linux-stable.git/arch/arc, branch v5.13.2

sched/core: Initialize the idle task with preemption disabled

2021-07-14T15:06:21+00:00

[ Upstream commit f1a0a376ca0c4ef1fc3d24e3e502acbb5b795674 ]

As pointed out by commit

  de9b8f5dcbd9 ("sched: Fix crash trying to dequeue/enqueue the idle thread")

init_idle() can and will be invoked more than once on the same idle
task. At boot time, it is invoked for the boot CPU thread by
sched_init(). Then smp_init() creates the threads for all the secondary
CPUs and invokes init_idle() on them.

As the hotplug machinery brings the secondaries to life, it will issue
calls to idle_thread_get(), which itself invokes init_idle() yet again.
In this case it's invoked twice more per secondary: at _cpu_up(), and at
bringup_cpu().

Given smp_init() already initializes the idle tasks for all *possible*
CPUs, no further initialization should be required. Now, removing
init_idle() from idle_thread_get() exposes some interesting expectations
with regards to the idle task's preempt_count: the secondary startup always
issues a preempt_disable(), requiring some reset of the preempt count to 0
between hot-unplug and hotplug, which is currently served by
idle_thread_get() -> idle_init().

Given the idle task is supposed to have preemption disabled once and never
see it re-enabled, it seems that what we actually want is to initialize its
preempt_count to PREEMPT_DISABLED and leave it there. Do that, and remove
init_idle() from idle_thread_get().

Secondary startups were patched via coccinelle:

  @begone@
  @@

  -preempt_disable();
  ...
  cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);

Signed-off-by: Valentin Schneider 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Link: https://lore.kernel.org/r/20210512094636.2958515-1-valentin.schneider@arm.com
Signed-off-by: Sasha Levin

ARC: fix CONFIG_HARDENED_USERCOPY

2021-06-11T00:37:00+00:00

Currently enabling this triggers a warning

| usercopy: Kernel memory overwrite attempt detected to kernel text (offset 155633, size 11)!
| usercopy: BUG: failure at mm/usercopy.c:99/usercopy_abort()!
|
|gcc generated __builtin_trap
|Path: /bin/busybox
|CPU: 0 PID: 84 Comm: init Not tainted 5.4.22
|
|[ECR ]: 0x00090005 => gcc generated __builtin_trap
|[EFA ]: 0x9024fcaa
|[BLINK ]: usercopy_abort+0x8a/0x8c
|[ERET ]: memfd_fcntl+0x0/0x470
|[STAT32]: 0x80080802 : IE K
|...
|...
|Stack Trace:
| memfd_fcntl+0x0/0x470
| usercopy_abort+0x8a/0x8c
| __check_object_size+0x10e/0x138
| copy_strings+0x1f4/0x38c
| __do_execve_file+0x352/0x848
| EV_Trap+0xcc/0xd0

The issue is triggered by an allocation in "init reclaimed" region.
ARC _stext emcompasses the init region (for historical reasons we wanted
the init.text to be under .text as well). This however trips up
__check_object_size()->check_kernel_text_object() which treats this as
object bleeding into kernel text.

Fix that by rezoning _stext to start from regular kernel .text and leave
out .init altogether.

Fixes: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/15
Reported-by: Evgeniy Didin 
Reviewed-by: Kees Cook 
Signed-off-by: Vineet Gupta

ARCv2: save ABI registers across signal handling

2021-06-11T00:21:38+00:00

ARCv2 has some configuration dependent registers (r30, r58, r59) which
could be targetted by the compiler. To keep the ABI stable, these were
unconditionally part of the glibc ABI
(sysdeps/unix/sysv/linux/arc/sys/ucontext.h:mcontext_t) however we
missed populating them (by saving/restoring them across signal
handling).

This patch fixes the issue by
 - adding arcv2 ABI regs to kernel struct sigcontext
 - populating them during signal handling

Change to struct sigcontext might seem like a glibc ABI change (although
it primarily uses ucontext_t:mcontext_t) but the fact is
 - it has only been extended (existing fields are not touched)
 - the old sigcontext was ABI incomplete to begin with anyways

Fixes: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/53
Cc: 
Tested-by: kernel test robot 
Reported-by: Vladimir Isaev 
Signed-off-by: Vineet Gupta

ARC: mm: Use max_high_pfn as a HIGHMEM zone border

2021-05-10T19:38:59+00:00

Commit 4af22ded0ecf ("arc: fix memory initialization for systems
with two memory banks") fixed highmem, but for the PAE case it causes
bug messages:

| BUG: Bad page state in process swapper  pfn:80000
| page:(ptrval) refcount:0 mapcount:1 mapping:00000000 index:0x0 pfn:0x80000 flags: 0x0()
| raw: 00000000 00000100 00000122 00000000 00000000 00000000 00000000 00000000
| raw: 00000000
| page dumped because: nonzero mapcount
| Modules linked in:
| CPU: 0 PID: 0 Comm: swapper Not tainted 5.12.0-rc5-00003-g1e43c377a79f #1

This is because the fix expects highmem to be always less than
lowmem and uses min_low_pfn as an upper zone border for highmem.

max_high_pfn should be ok for both highmem and highmem+PAE cases.

Fixes: 4af22ded0ecf ("arc: fix memory initialization for systems with two memory banks")
Signed-off-by: Vladimir Isaev 
Cc: Mike Rapoport 
Cc: stable@vger.kernel.org  #5.8 onwards
Signed-off-by: Vineet Gupta

ARC: mm: PAE: use 40-bit physical page mask

2021-05-10T19:38:59+00:00

32-bit PAGE_MASK can not be used as a mask for physical addresses
when PAE is enabled. PAGE_MASK_PHYS must be used for physical
addresses instead of PAGE_MASK.

