From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>,
"Paul E . McKenney" <paulmck@kernel.org>,
Boqun Feng <boqun.feng@gmail.com>,
"H . Peter Anvin" <hpa@zytor.com>, Paul Turner <pjt@google.com>,
linux-api@vger.kernel.org, Shuah Khan <shuah@kernel.org>,
linux-kselftest@vger.kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Florian Weimer <fw@deneb.enyo.de>,
Andy Lutomirski <luto@amacapital.net>,
Dave Watson <davejwatson@fb.com>,
Andrew Morton <akpm@linux-foundation.org>,
Russell King <linux@arm.linux.org.uk>,
Andi Kleen <andi@firstfloor.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
Ben Maurer <bmaurer@fb.com>, Steven Rostedt <rostedt@goodmis.org>,
Josh Triplett <josh@joshtriplett.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Michael Kerrisk <mtk.manpages@gmail.com>,
Joel Fernandes <joelaf@google.com>
Subject: [RFC PATCH 02/15] rseq: Remove broken uapi field layout on 32-bit little endian
Date: Mon, 24 Jan 2022 12:12:40 -0500 [thread overview]
Message-ID: <20220124171253.22072-3-mathieu.desnoyers@efficios.com> (raw)
In-Reply-To: <20220124171253.22072-1-mathieu.desnoyers@efficios.com>
The rseq rseq_cs.ptr.{ptr32,padding} uapi endianness handling is
entirely wrong on 32-bit little endian: a preprocessor logic mistake
wrongly uses the big endian field layout on 32-bit little endian
architectures.
Fortunately, those ptr32 accessors were never used within the kernel,
and only meant as a convenience for user-space.
Remove those and only leave the "ptr64" union field, as this is the only
thing really needed to express the ABI. Document how 32-bit
architectures are meant to interact with this "ptr64" union field.
Fixes: ec9c82e03a74 ("rseq: uapi: Declare rseq_cs field as union, update includes")
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Florian Weimer <fw@deneb.enyo.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-api@vger.kernel.org
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Watson <davejwatson@fb.com>
Cc: Paul Turner <pjt@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Ben Maurer <bmaurer@fb.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
---
include/uapi/linux/rseq.h | 17 ++++-------------
1 file changed, 4 insertions(+), 13 deletions(-)
diff --git a/include/uapi/linux/rseq.h b/include/uapi/linux/rseq.h
index 9a402fdb60e9..31290f2424a7 100644
--- a/include/uapi/linux/rseq.h
+++ b/include/uapi/linux/rseq.h
@@ -105,22 +105,13 @@ struct rseq {
* Read and set by the kernel. Set by user-space with single-copy
* atomicity semantics. This field should only be updated by the
* thread which registered this data structure. Aligned on 64-bit.
+ *
+ * 32-bit architectures should update the low order bits of the
+ * rseq_cs.ptr64 field, leaving the high order bits initialized
+ * to 0.
*/
union {
__u64 ptr64;
-#ifdef __LP64__
- __u64 ptr;
-#else
- struct {
-#if (defined(__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || defined(__BIG_ENDIAN)
- __u32 padding; /* Initialized to zero. */
- __u32 ptr32;
-#else /* LITTLE */
- __u32 ptr32;
- __u32 padding; /* Initialized to zero. */
-#endif /* ENDIAN */
- } ptr;
-#endif
} rseq_cs;
/*
--
2.17.1
next prev parent reply other threads:[~2022-01-24 17:13 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-24 17:12 [RFC PATCH 00/15] rseq uapi and selftest updates Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 01/15] selftests/rseq: introduce own copy of rseq uapi header Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` Mathieu Desnoyers [this message]
2022-01-25 12:21 ` [RFC PATCH 02/15] rseq: Remove broken uapi field layout on 32-bit little endian Christian Brauner
2022-01-25 14:41 ` Mathieu Desnoyers
2022-01-25 19:00 ` Mathieu Desnoyers
2022-01-26 8:03 ` Christian Brauner
2022-01-26 11:00 ` Florian Weimer
2022-01-26 17:16 ` David Laight
2022-01-26 18:59 ` Mathieu Desnoyers
2022-01-27 15:27 ` [RFC PATCH v2] " Mathieu Desnoyers
2022-01-28 8:52 ` Christian Brauner
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 03/15] selftests/rseq: Remove useless assignment to cpu variable Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 04/15] selftests/rseq: Remove volatile from __rseq_abi Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 05/15] selftests/rseq: Introduce rseq_get_abi() helper Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 06/15] selftests/rseq: Introduce thread pointer getters Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 07/15] selftests/rseq: Uplift rseq selftests for compatibility with glibc-2.35 Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 08/15] selftests/rseq: Fix ppc32: wrong rseq_cs 32-bit field pointer on big endian Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 09/15] selftests/rseq: Fix ppc32 missing instruction selection "u" and "x" for load/store Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 10/15] selftests/rseq: Fix ppc32 offsets by using long rather than off_t Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 11/15] selftests/rseq: Fix warnings about #if checks of undefined tokens Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 12/15] selftests/rseq: Remove arm/mips asm goto compiler work-around Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 13/15] selftests/rseq: Fix: work-around asm goto compiler bugs Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 14/15] selftests/rseq: x86-64: use %fs segment selector for accessing rseq thread area Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-24 17:12 ` [RFC PATCH 15/15] selftests/rseq: x86-32: use %gs " Mathieu Desnoyers
2022-02-03 14:33 ` [tip: sched/core] " tip-bot2 for Mathieu Desnoyers
2022-01-27 15:46 ` [RFC PATCH 00/15] rseq uapi and selftest updates Peter Zijlstra
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