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Y2038: nptl: Provide futex_abstimed_wait64 supporting 64 bit time

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This is the helper function, which uses struct __timespec64
to provide 64 bit absolute time to futex syscalls.

The aim of this function is to move convoluted pre-processor
macro code from sysdeps/nptl/lowlevellock-futex.h to C
function in futex-internal.c

The futex_abstimed_wait64 function has been put into a separate
file on the purpose - to avoid issues apparent on the m68k
architecture related to small number of available registers (there
is not enough registers to put all necessary arguments in them if
the above function would be added to futex-internal.h with
__always_inline attribute).

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
Lukasz Majewski 2020-09-08 10:54:35 +02:00
parent be9b0b9a01
commit b2cdadde4d
2 changed files with 76 additions and 0 deletions
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70
sysdeps/nptl/futex-internal.c
View File

@ -47,6 +47,29 @@ __futex_abstimed_wait_cancelable32 (unsigned int* futex_word,
pts32, NULL /* Unused. */,
FUTEX_BITSET_MATCH_ANY);
}
static int
__futex_abstimed_wait32 (unsigned int* futex_word,
unsigned int expected, clockid_t clockid,
const struct __timespec64* abstime,
int private)
{
struct timespec ts32;
if (abstime != NULL && ! in_time_t_range (abstime->tv_sec))
return -EOVERFLOW;
unsigned int clockbit = (clockid == CLOCK_REALTIME) ?
FUTEX_CLOCK_REALTIME : 0;
int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
if (abstime != NULL)
ts32 = valid_timespec64_to_timespec (*abstime);
return INTERNAL_SYSCALL_CALL (futex, futex_word, op, expected,
abstime != NULL ? &ts32 : NULL,
NULL /* Unused. */, FUTEX_BITSET_MATCH_ANY);
}
#endif
int
@ -99,3 +122,50 @@ __futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
futex_fatal_error ();
}
}
int
__futex_abstimed_wait64 (unsigned int* futex_word, unsigned int expected,
clockid_t clockid,
const struct __timespec64* abstime, int private)
{
unsigned int clockbit;
int err;
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__glibc_unlikely ((abstime != NULL) && (abstime->tv_sec < 0)))
return ETIMEDOUT;
if (! lll_futex_supported_clockid (clockid))
return EINVAL;
clockbit = (clockid == CLOCK_REALTIME) ? FUTEX_CLOCK_REALTIME : 0;
int op = __lll_private_flag (FUTEX_WAIT_BITSET | clockbit, private);
err = INTERNAL_SYSCALL_CALL (futex_time64, futex_word, op, expected,
abstime, NULL /* Unused. */,
FUTEX_BITSET_MATCH_ANY);
#ifndef __ASSUME_TIME64_SYSCALLS
if (err == -ENOSYS)
err = __futex_abstimed_wait32 (futex_word, expected,
clockid, abstime, private);
#endif
switch (err)
{
case 0:
case -EAGAIN:
case -EINTR:
case -ETIMEDOUT:
return -err;
case -EFAULT: /* Must have been caused by a glibc or application bug. */
case -EINVAL: /* Either due to wrong alignment, unsupported
clockid or due to the timeout not being
normalized. Must have been caused by a glibc or
application bug. */
case -ENOSYS: /* Must have been caused by a glibc bug. */
/* No other errors are documented at this time. */
default:
futex_fatal_error ();
}
}

6
sysdeps/nptl/futex-internal.h
View File

@ -529,4 +529,10 @@ __futex_abstimed_wait_cancelable64 (unsigned int* futex_word,
const struct __timespec64* abstime,
int private) attribute_hidden;
int
__futex_abstimed_wait64 (unsigned int* futex_word, unsigned int expected,
clockid_t clockid,
const struct __timespec64* abstime,
int private) attribute_hidden;
#endif /* futex-internal.h */