X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/1123a69b82b73a4edd1cc9012330de33919d171e..9b7c007d68cc9aabd52746479c68a8287a087fe3:/src/mc/mc_page_snapshot.cpp

diff --git a/src/mc/mc_page_snapshot.cpp b/src/mc/mc_page_snapshot.cpp
index c049b7d326..c8aa50fadd 100644
--- a/src/mc/mc_page_snapshot.cpp
+++ b/src/mc/mc_page_snapshot.cpp
@@ -1,5 +1,9 @@
+#include <unistd.h> // pread, pwrite
+
 #include "mc_page_store.h"
 #include "mc_mmu.h"
+#include "mc_private.h"
+#include "mc_snapshot.h"
 
 #include <xbt/mmalloc.h>
 
@@ -10,24 +14,56 @@ extern "C" {
 
 // ***** Region management:
 
-size_t* mc_take_page_snapshot_region(void* data, size_t page_count, uint64_t* pagemap, size_t* reference_pages)
+/** @brief Take a per-page snapshot of a region
+ *
+ *  @param data            The start of the region (must be at the beginning of a page)
+ *  @param pag_count       Number of pages of the region
+ *  @param pagemap         Linux kernel pagemap values fot this region (or NULL)
+ *  @param reference_pages Snapshot page numbers of the previous soft_dirty_reset (or NULL)
+ *  @return                Snapshot page numbers of this new snapshot
+ */
+size_t* mc_take_page_snapshot_region(mc_process_t process,
+  void* data, size_t page_count, uint64_t* pagemap, size_t* reference_pages)
 {
   size_t* pagenos = (size_t*) malloc(page_count * sizeof(size_t));
 
+  const bool is_self = MC_process_is_self(process);
+
+  void* temp = NULL;
+  if (!is_self)
+    temp = malloc(xbt_pagesize);
+
   for (size_t i=0; i!=page_count; ++i) {
     bool softclean = pagemap && !(pagemap[i] & SOFT_DIRTY);
-    if (softclean) {
+    if (softclean && reference_pages) {
       // The page is softclean, it is the same page as the reference page:
       pagenos[i] = reference_pages[i];
       mc_model_checker->pages->ref_page(reference_pages[i]);
     } else {
-      // Otherwise, we need to store the page the hard hard
+      // Otherwise, we need to store the page the hard way
       // (by reading its content):
       void* page = (char*) data + (i << xbt_pagebits);
-      pagenos[i] = mc_model_checker->pages->store_page(page);
+      xbt_assert(mc_page_offset(page)==0, "Not at the beginning of a page");
+      void* page_data;
+      if (is_self) {
+        page_data = page;
+      } else {
+        /* Adding another copy (and a syscall) will probably slow things a lot.
+           TODO, optimize this somehow (at least by grouping the syscalls)
+           if needed. Either:
+            - reduce the number of syscalls;
+            - let the application snapshot itself;
+            - move the segments in shared memory (this will break `fork` however).
+        */
+        page_data = temp;
+        MC_process_read(process, MC_ADDRESS_SPACE_READ_FLAGS_NONE,
+          temp, page, xbt_pagesize, MC_PROCESS_INDEX_DISABLED);
+      }
+      pagenos[i] = mc_model_checker->pages->store_page(page_data);
     }
   }
 
+  free(temp);
   return pagenos;
 }
 
@@ -38,21 +74,33 @@ void mc_free_page_snapshot_region(size_t* pagenos, size_t page_count)
   }
 }
 
-void mc_restore_page_snapshot_region(mc_mem_region_t region, size_t page_count, uint64_t* pagemap, mc_mem_region_t reference_region)
+/** @brief Restore a snapshot of a region
+ *
+ *  If possible, the restoration will be incremental
+ *  (the modified pages will not be touched).
+ *
+ *  @param start_addr
+ *  @param page_count       Number of pages of the region
+ *  @param pagenos
+ *  @param pagemap         Linux kernel pagemap values fot this region (or NULL)
+ *  @param reference_pages Snapshot page numbers of the previous soft_dirty_reset (or NULL)
+ */
+void mc_restore_page_snapshot_region(mc_process_t process,
+  void* start_addr, size_t page_count, size_t* pagenos, uint64_t* pagemap, size_t* reference_pagenos)
 {
   for (size_t i=0; i!=page_count; ++i) {
 
     bool softclean = pagemap && !(pagemap[i] & SOFT_DIRTY);
-    if (softclean && reference_region && reference_region->page_numbers[i] == region->page_numbers[i]) {
+    if (softclean && reference_pagenos && pagenos[i] == reference_pagenos[i]) {
       // The page is softclean and is the same as the reference one:
       // the page is already in the target state.
       continue;
     }
 
     // Otherwise, copy the page:
-    void* target_page = mc_page_from_number(region->start_addr, i);
-    const void* source_page = mc_model_checker->pages->get_page(region->page_numbers[i]);
-    memcpy(target_page, source_page, xbt_pagesize);
+    void* target_page = mc_page_from_number(start_addr, i);
+    const void* source_page = mc_model_checker->pages->get_page(pagenos[i]);
+    MC_process_write(process, source_page, target_page, xbt_pagesize);
   }
 }
 
@@ -87,7 +135,8 @@ static size_t pread_whole(int fd, void* buf, size_t count, off_t offset) {
   return res;
 }
 
