linux.git/arch/arc/kernel, branch v4.19

ARC: clone syscall to setp r25 as thread pointer

2018-10-05T21:33:29+00:00

Per ARC TLS ABI, r25 is designated TP (thread pointer register).
However so far kernel didn't do any special treatment, like setting up
usermode r25, even for CLONE_SETTLS. We instead relied on libc runtime
to do this, in say clone libc wrapper [1]. This was deliberate to keep
kernel ABI agnostic (userspace could potentially change TP, specially
for different ARC ISA say ARCompact vs. ARCv2 with different spare
registers etc)

However userspace setting up r25, after clone syscall opens a race, if
child is not scheduled and gets a signal instead. It starts off in
userspace not in clone but in a signal handler and anything TP sepcific
there such as pthread_self() fails which showed up with uClibc
testsuite nptl/tst-kill6 [2]

Fix this by having kernel populate r25 to TP value. So this locks in
ABI, but it was not going to change anyways, and fwiw is same for both
ARCompact (arc700 core) and ARCvs (HS3x cores)

[1] https://cgit.uclibc-ng.org/cgi/cgit/uclibc-ng.git/tree/libc/sysdeps/linux/arc/clone.S
[2] https://github.com/wbx-github/uclibc-ng-test/blob/master/test/nptl/tst-kill6.c

Fixes: ARC STAR 9001378481
Cc: stable@vger.kernel.org
Reported-by: Nikita Sobolev 
Signed-off-by: Vineet Gupta

ARC: cleanup show_faulting_vma()

2018-08-27T16:00:36+00:00

 - Remove unused variables
 - check return value of file_path

Signed-off-by: Eugeniy Paltsev 
Signed-off-by: Vineet Gupta

Merge branch 'perf/urgent' into perf/core, to pick up fixes

2018-07-25T09:47:02+00:00

Signed-off-by: Ingo Molnar

ARC: Improve cmpxchg syscall implementation

2018-07-09T18:22:05+00:00

This is used in configs lacking hardware atomics to emulate atomic r-m-w
for user space, implemented by disabling preemption in kernel.

However there are issues in current implementation:

1. Process not terminated if invalid user pointer passed:
   i.e. __get_user() failed.

2. The reason for this patch was __put_user() failure not being handled
   either, specifically for the COW break scenario.
   The zero page is initially wired up and read from __get_user()
   succeeds. A subsequent write by __put_user() induces a
   Protection Violation, but COW can't finish as Linux page fault
   handler is disabled due to preempt disable.
   And what's worse is we silently return the stale value to user space.
   Fix this specific case by re-enabling preemption and explicitly
   fixing up the fault and retrying the whole sequence over.

Cc: Max Filippov 
Cc: linux-arch@vger.kernel.org
Signed-off-by: Alexey Brodkin 
Signed-off-by: Peter Zijlstra 
Signed-off-by: Vineet Gupta 
[vgupta: rewrote the changelog]

bpf/error-inject/kprobes: Clear current_kprobe and enable preempt in kprobe

2018-06-21T10:33:19+00:00

Clear current_kprobe and enable preemption in kprobe
even if pre_handler returns !0.

This simplifies function override using kprobes.

Jprobe used to require to keep the preemption disabled and
keep current_kprobe until it returned to original function
entry. For this reason kprobe_int3_handler() and similar
arch dependent kprobe handers checks pre_handler result
and exit without enabling preemption if the result is !0.

After removing the jprobe, Kprobes does not need to
keep preempt disabled even if user handler returns !0
anymore.

But since the function override handler in error-inject
and bpf is also returns !0 if it overrides a function,
to balancing the preempt count, it enables preemption
and reset current kprobe by itself.

That is a bad design that is very buggy. This fixes
such unbalanced preempt-count and current_kprobes setting
in kprobes, bpf and error-inject.

Note: for powerpc and x86, this removes all preempt_disable
from kprobe_ftrace_handler because ftrace callbacks are
called under preempt disabled.

