* [PATCH] futex: Change 'utime' parameter to be 'const ... *'
@ 2020-11-28 12:39 Alejandro Colomar
2020-12-10 17:36 ` Alejandro Colomar (man-pages)
` (2 more replies)
0 siblings, 3 replies; 5+ messages in thread
From: Alejandro Colomar @ 2020-11-28 12:39 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar
Cc: Alejandro Colomar, Peter Zijlstra, Darren Hart, linux-kernel, linux-man
futex(2) says that 'utime' is a pointer to 'const'.
The implementation doesn't use 'const';
however, it _never_ modifies the contents of utime.
- futex() either uses 'utime' as a pointer to struct or as a 'u32'.
- In case it's used as a 'u32', it makes a copy of it,
and of course it is not dereferenced.
- In case it's used as a 'struct __kernel_timespec __user *',
the pointer is not dereferenced inside the futex() definition,
and it is only passed to a function: get_timespec64(),
which accepts a 'const struct __kernel_timespec __user *'.
context:
........
[[
FUTEX(2) Linux Programmer's Manual FUTEX(2)
NAME
futex - fast user-space locking
SYNOPSIS
#include <linux/futex.h>
#include <stdint.h>
#include <sys/time.h>
long futex(uint32_t *uaddr, int futex_op, uint32_t val,
const struct timespec *timeout, /* or: uint32_t val2 */
uint32_t *uaddr2, uint32_t val3);
Note: There is no glibc wrapper for this system call; see
NOTES.
]]
$ sed -n '/SYSCALL_DEFINE.(futex\>/,/^}/p' linux/kernel/futex.c
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
u32, val3)
{
struct timespec64 ts;
ktime_t t, *tp = NULL;
u32 val2 = 0;
int cmd = op & FUTEX_CMD_MASK;
if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
cmd == FUTEX_WAIT_BITSET ||
cmd == FUTEX_WAIT_REQUEUE_PI)) {
if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG))))
return -EFAULT;
if (get_timespec64(&ts, utime))
return -EFAULT;
if (!timespec64_valid(&ts))
return -EINVAL;
t = timespec64_to_ktime(ts);
if (cmd == FUTEX_WAIT)
t = ktime_add_safe(ktime_get(), t);
else if (!(op & FUTEX_CLOCK_REALTIME))
t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
tp = &t;
}
/*
* requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*.
* number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP.
*/
if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
val2 = (u32) (unsigned long) utime;
return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
}
$ sed -n '/get_timespec64(/,/;/p' linux/include/linux/time.h
int get_timespec64(struct timespec64 *ts,
const struct __kernel_timespec __user *uts);
...
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
---
Hello Thomas & Ingo,
I'm sorry I couldn't test the change in my computers,
as there is a bug since Linux 5.7 where I can't boot
(https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=974166).
Alex
kernel/futex.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index 00259c7e288e..28577c7d2805 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3792,8 +3792,8 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
- struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
- u32, val3)
+ const struct __kernel_timespec __user *, utime,
+ u32 __user *, uaddr2, u32, val3)
{
struct timespec64 ts;
ktime_t t, *tp = NULL;
--
2.29.2
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] futex: Change 'utime' parameter to be 'const ... *'
2020-11-28 12:39 [PATCH] futex: Change 'utime' parameter to be 'const ... *' Alejandro Colomar
@ 2020-12-10 17:36 ` Alejandro Colomar (man-pages)
2021-01-17 16:32 ` Ping: " Alejandro Colomar (man-pages)
2021-01-27 19:31 ` [tip: locking/core] futex: Change utime " tip-bot2 for Alejandro Colomar
2021-01-28 12:21 ` tip-bot2 for Alejandro Colomar
2 siblings, 1 reply; 5+ messages in thread
From: Alejandro Colomar (man-pages) @ 2020-12-10 17:36 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar
Cc: Peter Zijlstra, Darren Hart, linux-kernel, linux-man, linux-api
Hi Thomas & Ingo,
I tested the changes. Everything's OK.