Without this, init gets SIGSEGV if pte_modify was called:

| potentially unexpected fatal signal 11.
| Path: /bin/busybox
| CPU: 0 PID: 1 Comm: init Not tainted 5.12.0-rc5-00003-g1e43c377a79f-dirty
| Insn could not be fetched
|     @No matching VMA found
|  ECR: 0x00040000 EFA: 0x00000000 ERET: 0x00000000
| STAT: 0x80080082 [IE U     ]   BTA: 0x00000000
|  SP: 0x5f9ffe44  FP: 0x00000000 BLK: 0xaf3d4
| LPS: 0x000d093e LPE: 0x000d0950 LPC: 0x00000000
| r00: 0x00000002 r01: 0x5f9fff14 r02: 0x5f9fff20
| ...
| Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

Signed-off-by: Vladimir Isaev 
Reported-by: kernel test robot 
Cc: Vineet Gupta 
Cc: stable@vger.kernel.org
Signed-off-by: Vineet Gupta

ARC: entry: fix off-by-one error in syscall number validation

2021-05-10T19:38:59+00:00

We have NR_syscall syscalls from [0 .. NR_syscall-1].
However the check for invalid syscall number is "> NR_syscall" as
opposed to >=. This off-by-one error erronesously allows "NR_syscall"
to be treated as valid syscall causeing out-of-bounds access into
syscall-call table ensuing a crash (holes within syscall table have a
invalid-entry handler but this is beyond the array implementing the
table).

This problem showed up on v5.6 kernel when testing glibc 2.33 (v5.10
kernel capable, includng faccessat2 syscall 439). The v5.6 kernel has
NR_syscalls=439 (0 to 438). Due to the bug, 439 passed by glibc was
not handled as -ENOSYS but processed leading to a crash.

Link: https://github.com/foss-for-synopsys-dwc-arc-processors/linux/issues/48
Reported-by: Shahab Vahedi 
Cc: 
Signed-off-by: Vineet Gupta

ARC: kgdb: add 'fallthrough' to prevent a warning

2021-05-10T19:38:59+00:00

Use the 'fallthrough' macro to document that this switch case
does indeed fall through to the next case.

../arch/arc/kernel/kgdb.c: In function 'kgdb_arch_handle_exception':
../arch/arc/kernel/kgdb.c:141:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
  141 |   if (kgdb_hex2long(&ptr, &addr))
      |      ^
../arch/arc/kernel/kgdb.c:144:2: note: here
  144 |  case 'D':
      |  ^~~~

Cc: linux-snps-arc@lists.infradead.org
Signed-off-by: Randy Dunlap 
Signed-off-by: Vineet Gupta

arc: Fix typos/spellos

2021-05-10T19:38:59+00:00

s/commiting/committing/
s/defintion/definition/
s/gaurantees/guarantees/
s/interrpted/interrupted/
s/interrutps/interrupts/
s/succeded/succeeded/
s/unconditonally/unconditionally/

Reviewed-by: Christian Brauner 
Acked-by: Randy Dunlap 
Signed-off-by: Bhaskar Chowdhury 
Signed-off-by: Vineet Gupta

mm: drop redundant HAVE_ARCH_TRANSPARENT_HUGEPAGE

2021-05-05T18:27:25+00:00

HAVE_ARCH_TRANSPARENT_HUGEPAGE has duplicate definitions on platforms
that subscribe it.  Drop these reduntant definitions and instead just
select it on applicable platforms.

Link: https://lkml.kernel.org/r/1617259448-22529-7-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual 
Acked-by: Arnd Bergmann 
Acked-by: Vineet Gupta 		[arc]
Cc: Russell King 
Cc: Albert Ou 
Cc: Alexander Viro 
Cc: Benjamin Herrenschmidt 
Cc: Borislav Petkov 
Cc: Catalin Marinas 
Cc: Christian Borntraeger 
Cc: Heiko Carstens 
Cc: Helge Deller 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: "James E.J. Bottomley" 
Cc: Michael Ellerman 
Cc: Palmer Dabbelt 
Cc: Paul Mackerras 
Cc: Paul Walmsley 
Cc: Rich Felker 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Cc: Will Deacon 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: generalize ARCH_HAS_CACHE_LINE_SIZE

2021-05-05T18:27:25+00:00

Patch series "mm: some config cleanups", v2.

This series contains config cleanup patches which reduces code
duplication across platforms and also improves maintainability.  There
is no functional change intended with this series.

This patch (of 6):

ARCH_HAS_CACHE_LINE_SIZE config has duplicate definitions on platforms
that subscribe it.  Instead, just make it a generic option which can be
selected on applicable platforms.  This change reduces code duplication
and makes it cleaner.

Link: https://lkml.kernel.org/r/1617259448-22529-1-git-send-email-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/1617259448-22529-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual 
Acked-by: Catalin Marinas 	[arm64]
Acked-by: Vineet Gupta 		[arc]
Cc: Will Deacon 
Cc: Thomas Gleixner 
Cc: Ingo Molnar 
Cc: Borislav Petkov 
Cc: "H. Peter Anvin" 
Cc: Albert Ou 
Cc: Alexander Viro 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Christian Borntraeger 
Cc: Heiko Carstens 
Cc: Helge Deller 
Cc: "James E.J. Bottomley" 
Cc: Michael Ellerman 
Cc: Palmer Dabbelt 
Cc: Paul Mackerras 
Cc: Paul Walmsley 
Cc: Rich Felker 
Cc: Russell King 
Cc: Thomas Bogendoerfer 
Cc: Vasily Gorbik 
Cc: Yoshinori Sato 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds