locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns to READ_ONCE()/WRITE_ONCE()

Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.

For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.

However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:

----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()

// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch

virtual patch

@ depends on patch @
expression E1, E2;
@@

- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)

@ depends on patch @
expression E;
@@

- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

We are going to split <linux/sched/task_stack.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/task_stack.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Ensure that if userspace supplies insufficient data to
PTRACE_SETREGSET to fill all the registers, the thread's old
registers are preserved.

Cc: stable@vger.kernel.org
Signed-off-by: NDave Martin <Dave.Martin@arm.com>
Signed-off-by: NChris Metcalf <cmetcalf@mellanox.com>

Close the hole where ptrace can change a syscall out from under seccomp.
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Chris Metcalf <cmetcalf@mellanox.com>

Currently, if arch code wants to supply seccomp_data directly to
seccomp (which is generally much faster than having seccomp do it
using the syscall_get_xyz() API), it has to use the two-phase
seccomp hooks. Add it to the easy hooks, too.

Cc: linux-arch@vger.kernel.org
Signed-off-by: NAndy Lutomirski <luto@kernel.org>
Signed-off-by: NKees Cook <keescook@chromium.org>

This ensures that we always notify context tracking that we
have exited from user space no matter how we enter the kernel.
It is similar to how arm64 handles context tracking, for example.

This allows the removal of all the exception_enter() calls that
were added in commit 49e4e156 ("tile: support CONTEXT_TRACKING and
thus NOHZ_FULL").
Signed-off-by: NChris Metcalf <cmetcalf@ezchip.com>

Signed-off-by: NChris Metcalf <cmetcalf@ezchip.com>

Add the TIF_NOHZ flag appropriately.

Add call to user_exit() on entry to do_work_pending() and on entry
to syscalls via do_syscall_trace_enter(), and also the top of
do_syscall_trace_exit() just because it's done in x86.

Add call to user_enter() at the bottom of do_work_pending() once we
have no more work to do before returning to userspace.

Wrap all the trap code in exception_enter() / exception_exit().
Signed-off-by: NChris Metcalf <cmetcalf@ezchip.com>
Acked-by: NFrederic Weisbecker <fweisbec@gmail.com>

The r1 value is set based on the r0 value as we return to user space.
So tracing tools won't automatically see the right value.  Fix this by
generating the correct r1 value in do_syscall_trace_exit() rather
than trying to tamper with the hot path in syscall return.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

This change enables unaligned userspace memory access via a kernel
fast path on tilegx.  The kernel tracks user PC/instruction pairs
per-thread using a direct-mapped cache in userspace.  The cache
maps those PC/instruction pairs to JIT'ed instruction sequences that
load or store using byte-wide load store intructions and then
synthesize 2-, 4- or 8-byte load or store results.  Once an
instruction has been seen to generate an unaligned access once,
subsequent hits on that instruction typically require overhead
of only around 50 cycles if cache and TLB is hot.

We support the prctl() PR_GET_UNALIGN / PR_SET_UNALIGN sys call to
enable or disable unaligned fixups on a per-process basis.

To do this we pull some of the tilepro unaligned support out of the
single_step.c file; tilepro uses instruction disassembly for both
single-step and unaligned access support.  Since tilegx actually has
hardware singlestep support, though, it's cleaner to keep the tilegx
unaligned access code in a separate file.  While we're at it,
properly rename the tilepro-specific types, etc., to have tilepro
suffixes instead of generic tile suffixes.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

Currently the syscall number is passed, but it should be the return
value, which is kept in r0.
Signed-off-by: NSimon Marchi <simon.marchi@polymtl.ca>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> [using a raw 0 value]

This patch adds support for the TIF_SYSCALL_TRACEPOINT on the tile
architecture. Basically, it calls the appropriate tracepoints on syscall
entry and exit.
Signed-off-by: NSimon Marchi <simon.marchi@polymtl.ca>
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

Call tracehook functions for syscall tracing.

