[PATCH 1/3] futex: remove duplicated code
From: linux@armlinux.org.uk (Russell King - ARM Linux)
Date: 2017-03-04 13:14:36
Also in:
linux-alpha, linux-arch, linux-mips, linux-sh, linuxppc-dev, lkml, sparclinux
On Fri, Mar 03, 2017 at 01:27:10PM +0100, Jiri Slaby wrote:
quoted hunk
diff --git a/arch/arm/include/asm/futex.h b/arch/arm/include/asm/futex.h index 6795368ad023..cc414382dab4 100644 --- a/arch/arm/include/asm/futex.h +++ b/arch/arm/include/asm/futex.h@@ -128,20 +128,10 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, #endif /* !SMP */ static inline int -futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) +arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *uaddr) { - int op = (encoded_op >> 28) & 7; - int cmp = (encoded_op >> 24) & 15; - int oparg = (encoded_op << 8) >> 20; - int cmparg = (encoded_op << 20) >> 20; int oldval = 0, ret, tmp; - if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) - oparg = 1 << oparg; - - if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32))) - return -EFAULT; - #ifndef CONFIG_SMP preempt_disable(); #endif@@ -172,17 +162,9 @@ futex_atomic_op_inuser (int encoded_op, u32 __user *uaddr) preempt_enable(); #endif - if (!ret) { - switch (cmp) { - case FUTEX_OP_CMP_EQ: ret = (oldval == cmparg); break; - case FUTEX_OP_CMP_NE: ret = (oldval != cmparg); break; - case FUTEX_OP_CMP_LT: ret = (oldval < cmparg); break; - case FUTEX_OP_CMP_GE: ret = (oldval >= cmparg); break; - case FUTEX_OP_CMP_LE: ret = (oldval <= cmparg); break; - case FUTEX_OP_CMP_GT: ret = (oldval > cmparg); break; - default: ret = -ENOSYS; - } - } + if (!ret) + *oval = oldval; + return ret; }diff --git a/kernel/futex.c b/kernel/futex.c index b687cb22301c..c5ff9850952f 100644 --- a/kernel/futex.c +++ b/kernel/futex.c@@ -1457,6 +1457,42 @@ futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset) return ret; } +static int futex_atomic_op_inuser(int encoded_op, u32 __user *uaddr) +{ + int op = (encoded_op >> 28) & 7; + int cmp = (encoded_op >> 24) & 15; + int oparg = (encoded_op << 8) >> 20; + int cmparg = (encoded_op << 20) >> 20;
Hmm. oparg and cmparg look like they're doing these shifts to get sign extension of the 12-bit values by assuming that "int" is 32-bit - probably worth a comment, or for safety, they should be "s32" so it's not dependent on the bit-width of "int".
+ int oldval, ret; + + if (encoded_op & (FUTEX_OP_OPARG_SHIFT << 28)) + oparg = 1 << oparg;
I guess it doesn't matter that oparg can be >= the bit size of oparg (so large values produce an undefined result) as it's no different from userspace trying to do the same with large shifts.
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ ret = arch_futex_atomic_op_inuser(op, oparg, &oldval, uaddr);
+ if (ret)
+ return ret;
+
+ switch (cmp) {
+ case FUTEX_OP_CMP_EQ:
+ return oldval == cmparg;
+ case FUTEX_OP_CMP_NE:
+ return oldval != cmparg;
+ case FUTEX_OP_CMP_LT:
+ return oldval < cmparg;
+ case FUTEX_OP_CMP_GE:
+ return oldval >= cmparg;
+ case FUTEX_OP_CMP_LE:
+ return oldval <= cmparg;
+ case FUTEX_OP_CMP_GT:
+ return oldval > cmparg;
+ default:
+ return -ENOSYS;
+ }
+}
+
/*
* Wake up all waiters hashed on the physical page that is mapped
* to this virtual address:As it's no worse than our existing code, for the above, Acked-by: Russell King <redacted> Thanks. -- RMK's Patch system: http://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net.