[PATCH v2 0/2] lib/vsprintf: introduce stricter rules for %p extensions

[PATCH v2 0/2] lib/vsprintf: introduce stricter rules for %p extensions

[Andy Shevchenko]

Besides the code refactoring we introduce the following rules for %p extensions
here. i.e:

- fixed type extensions are always printed in hex format, prefixed by '0x',
  small letters, full field width on a running architecture (%pa[dp], %pNF)

- fallback to %p based on different kernel configuration will be under the same
  rule set as for fixed types above (%pCn when COMMON_CLK=n, %p[FfSsB] when
  KALLSYMS=n)

- fallback to %p of unimplemented extension will be under the same rule set as
  for fixed types above (%pN)

Since v1:
 - address comments from Joe and Rasmums (might be not all of them)
 - add patch 2
 - desribe in cover letter what is done besides refactoring

Andy Shevchenko (2):
  lib/vsprintf: refactor duplicate code to special_hex_number()
  lib/vsprintf: factor out %pN[F] handler as netdev_bits()

 lib/vsprintf.c | 70 ++++++++++++++++++++++++++++++++--------------------------
 1 file changed, 39 insertions(+), 31 deletions(-)

-- 
2.6.4

[PATCH v2 1/2] lib/vsprintf: refactor duplicate code to special_hex_number()

[Andy Shevchenko]

special_hex_number() is a helper to print a fixed size type in a hex format
with '0x' prefix, zero padding, and small letters. In the module we have
already several copies of such code. Consolidate them under
special_hex_number() helper.

There are couple of differences though.

It seems nobody cared about the output in case of CONFIG_KALLSYMS=n, when
printing symbol address, because the asked field width is not enough to care
last 2 characters in the string represantation of the pointer. Fixed here.

The %pNF specifier used to be allowed with a specific field width, though there
is neither any user of it nor mention the possibility in the documentation.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 lib/vsprintf.c | 53 +++++++++++++++++++++++++++--------------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 88ed574..6946431 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -514,6 +514,20 @@ char *number(char *buf, char *end, unsigned long long num,
 	return buf;
 }
 
+static noinline_for_stack
+char *special_hex_number(char *buf, char *end, unsigned long long num, int size)
+{
+	struct printf_spec spec;
+
+	spec.type = FORMAT_TYPE_PTR;
+	spec.field_width = 2 + 2 * size;	/* 0x + hex */
+	spec.flags = SPECIAL | SMALL | ZEROPAD;
+	spec.base = 16;
+	spec.precision = -1;
+
+	return number(buf, end, num, spec);
+}
+
 static void move_right(char *buf, char *end, unsigned len, unsigned spaces)
 {
 	size_t size;
@@ -649,11 +663,7 @@ char *symbol_string(char *buf, char *end, void *ptr,
 
 	return string(buf, end, sym, spec);
 #else
-	spec.field_width = 2 * sizeof(void *);
-	spec.flags |= SPECIAL | SMALL | ZEROPAD;
-	spec.base = 16;
-
-	return number(buf, end, value, spec);
+	return special_hex_number(buf, end, value, sizeof(void *));
 #endif
 }
 
@@ -1315,39 +1325,33 @@ char *uuid_string(char *buf, char *end, const u8 *addr,
 }
 
 static
-char *netdev_feature_string(char *buf, char *end, const u8 *addr,
-		      struct printf_spec spec)
+char *netdev_feature_string(char *buf, char *end, const void *addr)
 {
-	spec.flags |= SPECIAL | SMALL | ZEROPAD;
-	if (spec.field_width == -1)
-		spec.field_width = 2 + 2 * sizeof(netdev_features_t);
-	spec.base = 16;
+	unsigned long long num = *(const netdev_features_t *)addr;
+	int size = sizeof(netdev_features_t);
 
-	return number(buf, end, *(const netdev_features_t *)addr, spec);
+	return special_hex_number(buf, end, num, size);
 }
 
 static noinline_for_stack
-char *address_val(char *buf, char *end, const void *addr,
-		  struct printf_spec spec, const char *fmt)
+char *address_val(char *buf, char *end, const void *addr, const char *fmt)
 {
 	unsigned long long num;
-
-	spec.flags |= SPECIAL | SMALL | ZEROPAD;
-	spec.base = 16;
+	int size;
 
 	switch (fmt[1]) {
 	case 'd':
 		num = *(const dma_addr_t *)addr;
-		spec.field_width = sizeof(dma_addr_t) * 2 + 2;
+		size = sizeof(dma_addr_t);
 		break;
 	case 'p':
 	default:
 		num = *(const phys_addr_t *)addr;
-		spec.field_width = sizeof(phys_addr_t) * 2 + 2;
+		size = sizeof(phys_addr_t);
 		break;
 	}
 
-	return number(buf, end, num, spec);
+	return special_hex_number(buf, end, num, size);
 }
 
 static noinline_for_stack
@@ -1366,10 +1370,7 @@ char *clock(char *buf, char *end, struct clk *clk, struct printf_spec spec,
 #ifdef CONFIG_COMMON_CLK
 		return string(buf, end, __clk_get_name(clk), spec);
 #else
-		spec.base = 16;
-		spec.field_width = sizeof(unsigned long) * 2 + 2;
-		spec.flags |= SPECIAL | SMALL | ZEROPAD;
-		return number(buf, end, (unsigned long)clk, spec);
+		return special_hex_number(buf, end, (unsigned long)clk, sizeof(unsigned long));
 #endif
 	}
 }
@@ -1672,11 +1673,11 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 	case 'N':
 		switch (fmt[1]) {
 		case 'F':
-			return netdev_feature_string(buf, end, ptr, spec);
+			return netdev_feature_string(buf, end, ptr);
 		}
 		break;
 	case 'a':
-		return address_val(buf, end, ptr, spec, fmt);
+		return address_val(buf, end, ptr, fmt);
 	case 'd':
 		return dentry_name(buf, end, ptr, spec, fmt);
 	case 'C':
-- 
2.6.4

[PATCH v2 2/2] lib/vsprintf: factor out %pN[F] handler as netdev_bits()

[Andy Shevchenko]

Move switch case to the netdev_features_string() and rename it to
netdev_bits(). In the future we can extend it as needed.

Here we replace the fallback of %pN from '%p' with possible flags to sticter
'0x%p' without any flags variation.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 lib/vsprintf.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 6946431..5c22317 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1324,11 +1324,22 @@ char *uuid_string(char *buf, char *end, const u8 *addr,
 	return string(buf, end, uuid, spec);
 }
 
-static
-char *netdev_feature_string(char *buf, char *end, const void *addr)
+static noinline_for_stack
+char *netdev_bits(char *buf, char *end, const void *addr, const char *fmt)
 {
-	unsigned long long num = *(const netdev_features_t *)addr;
-	int size = sizeof(netdev_features_t);
+	unsigned long long num;
+	int size;
+
+	switch (fmt[1]) {
+	case 'F':
+		num = *(const netdev_features_t *)addr;
+		size = sizeof(netdev_features_t);
+		break;
+	default:
+		num = (unsigned long)addr;
+		size = sizeof(unsigned long);
+		break;
+	}
 
 	return special_hex_number(buf, end, num, size);
 }
@@ -1671,11 +1682,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 		break;
 
 	case 'N':
-		switch (fmt[1]) {
-		case 'F':
-			return netdev_feature_string(buf, end, ptr);
-		}
-		break;
+		return netdev_bits(buf, end, ptr, fmt);
 	case 'a':
 		return address_val(buf, end, ptr, fmt);
 	case 'd':
-- 
2.6.4