tools/nolibc: add stdarg.h header

This allows nolic to work with `-nostdinc` avoiding any reliance on
system headers.

The implementation has been lifted from musl libc 1.2.4.
There is already an implementation of stdarg.h in include/linux/stdarg.h
but that is GPL licensed and therefore not suitable for nolibc.

The used compiler builtins have been validated to be at least available
since GCC 4.1.2 and clang 3.0.0.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

tools/nolibc: add missing my_syscall6() for mips

It is able to pass the 6th argument like the 5th argument via the stack
for mips, let's add a new my_syscall6() now, see [1] for details:

The mips/o32 system call convention passes arguments 5 through 8 on
the user stack.

Both mmap() and pselect6() require my_syscall6().

[1]: https://man7.org/linux/man-pages/man2/syscall.2.html

Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

tools/nolibc: Fix build of stdio.h due to header ordering

When we added fd based file streams we created references to STx_FILENO in
stdio.h but these constants are declared in unistd.h which is the last file
included by the top level nolibc.h meaning those constants are not defined
when we try to build stdio.h. This causes programs using nolibc.h to fail
to build.

Reorder the headers to avoid this issue.

Fixes: d449546c957f ("tools/nolibc: implement fd-based FILE streams")
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: add support for stack protector

This is useful when using nolibc for security-critical tools.
Using nolibc has the advantage that the code is easily auditable and
sandboxable with seccomp as no unexpected syscalls are used.
Using compiler-assistent stack protection provides another security
mechanism.

For this to work the compiler and libc have to collaborate.

This patch adds the following parts to nolibc that are required by the
compiler:

* __stack_chk_guard: random sentinel value
* __stack_chk_fail: handler for detected stack smashes

In addition an initialization function is added that randomizes the
sentinel value.

Only support for global guards is implemented.
Register guards are useful in multi-threaded context which nolibc does
not provide support for.

Link: https://lwn.net/Articles/584225/

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: also mention how to build by just setting the include path

Now that a few basic include files are provided, some simple portable
programs may build, which will save them from having to surround their
includes with #ifndef NOLIBC. This patch mentions how to proceed, and
enumerates the list of files that are covered.

A comprehensive list of required include files is available here:

https://en.cppreference.com/w/c/header

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/time: create time.h with time()

The time() syscall is used by a few simple applications, and is trivial
to implement based on gettimeofday() that we already have. Let's create
the file to ease porting and provide the function. It never returns any
error, though it may segfault in case of invalid pointer, like other
implementations relying on gettimeofday().

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/signal: move raise() to signal.h

This function is normally found in signal.h, and providing the file
eases porting of existing programs. Let's move it there.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/unistd: extract msleep(), sleep(), tcsetpgrp() to unistd.h

These functions are normally provided by unistd.h. For ease of porting,
let's create the file and move them there.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/stdio: add a minimal set of stdio functions

This only provides getchar(), putchar(), and puts().

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/stdlib: move ltoa() to stdlib.h

This function is not standard and performs the opposite of atol(). Let's
move it with atol(). It's been split between a reentrant function and one
using a static buffer.

There's no more definition in nolibc.h anymore now.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/types: move makedev to types.h and make it a macro

The makedev() man page says it's supposed to be a macro and that some
OSes have it with the other ones in sys/types.h so it now makes sense
to move it to types.h as a macro. Let's also define major() and
minor() that perform the reverse operation.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/types: move the FD_* functions to macros in types.h

FD_SET, FD_CLR, FD_ISSET, FD_ZERO are often expected to be macros and
not functions. In addition we already have a file dedicated to such
macros and types used by syscalls, it's types.h, so let's move them
there and turn them to macros. FD_CLR() and FD_ISSET() were missing,
so they were added. FD_ZERO() now deals with its own loop so that it
doesn't rely on memset() that sets one byte at a time.

Cc: David Laight <David.Laight@aculab.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/ctype: split the is* functions to ctype.h

In fact there's only isdigit() for now. More should definitely be added.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/string: split the string functions into string.h

The string manipulation functions (mem*, str*) are now found in
string.h. The file depends on almost nothing and will be
usable from other includes if needed. Maybe more functions could
be added.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/stdlib: extract the stdlib-specific functions to their own file

The new file stdlib.h contains the definitions of functions that
are usually found in stdlib.h. Many more could certainly be added.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/sys: split the syscall definitions into their own file

The syscall definitions were moved to sys.h. They were arranged
in a more easily maintainable order, whereby the sys_xxx() and xxx()
functions were grouped together, which also enlights the occasional
mappings such as wait relying on wait4().

