rcutorture: minor nolibc fixes

A few macros had their rightmost backslash misaligned, and the pollfd struct definition resisted the previous code reindent. Nothing else changed.

Cc Paul E. McKenney <[email protected]>

Signed-off-by Willy Tarreau <[email protected]>

---
 tools/testing/selftests/rcutorture/bin/nolibc.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

tools/testing/selftests/rcutorture/bin/nolibc.h +7 -7

index 30bd27b..985364c 100644
@@ -81,9 +81,9 @@ typedef   signed long        time_t;
 
 /* for poll() */
 struct pollfd {
-    int fd;
-    short int events;
-    short int revents;
+	int fd;
+	short int events;
+	short int revents;
 };
 
 /* for select() */

@@ -239,7 +239,7 @@ struct stat {
 		"syscall\n"                                                   \
 		: "=a" (_ret)                                                 \
 		: "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })

@@ -255,7 +255,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1),                                                 \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })

@@ -272,7 +272,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1), "r"(_arg2),                                     \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })

@@ -290,7 +290,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1), "r"(_arg2), "r"(_arg3),                         \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })

Signature · 1 line

2.9.0

Quoted 6 lines · Willy Tarreau

A few macros had their rightmost backslash misaligned, and the pollfd struct definition resisted the previous code reindent. Nothing else changed.

Cc Paul E. McKenney <[email protected]>

Signed-off-by Willy Tarreau <[email protected]>

Reviewed-by Joey Pabalinas <[email protected]>

Quoted 60 lines

---
 tools/testing/selftests/rcutorture/bin/nolibc.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

tools/testing/selftests/rcutorture/bin/nolibc.h +7 -7

index 30bd27b..985364c 100644
@@ -81,9 +81,9 @@ typedef   signed long        time_t;
 
 /* for poll() */
 struct pollfd {
-    int fd;
-    short int events;
-    short int revents;
+	int fd;
+	short int events;
+	short int revents;
 };
 
 /* for select() */

@@ -239,7 +239,7 @@ struct stat {
 		"syscall\n"                                                   \
 		: "=a" (_ret)                                                 \
 		: "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })

@@ -255,7 +255,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1),                                                 \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })

@@ -272,7 +272,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1), "r"(_arg2),                                     \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })

@@ -290,7 +290,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1), "r"(_arg2), "r"(_arg3),                         \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })

Signature · 1 line

2.9.0

Signature · 2 lines

Cheers,
Joey Pabalinas

+ * - the lower level is the arch-specific syscall() definition, consisting in

+ *     assembly code in compound expressions. These are called my_syscall0() to
+ *     my_syscall6() depending on the number of arguments. The MIPS
+ *     implementation is limited to 5 arguments. All input arguments are cast
+ *     to a long stored in a register. These expressions always return the
+ *     syscall's return value as a signed long value which is often either a
+ *     pointer or the negated errno value.
+ *
+ *   - the second level is mostly architecture-independent. It is made of
+ *     static functions called sys_<name>() which rely on my_syscallN()
+ *     depending on the syscall definition. These functions are responsible
+ *     for exposing the appropriate types for the syscall arguments (int,
+ *     pointers, etc) and for setting the appropriate return type (often int).
+ *     A few of them are architecture-specific because the syscalls are not all
+ *     mapped exactly the same among architectures. For example, some archs do

+ *     not implement select() and need pselect6() instead, so the sys_select()
+ *     function will have to abstract this.
+ *
+ *   - the third level is the libc call definition. It exposes the lower raw
+ *     sys_<name>() calls in a way that looks like what a libc usually does,
+ *     takes care of specific input values, and of setting errno upon error.
+ *     There can be minor variations compared to standard libc calls. For
+ *     example the open() call always takes 3 args here.

/* some archs (at least aarch64) don't expose the regular syscalls anymore by
* default, either because they have an "_at" replacement, or because there are
* more modern alternatives. For now we'd rather still use them.

