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2c1903cbba
The commit 'sparc: Use Linux kABI for syscall return'
(86c5d2cf0ce046279baddc7faa27da71f1a89fde) 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 86c5d2cf0ce046279, 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>
213 lines
7.3 KiB
C
213 lines
7.3 KiB
C
/* Copyright (C) 2000-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _LINUX_SPARC_SYSDEP_H
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#define _LINUX_SPARC_SYSDEP_H 1
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#include <sysdeps/unix/sysdep.h>
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#include <sysdeps/unix/sysv/linux/sysdep.h>
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#include <sysdeps/sparc/sysdep.h>
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#ifdef __ASSEMBLER__
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#define ret retl; nop
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#define ret_NOERRNO retl; nop
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#define ret_ERRVAL retl; nop
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#define r0 %o0
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#define r1 %o1
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#define MOVE(x,y) mov x, y
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#else /* __ASSEMBLER__ */
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# define VDSO_NAME "LINUX_2.6"
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# define VDSO_HASH 61765110
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/* List of system calls which are supported as vsyscalls. */
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# ifdef __arch64__
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# define HAVE_CLOCK_GETTIME64_VSYSCALL "__vdso_clock_gettime"
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# else
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# define HAVE_CLOCK_GETTIME_VSYSCALL "__vdso_clock_gettime"
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# endif
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# define HAVE_GETTIMEOFDAY_VSYSCALL "__vdso_gettimeofday"
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#undef INTERNAL_SYSCALL
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#define INTERNAL_SYSCALL(name, nr, args...) \
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internal_syscall##nr(__SYSCALL_STRING, __NR_##name, args)
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#undef INTERNAL_SYSCALL_NCS
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#define INTERNAL_SYSCALL_NCS(name, nr, args...) \
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_internal_syscall##nr(__SYSCALL_STRING, "p", name, args)
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#define _internal_syscall0(string,nc,name,dummy...) \
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({ \
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register long __o0 __asm__ ("o0"); \
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long int _name = (long int) (name); \
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__asm __volatile (string : "=r" (__o0) : \
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[scn] nc (_name) : \
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__SYSCALL_CLOBBERS); \
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__o0; \
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})
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#define internal_syscall0(string,name,args...) \
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_internal_syscall0(string, "i", name, args)
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#define _internal_syscall1(string,nc,name,arg1) \
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({ \
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long int _arg1 = (long int) (arg1); \
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long int _name = (long int) (name); \
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register long int __o0 __asm__ ("o0") = _arg1; \
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__asm __volatile (string : "+r" (__o0) : \
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[scn] nc (_name) : \
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__SYSCALL_CLOBBERS); \
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__o0; \
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})
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#define internal_syscall1(string,name,args...) \
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_internal_syscall1(string, "i", name, args)
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#define _internal_syscall2(string,nc,name,arg1,arg2) \
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({ \
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long int _arg1 = (long int) (arg1); \
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long int _arg2 = (long int) (arg2); \
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long int _name = (long int) (name); \
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register long int __o0 __asm__ ("o0") = _arg1; \
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register long int __o1 __asm__ ("o1") = _arg2; \
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__asm __volatile (string : "+r" (__o0) : \
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[scn] nc (_name), "r" (__o1) : \
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__SYSCALL_CLOBBERS); \
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__o0; \
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})
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#define internal_syscall2(string,name,args...) \
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_internal_syscall2(string, "i", name, args)
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#define _internal_syscall3(string,nc,name,arg1,arg2,arg3) \
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({ \
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long int _arg1 = (long int) (arg1); \
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long int _arg2 = (long int) (arg2); \
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long int _arg3 = (long int) (arg3); \
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long int _name = (long int) (name); \
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register long int __o0 __asm__ ("o0") = _arg1; \
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register long int __o1 __asm__ ("o1") = _arg2; \
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register long int __o2 __asm__ ("o2") = _arg3; \
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__asm __volatile (string : "+r" (__o0) : \
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[scn] nc (_name), "r" (__o1), \
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"r" (__o2) : \
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__SYSCALL_CLOBBERS); \
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__o0; \
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})
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#define internal_syscall3(string,name,args...) \
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_internal_syscall3(string, "i", name, args)
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#define _internal_syscall4(string,nc,name,arg1,arg2,arg3,arg4) \
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({ \
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long int _arg1 = (long int) (arg1); \
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long int _arg2 = (long int) (arg2); \
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long int _arg3 = (long int) (arg3); \
