[Xen-devel] [RFC][PATCH] 2/3] [TOOLS][XENTRACE] Update tools to write data to disk in a known endian'ness.

[Tony Breeds <tony@xxxxxxxxxxxxxxxxxx>]

Use network byte order when writing data to disk, making the data portable to
any machine.

Signed-off-by: Tony Breeds <tony@xxxxxxxxxxxxxxxxxx>
---

 tools/xentrace/xentrace.c      |   47 ++++++++++++++++++++++++++++++++++-------
 tools/xentrace/xentrace_format |    7 +++---
 2 files changed, 44 insertions(+), 10 deletions(-)

Index: xen-unstable.hg-mainline.xentrace/tools/xentrace/xentrace.c
===================================================================
--- xen-unstable.hg-mainline.xentrace.orig/tools/xentrace/xentrace.c
+++ xen-unstable.hg-mainline.xentrace/tools/xentrace/xentrace.c
@@ -28,6 +28,20 @@
 
 #include <xenctrl.h>
 
+#include <arpa/inet.h> /* hton*(), ntoh*() */
+#include <endian.h>
+
+/* There is no 64-bit htonll, so create one */
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define        htonll(x)   ( (((uint64_t)htonl(x)) << 32) + htonl(x >> 32) )
+#define        ntohll(x)   ( (((uint64_t)ntohl(x)) << 32) + ntohl(x >> 32) )
+#else
+#define        htonll(x)   (x)
+#define        ntohll(x)   (x)
+#endif
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
 #define PERROR(_m, _a...)                                       \
 do {                                                            \
     int __saved_errno = errno;                                  \
@@ -90,12 +104,30 @@ struct timespec millis_to_timespec(unsig
  * Outputs the trace record to a filestream, prepending the CPU ID of the
  * source trace buffer.
  */
-void write_rec(unsigned int cpu, struct t_rec *rec, FILE *out)
+void write_rec(uint32_t cpu, struct t_rec *rec, FILE *out)
 {
     size_t written = 0;
-    written += fwrite(&cpu, sizeof(cpu), 1, out);
-    written += fwrite(rec, sizeof(*rec), 1, out);
-    if ( written != 2 )
+    int i;
+    /* Place network byte order representation in temp vars, rather than
+     * write back into kernel/xen memory */
+    uint64_t tmp64;
+    uint32_t tmp32;
+
+    tmp32 = htonl(cpu);
+    written += fwrite(&tmp32, sizeof(tmp32), 1, out);
+
+    tmp64 = htonll(rec->cycles);
+    written += fwrite(&tmp64, sizeof(tmp64), 1, out);
+
+    tmp32 = htonl(rec->event);
+    written += fwrite(&tmp32, sizeof(tmp32), 1, out);
+
+    for ( i=0; i<ARRAY_SIZE(rec->data); i++ ) {
+        tmp64 = htonl(rec->data[i]);
+        written += fwrite(&tmp64, sizeof(tmp64), 1, out);
+    }
+
+    if ( written != 8 )
     {
         PERROR("Failed to write trace record");
         exit(EXIT_FAILURE);
@@ -147,6 +179,7 @@ struct t_buf *map_tbufs(unsigned long tb
         exit(EXIT_FAILURE);
     }
 
+    /* On PPC (At least) the DOMID arg is ignored in dom0 */
     tbufs_mapped = xc_map_foreign_range(xc_handle, DOMID_XEN,
                                         size * num, PROT_READ | PROT_WRITE,
                                         tbufs_mfn);
@@ -253,7 +286,7 @@ struct t_rec **init_rec_ptrs(struct t_bu
 /**
  * get_num_cpus - get the number of logical CPUs
  */
-unsigned int get_num_cpus(void)
+uint32_t get_num_cpus(void)
 {
     xc_physinfo_t physinfo;
     int xc_handle = xc_interface_open();
@@ -282,14 +315,14 @@ unsigned int get_num_cpus(void)
  */
 int monitor_tbufs(FILE *logfile)
 {
-    int i;
+    uint32_t i;
 
     void *tbufs_mapped;          /* pointer to where the tbufs are mapped    */
     struct t_buf **meta;         /* pointers to the trace buffer metadata    */
     struct t_rec **data;         /* pointers to the trace buffer data areas
                                   * where they are mapped into user space.   */
     unsigned long tbufs_mfn;     /* mfn of the tbufs                         */
-    unsigned int  num;           /* number of trace buffers / logical CPUS   */
+    uint32_t num;                /* number of trace buffers / logical CPUS   */
     unsigned long size;          /* size of a single trace buffer            */
 
     int size_in_recs;
Index: xen-unstable.hg-mainline.xentrace/tools/xentrace/xentrace_format
===================================================================
--- xen-unstable.hg-mainline.xentrace.orig/tools/xentrace/xentrace_format
+++ xen-unstable.hg-mainline.xentrace/tools/xentrace/xentrace_format
@@ -84,10 +84,11 @@ interrupted = 0
 defs = read_defs(arg[0])
 
 # structure of trace record + prepended CPU id (as output by xentrace):
-# CPU(I) TSC(Q) EVENT(L) D1(L) D2(L) D3(L) D4(L) D5(L)
+# CPU(L) TSC(Q) EVENT(L) D1(Q) D2(Q) D3(Q) D4(Q) D5(Q)
 # read CPU id separately to avoid structure packing problems on 64-bit arch.
-CPUREC = "I"
-TRCREC = "QLLLLLL"
+# Force network byte order.
+CPUREC = "!L"
+TRCREC = "!QLQQQQQ"
 
 last_tsc = [0]
 


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