Cheers,
Alex
$ uname -a
Linux debian 5.10.0-rc7+alx3+ #4 SMP Thu Dec 10 18:05:03 CET 2020 x86_64
GNU/Linux
.../linux/tools/testing/selftests/futex$ sudo ./run.sh
[sudo] password for user:
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=0 owner=0 timeout=0ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=0 owner=0 timeout=0ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=1 owner=0 timeout=0ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=0 owner=1 timeout=0ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=1 owner=0 timeout=0ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=0 owner=1 timeout=0ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=1 owner=0 timeout=5000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=1 owner=0 timeout=5000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=1 owner=0 timeout=500000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=1 owner=0 timeout=500000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=0 owner=0 timeout=5000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=0 owner=0 timeout=5000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=0 owner=0 timeout=500000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=0 owner=0 timeout=500000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=0 owner=1 timeout=5000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=1 owner=0 timeout=5000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=0 owner=1 timeout=500000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=1 owner=0 timeout=500000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=1 locked=1 owner=0 timeout=2000000000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi: Test requeue functionality
# Arguments: broadcast=0 locked=1 owner=0 timeout=2000000000ns
ok 1 futex-requeue-pi
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi_mismatched_ops: Detect mismatched requeue_pi operations
ok 1 futex-requeue-pi-mismatched-ops
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_requeue_pi_signal_restart: Test signal handling during requeue_pi
# Arguments: <none>
ok 1 futex-requeue-pi-signal-restart
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_wait_timeout: Block on a futex and wait for timeout
# Arguments: timeout=100000ns
ok 1 futex-wait-timeout
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_wait_wouldblock: Test the unexpected futex value in FUTEX_WAIT
ok 1 futex-wait-wouldblock
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_wait_uninitialized_heap: Test the uninitialized futex value in
FUTEX_WAIT
ok 1 futex-wait-uninitialized-heap
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
TAP version 13
1..1
# futex_wait_private_mapped_file: Test the futex value of private file
mappings in FUTEX_WAIT
ok 1 futex-wait-private-mapped-file
# Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
On 11/28/20 1:39 PM, Alejandro Colomar wrote:
> futex(2) says that 'utime' is a pointer to 'const'.
> The implementation doesn't use 'const';
> however, it _never_ modifies the contents of utime.
>
> - futex() either uses 'utime' as a pointer to struct or as a 'u32'.
>
> - In case it's used as a 'u32', it makes a copy of it,
> and of course it is not dereferenced.
>
> - In case it's used as a 'struct __kernel_timespec __user *',
> the pointer is not dereferenced inside the futex() definition,
> and it is only passed to a function: get_timespec64(),
> which accepts a 'const struct __kernel_timespec __user *'.
>
> context:
> ........
>
> [[
> FUTEX(2) Linux Programmer's Manual FUTEX(2)
>
> NAME
> futex - fast user-space locking
>
> SYNOPSIS
> #include <linux/futex.h>
> #include <stdint.h>
> #include <sys/time.h>
>
> long futex(uint32_t *uaddr, int futex_op, uint32_t val,
> const struct timespec *timeout, /* or: uint32_t val2 */
> uint32_t *uaddr2, uint32_t val3);
>
> Note: There is no glibc wrapper for this system call; see
> NOTES.
> ]]
>
> $ sed -n '/SYSCALL_DEFINE.(futex\>/,/^}/p' linux/kernel/futex.c
> SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
> struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
> u32, val3)
> {
> struct timespec64 ts;
> ktime_t t, *tp = NULL;
> u32 val2 = 0;
> int cmd = op & FUTEX_CMD_MASK;
>
> if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
> cmd == FUTEX_WAIT_BITSET ||
> cmd == FUTEX_WAIT_REQUEUE_PI)) {
> if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG))))
> return -EFAULT;
> if (get_timespec64(&ts, utime))
> return -EFAULT;
> if (!timespec64_valid(&ts))
> return -EINVAL;
>
> t = timespec64_to_ktime(ts);
> if (cmd == FUTEX_WAIT)
> t = ktime_add_safe(ktime_get(), t);
> else if (!(op & FUTEX_CLOCK_REALTIME))
> t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
> tp = &t;
> }
> /*
> * requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*.
> * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP.
> */
> if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
> cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
> val2 = (u32) (unsigned long) utime;
>
> return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
> }
>
> $ sed -n '/get_timespec64(/,/;/p' linux/include/linux/time.h
> int get_timespec64(struct timespec64 *ts,
> const struct __kernel_timespec __user *uts);
>
> ...
>
> Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
> ---
>
> Hello Thomas & Ingo,
>
> I'm sorry I couldn't test the change in my computers,
> as there is a bug since Linux 5.7 where I can't boot
> (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=974166).
>
> Alex
>
> kernel/futex.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/futex.c b/kernel/futex.c
> index 00259c7e288e..28577c7d2805 100644
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -3792,8 +3792,8 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
>
>
> SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
> - struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
> - u32, val3)
> + const struct __kernel_timespec __user *, utime,
> + u32 __user *, uaddr2, u32, val3)
> {
> struct timespec64 ts;
> ktime_t t, *tp = NULL;
>
--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es
^ permalink raw reply [flat|nested] 5+ messages in thread
* Ping: [PATCH] futex: Change 'utime' parameter to be 'const ... *'
2020-12-10 17:36 ` Alejandro Colomar (man-pages)
@ 2021-01-17 16:32 ` Alejandro Colomar (man-pages)
0 siblings, 0 replies; 5+ messages in thread
From: Alejandro Colomar (man-pages) @ 2021-01-17 16:32 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar
Cc: Peter Zijlstra, Darren Hart, linux-kernel, linux-man, linux-api
Ping!
On 12/10/20 6:36 PM, Alejandro Colomar (man-pages) wrote:
> Hi Thomas & Ingo,
>
> I tested the changes. Everything's OK.
>
> Cheers,
>
> Alex
>
> $ uname -a
> Linux debian 5.10.0-rc7+alx3+ #4 SMP Thu Dec 10 18:05:03 CET 2020 x86_64
> GNU/Linux
>
> .../linux/tools/testing/selftests/futex$ sudo ./run.sh
> [sudo] password for user:
>
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=0 owner=0 timeout=0ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=0 owner=0 timeout=0ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=1 owner=0 timeout=0ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=0 owner=1 timeout=0ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=1 owner=0 timeout=0ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=0 owner=1 timeout=0ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=1 owner=0 timeout=5000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=1 owner=0 timeout=5000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=1 owner=0 timeout=500000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=1 owner=0 timeout=500000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=0 owner=0 timeout=5000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=0 owner=0 timeout=5000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=0 owner=0 timeout=500000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=0 owner=0 timeout=500000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=0 owner=1 timeout=5000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=1 owner=0 timeout=5000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=0 owner=1 timeout=500000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=1 owner=0 timeout=500000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=1 locked=1 owner=0 timeout=2000000000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_requeue_pi: Test requeue functionality
> # Arguments: broadcast=0 locked=1 owner=0 timeout=2000000000ns
> ok 1 futex-requeue-pi
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> TAP version 13
> 1..1
> # futex_requeue_pi_mismatched_ops: Detect mismatched requeue_pi operations
> ok 1 futex-requeue-pi-mismatched-ops
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> TAP version 13
> 1..1
> # futex_requeue_pi_signal_restart: Test signal handling during requeue_pi
> # Arguments: <none>
> ok 1 futex-requeue-pi-signal-restart
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> TAP version 13
> 1..1
> # futex_wait_timeout: Block on a futex and wait for timeout
> # Arguments: timeout=100000ns
> ok 1 futex-wait-timeout
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> TAP version 13
> 1..1
> # futex_wait_wouldblock: Test the unexpected futex value in FUTEX_WAIT
> ok 1 futex-wait-wouldblock
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
>
> TAP version 13
> 1..1
> # futex_wait_uninitialized_heap: Test the uninitialized futex value in
> FUTEX_WAIT
> ok 1 futex-wait-uninitialized-heap
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
> TAP version 13
> 1..1
> # futex_wait_private_mapped_file: Test the futex value of private file
> mappings in FUTEX_WAIT
> ok 1 futex-wait-private-mapped-file
> # Totals: pass:1 fail:0 xfail:0 xpass:0 skip:0 error:0
>
>
> On 11/28/20 1:39 PM, Alejandro Colomar wrote:
>> futex(2) says that 'utime' is a pointer to 'const'.
