (in bytes).  This exists only provide an
    * indirect path for passing the size of the initial heap to the heap
@@ -167,7 +175,12 @@ struct save_addrenv_s
 {
   FAR uint32_t text[ARCH_TEXT_NSECTS];
   FAR uint32_t data[ARCH_DATA_NSECTS];
+#ifdef CONFIG_BUILD_KERNEL
   FAR uint32_t heap[ARCH_HEAP_NSECTS];
+#ifdef CONFIG_MM_SHM
+  FAR uint32_t shm[ARCH_SHM_NSECTS];
+#endif
+#endif
 };
 
 typedef struct save_addrenv_s save_addrenv_t;
diff --git a/nuttx/arch/arm/src/armv7-a/addrenv.h b/nuttx/arch/arm/src/armv7-a/addrenv.h
index 60cfb342a..36d2cc7fe 100644
--- a/nuttx/arch/arm/src/armv7-a/addrenv.h
+++ b/nuttx/arch/arm/src/armv7-a/addrenv.h
@@ -125,7 +125,7 @@ int arm_addrenv_create_region(FAR uintptr_t **list, unsigned int listlen,
  ****************************************************************************/
 
 void arm_addrenv_destroy_region(FAR uintptr_t **list, unsigned int listlen,
-                                uintptr_t vaddr);
+                                uintptr_t vaddr, bool keep);
 
 #undef EXTERN
 #ifdef __cplusplus
diff --git a/nuttx/arch/arm/src/armv7-a/arm_addrenv.c b/nuttx/arch/arm/src/armv7-a/arm_addrenv.c
index 65a3308be..3b0617dcf 100644
--- a/nuttx/arch/arm/src/armv7-a/arm_addrenv.c
+++ b/nuttx/arch/arm/src/armv7-a/arm_addrenv.c
@@ -363,18 +363,26 @@ int up_addrenv_destroy(FAR group_addrenv_t *addrenv)
   /* Destroy the .text region */
 
   arm_addrenv_destroy_region(addrenv->text, ARCH_TEXT_NSECTS,
-                             CONFIG_ARCH_TEXT_VBASE);
+                             CONFIG_ARCH_TEXT_VBASE, false);
 
   /* Destroy the .bss/.data region */
 
   arm_addrenv_destroy_region(addrenv->data, ARCH_DATA_NSECTS,
-                             CONFIG_ARCH_DATA_VBASE);
+                             CONFIG_ARCH_DATA_VBASE, false);
 
 #ifdef CONFIG_BUILD_KERNEL
   /* Destroy the heap region */
 
   arm_addrenv_destroy_region(addrenv->heap, ARCH_HEAP_NSECTS,
-                             CONFIG_ARCH_HEAP_VBASE);
+                             CONFIG_ARCH_HEAP_VBASE, false);
+#ifdef CONFIG_MM_SHM
+  /* Destroy the shared memory region (without freeing the physical page
+   * data).
+   */
+
+  arm_addrenv_destroy_region(addrenv->heap, ARCH_SHM_NSECTS,
+                             CONFIG_ARCH_SHM_VBASE, true);
+#endif
 #endif
 
   memset(addrenv, 0, sizeof(group_addrenv_t));
@@ -578,6 +586,33 @@ int up_addrenv_select(FAR const group_addrenv_t *addrenv,
           mmu_l1_clrentry(vaddr);
         }
     }
+
+#ifdef CONFIG_MM_SHM
+  for (vaddr = CONFIG_ARCH_SHM_VBASE, i = 0;
+       i < ARCH_SHM_NSECTS;
+       vaddr += SECTION_SIZE, i++)
+    {
+      /* Save the old L1 page table entry */
+
+      if (oldenv)
+        {
+          oldenv->shm[i] = mmu_l1_getentry(vaddr);
+        }
+
+      /* Set (or clear) the new page table entry */
+
+      paddr = (uintptr_t)addrenv->shm[i];
+      if (paddr)
+        {
+          mmu_l1_setentry(paddr, vaddr, MMU_L1_PGTABFLAGS);
+        }
+      else
+        {
+          mmu_l1_clrentry(vaddr);
+        }
+    }
+
+#endif
 #endif
 
   return OK;
@@ -635,6 +670,18 @@ int up_addrenv_restore(FAR const save_addrenv_t *oldenv)
 
       mmu_l1_restore(vaddr, oldenv->heap[i]);
     }
+
+#ifdef CONFIG_MM_SHM
+  for (vaddr = CONFIG_ARCH_SHM_VBASE, i = 0;
+       i < ARCH_SHM_NSECTS;
+       vaddr += SECTION_SIZE, i++)
+    {
+      /* Restore the L1 page table entry */
+
+      mmu_l1_restore(vaddr, oldenv->shm[i]);
+    }
+
+#endif
 #endif
 
