1. 25 7月, 2015 2 次提交
  2. 23 7月, 2015 3 次提交
    • P
      powerpc: Use hardware RNG for arch_get_random_seed_* not arch_get_random_* · 01c9348c
      Paul Mackerras 提交于
      The hardware RNG on POWER8 and POWER7+ can be relatively slow, since
      it can only supply one 64-bit value per microsecond.  Currently we
      read it in arch_get_random_long(), but that slows down reading from
      /dev/urandom since the code in random.c calls arch_get_random_long()
      for every longword read from /dev/urandom.
      
      Since the hardware RNG supplies high-quality entropy on every read, it
      matches the semantics of arch_get_random_seed_long() better than those
      of arch_get_random_long().  Therefore this commit makes the code use
      the POWER8/7+ hardware RNG only for arch_get_random_seed_{long,int}
      and not for arch_get_random_{long,int}.
      
      This won't affect any other PowerPC-based platforms because none of
      them currently support a hardware RNG.  To make it clear that the
      ppc_md function pointer is used for arch_get_random_seed_*, we rename
      it from get_random_long to get_random_seed.
      Signed-off-by: NPaul Mackerras <paulus@samba.org>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      01c9348c
    • T
      powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers · 1c2cb594
      Thomas Huth 提交于
      The EPOW interrupt handler uses rtas_get_sensor(), which in turn
      uses rtas_busy_delay() to wait for RTAS becoming ready in case it
      is necessary. But rtas_busy_delay() is annotated with might_sleep()
      and thus may not be used by interrupts handlers like the EPOW handler!
      This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is
      enabled:
      
       BUG: sleeping function called from invalid context at arch/powerpc/kernel/rtas.c:496
       in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
       CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc2-thuth #6
       Call Trace:
       [c00000007ffe7b90] [c000000000807670] dump_stack+0xa0/0xdc (unreliable)
       [c00000007ffe7bc0] [c0000000000e1f14] ___might_sleep+0x134/0x180
       [c00000007ffe7c20] [c00000000002aec0] rtas_busy_delay+0x30/0xd0
       [c00000007ffe7c50] [c00000000002bde4] rtas_get_sensor+0x74/0xe0
       [c00000007ffe7ce0] [c000000000083264] ras_epow_interrupt+0x44/0x450
       [c00000007ffe7d90] [c000000000120260] handle_irq_event_percpu+0xa0/0x300
       [c00000007ffe7e70] [c000000000120524] handle_irq_event+0x64/0xc0
       [c00000007ffe7eb0] [c000000000124dbc] handle_fasteoi_irq+0xec/0x260
       [c00000007ffe7ef0] [c00000000011f4f0] generic_handle_irq+0x50/0x80
       [c00000007ffe7f20] [c000000000010f3c] __do_irq+0x8c/0x200
       [c00000007ffe7f90] [c0000000000236cc] call_do_irq+0x14/0x24
       [c00000007e6f39e0] [c000000000011144] do_IRQ+0x94/0x110
       [c00000007e6f3a30] [c000000000002594] hardware_interrupt_common+0x114/0x180
      
      Fix this issue by introducing a new rtas_get_sensor_fast() function
      that does not use rtas_busy_delay() - and thus can only be used for
      sensors that do not cause a BUSY condition - known as "fast" sensors.
      
      The EPOW sensor is defined to be "fast" in sPAPR - mpe.
      
      Fixes: 587f83e8 ("powerpc/pseries: Use rtas_get_sensor in RAS code")
      Signed-off-by: NThomas Huth <thuth@redhat.com>
      Reviewed-by: NNathan Fontenot <nfont@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      1c2cb594
    • T
      powerpc/rtas: Replace magic values with defines · 9ef03193
      Thomas Huth 提交于
      rtas.h already has some nice #defines for RTAS return status
      codes - let's use them instead of hard-coded "magic" values!
      Signed-off-by: NThomas Huth <thuth@redhat.com>
      Reviewed-by: NTyrel Datwyler <tyreld@linux.vnet.ibm.com>
      Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
      9ef03193
  3. 21 7月, 2015 3 次提交
  4. 16 7月, 2015 3 次提交
  5. 13 7月, 2015 11 次提交
  6. 11 7月, 2015 1 次提交
    • J
      parisc: Fix some PTE/TLB race conditions and optimize __flush_tlb_range based on timing results · 01ab6057
      John David Anglin 提交于
      The increased use of pdtlb/pitlb instructions seemed to increase the
      frequency of random segmentation faults building packages. Further, we
      had a number of cases where TLB inserts would repeatedly fail and all
      forward progress would stop. The Haskell ghc package caused a lot of
      trouble in this area. The final indication of a race in pte handling was
      this syslog entry on sibaris (C8000):
      
       swap_free: Unused swap offset entry 00000004
       BUG: Bad page map in process mysqld  pte:00000100 pmd:019bbec5
       addr:00000000ec464000 vm_flags:00100073 anon_vma:0000000221023828 mapping: (null) index:ec464
       CPU: 1 PID: 9176 Comm: mysqld Not tainted 4.0.0-2-parisc64-smp #1 Debian 4.0.5-1
       Backtrace:
        [<0000000040173eb0>] show_stack+0x20/0x38
        [<0000000040444424>] dump_stack+0x9c/0x110
        [<00000000402a0d38>] print_bad_pte+0x1a8/0x278
        [<00000000402a28b8>] unmap_single_vma+0x3d8/0x770
        [<00000000402a4090>] zap_page_range+0xf0/0x198
        [<00000000402ba2a4>] SyS_madvise+0x404/0x8c0
      
      Note that the pte value is 0 except for the accessed bit 0x100. This bit
      shouldn't be set without the present bit.
      
      It should be noted that the madvise system call is probably a trigger for many
      of the random segmentation faults.
      
      In looking at the kernel code, I found the following problems:
      
      1) The pte_clear define didn't take TLB lock when clearing a pte.
      2) We didn't test pte present bit inside lock in exception support.
      3) The pte and tlb locks needed to merged in order to ensure consistency
      between page table and TLB. This also has the effect of serializing TLB
      broadcasts on SMP systems.
      
      The attached change implements the above and a few other tweaks to try
      to improve performance. Based on the timing code, TLB purges are very
      slow (e.g., ~ 209 cycles per page on rp3440). Thus, I think it
      beneficial to test the split_tlb variable to avoid duplicate purges.
      Probably, all PA 2.0 machines have combined TLBs.
      
      I dropped using __flush_tlb_range in flush_tlb_mm as I realized all
      applications and most threads have a stack size that is too large to
      make this useful. I added some comments to this effect.
      
      Since implementing 1 through 3, I haven't had any random segmentation
      faults on mx3210 (rp3440) in about one week of building code and running
      as a Debian buildd.
      Signed-off-by: NJohn David Anglin <dave.anglin@bell.net>
      Cc: stable@vger.kernel.org # v3.18+
      Signed-off-by: NHelge Deller <deller@gmx.de>
      01ab6057
  7. 10 7月, 2015 6 次提交
  8. 09 7月, 2015 11 次提交