Quoted 15 lines · Willy Tarreau

+ * - the lower level is the arch-specific syscall() definition, consisting in

+ *     assembly code in compound expressions. These are called my_syscall0() to
+ *     my_syscall6() depending on the number of arguments. The MIPS
+ *     implementation is limited to 5 arguments. All input arguments are cast
+ *     to a long stored in a register. These expressions always return the
+ *     syscall's return value as a signed long value which is often either a
+ *     pointer or the negated errno value.
+ *
+ *   - the second level is mostly architecture-independent. It is made of
+ *     static functions called sys_<name>() which rely on my_syscallN()
+ *     depending on the syscall definition. These functions are responsible
+ *     for exposing the appropriate types for the syscall arguments (int,
+ *     pointers, etc) and for setting the appropriate return type (often int).
+ *     A few of them are architecture-specific because the syscalls are not all
+ *     mapped exactly the same among architectures. For example, some archs do

Quoted 8 lines

+ *     not implement select() and need pselect6() instead, so the sys_select()
+ *     function will have to abstract this.
+ *
+ *   - the third level is the libc call definition. It exposes the lower raw
+ *     sys_<name>() calls in a way that looks like what a libc usually does,
+ *     takes care of specific input values, and of setting errno upon error.
+ *     There can be minor variations compared to standard libc calls. For
+ *     example the open() call always takes 3 args here.

Shouldn't these sentences begin with a capitalized "The" for consistency?

Quoted 3 lines

/* some archs (at least aarch64) don't expose the regular syscalls anymore by
* default, either because they have an "_at" replacement, or because there are
* more modern alternatives. For now we'd rather still use them.

Also here. Shouldn't this begin with a capitalized "Some"?

Definitely! Same, I won't emit a patch just for this, Paul already queued it.

Quoted 1 line · Willy Tarreau

Definitely! Same, I won't emit a patch just for this, Paul already queued it.

Yeah, not that big a deal :)

Reviewed-by Joey Pabalinas <[email protected]>

The English rules for capitalization and lists are baroque and completely unsuited to word processors ("If any list item is longer than one line, capitalize all the items."), but in this case each item has multiple sentences, so it makes sense to capitalize.

Please see below for the updated commit, and thank you all!

And Happy New Year!!! ;-)

Quoted 6 lines · Joey Pabalinas

Quoted 1 line · Willy Tarreau

Definitely! Same, I won't emit a patch just for this, Paul already queued it.

Yeah, not that big a deal :)

Reviewed-by Joey Pabalinas <[email protected]>

But as long as I am rebasing to add the Reviewed-by, might as well update the others.

The English rules for capitalization and lists are baroque and completely unsuited to word processors ("If any list item is longer than one line, capitalize all the items."), but in this case each item has multiple sentences, so it makes sense to capitalize.

Please see below for the updated commit, and thank you all!

And Happy New Year!!! ;-)

Quoted 11 lines · Paul E. McKenney

Quoted 6 lines · Joey Pabalinas

Quoted 1 line · Willy Tarreau

Definitely! Same, I won't emit a patch just for this, Paul already queued it.

Yeah, not that big a deal :)

Reviewed-by Joey Pabalinas <[email protected]>

But as long as I am rebasing to add the Reviewed-by, might as well update the others.

Quoted 6 lines

The English rules for capitalization and lists are baroque and completely unsuited to word processors ("If any list item is longer than one line, capitalize all the items."), but in this case each item has multiple sentences, so it makes sense to capitalize.

Please see below for the updated commit, and thank you all!

Interesting, I had no idea it was actually that odd, hah.

Ingo rightfully asked for a bit more documentation in the nolibc header, so this patch adds some explanation about its purpose, how it's made, and how to use it.

Cc Ingo Molnar <[email protected]>

Cc Paul E. McKenney <[email protected]>

Cc Randy Dunlap <[email protected]>

Signed-off-by Willy Tarreau <[email protected]>

---
 tools/testing/selftests/rcutorture/bin/nolibc.h | 90 +++++++++++++++++++++----
 1 file changed, 78 insertions(+), 12 deletions(-)

tools/testing/selftests/rcutorture/bin/nolibc.h +78 -12

index 985364c..6643ba9 100644
@@ -3,6 +3,84 @@
  * Copyright (C) 2017-2018 Willy Tarreau <[email protected]>
  */
 
