mirror of
https://sourceware.org/git/glibc.git
synced 2025-05-20 16:33:46 +03:00
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>
132 lines
3.5 KiB
C
132 lines
3.5 KiB
C
/* Copyright (C) 1997-2024 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/>. */
|
|
|
|
#ifndef _LINUX_SPARC64_SYSDEP_H
|
|
#define _LINUX_SPARC64_SYSDEP_H 1
|
|
|
|
#include <sysdeps/unix/sysv/linux/sparc/sysdep.h>
|
|
|
|
#if IS_IN (rtld)
|
|
# include <dl-sysdep.h> /* Defines RTLD_PRIVATE_ERRNO. */
|
|
#endif
|
|
#include <tls.h>
|
|
|
|
#undef SYS_ify
|
|
#define SYS_ify(syscall_name) __NR_##syscall_name
|
|
|
|
#ifdef __ASSEMBLER__
|
|
|
|
#define LOADSYSCALL(x) mov __NR_##x, %g1
|
|
|
|
#undef PSEUDO
|
|
#define PSEUDO(name, syscall_name, args) \
|
|
.text; \
|
|
ENTRY(name); \
|
|
LOADSYSCALL(syscall_name); \
|
|
ta 0x6d; \
|
|
bcc,pt %xcc, 1f; \
|
|
nop; \
|
|
SYSCALL_ERROR_HANDLER \
|
|
1:
|
|
|
|
#undef PSEUDO_NOERRNO
|
|
#define PSEUDO_NOERRNO(name, syscall_name, args)\
|
|
.text; \
|
|
ENTRY(name); \
|
|
LOADSYSCALL(syscall_name); \
|
|
ta 0x6d;
|
|
|
|
#undef PSEUDO_ERRVAL
|
|
#define PSEUDO_ERRVAL(name, syscall_name, args) \
|
|
.text; \
|
|
ENTRY(name); \
|
|
LOADSYSCALL(syscall_name); \
|
|
ta 0x6d;
|
|
|
|
#undef PSEUDO_END
|
|
#define PSEUDO_END(name) \
|
|
END(name)
|
|
|
|
#ifndef PIC
|
|
# define SYSCALL_ERROR_HANDLER \
|
|
mov %o7, %g1; \
|
|
call __syscall_error; \
|
|
mov %g1, %o7;
|
|
#else
|
|
# if RTLD_PRIVATE_ERRNO
|
|
# define SYSCALL_ERROR_HANDLER \
|
|
0: SETUP_PIC_REG_LEAF(o2,g1) \
|
|
sethi %gdop_hix22(rtld_errno), %g1; \
|
|
xor %g1, %gdop_lox10(rtld_errno), %g1;\
|
|
ldx [%o2 + %g1], %g1, %gdop(rtld_errno); \
|
|
st %o0, [%g1]; \
|
|
jmp %o7 + 8; \
|
|
mov -1, %o0;
|
|
# elif defined _LIBC_REENTRANT
|
|
|
|
# if IS_IN (libc)
|
|
# define SYSCALL_ERROR_ERRNO __libc_errno
|
|
# else
|
|
# define SYSCALL_ERROR_ERRNO errno
|
|
# endif
|
|
# define SYSCALL_ERROR_HANDLER \
|
|
0: SETUP_PIC_REG_LEAF(o2,g1) \
|
|
sethi %tie_hi22(SYSCALL_ERROR_ERRNO), %g1; \
|
|
add %g1, %tie_lo10(SYSCALL_ERROR_ERRNO), %g1; \
|
|
ldx [%o2 + %g1], %g1, %tie_ldx(SYSCALL_ERROR_ERRNO);\
|
|
st %o0, [%g7 + %g1]; \
|
|
jmp %o7 + 8; \
|
|
mov -1, %o0;
|
|
# else
|
|
# define SYSCALL_ERROR_HANDLER \
|
|
0: SETUP_PIC_REG_LEAF(o2,g1) \
|
|
sethi %gdop_hix22(errno), %g1;\
|
|
xor %g1, %gdop_lox10(errno), %g1;\
|
|
ldx [%o2 + %g1], %g1, %gdop(errno);\
|
|
st %o0, [%g1]; \
|
|
jmp %o7 + 8; \
|
|
mov -1, %o0;
|
|
# endif /* _LIBC_REENTRANT */
|
|
#endif /* PIC */
|
|
|
|
#else /* __ASSEMBLER__ */
|
|
|
|
#define __SYSCALL_STRING \
|
|
"mov %[scn], %%g1;" \
|
|
"ta 0x6d;" \
|
|
"bcc,pt %%xcc, 1f;" \
|
|
" nop;" \
|
|
"sub %%g0, %%o0, %%o0;" \
|
|
"1:"
|
|
|
|
#define __SYSCALL_CLOBBERS \
|
|
"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", \
|
|
"f32", "f34", "f36", "f38", "f40", "f42", "f44", "f46", \
|
|
"f48", "f50", "f52", "f54", "f56", "f58", "f60", "f62", \
|
|
"cc", "memory"
|
|
|
|
#endif /* __ASSEMBLER__ */
|
|
|
|
/* This is the offset from the %sp to the backing store above the
|
|
register windows. So if you poke stack memory directly you add this. */
|
|
#define STACK_BIAS 2047
|
|
|
|
#endif /* linux/sparc64/sysdep.h */
|