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sparc: Fix restartable syscalls (BZ 32173)

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The commit 'sparc: Use Linux kABI for syscall return'
(86c5d2cf0c) did not take into account
a subtle sparc syscall kABI constraint.  For syscalls that might block
indefinitely, on an interrupt (like SIGCONT) the kernel will set the
instruction pointer to just before the syscall:

arch/sparc/kernel/signal_64.c
476 static void do_signal(struct pt_regs *regs, unsigned long orig_i0)
477 {
[...]
525                 if (restart_syscall) {
526                         switch (regs->u_regs[UREG_I0]) {
527                         case ERESTARTNOHAND:
528                         case ERESTARTSYS:
529                         case ERESTARTNOINTR:
530                                 /* replay the system call when we are done */
531                                 regs->u_regs[UREG_I0] = orig_i0;
532                                 regs->tpc -= 4;
533                                 regs->tnpc -= 4;
534                                 pt_regs_clear_syscall(regs);
535                                 fallthrough;
536                         case ERESTART_RESTARTBLOCK:
537                                 regs->u_regs[UREG_G1] = __NR_restart_syscall;
538                                 regs->tpc -= 4;
539                                 regs->tnpc -= 4;
540                                 pt_regs_clear_syscall(regs);
541                         }

However, on a SIGCONT it seems that 'g1' register is being clobbered after the
syscall returns.  Before 86c5d2cf0c, the 'g1' was always placed jus
before the 'ta' instruction which then reloads the syscall number and restarts
the syscall.

On master, where 'g1' might be placed before 'ta':

  $ cat test.c
  #include <unistd.h>

  int main ()
  {
    pause ();
  }
  $ gcc test.c -o test
  $ strace -f ./t
  [...]
  ppoll(NULL, 0, NULL, NULL, 0

On another terminal

  $ kill -STOP 2262828

  $ strace -f ./t
  [...]
  --- SIGSTOP {si_signo=SIGSTOP, si_code=SI_USER, si_pid=2521813, si_uid=8289} ---
  --- stopped by SIGSTOP ---

And then

  $ kill -CONT 2262828

Results in:

  --- SIGCONT {si_signo=SIGCONT, si_code=SI_USER, si_pid=2521813, si_uid=8289} ---
  restart_syscall(<... resuming interrupted ppoll ...>) = -1 EINTR (Interrupted system call)

Where the expected behaviour would be:

  $ strace -f ./t
  [...]
  ppoll(NULL, 0, NULL, NULL, 0)           = ? ERESTARTNOHAND (To be restarted if no handler)
  --- SIGSTOP {si_signo=SIGSTOP, si_code=SI_USER, si_pid=2521813, si_uid=8289} ---
  --- stopped by SIGSTOP ---
  --- SIGCONT {si_signo=SIGCONT, si_code=SI_USER, si_pid=2521813, si_uid=8289} ---
  ppoll(NULL, 0, NULL, NULL, 0

Just moving the 'g1' setting near the syscall asm is not suffice,
the compiler might optimize it away (as I saw on cancellation.c by
trying this fix).  Instead, I have change the inline asm to put the
'g1' setup in ithe asm block.  This would require to change the asm
constraint for INTERNAL_SYSCALL_NCS, since the syscall number is not
constant.

Checked on sparc64-linux-gnu.

Reported-by: René Rebe <rene@exactcode.de>
Tested-by: Sam James <sam@gentoo.org>
Reviewed-by: Sam James <sam@gentoo.org>
(cherry picked from commit 2c1903cbba)
This commit is contained in:
Adhemerval Zanella 2024-09-13 11:11:56 -03:00
parent 2e38c5a090
commit 1cd7e13289
5 changed files with 161 additions and 32 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
sysdeps/unix/sysv/linux/Makefile
View File

@ -227,6 +227,7 @@ tests += \
tst-scm_rights \
tst-sigtimedwait \
tst-sync_file_range \
tst-syscall-restart \
tst-sysconf-iov_max \
tst-sysvmsg-linux \
tst-sysvsem-linux \

