From: Thomas Gleixner <tglx@linutronix•de>
To: LKML <linux-kernel@vger•kernel.org>
Cc: "Peter Zijlstra" <peterz@infradead•org>,
"Darren Hart" <dvhart@infradead•org>,
"Davidlohr Bueso" <dave@stgolabs•net>,
"André Almeida" <andrealmeid@igalia•com>,
"kernel test robot" <lkp@intel•com>,
"Russell King" <linux@armlinux•org.uk>,
linux-arm-kernel@lists•infradead.org,
"Linus Torvalds" <torvalds@linux-foundation•org>,
x86@kernel•org, "Madhavan Srinivasan" <maddy@linux•ibm.com>,
"Michael Ellerman" <mpe@ellerman•id.au>,
"Nicholas Piggin" <npiggin@gmail•com>,
"Christophe Leroy" <christophe.leroy@csgroup•eu>,
linuxppc-dev@lists•ozlabs.org, "Paul Walmsley" <pjw@kernel•org>,
"Palmer Dabbelt" <palmer@dabbelt•com>,
linux-riscv@lists•infradead.org,
"Heiko Carstens" <hca@linux•ibm.com>,
"Christian Borntraeger" <borntraeger@linux•ibm.com>,
"Sven Schnelle" <svens@linux•ibm.com>,
linux-s390@vger•kernel.org,
"Mathieu Desnoyers" <mathieu.desnoyers@efficios•com>,
"Andrew Cooper" <andrew.cooper3@citrix•com>,
"David Laight" <david.laight.linux@gmail•com>,
"Julia Lawall" <Julia.Lawall@inria•fr>,
"Nicolas Palix" <nicolas.palix@imag•fr>,
"Alexander Viro" <viro@zeniv•linux.org.uk>,
"Christian Brauner" <brauner@kernel•org>,
"Jan Kara" <jack@suse•cz>,
linux-fsdevel@vger•kernel.org
Subject: [patch V5 10/12] futex: Convert to get/put_user_inline()
Date: Mon, 27 Oct 2025 09:44:00 +0100 (CET) [thread overview]
Message-ID: <20251027083745.736737934@linutronix.de> (raw)
In-Reply-To: 20251027083700.573016505@linutronix.de
From: Thomas Gleixner <tglx@linutronix•de>
Replace the open coded implementation with the new get/put_user_inline()
helpers. This might be replaced by a regular get/put_user(), but that needs
a proper performance evaluation.
No functional change intended
Signed-off-by: Thomas Gleixner <tglx@linutronix•de>
Cc: Peter Zijlstra <peterz@infradead•org>
Cc: Darren Hart <dvhart@infradead•org>
Cc: Davidlohr Bueso <dave@stgolabs•net>
Cc: "André Almeida" <andrealmeid@igalia•com>
---
V5: Rename again and remove the helpers
V4: Rename once moar
V3: Adapt to scope changes
V2: Convert to scoped variant
---
kernel/futex/core.c | 4 +--
kernel/futex/futex.h | 58 ++-------------------------------------------------
2 files changed, 5 insertions(+), 57 deletions(-)
---
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -581,7 +581,7 @@ int get_futex_key(u32 __user *uaddr, uns
if (flags & FLAGS_NUMA) {
u32 __user *naddr = (void *)uaddr + size / 2;
- if (futex_get_value(&node, naddr))
+ if (get_user_inline(node, naddr))
return -EFAULT;
if ((node != FUTEX_NO_NODE) &&
@@ -601,7 +601,7 @@ int get_futex_key(u32 __user *uaddr, uns
node = numa_node_id();
node_updated = true;
}
- if (node_updated && futex_put_value(node, naddr))
+ if (node_updated && put_user_inline(node, naddr))
return -EFAULT;
}
--- a/kernel/futex/futex.h
+++ b/kernel/futex/futex.h
@@ -281,63 +281,11 @@ static inline int futex_cmpxchg_value_lo
return ret;
}
-/*
- * This does a plain atomic user space read, and the user pointer has
- * already been verified earlier by get_futex_key() to be both aligned
- * and actually in user space, just like futex_atomic_cmpxchg_inatomic().
- *
- * We still want to avoid any speculation, and while __get_user() is
- * the traditional model for this, it's actually slower than doing
- * this manually these days.
- *
- * We could just have a per-architecture special function for it,
- * the same way we do futex_atomic_cmpxchg_inatomic(), but rather
- * than force everybody to do that, write it out long-hand using
- * the low-level user-access infrastructure.
- *
- * This looks a bit overkill, but generally just results in a couple
- * of instructions.
