linux.git/arch/powerpc/kernel/tm.S, branch v3.11 Linux kernel source tree powerpc/tm: Fix context switching TAR, PPR and DSCR SPRs 2013-08-09T08:07:12+00:00 Michael Neuling mikey@neuling.org 2013-08-09T07:29:31+00:00 28e61cc466d8daace4b0f04ba2b83e0bd68f5832 If a transaction is rolled back, the Target Address Register (TAR), Processor Priority Register (PPR) and Data Stream Control Register (DSCR) should be restored to the checkpointed values before the transaction began. Any changes to these SPRs inside the transaction should not be visible in the abort handler. Currently Linux doesn't save or restore the checkpointed TAR, PPR or DSCR. If we preempt a processes inside a transaction which has modified any of these, on process restore, that same transaction may be aborted we but we won't see the checkpointed versions of these SPRs. This adds checkpointed versions of these SPRs to the thread_struct and adds the save/restore of these three SPRs to the treclaim/trechkpt code. Without this if any of these SPRs are modified during a transaction, users may incorrectly see a speculated SPR value even if the transaction is aborted. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> [v3.10] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
If a transaction is rolled back, the Target Address Register (TAR), Processor
Priority Register (PPR) and Data Stream Control Register (DSCR) should be
restored to the checkpointed values before the transaction began.  Any changes
to these SPRs inside the transaction should not be visible in the abort
handler.

Currently Linux doesn't save or restore the checkpointed TAR, PPR or DSCR.  If
we preempt a processes inside a transaction which has modified any of these, on
process restore, that same transaction may be aborted we but we won't see the
checkpointed versions of these SPRs.

This adds checkpointed versions of these SPRs to the thread_struct and adds the
save/restore of these three SPRs to the treclaim/trechkpt code.

Without this if any of these SPRs are modified during a transaction, users may
incorrectly see a speculated SPR value even if the transaction is aborted.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> [v3.10]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc/tm: Clear MSR RI in non-recoverable TM code 2013-06-30T05:49:43+00:00 Michael Neuling mikey@neuling.org 2013-06-28T08:17:09+00:00 090b9284d72561644d17a6e568d29c9e472c9865 When we treclaim and trecheckpoint there's an unavoidable period when r1 will not be a valid kernel stack pointer. This patch clears the MSR recoverable interrupt (RI) bit over these regions to indicate we have an invalid kernel stack pointer. For treclaim, the region over which we clear MSR RI is larger than required to avoid the need for an extra costly mtmsrd. Thanks to Paulus for suggesting this change. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
When we treclaim and trecheckpoint there's an unavoidable period when r1
will not be a valid kernel stack pointer.

This patch clears the MSR recoverable interrupt (RI) bit over these
regions to indicate we have an invalid kernel stack pointer.

For treclaim, the region over which we clear MSR RI is larger than
required to avoid the need for an extra costly mtmsrd.

Thanks to Paulus for suggesting this change.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: fix compiling CONFIG_PPC_TRANSACTIONAL_MEM when CONFIG_ALTIVEC=n 2013-04-09T22:14:39+00:00 Michael Neuling mikey@neuling.org 2013-04-09T06:18:55+00:00 f110c0c1926028a233830c6166e4d40314420823 We can't compile a kernel with CONFIG_ALTIVEC=n when CONFIG_PPC_TRANSACTIONAL_MEM=y. We currently get: arch/powerpc/kernel/tm.S:320: Error: unsupported relocation against THREAD_VSCR arch/powerpc/kernel/tm.S:323: Error: unsupported relocation against THREAD_VR0 arch/powerpc/kernel/tm.S:323: Error: unsupported relocation against THREAD_VR0 etc. The below fixes this with a sprinkling of #ifdefs. This was found by mpe with kisskb: http://kisskb.ellerman.id.au/kisskb/buildresult/8539442/ Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> 
We can't compile a kernel with CONFIG_ALTIVEC=n when
CONFIG_PPC_TRANSACTIONAL_MEM=y.  We currently get:

arch/powerpc/kernel/tm.S:320: Error: unsupported relocation against THREAD_VSCR
arch/powerpc/kernel/tm.S:323: Error: unsupported relocation against THREAD_VR0
arch/powerpc/kernel/tm.S:323: Error: unsupported relocation against THREAD_VR0
etc.

The below fixes this with a sprinkling of #ifdefs.

This was found by mpe with kisskb:
  http://kisskb.ellerman.id.au/kisskb/buildresult/8539442/

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
powerpc: Add helper functions for transactional memory context switching 2013-02-15T05:58:52+00:00 Michael Neuling mikey@neuling.org 2013-02-13T16:21:35+00:00 98ae22e15b430bfed5def01ac1a88ec9396284c8 Here we add the helper functions to be used when context switching. These allow us to fully reclaim and recheckpoint a transaction. We introduce a new paca field called tm_scratch to help us store away register values when doing the low level tm reclaim register save. Signed-off-by: Matt Evans <matt@ozlabs.org> Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
Here we add the helper functions to be used when context switching.  These
allow us to fully reclaim and recheckpoint a transaction.

We introduce a new paca field called tm_scratch to help us store away register
values when doing the low level tm reclaim register save.

Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>