3
sysdeps/unix/sysv/linux/sparc/sparc32/sysdep.h
View File

@ -107,6 +107,7 @@ ENTRY(name); \
#else /* __ASSEMBLER__ */
#define __SYSCALL_STRING \
"mov %[scn], %%g1;" \
"ta 0x10;" \
"bcc 1f;" \
" nop;" \
@ -114,7 +115,7 @@ ENTRY(name); \
"1:"
#define __SYSCALL_CLOBBERS \
"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", \
"g1", "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", \
"f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15", \
"f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23", \
"f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31", \

3
sysdeps/unix/sysv/linux/sparc/sparc64/sysdep.h
View File

@ -106,6 +106,7 @@ ENTRY(name); \
#else /* __ASSEMBLER__ */
#define __SYSCALL_STRING \
"mov %[scn], %%g1;" \
"ta 0x6d;" \
"bcc,pt %%xcc, 1f;" \
" nop;" \
@ -113,7 +114,7 @@ ENTRY(name); \
"1:"
#define __SYSCALL_CLOBBERS \
"f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", \
"g1", "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7", \
"f8", "f9", "f10", "f11", "f12", "f13", "f14", "f15", \
"f16", "f17", "f18", "f19", "f20", "f21", "f22", "f23", \
"f24", "f25", "f26", "f27", "f28", "f29", "f30", "f31", \

