kernel/linux.git/arch/powerpc/include/asm/futex.h, branch linux-4.4.y

powerpc: Add a framework for user access tracking

2020-11-22T08:56:58+00:00

Backported from commit de78a9c42a79 ("powerpc: Add a framework for Kernel Userspace Access Protection"). Here we don't try to add the KUAP framework, we just want the helper functions because we want to put uaccess flush helpers in them. In terms of fixes, we don't need commit 1d8f739b07bd ("powerpc/kuap: Fix set direction in allow/prevent_user_access()") as we don't have real KUAP. Likewise as all our allows are noops and all our prevents are just flushes, we don't need commit 9dc086f1e9ef ("powerpc/futex: Fix incorrect user access blocking") The other 2 fixes we do need. The original description is: This patch implements a framework for Kernel Userspace Access Protection. Then subarches will have the possibility to provide their own implementation by providing setup_kuap() and allow/prevent_user_access(). Some platforms will need to know the area accessed and whether it is accessed from read, write or both. Therefore source, destination and size and handed over to the two functions. mpe: Rename to allow/prevent rather than unlock/lock, and add read/write wrappers. Drop the 32-bit code for now until we have an implementation for it. Add kuap to pt_regs for 64-bit as well as 32-bit. Don't split strings, use pr_crit_ratelimited(). Signed-off-by: Christophe Leroy Signed-off-by: Russell Currey Signed-off-by: Michael Ellerman Signed-off-by: Daniel Axtens Signed-off-by: Greg Kroah-Hartman

powerpc/futex: Fix warning: 'oldval' may be used uninitialized in this function

2019-10-07T19:01:00+00:00

[ Upstream commit 38a0d0cdb46d3f91534e5b9839ec2d67be14c59d ] We see warnings such as: kernel/futex.c: In function 'do_futex': kernel/futex.c:1676:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized] return oldval == cmparg; ^ kernel/futex.c:1651:6: note: 'oldval' was declared here int oldval, ret; ^ This is because arch_futex_atomic_op_inuser() only sets *oval if ret is 0 and GCC doesn't see that it will only use it when ret is 0. Anyway, the non-zero ret path is an error path that won't suffer from setting *oval, and as *oval is a local var in futex_atomic_op_inuser() it will have no impact. Signed-off-by: Christophe Leroy [mpe: reword change log slightly] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/86b72f0c134367b214910b27b9a6dd3321af93bb.1565774657.git.christophe.leroy@c-s.fr Signed-off-by: Sasha Levin

futex: Remove duplicated code and fix undefined behaviour

2018-05-26T06:48:50+00:00

commit 30d6e0a4190d37740e9447e4e4815f06992dd8c3 upstream. There is code duplicated over all architecture's headers for futex_atomic_op_inuser. Namely op decoding, access_ok check for uaddr, and comparison of the result. Remove this duplication and leave up to the arches only the needed assembly which is now in arch_futex_atomic_op_inuser. This effectively distributes the Will Deacon's arm64 fix for undefined behaviour reported by UBSAN to all architectures. The fix was done in commit 5f16a046f8e1 (arm64: futex: Fix undefined behaviour with FUTEX_OP_OPARG_SHIFT usage). Look there for an example dump. And as suggested by Thomas, check for negative oparg too, because it was also reported to cause undefined behaviour report. Note that s390 removed access_ok check in d12a29703 ("s390/uaccess: remove pointless access_ok() checks") as access_ok there returns true. We introduce it back to the helper for the sake of simplicity (it gets optimized away anyway). Signed-off-by: Jiri Slaby Signed-off-by: Thomas Gleixner Acked-by: Russell King Acked-by: Michael Ellerman (powerpc) Acked-by: Heiko Carstens [s390] Acked-by: Chris Metcalf [for tile] Reviewed-by: Darren Hart (VMware) Reviewed-by: Will Deacon [core/arm64] Cc: linux-mips@linux-mips.org Cc: Rich Felker Cc: linux-ia64@vger.kernel.org Cc: linux-sh@vger.kernel.org Cc: peterz@infradead.org Cc: Benjamin Herrenschmidt Cc: Max Filippov Cc: Paul Mackerras Cc: sparclinux@vger.kernel.org Cc: Jonas Bonn Cc: linux-s390@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: Yoshinori Sato Cc: linux-hexagon@vger.kernel.org Cc: Helge Deller Cc: "James E.J. Bottomley" Cc: Catalin Marinas Cc: Matt Turner Cc: linux-snps-arc@lists.infradead.org Cc: Fenghua Yu Cc: Arnd Bergmann Cc: linux-xtensa@linux-xtensa.org Cc: Stefan Kristiansson Cc: openrisc@lists.librecores.org Cc: Ivan Kokshaysky Cc: Stafford Horne Cc: linux-arm-kernel@lists.infradead.org Cc: Richard Henderson Cc: Chris Zankel Cc: Michal Simek Cc: Tony Luck Cc: linux-parisc@vger.kernel.org Cc: Vineet Gupta Cc: Ralf Baechle Cc: Richard Kuo Cc: linux-alpha@vger.kernel.org Cc: Martin Schwidefsky Cc: linuxppc-dev@lists.ozlabs.org Cc: "David S. Miller" Link: http://lkml.kernel.org/r/20170824073105.3901-1-jslaby@suse.cz Cc: Ben Hutchings Signed-off-by: Greg Kroah-Hartman

