tracing: add __print_flags_u64()

Patch series "DAX tracepoints, mm argument simplification", v4.

This contains both my DAX tracepoint code and Dave Jiang's MM argument
simplifications.  Dave's code was written with my tracepoint code as a
baseline, so it seemed simplest to keep them together in a single series.

This patch (of 7):

Add __print_flags_u64() and the helper trace_print_flags_seq_u64() in the
same spirit as __print_symbolic_u64() and trace_print_symbols_seq_u64().
These functions allow us to print symbols associated with flags that are
64 bits wide even on 32 bit machines.

These will be used by the DAX code so that we can print the flags set in a
pfn_t such as PFN_SG_CHAIN, PFN_SG_LAST, PFN_DEV and PFN_MAP.

Without this new function I was getting errors like the following when
compiling for i386:

  include/linux/pfn_t.h:13:22: warning: large integer implicitly truncated to unsigned type [-Woverflow]
   #define PFN_SG_CHAIN (1ULL << (BITS_PER_LONG_LONG - 1))
    ^

Link: http://lkml.kernel.org/r/1484085142-2297-2-git-send-email-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 38 insertions, 0 deletions

diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index aea6a1218c7d..070866c32eb9 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -124,6 +124,44 @@ EXPORT_SYMBOL(trace_print_symbols_seq);
 
 #if BITS_PER_LONG == 32
 const char *
+trace_print_flags_seq_u64(struct trace_seq *p, const char *delim,
+                      unsigned long long flags,
+                      const struct trace_print_flags_u64 *flag_array)
+{
+        unsigned long long mask;
+        const char *str;
+        const char *ret = trace_seq_buffer_ptr(p);
+        int i, first = 1;
+
+        for (i = 0;  flag_array[i].name && flags; i++) {
+
+                mask = flag_array[i].mask;
+                if ((flags & mask) != mask)
+                        continue;
+
+                str = flag_array[i].name;
+                flags &= ~mask;
+                if (!first && delim)
+                        trace_seq_puts(p, delim);
+                else
+                        first = 0;
+                trace_seq_puts(p, str);
+        }
+
+        /* check for left over flags */
+        if (flags) {
+                if (!first && delim)
+                        trace_seq_puts(p, delim);
+                trace_seq_printf(p, "0x%llx", flags);
+        }
+
+        trace_seq_putc(p, 0);
+
+        return ret;
+}
+EXPORT_SYMBOL(trace_print_flags_seq_u64);
+
+const char *
 trace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val,
                          const struct trace_print_flags_u64 *symbol_array)
 {