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/arch: split arch-specific code into individual files

In order to ease maintenance, this splits the arch-specific code into
one file per architecture. A common file "arch.h" is used to include the
right file among arch-* based on the detected architecture. Projects
which are already split per architecture could simply rename these
files to $arch/arch.h and get rid of the common arch.h. For this
reason, include guards were placed into each arch-specific file.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/types: split syscall-specific definitions into their own files

The macros and type definitions used by a number of syscalls were moved
to types.h where they will be easier to maintain. A few of them
are arch-specific and must not be moved there (e.g. O_*, sys_stat_struct).
A warning about them was placed at the top of the file.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc/std: move the standard type definitions to std.h

The ordering of includes and definitions for now is a bit of a mess, as
for example asm/signal.h is included after int definitions, but plenty of
structures are defined later as they rely on other includes.

Let's move the standard type definitions to a dedicated file that is
included first. We also move NULL there. This way all other includes
are aware of it, and we can bring asm/signal.h back to the top of the
file.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: guard the main file against multiple inclusion

Including nolibc.h multiple times results in build errors due to multiple
definitions. Let's add a guard against multiple inclusions.

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: use pselect6 on RISCV

This arch doesn't provide the old-style select() syscall, we have to
use pselect6().

Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Implement gettid()

Allow test programs to determine their thread ID.

Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: x86-64: Use `mov $60,%eax` instead of `mov $60,%rax`

Note that mov to 32-bit register will zero extend to 64-bit register.
Thus `mov $60,%eax` has the same effect with `mov $60,%rax`. Use the
shorter opcode to achieve the same thing.
```
b8 3c 00 00 00 mov $60,%eax (5 bytes) [1]
48 c7 c0 3c 00 00 00 mov $60,%rax (7 bytes) [2]
```
Currently, we use [2]. Change it to [1] for shorter code.

Signed-off-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: x86: Remove `r8`, `r9` and `r10` from the clobber list

Linux x86-64 syscall only clobbers rax, rcx and r11 (and "memory").

- rax for the return value.
- rcx to save the return address.
- r11 to save the rflags.

Other registers are preserved.

Having r8, r9 and r10 in the syscall clobber list is harmless, but this
results in a missed-optimization.

As the syscall doesn't clobber r8-r10, GCC should be allowed to reuse
their value after the syscall returns to userspace. But since they are
in the clobber list, GCC will always miss this opportunity.

Remove them from the x86-64 syscall clobber list to help GCC generate
better code and fix the comment.

See also the x86-64 ABI, section A.2 AMD64 Linux Kernel Conventions,
A.2.1 Calling Conventions [1].

Extra note:
Some people may think it does not really give a benefit to remove r8,
r9 and r10 from the syscall clobber list because the impression of
syscall is a C function call, and function call always clobbers those 3.

However, that is not the case for nolibc.h, because we have a potential
to inline the "syscall" instruction (which its opcode is "0f 05") to the
user functions.

All syscalls in the nolibc.h are written as a static function with inline
ASM and are likely always inline if we use optimization flag, so this is
a profit not to have r8, r9 and r10 in the clobber list.

Here is the example where this matters.

Consider the following C code:
```
#include "tools/include/nolibc/nolibc.h"
#define read_abc(a, b, c) __asm__ volatile("nop"::"r"(a),"r"(b),"r"(c))

int main(void)
{
int a = 0xaa;
int b = 0xbb;
int c = 0xcc;

read_abc(a, b, c);
write(1, "test\n", 5);
read_abc(a, b, c);

return 0;
}
```

Compile with:
gcc -Os test.c -o test -nostdlib

With r8, r9, r10 in the clobber list, GCC generates this:

0000000000001000 <main>:
1000: f3 0f 1e fa endbr64
1004: 41 54 push %r12
1006: 41 bc cc 00 00 00 mov $0xcc,%r12d
100c: 55 push %rbp
100d: bd bb 00 00 00 mov $0xbb,%ebp
1012: 53 push %rbx
1013: bb aa 00 00 00 mov $0xaa,%ebx
1018: 90 nop
1019: b8 01 00 00 00 mov $0x1,%eax
101e: bf 01 00 00 00 mov $0x1,%edi
1023: ba 05 00 00 00 mov $0x5,%edx
1028: 48 8d 35 d1 0f 00 00 lea 0xfd1(%rip),%rsi
102f: 0f 05 syscall
1031: 90 nop
1032: 31 c0 xor %eax,%eax
1034: 5b pop %rbx
1035: 5d pop %rbp
1036: 41 5c pop %r12
1038: c3 ret

GCC thinks that syscall will clobber r8, r9, r10. So it spills 0xaa,
0xbb and 0xcc to callee saved registers (r12, rbp and rbx). This is
clearly extra memory access and extra stack size for preserving them.

But syscall does not actually clobber them, so this is a missed
optimization.