powerpc: Fix atomic_xxx_return barrier semantics

2011-11-17T05:26:07+00:00

The Documentation/memory-barriers.txt document requires that atomic operations that return a value act as a memory barrier both before and after the actual atomic operation. Our current implementation doesn't guarantee this. More specifically, while a load following the isync can not be issued before stwcx. has completed, that completion doesn't architecturally means that the result of stwcx. is visible to other processors (or any previous stores for that matter) (typically, the other processors L1 caches can still hold the old value). This has caused an actual crash in RCU torture testing on Power 7 This fixes it by changing those atomic ops to use new macros instead of RELEASE/ACQUIRE barriers, called ATOMIC_ENTRY and ATMOIC_EXIT barriers, which are then defined respectively to lwsync and sync. I haven't had a chance to measure the performance impact (or rather what I measured with kernel compiles is in the noise, I yet have to find a more precise benchmark) Signed-off-by: Benjamin Herrenschmidt Acked-by: Paul E. McKenney

futex: Sanitize futex ops argument types

2011-03-11T11:23:31+00:00

Change futex_atomic_op_inuser and futex_atomic_cmpxchg_inatomic prototypes to use u32 types for the futex as this is the data type the futex core code uses all over the place. Signed-off-by: Michel Lespinasse Cc: Darren Hart Cc: Peter Zijlstra Cc: Matt Turner Cc: Russell King Cc: David Howells Cc: Tony Luck Cc: Michal Simek Cc: Ralf Baechle Cc: "James E.J. Bottomley" Cc: Benjamin Herrenschmidt Cc: Martin Schwidefsky Cc: Paul Mundt Cc: "David S. Miller" Cc: Chris Metcalf Cc: Linus Torvalds LKML-Reference: <20110311025058.GD26122@google.com> Signed-off-by: Thomas Gleixner

futex: Sanitize cmpxchg_futex_value_locked API

2011-03-11T11:23:08+00:00

The cmpxchg_futex_value_locked API was funny in that it returned either the original, user-exposed futex value OR an error code such as -EFAULT. This was confusing at best, and could be a source of livelocks in places that retry the cmpxchg_futex_value_locked after trying to fix the issue by running fault_in_user_writeable(). This change makes the cmpxchg_futex_value_locked API more similar to the get_futex_value_locked one, returning an error code and updating the original value through a reference argument. Signed-off-by: Michel Lespinasse Acked-by: Chris Metcalf [tile] Acked-by: Tony Luck [ia64] Acked-by: Thomas Gleixner Tested-by: Michal Simek [microblaze] Acked-by: David Howells [frv] Cc: Darren Hart Cc: Peter Zijlstra Cc: Matt Turner Cc: Russell King Cc: Ralf Baechle Cc: "James E.J. Bottomley" Cc: Benjamin Herrenschmidt Cc: Martin Schwidefsky Cc: Paul Mundt Cc: "David S. Miller" Cc: Linus Torvalds LKML-Reference: <20110311024851.GC26122@google.com> Signed-off-by: Thomas Gleixner

powerpc: Rename LWSYNC_ON_SMP to PPC_RELEASE_BARRIER, ISYNC_ON_SMP to PPC_ACQUIRE_BARRIER

2010-02-17T03:03:15+00:00

For performance reasons we are about to change ISYNC_ON_SMP to sometimes be lwsync. Now that the macro name doesn't make sense, change it and LWSYNC_ON_SMP to better explain what the barriers are doing. Signed-off-by: Anton Blanchard Signed-off-by: Benjamin Herrenschmidt

powerpc: Fix data-corrupting bug in __futex_atomic_op

2009-04-15T05:23:53+00:00

Richard Henderson pointed out that the powerpc __futex_atomic_op has a bug: it will write the wrong value if the stwcx. fails and it has to retry the lwarx/stwcx. loop, since 'oparg' will have been overwritten by the result from the first time around the loop. This happens because it uses the same register for 'oparg' (an input) as it uses for the result. This fixes it by using separate registers for 'oparg' and 'ret'. Cc: stable@kernel.org Signed-off-by: Paul Mackerras

powerpc: Move include files to arch/powerpc/include/asm

2008-08-04T02:02:00+00:00

from include/asm-powerpc. This is the result of a mkdir arch/powerpc/include/asm git mv include/asm-powerpc/* arch/powerpc/include/asm Followed by a few documentation/comment fixups and a couple of places where was being used explicitly. Of the latter only one was outside the arch code and it is a driver only built for powerpc. Signed-off-by: Stephen Rothwell Signed-off-by: Paul Mackerras