linux-kernel - Re: [PATCH] tools/nolibc: add support for Alpha

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Message-ID: <c39ae47e-8a07-44e3-8d71-d44fa804877d@t-8ch.de>
Date: Tue, 15 Jul 2025 16:42:10 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Willy Tarreau <w@....eu>
Cc: Richard Henderson <richard.henderson@...aro.org>, 
	Shuah Khan <shuah@...nel.org>, Matt Turner <mattst88@...il.com>, linux-kernel@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-alpha@...r.kernel.org, Arnd Bergmann <arnd@...db.de>, 
	John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Subject: Re: [PATCH] tools/nolibc: add support for Alpha

On 2025-07-15 08:28:09+0200, Willy Tarreau wrote:
> Hi,
> 
> On Mon, Jul 14, 2025 at 07:21:38AM +0200, Thomas Weißschuh wrote:
> > Hi Richard,
> > 
> > On 2025-07-13 16:21:58-0600, Richard Henderson wrote:
> > > On 7/13/25 14:08, Thomas Weißschuh wrote:
> > > > +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> > > > @@ -709,6 +709,10 @@ int run_startup(int min, int max)
> > > >   	/* checking NULL for argv/argv0, environ and _auxv is not enough, let's compare with sbrk(0) or &end */
> > > >   	extern char end;
> > > >   	char *brk = sbrk(0) != (void *)-1 ? sbrk(0) : &end;
> > > > +#if defined(__alpha__)
> > > > +	/* the ordering above does not work on an alpha kernel */
> > > > +	brk = NULL;
> > > > +#endif
> > > 
> > > The syscall api is different for brk on alpha.
> > > A change to sys_brk or brk in include/nolibc/sys.h is required.
> > 
> > You are referring to osf_brk, right?
> > I think that should work as-is with the current wrappers.
> 
> I finally managed to reinstall my DS10 to build and test this and FWIW
> the test passes:

Thanks for getting real hardware involved!

> 
>   $ ./nolibc-test 
>   Running test 'startup'
>   0 argc = 1                                                        [OK]
>   1 argv_addr = <0x11fc7b428>                                       [OK]
>   2 argv_environ = <0x11fc7b428>                                    [OK]
>   3 argv_total = 1                                                  [OK]
>   4 argv0_addr = <0x11fc7b665>                                      [OK]
>   5 argv0_str = <./nolibc-test>                                     [OK]
>   6 argv0_len = 13                                                  [OK]
>   7 environ_addr = <0x11fc7b438>                                    [OK]
>   8 environ_envp = <0x11fc7b438>                                    [OK]
>   9 environ_auxv = <0x11fc7b438>                                    [OK]
>   10 environ_total = 175                                            [OK]
>   11 environ_HOME = <0x11fc7b6f4>                                   [OK]
>   12 auxv_addr = <0x11fc7b4e8>                                      [OK]
>   13 auxv_AT_UID = 509                                              [OK]
>   14 constructor = 3                                                [OK]
>   15 linkage_errno = <0x1200200f8>                                  [OK]
>   16 linkage_constr = 3                                             [OK]
>   Errors during this test: 0
>   
>   Running test 'syscall'
>   0 access = 0                                                      [OK]
>   1 access_bad = -1 EPERM                                           [OK]
>   2 clock_getres = 0                                                [OK]
>   3 clock_gettime = 0                                               [OK]
>   4 clock_settime = -1 EINVAL                                       [OK]
>   5 getpid = 9201                                                   [OK]
>   6 getppid = 419                                                   [OK]
>   7 gettid = 9201                                                   [OK]
>   8 getpgid_self = 9201                                             [OK]
>   9 getpgid_bad = -1 ESRCH                                          [OK]
>   10 kill_0 = 0                                                     [OK]
>   11 kill_CONT = 0                                                  [OK]
>   12 kill_BADPID = -1 ESRCH                                         [OK]
>   13 sbrk_0 = <0x120024000>                                         [OK]
>   14 sbrk = 0                                                       [OK]
>   15 brk = 0                                                        [OK]
>   (...)
>   Total number of errors: 0
>   Exiting with status 0
> 
> The result is exactly the same if I comment that line that resets brk,
> as brk was apparently already NULL:
> 
>   13 sbrk_0 = <0x120024000>                                         [OK]
>   14 sbrk = 0                                                       [OK]
>   15 brk = 0                                                        [OK]

brk shouldn't be NULL I think. It looks instead like it's 0x120024000.
And it looks weird because the raw numbers look similar to my machine.

>   1 argv_addr = <0x11fc7b428>                                       [OK]

>   13 sbrk_0 = <0x120024000>                                         [OK]

argv is not greater than brk.

Could you double-check your test modification? How does it behave in QEMU for you?
Also could you provide your kernel config?

> > On alpha, mm->brk and mm->arg_start are ordered differently from other
> > architectures. Personally I think the nolibc tests are a bit bogus here.
> 
> I seem to remember that these are among the older minimal consistency
> tests and that it could be time to revisit this :-/

I do like them in general to be fair.