74
sysdeps/unix/sysv/linux/sparc/sysdep.h
View File

@ -50,97 +50,109 @@
#undef INTERNAL_SYSCALL_NCS
#define INTERNAL_SYSCALL_NCS(name, nr, args...) \
internal_syscall##nr(__SYSCALL_STRING, name, args)
_internal_syscall##nr(__SYSCALL_STRING, "p", name, args)
#define internal_syscall0(string,name,dummy...) \
#define _internal_syscall0(string,nc,name,dummy...) \
({ \
register long int __g1 __asm__ ("g1") = (name); \
register long __o0 __asm__ ("o0"); \
long int _name = (long int) (name); \
__asm __volatile (string : "=r" (__o0) : \
"r" (__g1) : \
[scn] nc (_name) : \
__SYSCALL_CLOBBERS); \
__o0; \
})
#define internal_syscall0(string,name,args...) \
_internal_syscall0(string, "i", name, args)
#define internal_syscall1(string,name,arg1) \
#define _internal_syscall1(string,nc,name,arg1) \
({ \
long int _arg1 = (long int) (arg1); \
register long int __g1 __asm__("g1") = (name); \
long int _name = (long int) (name); \
register long int __o0 __asm__ ("o0") = _arg1; \
__asm __volatile (string : "=r" (__o0) : \
"r" (__g1), "0" (__o0) : \
__asm __volatile (string : "+r" (__o0) : \
[scn] nc (_name) : \
__SYSCALL_CLOBBERS); \
__o0; \
})
#define internal_syscall1(string,name,args...) \
_internal_syscall1(string, "i", name, args)
#define internal_syscall2(string,name,arg1,arg2) \
#define _internal_syscall2(string,nc,name,arg1,arg2) \
({ \
long int _arg1 = (long int) (arg1); \
long int _arg2 = (long int) (arg2); \
register long int __g1 __asm__("g1") = (name); \
long int _name = (long int) (name); \
register long int __o0 __asm__ ("o0") = _arg1; \
register long int __o1 __asm__ ("o1") = _arg2; \
__asm __volatile (string : "=r" (__o0) : \
"r" (__g1), "0" (__o0), "r" (__o1) : \
__asm __volatile (string : "+r" (__o0) : \
[scn] nc (_name), "r" (__o1) : \
__SYSCALL_CLOBBERS); \
__o0; \
})
#define internal_syscall2(string,name,args...) \
_internal_syscall2(string, "i", name, args)
#define internal_syscall3(string,name,arg1,arg2,arg3) \
#define _internal_syscall3(string,nc,name,arg1,arg2,arg3) \
({ \
long int _arg1 = (long int) (arg1); \
long int _arg2 = (long int) (arg2); \
long int _arg3 = (long int) (arg3); \
register long int __g1 __asm__("g1") = (name); \
long int _name = (long int) (name); \
register long int __o0 __asm__ ("o0") = _arg1; \
register long int __o1 __asm__ ("o1") = _arg2; \
register long int __o2 __asm__ ("o2") = _arg3; \
__asm __volatile (string : "=r" (__o0) : \
"r" (__g1), "0" (__o0), "r" (__o1), \
__asm __volatile (string : "+r" (__o0) : \
[scn] nc (_name), "r" (__o1), \
"r" (__o2) : \
__SYSCALL_CLOBBERS); \
__o0; \
})
#define internal_syscall3(string,name,args...) \
_internal_syscall3(string, "i", name, args)
#define internal_syscall4(string,name,arg1,arg2,arg3,arg4) \
#define _internal_syscall4(string,nc,name,arg1,arg2,arg3,arg4) \
({ \
long int _arg1 = (long int) (arg1); \
long int _arg2 = (long int) (arg2); \
long int _arg3 = (long int) (arg3); \
long int _arg4 = (long int) (arg4); \
register long int __g1 __asm__("g1") = (name); \
long int _name = (long int) (name); \
register long int __o0 __asm__ ("o0") = _arg1; \
register long int __o1 __asm__ ("o1") = _arg2; \
register long int __o2 __asm__ ("o2") = _arg3; \
register long int __o3 __asm__ ("o3") = _arg4; \
__asm __volatile (string : "=r" (__o0) : \
"r" (__g1), "0" (__o0), "r" (__o1), \
__asm __volatile (string : "+r" (__o0) : \
[scn] nc (_name), "r" (__o1), \
"r" (__o2), "r" (__o3) : \
__SYSCALL_CLOBBERS); \
__o0; \
})
#define internal_syscall4(string,name,args...) \
_internal_syscall4(string, "i", name, args)
#define internal_syscall5(string,name,arg1,arg2,arg3,arg4,arg5) \
#define _internal_syscall5(string,nc,name,arg1,arg2,arg3,arg4,arg5) \
({ \
long int _arg1 = (long int) (arg1); \
long int _arg2 = (long int) (arg2); \
long int _arg3 = (long int) (arg3); \
long int _arg4 = (long int) (arg4); \
long int _arg5 = (long int) (arg5); \
register long int __g1 __asm__("g1") = (name); \
long int _name = (long int) (name); \
register long int __o0 __asm__ ("o0") = _arg1; \
register long int __o1 __asm__ ("o1") = _arg2; \
register long int __o2 __asm__ ("o2") = _arg3; \
register long int __o3 __asm__ ("o3") = _arg4; \
register long int __o4 __asm__ ("o4") = _arg5; \
__asm __volatile (string : "=r" (__o0) : \
"r" (__g1), "0" (__o0), "r" (__o1), \
__asm __volatile (string : "+r" (__o0) : \
[scn] nc (_name), "r" (__o1), \
"r" (__o2), "r" (__o3), "r" (__o4) : \
__SYSCALL_CLOBBERS); \
__o0; \
})
#define internal_syscall5(string,name,args...) \
_internal_syscall5(string, "i", name, args)
#define internal_syscall6(string,name,arg1,arg2,arg3,arg4,arg5,arg6) \
#define _internal_syscall6(string,nc,name,arg1,arg2,arg3,arg4,arg5,arg6)\
({ \
long int _arg1 = (long int) (arg1); \
long int _arg2 = (long int) (arg2); \
@ -148,20 +160,22 @@
long int _arg4 = (long int) (arg4); \
long int _arg5 = (long int) (arg5); \
long int _arg6 = (long int) (arg6); \
register long int __g1 __asm__("g1") = (name); \
long int _name = (long int) (name); \
register long int __o0 __asm__ ("o0") = _arg1; \
register long int __o1 __asm__ ("o1") = _arg2; \
register long int __o2 __asm__ ("o2") = _arg3; \
register long int __o3 __asm__ ("o3") = _arg4; \
register long int __o4 __asm__ ("o4") = _arg5; \
register long int __o5 __asm__ ("o5") = _arg6; \
__asm __volatile (string : "=r" (__o0) : \
"r" (__g1), "0" (__o0), "r" (__o1), \
__asm __volatile (string : "+r" (__o0) : \
[scn] nc (_name), "r" (__o1), \
"r" (__o2), "r" (__o3), "r" (__o4), \
"r" (__o5) : \
__SYSCALL_CLOBBERS); \
__o0; \
})
#define internal_syscall6(string,name,args...) \
_internal_syscall6(string, "i", name, args)
#define INLINE_CLONE_SYSCALL(arg1,arg2,arg3,arg4,arg5) \
({ \
@ -170,15 +184,15 @@
long int _arg3 = (long int) (arg3); \
long int _arg4 = (long int) (arg4); \
long int _arg5 = (long int) (arg5); \
long int _name = __NR_clone; \
register long int __o0 __asm__ ("o0") = _arg1; \
register long int __o1 __asm__ ("o1") = _arg2; \
register long int __o2 __asm__ ("o2") = _arg3; \
register long int __o3 __asm__ ("o3") = _arg4; \
register long int __o4 __asm__ ("o4") = _arg5; \
register long int __g1 __asm__ ("g1") = __NR_clone; \
__asm __volatile (__SYSCALL_STRING : \
"=r" (__o0), "=r" (__o1) : \
"r" (__g1), "0" (__o0), "1" (__o1), \
[scn] "i" (_name), "0" (__o0), "1" (__o1), \
"r" (__o2), "r" (__o3), "r" (__o4) : \
__SYSCALL_CLOBBERS); \
if (__glibc_unlikely ((unsigned long int) (__o0) > -4096UL)) \

