linux-stable.git/arch/arc, branch v3.18.40

ARC: mm: don't loose PTE_SPECIAL in pte_modify()

2016-08-22T16:23:22+00:00

[ Upstream commit 3925a16ae980c79d1a8fd182d7f9487da1edd4dc ]

LTP madvise05 was generating mm splat

| [ARCLinux]# /sd/ltp/testcases/bin/madvise05
| BUG: Bad page map in process madvise05  pte:80e08211 pmd:9f7d4000
| page:9fdcfc90 count:1 mapcount:-1 mapping:  (null) index:0x0 flags: 0x404(referenced|reserved)
| page dumped because: bad pte
| addr:200b8000 vm_flags:00000070 anon_vma:  (null) mapping:  (null) index:1005c
| file:  (null) fault:  (null) mmap:  (null) readpage:  (null)
| CPU: 2 PID: 6707 Comm: madvise05

And for newer kernels, the system was rendered unusable afterwards.

The problem was mprotect->pte_modify() clearing PTE_SPECIAL (which is
set to identify the special zero page wired to the pte).
When pte was finally unmapped, special casing for zero page was not
done, and instead it was treated as a "normal" page, tripping on the
map counts etc.

This fixes ARC STAR 9001053308

Cc: 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

arc: unwind: warn only once if DW2_UNWIND is disabled

2016-07-12T12:47:16+00:00

[ Upstream commit 9bd54517ee86cb164c734f72ea95aeba4804f10b ]

If CONFIG_ARC_DW2_UNWIND is disabled every time arc_unwind_core()
gets called following message gets printed in debug console:
----------------->8---------------
CONFIG_ARC_DW2_UNWIND needs to be enabled
----------------->8---------------

That message makes sense if user indeed wants to see a backtrace or
get nice function call-graphs in perf but what if user disabled
unwinder for the purpose? Why pollute his debug console?

So instead we'll warn user about possibly missing feature once and
let him decide if that was what he or she really wanted.

Signed-off-by: Alexey Brodkin 
Cc: stable@vger.kernel.org
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: unwind: ensure that .debug_frame is generated (vs. .eh_frame)

2016-07-12T12:47:15+00:00

[ Upstream commit f52e126cc7476196f44f3c313b7d9f0699a881fc ]

With recent binutils update to support dwarf CFI pseudo-ops in gas, we
now get .eh_frame vs. .debug_frame. Although the call frame info is
exactly the same in both, the CIE differs, which the current kernel
unwinder can't cope with.

This broke both the kernel unwinder as well as loadable modules (latter
because of a new unhandled relo R_ARC_32_PCREL from .rela.eh_frame in
the module loader)

The ideal solution would be to switch unwinder to .eh_frame.
For now however we can make do by just ensureing .debug_frame is
generated by removing -fasynchronous-unwind-tables

 .eh_frame    generated with -gdwarf-2 -fasynchronous-unwind-tables
 .debug_frame generated with -gdwarf-2

Fixes STAR 9001058196

Cc: stable@vger.kernel.org
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: add smp barriers around atomics per Documentation/atomic_ops.txt

2015-07-05T14:12:50+00:00

[ Upstream commit 2576c28e3f623ed401db7e6197241865328620ef ]

 - arch_spin_lock/unlock were lacking the ACQUIRE/RELEASE barriers
   Since ARCv2 only provides load/load, store/store and all/all, we need
   the full barrier

 - LLOCK/SCOND based atomics, bitops, cmpxchg, which return modified
   values were lacking the explicit smp barriers.

 - Non LLOCK/SCOND varaints don't need the explicit barriers since that
   is implicity provided by the spin locks used to implement the
   critical section (the spin lock barriers in turn are also fixed in
   this commit as explained above

Cc: Paul E. McKenney 
Cc: stable@vger.kernel.org
Acked-by: Peter Zijlstra (Intel) 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: add compiler barrier to LLSC based cmpxchg

2015-07-05T14:12:50+00:00

[ Upstream commit d57f727264f1425a94689bafc7e99e502cb135b5 ]

When auditing cmpxchg call sites, Chuck noted that gcc was optimizing
away some of the desired LDs.

|	do {
|		new = old = *ipi_data_ptr;
|		new |= 1U << msg;
|	} while (cmpxchg(ipi_data_ptr, old, new) != old);

was generating to below

| 8015cef8:	ld         r2,[r4,0]  <-- First LD
| 8015cefc:	bset       r1,r2,r1
|
| 8015cf00:	llock      r3,[r4]  <-- atomic op
| 8015cf04:	brne       r3,r2,8015cf10
| 8015cf08:	scond      r1,[r4]
| 8015cf0c:	bnz        8015cf00
|
| 8015cf10:	brne       r3,r2,8015cf00  <-- Branch doesn't go to orig LD

Although this was fixed by adding a ACCESS_ONCE in this call site, it
seems safer (for now at least) to add compiler barrier to LLSC based
cmpxchg

Reported-by: Chuck Jordan 
Cc: 
Acked-by: Peter Zijlstra (Intel) 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: unbork !LLSC build

2015-06-10T17:42:46+00:00

[ Upstream commit daaf40e53b5dbdf75255d58a45ce8ac65ca511a8 ]

Fixes: f7d11e93ee97a locking,arch,arc: Fold atomic_ops
Cc:  # 3.18
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: signal handling robustify

2015-04-23T03:31:18+00:00

[ Upstream commit e4140819dadc3624accac8294881bca8a3cba4ed ]

A malicious signal handler / restorer can DOS the system by fudging the
user regs saved on stack, causing weird things such as sigreturn returning
to user mode PC but cpu state still being kernel mode....

