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2013-10-03powerpc/tm: Switch out userspace PPR and DSCR soonerMichael Neuling
When we do a treclaim or trecheckpoint we end up running with userspace PPR and DSCR values. Currently we don't do anything special to avoid running with user values which could cause a severe performance degradation. This patch moves the PPR and DSCR save and restore around treclaim and trecheckpoint so that we run with user values for a much shorter period. More care is taken with the PPR as it's impact is greater than the DSCR. This is similar to user exceptions, where we run HTM_MEDIUM early to ensure that we don't run with a userspace PPR values in the kernel. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> # 3.9+ Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-10-03powerpc/tm: Turn interrupts hard off in tm_reclaim()Michael Neuling
We can't take IRQs in tm_reclaim as we might have a bogus r13 and r1. This turns IRQs hard off in this function. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> # 3.9+ Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-08-27Merge branch 'merge' into nextBenjamin Herrenschmidt
Merge stuff that already went into Linus via "merge" which are pre-reqs for subsequent patches
2013-08-14powerpc: Fix VRSAVE handlingPaul Mackerras
Since 2002, the kernel has not saved VRSAVE on exception entry and restored it on exit; rather, VRSAVE gets context-switched in _switch. This means that when executing in process context in the kernel, the userspace VRSAVE value is live in the VRSAVE register. However, the signal code assumes that current->thread.vrsave holds the current VRSAVE value, which is incorrect. Therefore, this commit changes it to use the actual VRSAVE register instead. (It still uses current->thread.vrsave as a temporary location to store it in, as __get_user and __put_user can only transfer to/from a variable, not an SPR.) This also modifies the transactional memory code to save and restore VRSAVE regardless of whether VMX is enabled in the MSR. This is because accesses to VRSAVE are not controlled by the MSR.VEC bit, but can happen at any time. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2013-08-09powerpc/tm: Fix context switching TAR, PPR and DSCR SPRsMichael Neuling
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>
2013-06-30powerpc/tm: Clear MSR RI in non-recoverable TM codeMichael Neuling
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>
2013-04-10powerpc: fix compiling CONFIG_PPC_TRANSACTIONAL_MEM when CONFIG_ALTIVEC=nMichael Neuling
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>
2013-02-15powerpc: Add helper functions for transactional memory context switchingMichael Neuling
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>