2 files changed, 128 insertions, 0 deletions

diff --git a/lib/test_printf.c b/lib/test_printf.c
index 4f6ae60433bc..563f10e6876a 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -17,6 +17,9 @@
 #include <linux/socket.h>
 #include <linux/in.h>
 
+#include <linux/gfp.h>
+#include <linux/mm.h>
+
 #define BUF_SIZE 256
 #define PAD_SIZE 16
 #define FILL_CHAR '$'
@@ -411,6 +414,55 @@ netdev_features(void)
 }
 
 static void __init
+flags(void)
+{
+        unsigned long flags;
+        gfp_t gfp;
+        char *cmp_buffer;
+
+        flags = 0;
+        test("", "%pGp", &flags);
+
+        /* Page flags should filter the zone id */
+        flags = 1UL << NR_PAGEFLAGS;
+        test("", "%pGp", &flags);
+
+        flags |= 1UL << PG_uptodate | 1UL << PG_dirty | 1UL << PG_lru
+                | 1UL << PG_active | 1UL << PG_swapbacked;
+        test("uptodate|dirty|lru|active|swapbacked", "%pGp", &flags);
+
+
+        flags = VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC
+                        | VM_DENYWRITE;
+        test("read|exec|mayread|maywrite|mayexec|denywrite", "%pGv", &flags);
+
+        gfp = GFP_TRANSHUGE;
+        test("GFP_TRANSHUGE", "%pGg", &gfp);
+
+        gfp = GFP_ATOMIC|__GFP_DMA;
+        test("GFP_ATOMIC|GFP_DMA", "%pGg", &gfp);
+
+        gfp = __GFP_ATOMIC;
+        test("__GFP_ATOMIC", "%pGg", &gfp);
+
+        cmp_buffer = kmalloc(BUF_SIZE, GFP_KERNEL);
+        if (!cmp_buffer)
+                return;
+
+        /* Any flags not translated by the table should remain numeric */
+        gfp = ~__GFP_BITS_MASK;
+        snprintf(cmp_buffer, BUF_SIZE, "%#lx", (unsigned long) gfp);
+        test(cmp_buffer, "%pGg", &gfp);
+
+        snprintf(cmp_buffer, BUF_SIZE, "__GFP_ATOMIC|%#lx",
+                                                        (unsigned long) gfp);
+        gfp |= __GFP_ATOMIC;
+        test(cmp_buffer, "%pGg", &gfp);
+
+        kfree(cmp_buffer);
+}
+
+static void __init
 test_pointer(void)
 {
         plain();
@@ -428,6 +480,7 @@ test_pointer(void)
         struct_clk();
         bitmap();
         netdev_features();
+        flags();
 }
 
 static int __init
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index f44e178e6ede..525c8e19bda2 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -35,6 +35,8 @@
 #include <linux/blkdev.h>
 #endif
 
+#include "../mm/internal.h"     /* For the trace_print_flags arrays */
+
 #include <asm/page.h>           /* for PAGE_SIZE */
 #include <asm/sections.h>       /* for dereference_function_descriptor() */
 #include <asm/byteorder.h>      /* cpu_to_le16 */
@@ -1407,6 +1409,72 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
         }
 }
 
+static
+char *format_flags(char *buf, char *end, unsigned long flags,
+                                        const struct trace_print_flags *names)
+{
+        unsigned long mask;
+        const struct printf_spec strspec = {
+                .field_width = -1,
+                .precision = -1,
+        };
+        const struct printf_spec numspec = {
+                .flags = SPECIAL|SMALL,
+                .field_width = -1,
+                .precision = -1,
+                .base = 16,
+        };
+
+        for ( ; flags && names->name; names++) {
+                mask = names->mask;
+                if ((flags & mask) != mask)
+                        continue;
+
+                buf = string(buf, end, names->name, strspec);
+
+                flags &= ~mask;
+                if (flags) {
+                        if (buf < end)
+                                *buf = '|';
+                        buf++;
+                }
+        }
+
+        if (flags)
+                buf = number(buf, end, flags, numspec);
+
+        return buf;
+}
+
+static noinline_for_stack
+char *flags_string(char *buf, char *end, void *flags_ptr, const char *fmt)
+{
+        unsigned long flags;
+        const struct trace_print_flags *names;
+
+        switch (fmt[1]) {
+        case 'p':
+                flags = *(unsigned long *)flags_ptr;
+                /* Remove zone id */
+                flags &= (1UL << NR_PAGEFLAGS) - 1;
+                names = pageflag_names;
+                break;
+        case 'v':
+                flags = *(unsigned long *)flags_ptr;
+                names = vmaflag_names;
+                break;
+        case 'g':
+                flags = *(gfp_t *)flags_ptr;
+                names = gfpflag_names;
+                break;
+        default:
+                WARN_ONCE(1, "Unsupported flags modifier: %c\n", fmt[1]);
+                return buf;
+        }
+
+        return format_flags(buf, end, flags, names);
+}
+
 int kptr_restrict __read_mostly;
 
 /*
@@ -1495,6 +1563,11 @@ int kptr_restrict __read_mostly;
  * - 'Cn' For a clock, it prints the name (Common Clock Framework) or address
  *        (legacy clock framework) of the clock
  * - 'Cr' For a clock, it prints the current rate of the clock
+ * - 'G' For flags to be printed as a collection of symbolic strings that would
+ *       construct the specific value. Supported flags given by option:
+ *       p page flags (see struct page) given as pointer to unsigned long
+ *       g gfp flags (GFP_* and __GFP_*) given as pointer to gfp_t
+ *       v vma flags (VM_*) given as pointer to unsigned long
  *
  * ** Please update also Documentation/printk-formats.txt when making changes **
  *
@@ -1648,6 +1721,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
                 return bdev_name(buf, end, ptr, spec, fmt);
 #endif
 
+        case 'G':
+                return flags_string(buf, end, ptr, fmt);
         }
         spec.flags |= SMALL;
         if (spec.field_width == -1) {