[PATCH v4 06/15] futex2: Add compatibility entry point for x86_x32 ABI

André Almeida
2021-06-03T20:00:54Z

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@collabora.com>
---
kernel/futex2.c | 36 +++++++++++++++++++++++++++++++++++-
1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/kernel/futex2.c b/kernel/futex2.c
index 1e97e5f2e793..5fd0b3d73b53 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
@@ -910,7 +914,16 @@ 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_waitv(futexv, nr_futexes, timo, flags);

@@ -1215,6 +1228,27 @@ SYSCALL_DEFINE6(futex_requeue, struct futex_requeue __user *, uaddr1,
if (ret)
return ret;

+#ifdef CONFIG_X86_X32_ABI
+ if (in_x32_syscall()) {
+ ret = compat_futex_parse_requeue(&rq1, (struct compat_futex_requeue *)uaddr1);
+ if (ret)
+ return ret;
+
+ ret = compat_futex_parse_requeue(&rq2, (struct compat_futex_requeue *)uaddr2);
+ if (ret)
+ return ret;
+ } else
+#endif
+ {
+ ret = futex_parse_requeue(&rq1, uaddr1);
+ if (ret)
+ return ret;
+
+ ret = futex_parse_requeue(&rq2, uaddr2);
+ if (ret)
+ return ret;
+ }
+
return __futex_requeue(rq1, rq2, nr_wake, nr_requeue, cmpval);
}

--
2.31.1