>> The implementation doesn't use 'const';
>> however, it _never_ modifies the contents of utime.
>>
>> - futex() either uses 'utime' as a pointer to struct or as a 'u32'.
>>
>> - In case it's used as a 'u32', it makes a copy of it,
>> and of course it is not dereferenced.
>>
>> - In case it's used as a 'struct __kernel_timespec __user *',
>> the pointer is not dereferenced inside the futex() definition,
>> and it is only passed to a function: get_timespec64(),
>> which accepts a 'const struct __kernel_timespec __user *'.
>>
>> context:
>> ........
>>
>> [[
>> FUTEX(2) Linux Programmer's Manual FUTEX(2)
>>
>> NAME
>> futex - fast user-space locking
>>
>> SYNOPSIS
>> #include <linux/futex.h>
>> #include <stdint.h>
>> #include <sys/time.h>
>>
>> long futex(uint32_t *uaddr, int futex_op, uint32_t val,
>> const struct timespec *timeout, /* or: uint32_t val2 */
>> uint32_t *uaddr2, uint32_t val3);
>>
>> Note: There is no glibc wrapper for this system call; see
>> NOTES.
>> ]]
>>
>> $ sed -n '/SYSCALL_DEFINE.(futex\>/,/^}/p' linux/kernel/futex.c
>> SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
>> struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
>> u32, val3)
>> {
>> struct timespec64 ts;
>> ktime_t t, *tp = NULL;
>> u32 val2 = 0;
>> int cmd = op & FUTEX_CMD_MASK;
>>
>> if (utime && (cmd == FUTEX_WAIT || cmd == FUTEX_LOCK_PI ||
>> cmd == FUTEX_WAIT_BITSET ||
>> cmd == FUTEX_WAIT_REQUEUE_PI)) {
>> if (unlikely(should_fail_futex(!(op & FUTEX_PRIVATE_FLAG))))
>> return -EFAULT;
>> if (get_timespec64(&ts, utime))
>> return -EFAULT;
>> if (!timespec64_valid(&ts))
>> return -EINVAL;
>>
>> t = timespec64_to_ktime(ts);
>> if (cmd == FUTEX_WAIT)
>> t = ktime_add_safe(ktime_get(), t);
>> else if (!(op & FUTEX_CLOCK_REALTIME))
>> t = timens_ktime_to_host(CLOCK_MONOTONIC, t);
>> tp = &t;
>> }
>> /*
>> * requeue parameter in 'utime' if cmd == FUTEX_*_REQUEUE_*.
>> * number of waiters to wake in 'utime' if cmd == FUTEX_WAKE_OP.
>> */
>> if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE ||
>> cmd == FUTEX_CMP_REQUEUE_PI || cmd == FUTEX_WAKE_OP)
>> val2 = (u32) (unsigned long) utime;
>>
>> return do_futex(uaddr, op, val, tp, uaddr2, val2, val3);
>> }
>>
>> $ sed -n '/get_timespec64(/,/;/p' linux/include/linux/time.h
>> int get_timespec64(struct timespec64 *ts,
>> const struct __kernel_timespec __user *uts);
>>
>> ...