The check for TIF_SYSCALL_TRACE was removed, because the same check is
done right before in the assembly file.
Signed-off-by: NSimon Marchi <simon.marchi@polymtl.ca>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com> [with ptrace.h fixup]

This patch changes arch_ptrace on tile so that it uses user_regset
to implement the PTRACE_GETREGS and PTRACE_SETREGS operations.
Signed-off-by: NSimon Marchi <simon.marchi@polymtl.ca>
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

This is a basic implementation of user_regset for the tile
architecture. It reuses the basic blocks that were already there.
Signed-off-by: NSimon Marchi <simon.marchi@polymtl.ca>
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

Use the newer idioms for setting PTRACE_O_xxx and PT_TRACE_xxx flags.
Only set/clear tile-specific flags if the generic routine returns
success, since otherwise we want to avoid setting any flags at all.
Atomically update the ptrace flags with the new values.  Eliminate
the PT_TRACE_MASK_TILE bitmask and just shift PTRACE_O_MASK_TILE.
Add a BUILD_BUG_ON to avoid overlapping with generic bits.
Acked-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

This flag is set for ptrace GETREGS or PEEKUSER for processes
that are COMPAT, i.e. 32-bit.  This allows things like strace
to easily discover what personality to use, for example.
Acked-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

The kernel was allowing any component of the pt_regs to be updated either
by signal handlers writing to the stack, or by processes writing via
PTRACE_POKEUSR or PTRACE_SETREGS, which meant they could set their PL
up from 0 to 1 and get access to kernel code and data (or, in practice,
cause a kernel panic).  We now always reset the ex1 field, allowing the
user to set their ICS bit only.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

Remove checking @addr less than 0 because @addr is now unsigned.
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Acked-by: NChris Metcalf <cmetcalf@tilera.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix up the arguments to arch_ptrace() to take account of the fact that
@addr and @data are now unsigned long rather than long as of a preceding
patch in this series.
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Cc: <linux-arch@vger.kernel.org>
Acked-by: NRoland McGrath <roland@redhat.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Previously, we tried to pass 64-bit arguments through the
"COMPAT" mode 32-bit syscall API, which turned out not to work
well.  Now we just use straight 32-bit arguments in COMPAT mode,
thus requiring individual registers to be read/written with
two syscalls.  Of course this is uncommon, since usually all
the registers are read or written at once.

The restructuring applies to all the tile platforms, but is
plausibly better than the original code in any case.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>

This commit is primarily changes caused by reviewing "sparse"
and "checkpatch" output on our sources, so is somewhat noisy, since
things like "printk() -> pr_err()" (or whatever) throughout the
codebase tend to get tedious to read.  Rather than trying to tease
apart precisely which things changed due to which type of code
review, this commit includes various cleanups in the code:

- sparse: Add declarations in headers for globals.
- sparse: Fix __user annotations.
- sparse: Using gfp_t consistently instead of int.
- sparse: removing functions not actually used.
- checkpatch: Clean up printk() warnings by using pr_info(), etc.;
  also avoid partial-line printks except in bootup code.
  - checkpatch: Use exposed structs rather than typedefs.
  - checkpatch: Change some C99 comments to C89 comments.

In addition, a couple of minor other changes are rolled in
to this commit:

- Add support for a "raise" instruction to cause SIGFPE, etc., to be raised.
- Remove some compat code that is unnecessary when we fully eliminate
  some of the deprecated syscalls from the generic syscall ABI.
- Update the tile_defconfig to reflect current config contents.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>

This change is the core kernel support for TILEPro and TILE64 chips.
No driver support (except the console driver) is included yet.

This includes the relevant Linux headers in asm/; the low-level
low-level "Tile architecture" headers in arch/, which are
shared with the hypervisor, etc., and are build-system agnostic;
and the relevant hypervisor headers in hv/.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Reviewed-by: NPaul Mundt <lethal@linux-sh.org>