[PATCH v4 02/28] printk: Add print format (%pra) for struct range

Ira Weiny
2024-10-07T23:16:19Z

The use of struct range in the CXL subsystem is growing. In particular,
the addition of Dynamic Capacity devices uses struct range in a number
of places which are reported in debug and error messages.

To wit requiring the printing of the start/end fields in each print
became cumbersome. Dan Williams mentions in [1] that it might be time
to have a print specifier for struct range similar to struct resource

A few alternatives were considered including '%par', '%r', and '%pn'.
%pra follows that struct range is similar to struct resource (%p[rR])
but need to be different. Based on discussions with Petr and Andy
'%pra' was chosen.[2]

Andy also suggested to keep the range prints similar to struct resource
though combined code. Add hex_range() to handle printing for both
pointer types.

To: Petr Mladek <pmladek@suse.com>
To: Steven Rostedt <rostedt@goodmis.org>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Jonathan Corbet <corbet@lwn.net> (maintainer:DOCUMENTATION)
Cc: linux-doc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org (open list)
Link: https://lore.kernel.org/all/663922b475e50_d54d72945b@dwillia2-xfh.jf.intel.com.notmuch/ [1]
Link: https://lore.kernel.org/all/66cea3bf3332f_f937b29424@iweiny-mobl.notmuch/ [2]
Suggested-by: "Dan Williams" <dan.j.williams@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>

---
Changes:
[Andy: create new hex_range() and use it in both range/resource]
[Petr/Andy: Use %pra]
[Andy: Add test case start > end]
[Petr: Update documentation]
[Petr: use 'range -']
[Petr: fixup printf_spec specifiers]
[Petr: add lib/test_printf test]
---
Documentation/core-api/printk-formats.rst | 13 ++++++++
lib/test_printf.c | 26 +++++++++++++++
lib/vsprintf.c | 55 +++++++++++++++++++++++++++----
3 files changed, 88 insertions(+), 6 deletions(-)

diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 14e093da3ccd..03b102fc60bb 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -231,6 +231,19 @@ width of the CPU data path.

Passed by reference.

+Struct Range
+------------
+
+::
+
+ %pra [range 0x0000000060000000-0x000000006fffffff]
+ %pra [range 0x0000000060000000]
+
+For printing struct range. struct range holds an arbitrary range of u64
+values. If start is equal to end only 1 value is printed.
+
+Passed by reference.
+
DMA address types dma_addr_t
----------------------------

diff --git a/lib/test_printf.c b/lib/test_printf.c
index 5afdf5efc627..e3e75b6d10a0 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -432,6 +432,31 @@ struct_resource(void)
"%pR", &test_resource);
}

+static void __init
+struct_range(void)
+{
+ struct range test_range = {
+ .start = 0xc0ffee00ba5eba11,
+ .end = 0xc0ffee00ba5eba11,
+ };
+
+ test("[range 0xc0ffee00ba5eba11]", "%pra", &test_range);
+
+ test_range = (struct range) {
+ .start = 0xc0ffee,
+ .end = 0xba5eba11,
+ };
+ test("[range 0x0000000000c0ffee-0x00000000ba5eba11]",
+ "%pra", &test_range);
+
+ test_range = (struct range) {
+ .start = 0xba5eba11,
+ .end = 0xc0ffee,
+ };
+ test("[range 0x00000000ba5eba11-0x0000000000c0ffee]",
+ "%pra", &test_range);
+}
+
static void __init
addr(void)
{
@@ -807,6 +832,7 @@ test_pointer(void)
symbol_ptr();
kernel_ptr();
struct_resource();
+ struct_range();
addr();
escaped_str();
hex_string();
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 09f022ba1c05..f8f5ed8f4d39 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1039,6 +1039,19 @@ static const struct printf_spec default_dec04_spec = {
.flags = ZEROPAD,
};

+static noinline_for_stack
+char *hex_range(char *buf, char *end, u64 start_val, u64 end_val,
+ struct printf_spec spec)
+{
+ buf = number(buf, end, start_val, spec);
+ if (start_val != end_val) {
+ if (buf < end)
+ *buf++ = '-';
+ buf = number(buf, end, end_val, spec);
+ }
+ return buf;
+}
+
static noinline_for_stack
char *resource_string(char *buf, char *end, struct resource *res,
struct printf_spec spec, const char *fmt)
@@ -1115,11 +1128,7 @@ char *resource_string(char *buf, char *end, struct resource *res,
p = string_nocheck(p, pend, "size ", str_spec);
p = number(p, pend, resource_size(res), *specp);
} else {
- p = number(p, pend, res->start, *specp);
- if (res->start != res->end) {
- *p++ = '-';
- p = number(p, pend, res->end, *specp);
- }
+ p = hex_range(p, pend, res->start, res->end, *specp);
}
if (decode) {
if (res->flags & IORESOURCE_MEM_64)
@@ -1140,6 +1149,34 @@ char *resource_string(char *buf, char *end, struct resource *res,
return string_nocheck(buf, end, sym, spec);
}

+static noinline_for_stack
+char *range_string(char *buf, char *end, const struct range *range,
+ struct printf_spec spec, const char *fmt)
+{
+#define RANGE_DECODED_BUF_SIZE ((2 * sizeof(struct range)) + 4)
+#define RANGE_PRINT_BUF_SIZE sizeof("[range -]")
+ char sym[RANGE_DECODED_BUF_SIZE + RANGE_PRINT_BUF_SIZE];
+ char *p = sym, *pend = sym + sizeof(sym);
+
+ struct printf_spec range_spec = {
+ .field_width = 2 + 2 * sizeof(range->start), /* 0x + 2 * 8 */
+ .flags = SPECIAL | SMALL | ZEROPAD,
+ .base = 16,
+ .precision = -1,
+ };
+
+ if (check_pointer(&buf, end, range, spec))
+ return buf;
+
+ *p++ = '[';
+ p = string_nocheck(p, pend, "range ", default_str_spec);
+ p = hex_range(p, pend, range->start, range->end, range_spec);
+ *p++ = ']';
+ *p = '\0';
+
+ return string_nocheck(buf, end, sym, spec);
+}
+
static noinline_for_stack
char *hex_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
const char *fmt)
@@ -2277,6 +2314,7 @@ char *rust_fmt_argument(char *buf, char *end, void *ptr);
* - 'Bb' as above with module build ID (for use in backtraces)
* - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]
* - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
+ * - 'ra' struct ranges [range 0x00 - 0xff]
* - 'b[l]' For a bitmap, the number of bits is determined by the field
* width which must be explicitly specified either as part of the
* format string '%32b[l]' or through '%*b[l]', [l] selects
@@ -2399,8 +2437,13 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
fallthrough;
case 'B':
return symbol_string(buf, end, ptr, spec, fmt);
- case 'R':
case 'r':
+ switch (fmt[1]) {
+ case 'a':
+ return range_string(buf, end, ptr, spec, fmt);
+ }
+ fallthrough;
+ case 'R':
return resource_string(buf, end, ptr, spec, fmt);
case 'h':
return hex_string(buf, end, ptr, spec, fmt);

--
2.46.0