Now without r8, r9, r10 in the clobber list, GCC generates better code:

0000000000001000 <main>:
1000: f3 0f 1e fa endbr64
1004: 41 b8 aa 00 00 00 mov $0xaa,%r8d
100a: 41 b9 bb 00 00 00 mov $0xbb,%r9d
1010: 41 ba cc 00 00 00 mov $0xcc,%r10d
1016: 90 nop
1017: b8 01 00 00 00 mov $0x1,%eax
101c: bf 01 00 00 00 mov $0x1,%edi
1021: ba 05 00 00 00 mov $0x5,%edx
1026: 48 8d 35 d3 0f 00 00 lea 0xfd3(%rip),%rsi
102d: 0f 05 syscall
102f: 90 nop
1030: 31 c0 xor %eax,%eax
1032: c3 ret

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: David Laight <David.Laight@ACULAB.COM>
Acked-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id>
Link: https://gitlab.com/x86-psABIs/x86-64-ABI/-/wikis/x86-64-psABI [1]
Link: https://lore.kernel.org/lkml/20211011040344.437264-1-ammar.faizi@students.amikom.ac.id/
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: fix incorrect truncation of exit code

Ammar Faizi reported that our exit code handling is wrong. We truncate
it to the lowest 8 bits but the syscall itself is expected to take a
regular 32-bit signed integer, not an unsigned char. It's the kernel
that later truncates it to the lowest 8 bits. The difference is visible
in strace, where the program below used to show exit(255) instead of
exit(-1):

int main(void)
{
return -1;
}

This patch applies the fix to all archs. x86_64, i386, arm64, armv7 and
mips were all tested and confirmed to work fine now. Risc-v was not
tested but the change is trivial and exactly the same as for other archs.

Reported-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id>
Cc: stable@vger.kernel.org
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: i386: fix initial stack alignment

After re-checking in the spec and comparing stack offsets with glibc,
The last pushed argument must be 16-byte aligned (i.e. aligned before the
call) so that in the callee esp+4 is multiple of 16, so the principle is
the 32-bit equivalent to what Ammar fixed for x86_64. It's possible that
32-bit code using SSE2 or MMX could have been affected. In addition the
frame pointer ought to be zero at the deepest level.

Link: https://gitlab.com/x86-psABIs/i386-ABI/-/wikis/Intel386-psABI
Cc: Ammar Faizi <ammar.faizi@students.amikom.ac.id>
Cc: stable@vger.kernel.org
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: x86-64: Fix startup code bug

Before this patch, the `_start` function looks like this:
```
0000000000001170 <_start>:
1170: pop %rdi
1171: mov %rsp,%rsi
1174: lea 0x8(%rsi,%rdi,8),%rdx
1179: and $0xfffffffffffffff0,%rsp
117d: sub $0x8,%rsp
1181: call 1000 <main>
1186: movzbq %al,%rdi
118a: mov $0x3c,%rax
1191: syscall
1193: hlt
1194: data16 cs nopw 0x0(%rax,%rax,1)
119f: nop
```
Note the "and" to %rsp with $-16, it makes the %rsp be 16-byte aligned,
but then there is a "sub" with $0x8 which makes the %rsp no longer
16-byte aligned, then it calls main. That's the bug!

What actually the x86-64 System V ABI mandates is that right before the
"call", the %rsp must be 16-byte aligned, not after the "call". So the
"sub" with $0x8 here breaks the alignment. Remove it.

An example where this rule matters is when the callee needs to align
its stack at 16-byte for aligned move instruction, like `movdqa` and
`movaps`. If the callee can't align its stack properly, it will result
in segmentation fault.

x86-64 System V ABI also mandates the deepest stack frame should be
zero. Just to be safe, let's zero the %rbp on startup as the content
of %rbp may be unspecified when the program starts. Now it looks like
this:
```
0000000000001170 <_start>:
1170: pop %rdi
1171: mov %rsp,%rsi
1174: lea 0x8(%rsi,%rdi,8),%rdx
1179: xor %ebp,%ebp # zero the %rbp
117b: and $0xfffffffffffffff0,%rsp # align the %rsp
117f: call 1000 <main>
1184: movzbq %al,%rdi
1188: mov $0x3c,%rax
118f: syscall
1191: hlt
1192: data16 cs nopw 0x0(%rax,%rax,1)
119d: nopl (%rax)
```

Cc: Bedirhan KURT <windowz414@gnuweeb.org>
Cc: Louvian Lyndal <louvianlyndal@gmail.com>
Reported-by: Peter Cordes <peter@cordes.ca>
Signed-off-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id>
[wt: I did this on purpose due to a misunderstanding of the spec, other
archs will thus have to be rechecked, particularly i386]
Cc: stable@vger.kernel.org
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Implement msleep()

Allow users to implement shorter delays than a full second by implementing
msleep().

Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools: include: nolibc: Fix a typo occured to occurred in the file nolibc.h

s/occured/occurred/

Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Fix position of -lgcc in the documented example

The documentation header in the nolibc.h file provides an example command
line, but it places the -lgcc argument before the source files, which
can fail with libgcc.a (e.g. on ARM when uidiv is needed). This commit
therefore moves the -lgcc to the end of the command line, hopefully
before this example leaks into makefiles. This is a port of nolibc's
upstream commit b5e282089223 to the Linux kernel.

Fixes: 66b6f755ad45 ("rcutorture: Import a copy of nolibc")
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Emit detailed error for missing alternate syscall number definitions

Some syscalls can be implemented from different __NR_* variants. For
example, sys_dup2() can be implemented based on __NR_dup3 or __NR_dup2.
In this case it is useful to mention both alternatives in error messages
when neither are detected. This information will help the user search for
the right one (e.g __NR_dup3) instead of just the fallback (__NR_dup2)
which might not exist on the platform.

This is a port of nolibc's upstream commit a21080d2ba41 to the Linux
kernel.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/lkml/20210120145447.GC77728@C02TD0UTHF1T.local/
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Remove incorrect definitions of __ARCH_WANT_*

The __ARCH_WANT_* definitions were added in order to support aarch64
when it was missing some syscall definitions (including __NR_dup2,
__NR_fork, and __NR_getpgrp), but these __ARCH_WANT_* definitions were
actually wrong because these syscalls do not exist on this platform.
Defining these resulted in exposing invalid definitions, resulting in
failures on aarch64.

The missing syscalls were since implemented based on the newer ones
(__NR_dup3, __NR_clone, __NR_getpgid) so these incorrect __ARCH_WANT_*
definitions are no longer needed.

Thanks to Mark Rutland for spotting this incorrect analysis and
explaining why it was wrong.

This is a port of nolibc's upstream commit 00b1b0d9b2a4 to the Linux
kernel.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/lkml/20210119153147.GA5083@paulmck-ThinkPad-P72
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Get timeval, timespec and timezone from linux/time.h

The definitions of timeval(), timespec() and timezone() conflict with
linux/time.h when building, so this commit takes them directly from
linux/time.h. This is a port of nolibc's upstream commit dc45f5426b0c
to the Linux kernel.

Fixes: 66b6f755ad45 ("rcutorture: Import a copy of nolibc")
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Implement poll() based on ppoll()

Some architectures like arm64 do not implement poll() and have to use
ppoll() instead. This commit therefore makes poll() use ppoll() when
available. This is a port of nolibc's upstream commit 800f75c13ede to
the Linux kernel.

Fixes: 66b6f755ad45 ("rcutorture: Import a copy of nolibc")
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Implement fork() based on clone()

Some archs such as arm64 do not have fork() and have to use clone()
instead. This commit therefore makes fork() use clone() when
available. This requires including signal.h to get the definition of
SIGCHLD. This is a port of nolibc's upstream commit d2dc42fd6149 to
the Linux kernel.

Fixes: 66b6f755ad45 ("rcutorture: Import a copy of nolibc")
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Make getpgrp() fall back to getpgid(0)

The getpgrp() syscall is not implemented on arm64, so this commit instead
uses getpgid(0) when getpgrp() is not available. This is a port of
nolibc's upstream commit 2379f25073f9 to the Linux kernel.

Fixes: 66b6f755ad45 ("rcutorture: Import a copy of nolibc")
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Make dup2() rely on dup3() when available

A recent boot failure on 5.4-rc3 on arm64 revealed that sys_dup2()
is not available and that only sys_dup3() is implemented. This commit
detects this and falls back to sys_dup3() when available. This is a
port of nolibc's upstream commit fd5272ec2c66 to the Linux kernel.

Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Add the definition for dup()

This commit adds the dup() function, which was omitted when sys_dup()
was defined. This is a port of nolibc's upstream commit 47cc42a79c92
to the Linux kernel.

Fixes: 66b6f755ad45 ("rcutorture: Import a copy of nolibc")
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/nolibc: Fix a spelling error in a comment

Fix a spelling in the comment line.

s/memry/memory/p

This is on linux-next.

Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

rcutorture/nolibc: Fix a typo in header file

This fixes a typo. Before this, the AT_FDCWD macro would be defined
regardless of whether or not it's been defined before.

Signed-off-by: Samuel Hernandez <sam.hernandez.amador@gmail.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tool headers nolibc: add RISCV support

This adds support for the RISCV architecture (32 and 64 bit) to the
nolibc header file.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
[willy: minimal rewording of the commit message]
Signed-off-by: Willy Tarreau <w@1wt.eu>

tools headers: Move the nolibc header from rcutorture to tools/include/nolibc/

As suggested by Ingo, this header file might benefit other tools than
just rcutorture. For now it's quite limited, but is easy to extend, so
exposing it into tools/include/nolibc/ will make it much easier to
adopt by other tools.

The mkinitrd.sh script in rcutorture was updated to use this new location.

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>