From: Miguel Ojeda <ojeda@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
Jarkko Sakkinen <jarkko@kernel.org>,
Miguel Ojeda <ojeda@kernel.org>, Gary Guo <gary@garyguo.net>,
Kees Cook <keescook@chromium.org>, Petr Mladek <pmladek@suse.com>,
Alex Gaynor <alex.gaynor@gmail.com>,
Wedson Almeida Filho <wedsonaf@google.com>,
Steven Rostedt <rostedt@goodmis.org>,
Sergey Senozhatsky <senozhatsky@chromium.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Jonathan Corbet <corbet@lwn.net>,
linux-doc@vger.kernel.org
Subject: [PATCH v7 14/25] vsprintf: add new `%pA` format specifier
Date: Mon, 23 May 2022 04:01:27 +0200 [thread overview]
Message-ID: <20220523020209.11810-15-ojeda@kernel.org> (raw)
In-Reply-To: <20220523020209.11810-1-ojeda@kernel.org>
From: Gary Guo <gary@garyguo.net>
This patch adds a format specifier `%pA` to `vsprintf` which formats
a pointer as `core::fmt::Arguments`. Doing so allows us to directly
format to the internal buffer of `printf`, so we do not have to use
a temporary buffer on the stack to pre-assemble the message on
the Rust side.
This specifier is intended only to be used from Rust and not for C, so
`checkpatch.pl` is intentionally unchanged to catch any misuse.
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Petr Mladek <pmladek@suse.com>
Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Gary Guo <gary@garyguo.net>
Co-developed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
Documentation/core-api/printk-formats.rst | 10 ++++++++++
lib/vsprintf.c | 13 +++++++++++++
2 files changed, 23 insertions(+)
diff --git a/Documentation/core-api/printk-formats.rst b/Documentation/core-api/printk-formats.rst
index 5e89497ba314..dbe1aacc79d0 100644
--- a/Documentation/core-api/printk-formats.rst
+++ b/Documentation/core-api/printk-formats.rst
@@ -625,6 +625,16 @@ Examples::
%p4cc Y10 little-endian (0x20303159)
%p4cc NV12 big-endian (0xb231564e)
+Rust
+----
+
+::
+
+ %pA
+
+Only intended to be used from Rust code to format ``core::fmt::Arguments``.
+Do *not* use it from C.
+
Thanks
======
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 40d26a07a133..00f71f91d991 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -2270,6 +2270,9 @@ int __init no_hash_pointers_enable(char *str)
}
early_param("no_hash_pointers", no_hash_pointers_enable);
+/* Used for Rust formatting ('%pA'). */
+char *rust_fmt_argument(char *buf, char *end, void *ptr);
+
/*
* Show a '%p' thing. A kernel extension is that the '%p' is followed
* by an extra set of alphanumeric characters that are extended format
@@ -2396,6 +2399,10 @@ early_param("no_hash_pointers", no_hash_pointers_enable);
*
* Note: The default behaviour (unadorned %p) is to hash the address,
* rendering it useful as a unique identifier.
+ *
+ * There is also a '%pA' format specifier, but it is only intended to be used
+ * from Rust code to format core::fmt::Arguments. Do *not* use it from C.
+ * See rust/kernel/print.rs for details.
*/
static noinline_for_stack
char *pointer(const char *fmt, char *buf, char *end, void *ptr,
@@ -2468,6 +2475,12 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
return device_node_string(buf, end, ptr, spec, fmt + 1);
case 'f':
return fwnode_string(buf, end, ptr, spec, fmt + 1);
+ case 'A':
+ if (!IS_ENABLED(CONFIG_RUST)) {
+ WARN_ONCE(1, "Please remove %%pA from non-Rust code\n");
+ return error_string(buf, end, "(%pA?)", spec);
+ }
+ return rust_fmt_argument(buf, end, ptr);
case 'x':
return pointer_string(buf, end, ptr, spec);
case 'e':
--
2.36.1
next prev parent reply other threads:[~2022-05-23 2:05 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-23 2:01 [PATCH v7 00/25] Rust support Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 01/25] kallsyms: avoid hardcoding the buffer size Miguel Ojeda
2022-05-23 19:45 ` Jarkko Sakkinen
2022-05-23 19:55 ` Jarkko Sakkinen
2022-05-24 16:21 ` Miguel Ojeda
2022-05-26 4:54 ` Jarkko Sakkinen
2022-05-23 2:01 ` [PATCH v7 02/25] kallsyms: support "big" kernel symbols Miguel Ojeda
2022-05-23 20:30 ` Jarkko Sakkinen
2022-05-23 2:01 ` [PATCH v7 03/25] kallsyms: increase maximum kernel symbol length to 512 Miguel Ojeda
2022-05-23 20:31 ` Jarkko Sakkinen
2022-05-24 18:07 ` Miguel Ojeda
2022-05-27 16:25 ` Jarkko Sakkinen
2022-05-30 13:01 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 04/25] kunit: take `kunit_assert` as `const` Miguel Ojeda
2022-05-23 17:15 ` Daniel Latypov
2022-05-23 18:14 ` Shuah Khan
2022-05-24 12:37 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 05/25] rust: add C helpers Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 06/25] rust: add `compiler_builtins` crate Miguel Ojeda
2022-05-23 18:37 ` Nick Desaulniers
2022-05-23 23:41 ` Gary Guo
2022-05-25 21:29 ` Nick Desaulniers
2022-05-24 12:29 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 07/25] rust: import upstream `alloc` crate Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 08/25] rust: adapt `alloc` crate to the kernel Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 09/25] rust: add `build_error` crate Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 10/25] rust: add `macros` crate Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 11/25] rust: add `kernel` crate's `sync` module Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 12/25] rust: add `kernel` crate Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 13/25] rust: export generated symbols Miguel Ojeda
2022-05-23 2:01 ` Miguel Ojeda [this message]
2022-05-23 2:01 ` [PATCH v7 15/25] scripts: checkpatch: diagnose uses of `%pA` in the C side Miguel Ojeda
2022-05-23 2:17 ` Joe Perches
2022-05-24 16:35 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 16/25] scripts: checkpatch: enable language-independent checks for Rust Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 17/25] scripts: add `rustdoc_test_{builder,gen}.py` scripts Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 18/25] scripts: add `generate_rust_analyzer.py` scripts Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 19/25] scripts: decode_stacktrace: demangle Rust symbols Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 20/25] docs: add Rust documentation Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 21/25] Kbuild: add Rust support Miguel Ojeda
2022-05-23 18:44 ` Nick Desaulniers
2022-05-24 15:12 ` Miguel Ojeda
2022-05-25 22:25 ` Nick Desaulniers
2022-05-30 13:39 ` Miguel Ojeda
2022-07-16 8:21 ` Masahiro Yamada
2022-07-16 8:57 ` Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 22/25] samples: add Rust examples Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 23/25] MAINTAINERS: Rust Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 24/25] [RFC] drivers: gpio: PrimeCell PL061 in Rust Miguel Ojeda
2022-05-23 2:01 ` [PATCH v7 25/25] [RFC] drivers: android: Binder IPC " Miguel Ojeda
2022-07-16 12:42 ` [PATCH v7 00/25] Rust support Conor Dooley
2022-07-16 13:36 ` Miguel Ojeda
2022-07-16 13:51 ` Conor.Dooley
2022-07-16 13:56 ` Miguel Ojeda
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