   return OK;
diff --git a/nuttx/arch/arm/src/armv7-a/arm_addrenv_ustack.c b/nuttx/arch/arm/src/armv7-a/arm_addrenv_ustack.c
index 02bc18cea..97da35992 100644
--- a/nuttx/arch/arm/src/armv7-a/arm_addrenv_ustack.c
+++ b/nuttx/arch/arm/src/armv7-a/arm_addrenv_ustack.c
@@ -204,7 +204,7 @@ int up_addrenv_ustackfree(FAR struct tcb_s *tcb)
   /* Destroy the stack region */
 
   arm_addrenv_destroy_region(tcb->xcp.ustack, ARCH_STACK_NSECTS,
-                             CONFIG_ARCH_STACK_VBASE);
+                             CONFIG_ARCH_STACK_VBASE, false);
 
   memset(tcb->xcp.ustack, 0, ARCH_STACK_NSECTS * sizeof(uintptr_t *));
   return OK;
diff --git a/nuttx/arch/arm/src/armv7-a/arm_addrenv_utils.c b/nuttx/arch/arm/src/armv7-a/arm_addrenv_utils.c
index fbcdaa70c..7f0d415f2 100644
--- a/nuttx/arch/arm/src/armv7-a/arm_addrenv_utils.c
+++ b/nuttx/arch/arm/src/armv7-a/arm_addrenv_utils.c
@@ -228,7 +228,7 @@ int arm_addrenv_create_region(FAR uintptr_t **list, unsigned int listlen,
  ****************************************************************************/
 
 void arm_addrenv_destroy_region(FAR uintptr_t **list, unsigned int listlen,
-                                uintptr_t vaddr)
+                                uintptr_t vaddr, bool keep)
 {
   irqstate_t flags;
   uintptr_t paddr;
@@ -266,15 +266,23 @@ void arm_addrenv_destroy_region(FAR uintptr_t **list, unsigned int listlen,
           l2table = (FAR uint32_t *)(ARCH_SCRATCH_VBASE | (paddr & SECTION_MASK));
 #endif
 
-          /* Return the allocated pages to the page allocator */
+          /* Return the allocated pages to the page allocator unless we were
+           * asked to keep the page data.  We keep the page data only for
+           * the case of shared memory.  In that case, we need to tear down
+           * the mapping and page table entries, but keep the raw page data
+           * will still may be mapped by other user processes.
+           */
 
-          for (j = 0; j < ENTRIES_PER_L2TABLE; j++)
+          if (!keep)
             {
-              paddr = *l2table++;
-              if (paddr != 0)
+              for (j = 0; j < ENTRIES_PER_L2TABLE; j++)
                 {
-                  paddr &= PTE_SMALL_PADDR_MASK;
-                  mm_pgfree(paddr, 1);
+                  paddr = *l2table++;
+                  if (paddr != 0)
+                    {
+                      paddr &= PTE_SMALL_PADDR_MASK;
+                      mm_pgfree(paddr, 1);
+                    }
                 }
             }
 
diff --git a/nuttx/include/nuttx/addrenv.h b/nuttx/include/nuttx/addrenv.h
index 586afbf7d..4aaa2d550 100644
--- a/nuttx/include/nuttx/addrenv.h
+++ b/nuttx/include/nuttx/addrenv.h
@@ -197,6 +197,7 @@
 #    define CONFIG_ARCH_SHM_NPAGES 1
 #  endif
 
+#  define ARCH_SHM_MAXPAGES   (CONFIG_ARCH_SHM_NPAGES * CONFIG_ARCH_SHM_MAXREGIONS)
 #  define ARCH_SHM_REGIONSIZE (CONFIG_ARCH_SHM_NPAGES * CONFIG_MM_PGSIZE)
 #  define ARCH_SHM_SIZE       (CONFIG_ARCH_SHM_MAXREGIONS * ARCH_SHM_REGIONSIZE)
 #  define ARCH_SHM_VEND       (CONFIG_ARCH_SHM_VBASE + ARCH_SHM_SIZE)
@@ -235,6 +236,8 @@
  * Public Types
  ****************************************************************************/
 
+#ifndef __ASSEMBLY__
+
 /* Reserved .bss/.data region.  In the kernel build (CONFIG_BUILD_KERNEL),
  * the region at the beginning of the .bss/.data region is reserved for use
  * by the OS.  This reserved region contains support for:
@@ -353,5 +356,6 @@ struct addrenv_reserve_s
 
 /* Prototyped in include/nuttx/arch.h as part of the OS/platform interface */
 
+#endif /* __ASSEMBLY__ */
 #endif /* CONFIG_ARCH_ADDRENV */
 #endif /* __INCLUDE_NUTTX_ADDRENV_H */