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  1. 30 May, 2018 3 commits
    • Maciej W. Rozycki's avatar
      MIPS: Fix ptrace(2) PTRACE_PEEKUSR and PTRACE_POKEUSR accesses to o32 FGRs · 0ed5a213
      Maciej W. Rozycki authored 
      commit 9a3a92cc upstream.

Check the TIF_32BIT_FPREGS task setting of the tracee rather than the
tracer in determining the layout of floating-point general registers in
the floating-point context, correcting access to odd-numbered registers
for o32 tracees where the setting disagrees between the two processes.

Fixes: 597ce172 ("MIPS: Support for 64-bit FP with O32 binaries")
Signed-off-by: default avatarMaciej W. Rozycki <macro@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.14+
Signed-off-by: default avatarJames Hogan <jhogan@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0ed5a213
    • Maciej W. Rozycki's avatar
      MIPS: ptrace: Expose FIR register through FP regset · b1e0cf61
      Maciej W. Rozycki authored 
      commit 71e909c0 upstream.

Correct commit 7aeb753b ("MIPS: Implement task_user_regset_view.")
and expose the FIR register using the unused 4 bytes at the end of the
NT_PRFPREG regset.  Without that register included clients cannot use
the PTRACE_GETREGSET request to retrieve the complete FPU register set
and have to resort to one of the older interfaces, either PTRACE_PEEKUSR
or PTRACE_GETFPREGS, to retrieve the missing piece of data.  Also the
register is irreversibly missing from core dumps.

This register is architecturally hardwired and read-only so the write
path does not matter.  Ignore data supplied on writes then.

Fixes: 7aeb753b ("MIPS: Implement task_user_regset_view.")
Signed-off-by: default avatarJames Hogan <jhogan@kernel.org>
Signed-off-by: default avatarMaciej W. Rozycki <macro@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 3.13+
Patchwork: https://patchwork.linux-mips.org/patch/19273/Signed-off-by: default avatarJames Hogan <jhogan@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b1e0cf61
    • NeilBrown's avatar
      MIPS: c-r4k: Fix data corruption related to cache coherence · aa9a00ef
      NeilBrown authored 
      commit 55a2aa08 upstream.

When DMA will be performed to a MIPS32 1004K CPS, the L1-cache for the
range needs to be flushed and invalidated first.
The code currently takes one of two approaches.
1/ If the range is less than the size of the dcache, then HIT type
   requests flush/invalidate cache lines for the particular addresses.
   HIT-type requests a globalised by the CPS so this is safe on SMP.

2/ If the range is larger than the size of dcache, then INDEX type
   requests flush/invalidate the whole cache. INDEX type requests affect
   the local cache only. CPS does not propagate them in any way. So this
   invalidation is not safe on SMP CPS systems.

Data corruption due to '2' can quite easily be demonstrated by
repeatedly "echo 3 > /proc/sys/vm/drop_caches" and then sha1sum a file
that is several times the size of available memory. Dropping caches
means that large contiguous extents (large than dcache) are more likely.

This was not a problem before Linux-4.8 because option 2 was never used
if CONFIG_MIPS_CPS was defined. The commit which removed that apparently
didn't appreciate the full consequence of the change.

We could, in theory, globalize the INDEX based flush by sending an IPI
to other cores. These cache invalidation routines can be called with
interrupts disabled and synchronous IPI require interrupts to be
enabled. Asynchronous IPI may not trigger writeback soon enough. So we
cannot use IPI in practice.

We can already test if IPI would be needed for an INDEX operation with
r4k_op_needs_ipi(R4K_INDEX). If this is true then we mustn't try the
INDEX approach as we cannot use IPI. If this is false (e.g. when there
is only one core and hence one L1 cache) then it is safe to use the
INDEX approach without IPI.

This patch avoids options 2 if r4k_op_needs_ipi(R4K_INDEX), and so
eliminates the corruption.

Fixes: c00ab489 ("MIPS: Remove cpu_has_safe_index_cacheops")
Signed-off-by: default avatarNeilBrown <neil@brown.name>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@linux-mips.org
Cc: <stable@vger.kernel.org> # 4.8+
Patchwork: https://patchwork.linux-mips.org/patch/19259/Signed-off-by: default avatarJames Hogan <jhogan@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      aa9a00ef
  3. 25 May, 2018 37 commits
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