+/*
+ * This file is designed to be used as a libc alternative for minimal programs
+ * with very limited requirements. It consists of a small number of syscall and
+ * type definitions, and the minimal startup code needed to call main().
+ * All syscalls are declared as static functions so that they can be optimized
+ * away by the compiler when not used.
+ *
+ * Syscalls are split into 3 levels:
+ *   - the lower level is the arch-specific syscall() definition, consisting in
+ *     assembly code in compound expressions. These are called my_syscall0() to
+ *     my_syscall6() depending on the number of arguments. The MIPS
+ *     implementation is limited to 5 arguments. All input arguments are cast
+ *     to a long stored in a register. These expressions always return the
+ *     syscall's return value as a signed long value which is often either a
+ *     pointer or the negated errno value.
+ *
+ *   - the second level is mostly architecture-independent. It is made of
+ *     static functions called sys_<name>() which rely on my_syscallN()
+ *     depending on the syscall definition. These functions are responsible
+ *     for exposing the appropriate types for the syscall arguments (int,
+ *     pointers, etc) and for setting the appropriate return type (often int).
+ *     A few of them are architecture-specific because the syscalls are not all
+ *     mapped exactly the same among architectures. For example, some archs do
+ *     not implement select() and need pselect6() instead, so the sys_select()
+ *     function will have to abstract this.
+ *
+ *   - the third level is the libc call definition. It exposes the lower raw
+ *     sys_<name>() calls in a way that looks like what a libc usually does,
+ *     takes care of specific input values, and of setting errno upon error.
+ *     There can be minor variations compared to standard libc calls. For
+ *     example the open() call always takes 3 args here.
+ *
+ * The errno variable is declared static and unused. This way it can be
+ * optimized away if not used. However this means that a program made of
+ * multiple C files may observe different errno values (one per C file). For
+ * the type of programs this project targets it usually is not a problem. The
+ * resulting program may even be reduced by defining the NOLIBC_IGNORE_ERRNO
+ * macro, in which case the errno value will never be assigned.
+ *
+ * Some stdint-like integer types are defined. These are valid on all currently
+ * supported architectures, because signs are enforced, ints are assumed to be
+ * 32 bits, longs the size of a pointer and long long 64 bits. If more
+ * architectures have to be supported, this may need to be adapted.
+ *
+ * Some macro definitions like the O_* values passed to open(), and some
+ * structures like the sys_stat struct depend on the architecture.
+ *
+ * The definitions start with the architecture-specific parts, which are picked
+ * based on what the compiler knows about the target architecture, and are
+ * completed with the generic code. Since it is the compiler which sets the
+ * target architecture, cross-compiling normally works out of the box without
+ * having to specify anything.
+ *
+ * Finally some very common libc-level functions are provided. It is the case
+ * for a few functions usually found in string.h, ctype.h, or stdlib.h. Nothing
+ * is currently provided regarding stdio emulation.
+ *
+ * The macro NOLIBC is always defined, so that it is possible for a program to
+ * check this macro to know if it is being built against and decide to disable
+ * some features or simply not to include some standard libc files.
+ *
+ * Ideally this file should be split in multiple files for easier long term
+ * maintenance, but provided as a single file as it is now, it's quite
+ * convenient to use. Maybe some variations involving a set of includes at the
+ * top could work.
+ *
+ * A simple static executable may be built this way :
+ *      $ gcc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \
+ *            -static -include nolibc.h -lgcc -o hello hello.c
+ *
+ * A very useful calling convention table may be found here :
+ *      http://man7.org/linux/man-pages/man2/syscall.2.html
+ *
+ * This doc is quite convenient though not necessarily up to date :
+ *      https://w3challs.com/syscalls/
+ *
+ */
+
 /* some archs (at least aarch64) don't expose the regular syscalls anymore by
  * default, either because they have an "_at" replacement, or because there are
  * more modern alternatives. For now we'd rather still use them.

@@ -19,18 +97,6 @@
 
 #define NOLIBC
 
-/* Build a static executable this way :
- *      $ gcc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \
- *            -static -include nolibc.h -lgcc -o hello hello.c
- *
- * Useful calling convention table found here :
- *      http://man7.org/linux/man-pages/man2/syscall.2.html
- *
- * This doc is even better :
- *      https://w3challs.com/syscalls/
- */
-
-
 /* this way it will be removed if unused */
 static int errno;