- */
-static __always_inline int futex_get_value(u32 *dest, u32 __user *from)
-{
- u32 val;
-
- if (can_do_masked_user_access())
- from = masked_user_access_begin(from);
- else if (!user_read_access_begin(from, sizeof(*from)))
- return -EFAULT;
- unsafe_get_user(val, from, Efault);
- user_read_access_end();
- *dest = val;
- return 0;
-Efault:
- user_read_access_end();
- return -EFAULT;
-}
-
-static __always_inline int futex_put_value(u32 val, u32 __user *to)
-{
- if (can_do_masked_user_access())
- to = masked_user_access_begin(to);
- else if (!user_write_access_begin(to, sizeof(*to)))
- return -EFAULT;
- unsafe_put_user(val, to, Efault);
- user_write_access_end();
- return 0;
-Efault:
- user_write_access_end();
- return -EFAULT;
-}
-
+/* Read from user memory with pagefaults disabled */
static inline int futex_get_value_locked(u32 *dest, u32 __user *from)
{
- int ret;
-
- pagefault_disable();
- ret = futex_get_value(dest, from);
- pagefault_enable();
-
- return ret;
+ guard(pagefault)();
+ return get_user_inline(*dest, from);
}
extern void __futex_unqueue(struct futex_q *q);
next prev parent reply other threads:[~2025-10-27 8:45 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-27 8:43 [patch V5 00/12] uaccess: Provide and use scopes for user access Thomas Gleixner
2025-10-27 8:43 ` [patch V5 01/12] ARM: uaccess: Implement missing __get_user_asm_dword() Thomas Gleixner
2025-10-28 13:35 ` Mathieu Desnoyers
2025-10-27 8:43 ` [patch V5 02/12] uaccess: Provide ASM GOTO safe wrappers for unsafe_*_user() Thomas Gleixner
2025-10-27 12:12 ` Andrew Cooper
2025-10-28 13:44 ` Mathieu Desnoyers
2025-10-28 14:04 ` Yann Ylavic
2025-10-28 15:53 ` Thomas Gleixner
2025-10-29 9:40 ` [patch V6 " Thomas Gleixner
2025-12-19 8:10 ` patchwork-bot+linux-riscv
2025-11-04 6:11 ` [patch V5 " Christophe Leroy
2025-10-27 8:43 ` [patch V5 03/12] x86/uaccess: Use unsafe wrappers for ASM GOTO Thomas Gleixner
2025-10-28 13:50 ` Mathieu Desnoyers
2025-10-27 8:43 ` [patch V5 04/12] powerpc/uaccess: " Thomas Gleixner
2025-10-28 13:51 ` Mathieu Desnoyers
2025-11-04 6:15 ` Christophe Leroy
2025-10-27 8:43 ` [patch V5 05/12] riscv/uaccess: " Thomas Gleixner
2025-10-28 13:52 ` Mathieu Desnoyers
2025-10-27 8:43 ` [patch V5 06/12] s390/uaccess: " Thomas Gleixner
2025-10-28 13:54 ` Mathieu Desnoyers
2025-10-27 8:43 ` [patch V5 07/12] uaccess: Provide scoped user access regions Thomas Gleixner
2025-10-28 14:11 ` Mathieu Desnoyers
2025-11-04 6:20 ` Christophe Leroy
2025-11-07 19:17 ` David Laight
2025-10-27 8:43 ` [patch V5 08/12] uaccess: Provide put/get_user_inline() Thomas Gleixner
2025-10-28 14:12 ` Mathieu Desnoyers
2025-11-04 6:30 ` Christophe Leroy
2025-10-27 8:43 ` [patch V5 09/12] [RFC] coccinelle: misc: Add scoped_masked_$MODE_access() checker script Thomas Gleixner
2025-10-27 8:44 ` Thomas Gleixner [this message]
2025-10-28 14:24 ` [patch V5 10/12] futex: Convert to get/put_user_inline() Mathieu Desnoyers
2025-10-28 15:56 ` Thomas Gleixner
2025-10-28 16:02 ` Mathieu Desnoyers
2025-10-28 16:13 ` Linus Torvalds
2025-11-04 6:31 ` Christophe Leroy
2025-10-27 8:44 ` [patch V5 11/12] x86/futex: Convert to scoped user access Thomas Gleixner
2025-10-27 8:44 ` [patch V5 12/12] select: " Thomas Gleixner
2025-10-28 14:42 ` Mathieu Desnoyers
2025-11-04 6:32 ` Christophe Leroy
2025-10-27 15:53 ` [patch V5 00/12] uaccess: Provide and use scopes for " Linus Torvalds
2025-10-29 10:23 ` Peter Zijlstra
2025-11-03 14:46 ` Peter Zijlstra
2025-11-04 6:35 ` Christophe Leroy
2025-12-19 8:10 ` patchwork-bot+linux-riscv
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