-static inline void mc_ensure_fd(int* fd, const char* path, int flags) {
+static inline  __attribute__ ((always_inline))
+void mc_ensure_fd(int* fd, const char* path, int flags) {
   if (*fd != -1)
     return;
   *fd = open(path, flags);
@@ -137,56 +186,72 @@ static void mc_read_pagemap(uint64_t* pagemap, size_t page_start, size_t page_co
 
 // ***** High level API
 
-mc_mem_region_t mc_region_new_sparse(int type, void *start_addr, size_t size, mc_mem_region_t ref_reg)
+mc_mem_region_t mc_region_new_sparse(mc_region_type_t region_type,
+  void *start_addr, void* permanent_addr, size_t size,
+  mc_mem_region_t ref_reg)
 {
-  mc_mem_region_t new_reg = xbt_new(s_mc_mem_region_t, 1);
+  mc_process_t process = &mc_model_checker->process;
 
-  new_reg->start_addr = start_addr;
-  new_reg->data = NULL;
-  new_reg->size = size;
-  new_reg->page_numbers = NULL;
+  mc_mem_region_t region = xbt_new(s_mc_mem_region_t, 1);
+  region->region_type = region_type;
+  region->storage_type = MC_REGION_STORAGE_TYPE_CHUNKED;
+  region->start_addr = start_addr;
+  region->permanent_addr = permanent_addr;
+  region->size = size;
 
   xbt_assert((((uintptr_t)start_addr) & (xbt_pagesize-1)) == 0,
     "Not at the beginning of a page");
+  xbt_assert((((uintptr_t)permanent_addr) & (xbt_pagesize-1)) == 0,
+    "Not at the beginning of a page");
   size_t page_count = mc_page_count(size);
 
   uint64_t* pagemap = NULL;
-  if (mc_model_checker->parent_snapshot) {
-      pagemap = (uint64_t*) mmalloc_no_memset((xbt_mheap_t) mc_heap, sizeof(uint64_t) * page_count);
-      mc_read_pagemap(pagemap, mc_page_number(NULL, start_addr), page_count);
+  if (_sg_mc_soft_dirty && mc_model_checker->parent_snapshot &&
+      MC_process_is_self(process)) {
+      pagemap = (uint64_t*) malloc_no_memset(sizeof(uint64_t) * page_count);
+      mc_read_pagemap(pagemap, mc_page_number(NULL, permanent_addr), page_count);
   }
 
+  size_t* reg_page_numbers = NULL;
+  if (ref_reg!=NULL && ref_reg->storage_type == MC_REGION_STORAGE_TYPE_CHUNKED)
+    reg_page_numbers = ref_reg->chunked.page_numbers;
+
   // Take incremental snapshot:
-  new_reg->page_numbers = mc_take_page_snapshot_region(start_addr, page_count, pagemap,
-    ref_reg==NULL ? NULL : ref_reg->page_numbers);
+  region->chunked.page_numbers = mc_take_page_snapshot_region(process,
+    permanent_addr, page_count, pagemap, reg_page_numbers);
 
   if(pagemap) {
-    mfree((xbt_mheap_t) mc_heap, pagemap);
+    mfree(mc_heap, pagemap);
   }
-  return new_reg;
+  return region;
 }
 
-void mc_region_restore_sparse(mc_mem_region_t reg, mc_mem_region_t ref_reg)
+void mc_region_restore_sparse(mc_process_t process, mc_mem_region_t reg, mc_mem_region_t ref_reg)
 {
-  xbt_assert((((uintptr_t)reg->start_addr) & (xbt_pagesize-1)) == 0,
+  xbt_assert((((uintptr_t)reg->permanent_addr) & (xbt_pagesize-1)) == 0,
     "Not at the beginning of a page");
   size_t page_count = mc_page_count(reg->size);
 
   uint64_t* pagemap = NULL;
 
   // Read soft-dirty bits if necessary in order to know which pages have changed:
-  if (mc_model_checker->parent_snapshot) {
-    pagemap = (uint64_t*) mmalloc_no_memset((xbt_mheap_t) mc_heap, sizeof(uint64_t) * page_count);
-    mc_read_pagemap(pagemap, mc_page_number(NULL, reg->start_addr), page_count);
+  if (_sg_mc_soft_dirty && mc_model_checker->parent_snapshot
+      && MC_process_is_self(process)) {
+    pagemap = (uint64_t*) malloc_no_memset(sizeof(uint64_t) * page_count);
+    mc_read_pagemap(pagemap, mc_page_number(NULL, reg->permanent_addr), page_count);
   }
 
-  // Incremental per-page snapshot restoration:
-  mc_restore_page_snapshot_region(reg, page_count, pagemap, ref_reg);
+  // Incremental per-page snapshot restoration:s
+  size_t* reg_page_numbers = NULL;
+  if (ref_reg && ref_reg->storage_type == MC_REGION_STORAGE_TYPE_CHUNKED)
+    reg_page_numbers = ref_reg->chunked.page_numbers;
+
+  mc_restore_page_snapshot_region(process,
+    reg->permanent_addr, page_count, reg->chunked.page_numbers,
+    pagemap, reg_page_numbers);
 
-  // This is funny, the restoration can restore the state of the current heap,
-  // if this happen free(pagemap) would free from the wrong heap:
   if(pagemap) {
-    mfree((xbt_mheap_t) mc_heap, pagemap);
+    free(pagemap);
   }
 }