112
sysdeps/unix/sysv/linux/tst-syscall-restart.c Normal file
View File

@ -0,0 +1,112 @@
/* Test if a syscall is correctly restarted.
Copyright (C) 2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <support/xsignal.h>
#include <support/check.h>
#include <support/process_state.h>
#include <support/xunistd.h>
#include <support/xthread.h>
#include <sys/wait.h>
static int
check_pid (pid_t pid)
{
/* Wait until the child has called pause and it blocking on kernel. */
support_process_state_wait (pid, support_process_state_sleeping);
TEST_COMPARE (kill (pid, SIGSTOP), 0);
/* Adding process_state_tracing_stop ('t') allows the test to work under
trace programs such as ptrace. */
support_process_state_wait (pid, support_process_state_stopped
| support_process_state_tracing_stop);
TEST_COMPARE (kill (pid, SIGCONT), 0);
enum support_process_state state
= support_process_state_wait (pid, support_process_state_sleeping
| support_process_state_zombie);
TEST_COMPARE (state, support_process_state_sleeping);
TEST_COMPARE (kill (pid, SIGTERM), 0);
siginfo_t info;
TEST_COMPARE (waitid (P_PID, pid, &info, WEXITED), 0);
TEST_COMPARE (info.si_signo, SIGCHLD);
TEST_COMPARE (info.si_code, CLD_KILLED);
TEST_COMPARE (info.si_status, SIGTERM);
TEST_COMPARE (info.si_pid, pid);
return 0;
}
static void *
tf (void *)
{
pause ();
return NULL;
}
static void
child_mt (void)
{
/* Let only the created thread to handle signals. */
sigset_t set;
sigfillset (&set);
xpthread_sigmask (SIG_BLOCK, &set, NULL);
sigdelset (&set, SIGSTOP);
sigdelset (&set, SIGCONT);
sigdelset (&set, SIGTERM);
pthread_attr_t attr;
xpthread_attr_init (&attr);
TEST_COMPARE (pthread_attr_setsigmask_np (&attr, &set), 0);
xpthread_join (xpthread_create (&attr, tf, NULL));
}
static void
do_test_syscall (bool multithread)
{
pid_t pid = xfork ();
if (pid == 0)
{
if (multithread)
child_mt ();
else
pause ();
_exit (127);
}
check_pid (pid);
}
static int
do_test (void)
{
/* Check for both single and multi thread, since they use different syscall
mechanisms. */
do_test_syscall (false);
do_test_syscall (true);
return 0;
}
#include <support/test-driver.c>