Re: [PATCH 7/8] nptl: Add public rseq symbols and <sys/rseq.h>

[Szabolcs Nagy <szabolcs.nagy@arm.com>]

The 12/07/2021 14:03, Florian Weimer via Libc-alpha wrote:
> diff --git a/sysdeps/unix/sysv/linux/tst-rseq.c b/sysdeps/unix/sysv/linux/tst-rseq.c
> index 926376b6a5..572c11166f 100644
> --- a/sysdeps/unix/sysv/linux/tst-rseq.c
> +++ b/sysdeps/unix/sysv/linux/tst-rseq.c
> @@ -29,12 +29,20 @@
>  # include <stdlib.h>
>  # include <string.h>
>  # include <syscall.h>
> +# include <thread_pointer.h>
> +# include <tls.h>
>  # include "tst-rseq.h"
>  
>  static void
>  do_rseq_main_test (void)
>  {
> +  struct pthread *pd = THREAD_SELF;
> +
>    TEST_VERIFY_EXIT (rseq_thread_registered ());
> +  TEST_COMPARE (__rseq_flags, 0);
> +  TEST_VERIFY ((char *) __thread_pointer () + __rseq_offset
> +               == (char *) &pd->rseq_area);
> +  TEST_COMPARE (__rseq_size, sizeof (pd->rseq_area));
>  }

sorry i just tested the committed patches on 32bit arm
(on 64bit kernel) and there is a tls alignment issue

FAIL: nptl/tst-tls3
FAIL: nptl/tst-tls3-malloc
FAIL: nptl/tst-tls5

outputs:

initial thread's struct pthread not aligned enough
initial thread's struct pthread not aligned enough
pthread_self () = 0xf7e2d350, size 1408, align 32, WRONG ALIGNMENT

and rseq registration fails with EINVAL causing

FAIL: misc/tst-rseq

output is

../sysdeps/unix/sysv/linux/tst-rseq.c:45: numeric comparison failure
   left: 0 (0x0); from: __rseq_size
  right: 32 (0x20); from: sizeof (pd->rseq_area)
error: 1 test failures

strace has

...
set_tls(0xf7e41e30)                     = 0
set_tid_address(0xf7e41918)             = 1181659
set_robust_list(0xf7e41920, 12)         = 0
syscall_0x18e(0xf7e41e10, 0x20, 0, 0xe7f5def3, 0xf7e418b0, 0xf7e41e30) = -1 (errno 22)
mprotect(0xf7df6000, 8192, PROT_READ)   = 0
mprotect(0xf7e15000, 4096, PROT_READ)   = 0
mprotect(0xf7e44000, 8192, PROT_READ)   = 0
ugetrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM_INFINITY}) = 0
mmap2(NULL, 8, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0) = 0xf7e40000
getrandom("\x44\x21\x97\xf7", 4, GRND_NONBLOCK) = 4
syscall_0x18e(0, 0, 0, 0, 0xffc1be68, 0x1) = -1 (errno 22)
write(1, "../sysdeps/unix/sysv/linux/tst-r"..., 69) = 69
write(1, "   left: ", 9)                = 9
...

0x18e is __NR_rseq and errno 22 is EINVAL.