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long int _arg4 = (long int) (arg4); \
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long int _name = (long int) (name); \
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register long int __o0 __asm__ ("o0") = _arg1; \
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register long int __o1 __asm__ ("o1") = _arg2; \
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register long int __o2 __asm__ ("o2") = _arg3; \
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register long int __o3 __asm__ ("o3") = _arg4; \
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__asm __volatile (string : "+r" (__o0) : \
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[scn] nc (_name), "r" (__o1), \
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"r" (__o2), "r" (__o3) : \
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__SYSCALL_CLOBBERS); \
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__o0; \
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})
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#define internal_syscall4(string,name,args...) \
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_internal_syscall4(string, "i", name, args)
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#define _internal_syscall5(string,nc,name,arg1,arg2,arg3,arg4,arg5) \
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({ \
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long int _arg1 = (long int) (arg1); \
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long int _arg2 = (long int) (arg2); \
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long int _arg3 = (long int) (arg3); \
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long int _arg4 = (long int) (arg4); \
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long int _arg5 = (long int) (arg5); \
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long int _name = (long int) (name); \
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register long int __o0 __asm__ ("o0") = _arg1; \
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register long int __o1 __asm__ ("o1") = _arg2; \
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register long int __o2 __asm__ ("o2") = _arg3; \
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register long int __o3 __asm__ ("o3") = _arg4; \
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register long int __o4 __asm__ ("o4") = _arg5; \
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__asm __volatile (string : "+r" (__o0) : \
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[scn] nc (_name), "r" (__o1), \
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"r" (__o2), "r" (__o3), "r" (__o4) : \
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__SYSCALL_CLOBBERS); \
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__o0; \
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})
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#define internal_syscall5(string,name,args...) \
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_internal_syscall5(string, "i", name, args)
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#define _internal_syscall6(string,nc,name,arg1,arg2,arg3,arg4,arg5,arg6)\
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({ \
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long int _arg1 = (long int) (arg1); \
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long int _arg2 = (long int) (arg2); \
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long int _arg3 = (long int) (arg3); \
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long int _arg4 = (long int) (arg4); \
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long int _arg5 = (long int) (arg5); \
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long int _arg6 = (long int) (arg6); \
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long int _name = (long int) (name); \
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register long int __o0 __asm__ ("o0") = _arg1; \
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register long int __o1 __asm__ ("o1") = _arg2; \
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register long int __o2 __asm__ ("o2") = _arg3; \
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register long int __o3 __asm__ ("o3") = _arg4; \
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register long int __o4 __asm__ ("o4") = _arg5; \
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register long int __o5 __asm__ ("o5") = _arg6; \
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__asm __volatile (string : "+r" (__o0) : \
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[scn] nc (_name), "r" (__o1), \
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"r" (__o2), "r" (__o3), "r" (__o4), \
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"r" (__o5) : \
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__SYSCALL_CLOBBERS); \
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__o0; \
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})
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#define internal_syscall6(string,name,args...) \
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_internal_syscall6(string, "i", name, args)
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#define INLINE_CLONE_SYSCALL(arg1,arg2,arg3,arg4,arg5) \
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({ \
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long int _arg1 = (long int) (arg1); \
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long int _arg2 = (long int) (arg2); \
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long int _arg3 = (long int) (arg3); \
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long int _arg4 = (long int) (arg4); \
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long int _arg5 = (long int) (arg5); \
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long int _name = __NR_clone; \
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register long int __o0 __asm__ ("o0") = _arg1; \
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register long int __o1 __asm__ ("o1") = _arg2; \
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register long int __o2 __asm__ ("o2") = _arg3; \
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register long int __o3 __asm__ ("o3") = _arg4; \
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register long int __o4 __asm__ ("o4") = _arg5; \
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__asm __volatile (__SYSCALL_STRING : \
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"=r" (__o0), "=r" (__o1) : \
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[scn] "i" (_name), "0" (__o0), "1" (__o1), \
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"r" (__o2), "r" (__o3), "r" (__o4) : \
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__SYSCALL_CLOBBERS); \
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if (__glibc_unlikely ((unsigned long int) (__o0) > -4096UL)) \
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{ \
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__set_errno (-__o0); \
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__o0 = -1L; \
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} \
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else \
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{ \
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__o0 &= (__o1 - 1); \
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} \
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__o0; \
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})
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#endif /* __ASSEMBLER__ */
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#endif /* _LINUX_SPARC_SYSDEP_H */
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