>>
>> Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
>> ---
>>
>> Hello Thomas & Ingo,
>>
>> I'm sorry I couldn't test the change in my computers,
>> as there is a bug since Linux 5.7 where I can't boot
>> (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=974166).
>>
>> Alex
>>
>> kernel/futex.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/futex.c b/kernel/futex.c
>> index 00259c7e288e..28577c7d2805 100644
>> --- a/kernel/futex.c
>> +++ b/kernel/futex.c
>> @@ -3792,8 +3792,8 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
>>
>>
>> SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
>> - struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
>> - u32, val3)
>> + const struct __kernel_timespec __user *, utime,
>> + u32 __user *, uaddr2, u32, val3)
>> {
>> struct timespec64 ts;
>> ktime_t t, *tp = NULL;
>>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* [tip: locking/core] futex: Change utime parameter to be 'const ... *'
2020-11-28 12:39 [PATCH] futex: Change 'utime' parameter to be 'const ... *' Alejandro Colomar
2020-12-10 17:36 ` Alejandro Colomar (man-pages)
@ 2021-01-27 19:31 ` tip-bot2 for Alejandro Colomar
2021-01-28 12:21 ` tip-bot2 for Alejandro Colomar
2 siblings, 0 replies; 5+ messages in thread
From: tip-bot2 for Alejandro Colomar @ 2021-01-27 19:31 UTC (permalink / raw)
To: linux-tip-commits; +Cc: Alejandro Colomar, Thomas Gleixner, x86, linux-kernel
The following commit has been merged into the locking/core branch of tip:
Commit-ID: 3018a08401300005536817507dd14c2a7c4ffa69
Gitweb: https://git.kernel.org/tip/3018a08401300005536817507dd14c2a7c4ffa69
Author: Alejandro Colomar <alx.manpages@gmail.com>
AuthorDate: Sat, 28 Nov 2020 13:39:46 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 27 Jan 2021 12:30:02 +01:00
futex: Change utime parameter to be 'const ... *'
futex(2) says that 'utime' is a pointer to 'const'. The implementation
doesn't use 'const'; however, it _never_ modifies the contents of utime.
- futex() either uses 'utime' as a pointer to struct or as a 'u32'.
- In case it's used as a 'u32', it makes a copy of it, and of course it is
not dereferenced.
- In case it's used as a 'struct __kernel_timespec __user *', the pointer
is not dereferenced inside the futex() definition, and it is only passed
to a function: get_timespec64(), which accepts a 'const struct
__kernel_timespec __user *'.
[ tglx: Make the same change to the compat syscall ]
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201128123945.4592-1-alx.manpages@gmail.com
---
kernel/futex.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index c47d101..d0775aa 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3790,8 +3790,8 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
- struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
- u32, val3)
+ const struct __kernel_timespec __user *, utime,
+ u32 __user *, uaddr2, u32, val3)
{
struct timespec64 ts;
ktime_t t, *tp = NULL;
@@ -3986,7 +3986,7 @@ err_unlock:
#ifdef CONFIG_COMPAT_32BIT_TIME
SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
- struct old_timespec32 __user *, utime, u32 __user *, uaddr2,
+ const struct old_timespec32 __user *, utime, u32 __user *, uaddr2,
u32, val3)
{
struct timespec64 ts;
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [tip: locking/core] futex: Change utime parameter to be 'const ... *'
2020-11-28 12:39 [PATCH] futex: Change 'utime' parameter to be 'const ... *' Alejandro Colomar
2020-12-10 17:36 ` Alejandro Colomar (man-pages)
2021-01-27 19:31 ` [tip: locking/core] futex: Change utime " tip-bot2 for Alejandro Colomar
@ 2021-01-28 12:21 ` tip-bot2 for Alejandro Colomar
2 siblings, 0 replies; 5+ messages in thread
From: tip-bot2 for Alejandro Colomar @ 2021-01-28 12:21 UTC (permalink / raw)
To: linux-tip-commits; +Cc: Alejandro Colomar, Thomas Gleixner, x86, linux-kernel
The following commit has been merged into the locking/core branch of tip:
Commit-ID: 1ce53e2c2ac069e7b3c400a427002a70deb4a916
Gitweb: https://git.kernel.org/tip/1ce53e2c2ac069e7b3c400a427002a70deb4a916
Author: Alejandro Colomar <alx.manpages@gmail.com>
AuthorDate: Sat, 28 Nov 2020 13:39:46 +01:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Thu, 28 Jan 2021 13:20:18 +01:00
futex: Change utime parameter to be 'const ... *'
futex(2) says that 'utime' is a pointer to 'const'. The implementation
doesn't use 'const'; however, it _never_ modifies the contents of utime.
