[PATCH v2 1/1] kernel.h: Split out COUNT_ARGS() and CONCATENATE() to args.h

From: Andy Shevchenko
Date: Fri Jul 14 2023 - 10:22:49 EST

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kernel.h is being used as a dump for all kinds of stuff for a long time.
The COUNT_ARGS() and CONCATENATE() macros may be used in some places
without need of the full kernel.h dependency train with it.

Here is the attempt on cleaning it up by splitting out these macros().

While at it, include new header where it's being used and drop custom
implementation of these macros and document how it works.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
v2: converted existing users at the same time, documented (Andrew, Rasmus)
arch/x86/include/asm/rmwcc.h | 11 +++--------
include/kunit/test.h | 1 +
include/linux/args.h | 28 ++++++++++++++++++++++++++++
include/linux/arm-smccc.h | 27 ++++++++++-----------------
include/linux/genl_magic_struct.h | 8 +++-----
include/linux/kernel.h | 7 -------
include/linux/pci.h | 2 +-
include/trace/bpf_probe.h | 2 ++
8 files changed, 48 insertions(+), 38 deletions(-)
create mode 100644 include/linux/args.h

diff --git a/arch/x86/include/asm/rmwcc.h b/arch/x86/include/asm/rmwcc.h
index 7fa611216417..4b081e0d3306 100644
--- a/arch/x86/include/asm/rmwcc.h
+++ b/arch/x86/include/asm/rmwcc.h
@@ -2,12 +2,7 @@
#ifndef _ASM_X86_RMWcc
#define _ASM_X86_RMWcc

-/* This counts to 12. Any more, it will return 13th argument. */
-#define __RMWcc_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _n, X...) _n
-#define RMWcc_ARGS(X...) __RMWcc_ARGS(, ##X, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
-
-#define __RMWcc_CONCAT(a, b) a ## b
-#define RMWcc_CONCAT(a, b) __RMWcc_CONCAT(a, b)
+#include <linux/args.h>

#define __CLOBBERS_MEM(clb...) "memory", ## clb

@@ -48,7 +43,7 @@ cc_label: c = true; \
#define GEN_UNARY_RMWcc_3(op, var, cc) \
GEN_UNARY_RMWcc_4(op, var, cc, "%[var]")

-#define GEN_UNARY_RMWcc(X...) RMWcc_CONCAT(GEN_UNARY_RMWcc_, RMWcc_ARGS(X))(X)
+#define GEN_UNARY_RMWcc(X...) CONCATENATE(GEN_UNARY_RMWcc_, COUNT_ARGS(X))(X)

#define GEN_BINARY_RMWcc_6(op, var, cc, vcon, _val, arg0) \
__GEN_RMWcc(op " %[val], " arg0, var, cc, \
@@ -57,7 +52,7 @@ cc_label: c = true; \
#define GEN_BINARY_RMWcc_5(op, var, cc, vcon, val) \
GEN_BINARY_RMWcc_6(op, var, cc, vcon, val, "%[var]")

-#define GEN_BINARY_RMWcc(X...) RMWcc_CONCAT(GEN_BINARY_RMWcc_, RMWcc_ARGS(X))(X)
+#define GEN_BINARY_RMWcc(X...) CONCATENATE(GEN_BINARY_RMWcc_, COUNT_ARGS(X))(X)

#define GEN_UNARY_SUFFIXED_RMWcc(op, suffix, var, cc, clobbers...) \
__GEN_RMWcc(op " %[var]\n\t" suffix, var, cc, \
diff --git a/include/kunit/test.h b/include/kunit/test.h
index 23120d50499e..107c81431634 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -12,6 +12,7 @@
#include <kunit/assert.h>
#include <kunit/try-catch.h>

+#include <linux/args.h>
#include <linux/compiler.h>
#include <linux/container_of.h>
#include <linux/err.h>
diff --git a/include/linux/args.h b/include/linux/args.h
new file mode 100644
index 000000000000..8ff60a54eb7d
--- /dev/null
+++ b/include/linux/args.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_ARGS_H
+#define _LINUX_ARGS_H
+
+/*
+ * How do these macros work?
+ *
+ * In __COUNT_ARGS() _0 to _12 are just placeholders from the start
+ * in order to make sure _n is positioned over the correct number
+ * from 12 to 0 (depending on X, which is a variadic argument list).
+ * They serve no purpose other than occupying a position. Since each
+ * macro parameter must have a distinct identifier, those identifiers
+ * are as good as any.
+ *
+ * In COUNT_ARGS() we use actual integers, so __COUNT_ARGS() returns
+ * that as _n.
+ */
+
+/* This counts to 12. Any more, it will return 13th argument. */
+#define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _n, X...) _n
+#define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+
+/* Concatenate two parameters, but allow them to be expanded beforehand. */
+#define __CONCAT(a, b) a ## b
+#define CONCATENATE(a, b) __CONCAT(a, b)
+
+#endif /* _LINUX_ARGS_H */
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index f196c19f8e55..2865b14c2bba 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -5,6 +5,7 @@
#ifndef __LINUX_ARM_SMCCC_H
#define __LINUX_ARM_SMCCC_H

