linux-kernel - [RFC PATCH 05/13] futex2: Add compatibility entry point for x86

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Message-Id: <20210215152404.250281-6-andrealmeid@collabora.com>
Date:   Mon, 15 Feb 2021 12:23:56 -0300
From:   André Almeida <andrealmeid@...labora.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Darren Hart <dvhart@...radead.org>,
        linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     kernel@...labora.com, krisman@...labora.com,
        pgriffais@...vesoftware.com, z.figura12@...il.com,
        joel@...lfernandes.org, malteskarupke@...tmail.fm,
        linux-api@...r.kernel.org, fweimer@...hat.com,
        libc-alpha@...rceware.org, linux-kselftest@...r.kernel.org,
        shuah@...nel.org, acme@...nel.org, corbet@....net,
        André Almeida <andrealmeid@...labora.com>
Subject: [RFC PATCH 05/13] futex2: Add compatibility entry point for x86_x32 ABI

New syscalls should use the same entry point for x86_64 and x86_x32
paths. Add a wrapper for x32 calls to use parse functions that assumes
32bit pointers.

Signed-off-by: André Almeida <andrealmeid@...labora.com>
---
 kernel/futex2.c | 42 +++++++++++++++++++++++++++++++++++-------
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/kernel/futex2.c b/kernel/futex2.c
index bad8c183cf9f..8a8b45f98d3b 100644
--- a/kernel/futex2.c
+++ b/kernel/futex2.c
@@ -23,6 +23,10 @@
 #include <linux/syscalls.h>
 #include <uapi/linux/futex.h>
 
+#ifdef CONFIG_X86_64
+#include <linux/compat.h>
+#endif
+
 /**
  * struct futex_key - Components to build unique key for a futex
  * @pointer: Pointer to current->mm or inode's UUID for file backed futexes
@@ -875,7 +879,16 @@ SYSCALL_DEFINE4(futex_waitv, struct futex_waitv __user *, waiters,
 	futexv->hint = false;
 	futexv->task = current;
 
-	ret = futex_parse_waitv(futexv, waiters, nr_futexes);
+#ifdef CONFIG_X86_X32_ABI
+	if (in_x32_syscall()) {
+		ret = compat_futex_parse_waitv(futexv, (struct compat_futex_waitv *)waiters,
+					       nr_futexes);
+	} else
+#endif
+	{
+		ret = futex_parse_waitv(futexv, waiters, nr_futexes);
+	}
+
 	if (!ret)
 		ret = futex_set_timer_and_wait(futexv, nr_futexes, timo, flags);
 
@@ -1181,13 +1194,28 @@ SYSCALL_DEFINE6(futex_requeue, struct futex_requeue __user *, uaddr1,
 	if (flags)
 		return -EINVAL;
 
-	ret = futex_parse_requeue(&rq1, uaddr1, &shared1);
-	if (ret)
-		return ret;
+#ifdef CONFIG_X86_X32_ABI
+	if (in_x32_syscall()) {
+		ret = compat_futex_parse_requeue(&rq1, (struct compat_futex_requeue *)uaddr1,
+						 &shared1);
+		if (ret)
+			return ret;
 
-	ret = futex_parse_requeue(&rq2, uaddr2, &shared2);
-	if (ret)
-		return ret;
+		ret = compat_futex_parse_requeue(&rq2, (struct compat_futex_requeue *)uaddr2,
+						 &shared2);
+		if (ret)
+			return ret;
+	} else
+#endif
+	{
+		ret = futex_parse_requeue(&rq1, uaddr1, &shared1);
+		if (ret)
+			return ret;
+
+		ret = futex_parse_requeue(&rq2, uaddr2, &shared2);
+		if (ret)
+			return ret;
+	}
 
 	return __futex_requeue(rq1, rq2, nr_wake, nr_requeue, cmpval, shared1, shared2);
 }
-- 
2.30.1