Ensure that in sigreturn path status32 always has U bit; any other bogosity
(gargbage PC etc) will be taken care of by normal user mode exceptions mechanisms.

Reproducer signal handler:

    void handle_sig(int signo, siginfo_t *info, void *context)
    {
	ucontext_t *uc = context;
	struct user_regs_struct *regs = &(uc->uc_mcontext.regs);

	regs->scratch.status32 = 0;
    }

Before the fix, kernel would go off to weeds like below:

    --------->8-----------
    [ARCLinux]$ ./signal-test
    Path: /signal-test
    CPU: 0 PID: 61 Comm: signal-test Not tainted 4.0.0-rc5+ #65
    task: 8f177880 ti: 5ffe6000 task.ti: 8f15c000

    [ECR   ]: 0x00220200 => Invalid Write @ 0x00000010 by insn @ 0x00010698
    [EFA   ]: 0x00000010
    [BLINK ]: 0x2007c1ee
    [ERET  ]: 0x10698
    [STAT32]: 0x00000000 :                                   <--------
    BTA: 0x00010680	 SP: 0x5ffe7e48	 FP: 0x00000000
    LPS: 0x20003c6c	LPE: 0x20003c70	LPC: 0x00000000
    ...
    --------->8-----------

Reported-by: Alexey Brodkin 
Cc: 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: SA_SIGINFO ucontext regs off-by-one

2015-04-23T03:31:10+00:00

[ Upstream commit 6914e1e3f63caa829431160f0f7093292daef2d5 ]

The regfile provided to SA_SIGINFO signal handler as ucontext was off by
one due to pt_regs gutter cleanups in 2013.

Before handling signal, user pt_regs are copied onto user_regs_struct and copied
back later. Both structs are binary compatible. This was all fine until
commit 2fa919045b72 (ARC: pt_regs update #2) which removed the empty stack slot
at top of pt_regs (corresponding to first pad) and made the corresponding
fixup in struct user_regs_struct (the pad in there was moved out of
@scratch - not removed altogether as it is part of ptrace ABI)

 struct user_regs_struct {
+       long pad;
        struct {
-               long pad;
                long bta, lp_start, lp_end,....
        } scratch;
 ...
 }

This meant that now user_regs_struct was off by 1 reg w.r.t pt_regs and
signal code needs to user_regs_struct.scratch to reflect it as pt_regs,
which is what this commit does.

This problem was hidden for 2 years, because both save/restore, despite
using wrong location, were using the same location. Only an interim
inspection (reproducer below) exposed the issue.

     void handle_segv(int signo, siginfo_t *info, void *context)
     {
 	ucontext_t *uc = context;
	struct user_regs_struct *regs = &(uc->uc_mcontext.regs);

	printf("regs %x %x\n",               <=== prints 7 8 (vs. 8 9)
               regs->scratch.r8, regs->scratch.r9);
     }

     int main()
     {
	struct sigaction sa;

	sa.sa_sigaction = handle_segv;
	sa.sa_flags = SA_SIGINFO;
	sigemptyset(&sa.sa_mask);
	sigaction(SIGSEGV, &sa, NULL);

	asm volatile(
	"mov	r7, 7	\n"
	"mov	r8, 8	\n"
	"mov	r9, 9	\n"
	"mov	r10, 10	\n"
	:::"r7","r8","r9","r10");

	*((unsigned int*)0x10) = 0;
     }

Fixes: 2fa919045b72ec892e "ARC: pt_regs update #2: Remove unused gutter at start of pt_regs"
CC: 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: Fix KSTK_ESP()

2015-03-14T19:37:27+00:00

commit 13648b0118a24f4fc76c34e6c7b6ccf447e46a2a upstream.

/proc//maps currently don't annotate stack vma with "[stack]"
This is because KSTK_ESP ie expected to return usermode SP of tsk while
currently it returns the kernel mode SP of a sleeping tsk.

While the fix is trivial, we also need to adjust the ARC kernel stack
unwinder to not use KSTK_SP and friends any more.

Reported-and-suggested-by: Alexey Brodkin 
Signed-off-by: Vineet Gupta 
Signed-off-by: Sasha Levin

ARC: fix page address calculation if PAGE_OFFSET != LINUX_LINK_BASE

2015-03-06T22:53:01+00:00

commit 06f34e1c28f3608b0ce5b310e41102d3fe7b65a1 upstream.

We used to calculate page address differently in 2 cases:

1. In virt_to_page(x) we do
 --->8---
 mem_map + (x - CONFIG_LINUX_LINK_BASE) >> PAGE_SHIFT
 --->8---

2. In in pte_page(x) we do
 --->8---
 mem_map + (pte_val(x) - PAGE_OFFSET) >> PAGE_SHIFT
 --->8---

That leads to problems in case PAGE_OFFSET != CONFIG_LINUX_LINK_BASE -
different pages will be selected depending on where and how we calculate
page address.

In particular in the STAR 9000853582 when gdb attempted to read memory
of another process it got improper page in get_user_pages() because this
is exactly one of the places where we search for a page by pte_page().

The fix is trivial - we need to calculate page address similarly in both
cases.

Signed-off-by: Alexey Brodkin 
Signed-off-by: Vineet Gupta 
Signed-off-by: Greg Kroah-Hartman