Signed-off-by: Masami Hiramatsu 
Acked-by: Thomas Gleixner 
Acked-by: Naveen N. Rao 
Cc: Alexei Starovoitov 
Cc: Ananth N Mavinakayanahalli 
Cc: Andrew Morton 
Cc: Benjamin Herrenschmidt 
Cc: Catalin Marinas 
Cc: David S. Miller 
Cc: Fenghua Yu 
Cc: Heiko Carstens 
Cc: James Hogan 
Cc: Josef Bacik 
Cc: Linus Torvalds 
Cc: Martin Schwidefsky 
Cc: Michael Ellerman 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Ralf Baechle 
Cc: Rich Felker 
Cc: Russell King 
Cc: Steven Rostedt 
Cc: Tony Luck 
Cc: Vineet Gupta 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Cc: linux-arch@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-ia64@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-s390@vger.kernel.org
Cc: linux-sh@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: sparclinux@vger.kernel.org
Link: https://lore.kernel.org/lkml/152942494574.15209.12323837825873032258.stgit@devbox
Signed-off-by: Ingo Molnar

ARC/kprobes: Don't call the ->break_handler() in ARC kprobes code

2018-06-21T10:33:13+00:00

Don't call the ->break_handler() from the ARC kprobes code,
because it was only used by jprobes which got removed.

Signed-off-by: Masami Hiramatsu 
Acked-by: Thomas Gleixner 
Cc: Ananth N Mavinakayanahalli 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Vineet Gupta 
Cc: linux-arch@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Link: https://lore.kernel.org/lkml/152942468446.15209.13773902741600803798.stgit@devbox
Signed-off-by: Ingo Molnar

ARC/kprobes: Remove jprobe implementation

2018-06-21T10:33:06+00:00

Remove arch dependent setjump/longjump functions
and unused fields in kprobe_ctlblk for jprobes
from arch/arc.

Signed-off-by: Masami Hiramatsu 
Acked-by: Thomas Gleixner 
Cc: Ananth N Mavinakayanahalli 
Cc: Andrew Morton 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Vineet Gupta 
Cc: linux-arch@vger.kernel.org
Cc: linux-snps-arc@lists.infradead.org
Link: https://lore.kernel.org/lkml/152942436460.15209.3038881268172249579.stgit@devbox
Signed-off-by: Ingo Molnar

ARC: Enable machine_desc->init_per_cpu for !CONFIG_SMP

2018-06-20T23:12:06+00:00

machine_desc->init_per_cpu() hook is supposed to be per cpu
initialization and would seem to apply  equally to UP and/or SMP.
Infact the comment in header file seems to suggest it works for
UP too, which was not the case and this patch.

This enables !CONFIG_SMP build for platforms such as hsdk.

Signed-off-by: Alexey Brodkin 
Signed-off-by: Vineet Gupta 
[vgupta: trimmeed changelog]

Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2018-04-06T18:07:08+00:00

Pull misc vfs updates from Al Viro:
 "Assorted stuff, including Christoph's I_DIRTY patches"

* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  fs: move I_DIRTY_INODE to fs.h
  ubifs: fix bogus __mark_inode_dirty(I_DIRTY_SYNC | I_DIRTY_DATASYNC) call
  ntfs: fix bogus __mark_inode_dirty(I_DIRTY_SYNC | I_DIRTY_DATASYNC) call
  gfs2: fix bogus __mark_inode_dirty(I_DIRTY_SYNC | I_DIRTY_DATASYNC) calls
  fs: fold open_check_o_direct into do_dentry_open
  vfs: Replace stray non-ASCII homoglyph characters with their ASCII equivalents
  vfs: make sure struct filename->iname is word-aligned
  get rid of pointless includes of fs_struct.h
  [poll] annotate SAA6588_CMD_POLL users

Merge tag 'arc-4.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

2018-03-01T22:32:23+00:00

Pull ARC fixes from Vineet Gupta:

 - MCIP aka ARconnect fixes for SMP builds [Euginey]

 - preventive fix for SLC (L2 cache) flushing [Euginey]

 - Kconfig default fix [Ulf Magnusson]

 - trailing semicolon fixes [Luis de Bethencourt]

 - other assorted minor fixes

* tag 'arc-4.15-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: setup cpu possible mask according to possible-cpus dts property
  ARC: mcip: update MCIP debug mask when the new cpu came online
  ARC: mcip: halt GFRC counter when ARC cores halt
  ARCv2: boot log: fix HS48 release number
  arc: dts: use 'atmel' as manufacturer for at24 in axs10x_mb
  ARC: Fix malformed ARC_EMUL_UNALIGNED default
  ARC: boot log: Fix trailing semicolon
  ARC: dw2 unwind: Fix trailing semicolon
  ARC: Enable fatal signals on boot for dev platforms
  ARCv2: Don't pretend we may set L-bit in STATUS32 with kflag instruction
  ARCv2: cache: fix slc_entire_op: flush only instead of flush-n-inv