linux-stable.git/tools/include/nolibc, branch v5.15.78

tools/nolibc/string: Fix memcmp() implementation

2022-11-10T17:15:38+00:00

commit b3f4f51ea68a495f8a5956064c33dce711a2df91 upstream.

The C standard says that memcmp() must treat the buffers as consisting
of "unsigned chars". If char happens to be unsigned, the casts are ok,
but then obviously the c1 variable can never contain a negative
value. And when char is signed, the casts are wrong, and there's still
a problem with using an 8-bit quantity to hold the difference, because
that can range from -255 to +255.

For example, assuming char is signed, comparing two 1-byte buffers,
one containing 0x00 and another 0x80, the current implementation would
return -128 for both memcmp(a, b, 1) and memcmp(b, a, 1), whereas one
of those should of course return something positive.

Signed-off-by: Rasmus Villemoes 
Fixes: 66b6f755ad45 ("rcutorture: Import a copy of nolibc")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Greg Kroah-Hartman

tools/nolibc: fix incorrect truncation of exit code

2022-01-27T10:02:51+00:00

commit de0244ae40ae91145faaf164a4252347607c3711 upstream.

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 
Cc: stable@vger.kernel.org
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Greg Kroah-Hartman

tools/nolibc: i386: fix initial stack alignment

2022-01-27T10:02:51+00:00

commit ebbe0d8a449d183fa43b42d84fcb248e25303985 upstream.

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 
Cc: stable@vger.kernel.org
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Greg Kroah-Hartman

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

2022-01-27T10:02:51+00:00

commit 937ed91c712273131de6d2a02caafd3ee84e0c72 upstream.

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 
    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 
    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 
Cc: Louvian Lyndal 
Reported-by: Peter Cordes 
Signed-off-by: Ammar Faizi 
[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 
Signed-off-by: Paul E. McKenney 
Signed-off-by: Greg Kroah-Hartman

tools/nolibc: Implement msleep()

2021-07-20T20:42:26+00:00

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

Signed-off-by: Mark Brown 
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

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

2021-07-20T20:42:26+00:00

s/occured/occurred/

Signed-off-by: Bhaskar Chowdhury 
Acked-by: Randy Dunlap 
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

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

2021-01-21T18:06:45+00:00

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 
Tested-by: Mark Rutland  [arm64]
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

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

2021-01-21T18:06:45+00:00

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 
Link: https://lore.kernel.org/lkml/20210120145447.GC77728@C02TD0UTHF1T.local/
Tested-by: Valentin Schneider 
Tested-by: Mark Rutland  [arm64]
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

tools/nolibc: Remove incorrect definitions of __ARCH_WANT_*

2021-01-21T18:06:45+00:00

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 
Link: https://lore.kernel.org/lkml/20210119153147.GA5083@paulmck-ThinkPad-P72
Tested-by: Valentin Schneider 
Tested-by: Mark Rutland  [arm64]
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney

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

2021-01-21T18:06:45+00:00

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 
Tested-by: Mark Rutland  [arm64]
Signed-off-by: Willy Tarreau 
Signed-off-by: Paul E. McKenney