port: mmap offset alignment on Windows

On Windows the mmap offset is not aligned to the page size but to the
allocator granularity which is usually bigger than the page size. Add a new
internal function to the mmap compat code to get the proper offset alignment
size for each platform.

See the "dwFileOffsetLow" section for more details :
https://docs.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-mapviewoffile

Change-Id: Ic26dc53862719892738a88b3dcea6a15901a0c94
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/2107
Reviewed-by: Simon Marchi <simon.marchi@efficios.com>
Tested-by: jenkins <jenkins@lttng.org>

diff --git a/src/common/mmap-align.h b/src/common/mmap-align.h
index 033d6c4a92916ce651fc14590887c52d46d82d5b..c42cdeb34da234b02490db1f0cf25c6fe877893f 100644 (file)
--- a/src/common/mmap-align.h
+++ b/src/common/mmap-align.h
@@ -46,29 +46,11 @@ struct mmap_align {
        size_t length;                  /* virtual mmap length */
 };
 
-#ifdef __WIN32__
-#include <windows.h>
-
-/*
- * On windows the memory mapping offset must be aligned to the memory
- * allocator allocation granularity and not the page size.
- */
-static inline
-off_t get_page_aligned_offset(off_t offset, size_t page_size)
-{
-       SYSTEM_INFO sysinfo;
-
-       GetNativeSystemInfo(&sysinfo);
-
-       return ALIGN_FLOOR(offset, sysinfo.dwAllocationGranularity);
-}
-#else
 static inline
-off_t get_page_aligned_offset(off_t offset, size_t page_size)
+off_t get_page_aligned_offset(off_t offset, int log_level)
 {
-       return ALIGN_FLOOR(offset, page_size);
+       return ALIGN_FLOOR(offset, bt_mmap_get_offset_align_size(log_level));
 }
-#endif
 
 static inline
 struct mmap_align *mmap_align(size_t length, int prot,
@@ -84,7 +66,7 @@ struct mmap_align *mmap_align(size_t length, int prot,
        if (!mma)
                return MAP_FAILED;
        mma->length = length;
-       page_aligned_offset = get_page_aligned_offset(offset, page_size);
+       page_aligned_offset = get_page_aligned_offset(offset, log_level);
        /*
         * Page aligned length needs to contain the requested range.
         * E.g., for a small range that fits within a single page, we might

diff --git a/src/compat/mman.c b/src/compat/mman.c
index 1a7638c98381e0d6511a3a78f597e43015d90df7..d2019d2bd2d6ed2a81679ba287db43b0754739df 100644 (file)
--- a/src/compat/mman.c
+++ b/src/compat/mman.c
@@ -300,4 +300,17 @@ end:
        return ret;
 }
 
+BT_HIDDEN
+size_t bt_mmap_get_offset_align_size(int log_level)
+{
+       SYSTEM_INFO sysinfo;
+
+       GetNativeSystemInfo(&sysinfo);
+       BT_LOG_WRITE_CUR_LVL(BT_LOG_DEBUG, log_level, BT_LOG_TAG,
+               "Allocator granularity is %lu.",
+               sysinfo.dwAllocationGranularity);
+
+       return sysinfo.dwAllocationGranularity;
+}
+
 #endif

diff --git a/src/compat/mman.h b/src/compat/mman.h
index bdab9d1903fbab5e08227f4d498cef8de69050c3..4ed889ace50d8f0b604598ee0161841656db859a 100644 (file)
--- a/src/compat/mman.h
+++ b/src/compat/mman.h
@@ -50,9 +50,16 @@ void *bt_mmap(void *addr, size_t length, int prot, int flags, int fd,
 
 int bt_munmap(void *addr, size_t length);
 
+/*
+ * On Windows the memory mapping offset must be aligned to the memory
+ * allocator allocation granularity and not the page size.
+ */
+size_t bt_mmap_get_offset_align_size(int log_level);
+
 #else /* __MINGW32__ */
 
 #include <sys/mman.h>
+#include "common/common.h"
 
 static inline
 void *bt_mmap(void *addr, size_t length, int prot, int flags, int fd,
@@ -66,6 +73,16 @@ int bt_munmap(void *addr, size_t length)
 {
        return munmap(addr, length);
 }
+
+/*
+ * On other platforms the memory mapping offset must be aligned to the
+ * page size.
+ */
+static inline
+size_t bt_mmap_get_offset_align_size(int log_level)
+{
+       return bt_common_get_page_size(log_level);
+}
 #endif /* __MINGW32__ */
 
 #ifndef MAP_ANONYMOUS

diff --git a/src/plugins/ctf/fs-src/data-stream-file.c b/src/plugins/ctf/fs-src/data-stream-file.c
index 6ddb8a34d0f861c921cde8fe3c50161e818a0902..924a2be788c5fe9b450862d82118005537ecdd2b 100644 (file)
--- a/src/plugins/ctf/fs-src/data-stream-file.c
+++ b/src/plugins/ctf/fs-src/data-stream-file.c
@@ -251,7 +251,7 @@ enum bt_msg_iter_medium_status medop_seek(enum bt_msg_iter_seek_whence whence,
 
 map_requested_offset:
        offset_in_mapping = offset %
-               bt_common_get_page_size(ds_file->log_level);
+               bt_mmap_get_offset_align_size(ds_file->log_level);
 
        ds_file->mmap_offset = offset - offset_in_mapping;
        ds_file->request_offset = offset_in_mapping;
@@ -642,7 +642,7 @@ struct ctf_fs_ds_file *ctf_fs_ds_file_create(
                bt_logging_level log_level)
 {
        int ret;
-       const size_t page_size = bt_common_get_page_size(log_level);
+       const size_t offset_align = bt_mmap_get_offset_align_size(log_level);
        struct ctf_fs_ds_file *ds_file = g_new0(struct ctf_fs_ds_file, 1);
 
        if (!ds_file) {
@@ -672,7 +672,7 @@ struct ctf_fs_ds_file *ctf_fs_ds_file_create(
                goto error;
        }
 
-       ds_file->mmap_max_len = page_size * 2048;
+       ds_file->mmap_max_len = offset_align * 2048;
 
        goto end;