- futex() either uses 'utime' as a pointer to struct or as a 'u32'.
- In case it's used as a 'u32', it makes a copy of it, and of course it is
not dereferenced.
- In case it's used as a 'struct __kernel_timespec __user *', the pointer
is not dereferenced inside the futex() definition, and it is only passed
to a function: get_timespec64(), which accepts a 'const struct
__kernel_timespec __user *'.
[ tglx: Make the same change to the compat syscall and fixup the prototypes. ]
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201128123945.4592-1-alx.manpages@gmail.com
---
include/linux/syscalls.h | 8 ++++----
kernel/futex.c | 6 +++---
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index f3929af..5cb74ed 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -583,11 +583,11 @@ asmlinkage long sys_unshare(unsigned long unshare_flags);
/* kernel/futex.c */
asmlinkage long sys_futex(u32 __user *uaddr, int op, u32 val,
- struct __kernel_timespec __user *utime, u32 __user *uaddr2,
- u32 val3);
+ const struct __kernel_timespec __user *utime,
+ u32 __user *uaddr2, u32 val3);
asmlinkage long sys_futex_time32(u32 __user *uaddr, int op, u32 val,
- struct old_timespec32 __user *utime, u32 __user *uaddr2,
- u32 val3);
+ const struct old_timespec32 __user *utime,
+ u32 __user *uaddr2, u32 val3);
asmlinkage long sys_get_robust_list(int pid,
struct robust_list_head __user * __user *head_ptr,
size_t __user *len_ptr);
diff --git a/kernel/futex.c b/kernel/futex.c
index c47d101..d0775aa 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3790,8 +3790,8 @@ long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
SYSCALL_DEFINE6(futex, u32 __user *, uaddr, int, op, u32, val,
- struct __kernel_timespec __user *, utime, u32 __user *, uaddr2,
- u32, val3)
+ const struct __kernel_timespec __user *, utime,
+ u32 __user *, uaddr2, u32, val3)
{
struct timespec64 ts;
ktime_t t, *tp = NULL;
@@ -3986,7 +3986,7 @@ err_unlock:
#ifdef CONFIG_COMPAT_32BIT_TIME
SYSCALL_DEFINE6(futex_time32, u32 __user *, uaddr, int, op, u32, val,
- struct old_timespec32 __user *, utime, u32 __user *, uaddr2,
+ const struct old_timespec32 __user *, utime, u32 __user *, uaddr2,
u32, val3)
{
struct timespec64 ts;
^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-01-28 12:22 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-28 12:39 [PATCH] futex: Change 'utime' parameter to be 'const ... *' Alejandro Colomar
2020-12-10 17:36 ` Alejandro Colomar (man-pages)
2021-01-17 16:32 ` Ping: " Alejandro Colomar (man-pages)
2021-01-27 19:31 ` [tip: locking/core] futex: Change utime " tip-bot2 for Alejandro Colomar
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