+#include <linux/args.h>
#include <linux/init.h>
#include <uapi/linux/const.h>

@@ -413,11 +414,6 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,

#endif

-#define ___count_args(_0, _1, _2, _3, _4, _5, _6, _7, _8, x, ...) x
-
-#define __count_args(...) \
- ___count_args(__VA_ARGS__, 7, 6, 5, 4, 3, 2, 1, 0)
-
#define __constraint_read_0 "r" (arg0)
#define __constraint_read_1 __constraint_read_0, "r" (arg1)
#define __constraint_read_2 __constraint_read_1, "r" (arg2)
@@ -475,14 +471,6 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
__declare_arg_6(a0, a1, a2, a3, a4, a5, a6, res); \
register typeof(a7) arg7 asm("r7") = __a7

-#define ___declare_args(count, ...) __declare_arg_ ## count(__VA_ARGS__)
-#define __declare_args(count, ...) ___declare_args(count, __VA_ARGS__)
-
-#define ___constraints(count) \
- : __constraint_read_ ## count \
- : smccc_sve_clobbers "memory"
-#define __constraints(count) ___constraints(count)
-
/*
* We have an output list that is not necessarily used, and GCC feels
* entitled to optimise the whole sequence away. "volatile" is what
@@ -494,11 +482,13 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
register unsigned long r1 asm("r1"); \
register unsigned long r2 asm("r2"); \
register unsigned long r3 asm("r3"); \
- __declare_args(__count_args(__VA_ARGS__), __VA_ARGS__); \
+ CONCATENATE(__declare_arg_, COUNT_ARGS(__VA_ARGS__)); \
asm volatile(SMCCC_SVE_CHECK \
inst "\n" : \
"=r" (r0), "=r" (r1), "=r" (r2), "=r" (r3) \
- __constraints(__count_args(__VA_ARGS__))); \
+ : CONCATENATE(__constraint_read_, \
+ COUNT_ARGS(__VA_ARGS__)) \
+ : smccc_sve_clobbers "memory"); \
if (___res) \
*___res = (typeof(*___res)){r0, r1, r2, r3}; \
} while (0)
@@ -542,8 +532,11 @@ asmlinkage void __arm_smccc_hvc(unsigned long a0, unsigned long a1,
*/
#define __fail_smccc_1_1(...) \
do { \
- __declare_args(__count_args(__VA_ARGS__), __VA_ARGS__); \
- asm ("" : __constraints(__count_args(__VA_ARGS__))); \
+ CONCATENATE(__declare_arg_, COUNT_ARGS(__VA_ARGS__)); \
+ asm ("" : \
+ : CONCATENATE(__constraint_read_, \
+ COUNT_ARGS(__VA_ARGS__)) \
+ : smccc_sve_clobbers "memory"); \
if (___res) \
___res->a0 = SMCCC_RET_NOT_SUPPORTED; \
} while (0)
diff --git a/include/linux/genl_magic_struct.h b/include/linux/genl_magic_struct.h
index f81d48987528..a419d93789ff 100644
--- a/include/linux/genl_magic_struct.h
+++ b/include/linux/genl_magic_struct.h
@@ -14,14 +14,12 @@
# error "you need to define GENL_MAGIC_INCLUDE_FILE before inclusion"
#endif

+#include <linux/args.h>
#include <linux/genetlink.h>
#include <linux/types.h>

-#define CONCAT__(a,b) a ## b
-#define CONCAT_(a,b) CONCAT__(a,b)
-
-extern int CONCAT_(GENL_MAGIC_FAMILY, _genl_register)(void);
-extern void CONCAT_(GENL_MAGIC_FAMILY, _genl_unregister)(void);
+extern int CONCATENATE(GENL_MAGIC_FAMILY, _genl_register)(void);
+extern void CONCATENATE(GENL_MAGIC_FAMILY, _genl_unregister)(void);

/*
* Extension of genl attribute validation policies {{{2
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 0b00e1aef33d..15d9496db169 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -419,13 +419,6 @@ ftrace_vprintk(const char *fmt, va_list ap)
static inline void ftrace_dump(enum ftrace_dump_mode oops_dump_mode) { }
#endif /* CONFIG_TRACING */

-/* This counts to 12. Any more, it will return 13th argument. */
-#define __COUNT_ARGS(_0, _1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _n, X...) _n
-#define COUNT_ARGS(X...) __COUNT_ARGS(, ##X, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
-
-#define __CONCAT(a, b) a ## b
-#define CONCATENATE(a, b) __CONCAT(a, b)
-
/* Rebuild everything on CONFIG_FTRACE_MCOUNT_RECORD */
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
# define REBUILD_DUE_TO_FTRACE_MCOUNT_RECORD
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 0ff7500772e6..eeb2e6f6130f 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -23,7 +23,7 @@
#ifndef LINUX_PCI_H
#define LINUX_PCI_H

-
+#include <linux/args.h>
#include <linux/mod_devicetable.h>

#include <linux/types.h>
diff --git a/include/trace/bpf_probe.h b/include/trace/bpf_probe.h
index 1f7fc1fc590c..e609cd7da47e 100644
--- a/include/trace/bpf_probe.h
+++ b/include/trace/bpf_probe.h
@@ -12,6 +12,8 @@
#undef __perf_task
#define __perf_task(t) (t)

+#include <linux/args.h>
+
/* cast any integer, pointer, or small struct to u64 */
#define UINTTYPE(size) \
__typeof__(__builtin_choose_expr(size == 1, (u8)1, \
--
2.40.0.1.gaa8946217a0b

Next message: Tobias Huschle: "Re: [Patch v3 3/6] sched/fair: Implement prefer sibling imbalance calculation between asymmetric groups"
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