This moves us to save the Target Address Register (TAR) a earlier in __switch_to. It introduces a new function save_tar() to do this. We need to save the TAR earlier as we will overwrite it in the transactional memory reclaim/recheckpoint path. We are going to do this in a subsequent patch which will fix saving the TAR register when it's modified inside a transaction. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> [v3.10] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
POWER8 allows the DSCR to be accessed directly from userspace via a new SPR number 0x3 (Rather than 0x11. DSCR SPR number 0x11 is still used on POWER8 but like POWER7, is only accessible in HV and OS modes). Currently, we allow this by setting H/FSCR DSCR bit on boot. Unfortunately this doesn't work, as the kernel needs to see the DSCR change so that it knows to no longer restore the system wide version of DSCR on context switch (ie. to set thread.dscr_inherit). This clears the H/FSCR DSCR bit initially. If a process then accesses the DSCR (via SPR 0x3), it'll trap into the kernel where we set thread.dscr_inherit in facility_unavailable_exception(). We also change _switch() so that we set or clear the H/FSCR DSCR bit based on the thread.dscr_inherit. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> [v3.10] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
On BookE (Branch taken + Single Step) is as same as Branch Taken on BookS and in Linux we simulate BookS behavior for BookE as well. When doing so, in Branch taken handling we want to set DBCR0_IC but we update the current->thread->dbcr0 and not DBCR0. Now on 64bit the current->thread.dbcr0 (and other debug registers) is synchronized ONLY on context switch flow. But after handling Branch taken in debug exception if we return back to user space without context switch then single stepping change (DBCR0_ICMP) does not get written in h/w DBCR0 and Instruction Complete exception does not happen. This fixes using ptrace reliably on BookE-PowerPC lmbench latency test (lat_syscall) Results are (they varies a little on each run) 1) ./lat_syscall <action> /dev/shm/uImage action: Open read write stat fstat null Before: 3.8618 0.2017 0.2851 1.6789 0.2256 0.0856 After: 3.8580 0.2017 0.2851 1.6955 0.2255 0.0856 1) ./lat_syscall -P 2 -N 10 <action> /dev/shm/uImage action: Open read write stat fstat null Before: 4.1388 0.2238 0.3066 1.7106 0.2256 0.0856 After: 4.1413 0.2236 0.3062 1.7107 0.2256 0.0856 [ Slightly modified to avoid extra branch in the fast path on Book3S and fix build on all non-BookE 64-bit -- BenH ] Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
In commit 59affcd I added context switching of more PMU SPRs, because they are potentially exposed to userspace on Power8. However despite me being a smart arse in the commit message it's actually not correct. In particular it interacts badly with a global perf record. We will have to do something more complicated, but that will have to wait for 3.11. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
On context switch, we should have no prefetch streams leak from one userspace process to another. This frees up prefetch resources for the next process. Based on patch from Milton Miller. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
In commit 9353374 "Context switch the new EBB SPRs" we added support for context switching some new EBB SPRs. However despite four of us signing off on that patch we missed some. To be fair these are not actually new SPRs, but they are now potentially user accessible so need to be context switched. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Pull powerpc fixes from Benjamin Herrenschmidt: "This is mostly bug fixes (some of them regressions, some of them I deemed worth merging now) along with some patches from Li Zhong hooking up the new context tracking stuff (for the new full NO_HZ)" * 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc: (25 commits) powerpc: Set show_unhandled_signals to 1 by default powerpc/perf: Fix setting of "to" addresses for BHRB powerpc/pmu: Fix order of interpreting BHRB target entries powerpc/perf: Move BHRB code into CONFIG_PPC64 region powerpc: select HAVE_CONTEXT_TRACKING for pSeries powerpc: Use the new schedule_user API on userspace preemption powerpc: Exit user context on notify resume powerpc: Exception hooks for context tracking subsystem powerpc: Syscall hooks for context tracking subsystem powerpc/booke64: Fix kernel hangs at kernel_dbg_exc powerpc: Fix irq_set_affinity() return values powerpc: Provide __bswapdi2 powerpc/powernv: Fix starting of secondary CPUs on OPALv2 and v3 powerpc/powernv: Detect OPAL v3 API version powerpc: Fix MAX_STACK_TRACE_ENTRIES too low warning again powerpc: Make CONFIG_RTAS_PROC depend on CONFIG_PROC_FS powerpc: Bring all threads online prior to migration/hibernation powerpc/rtas_flash: Fix validate_flash buffer overflow issue powerpc/kexec: Fix kexec when using VMX optimised memcpy powerpc: Fix build errors STRICT_MM_TYPECHECKS ...
This patch corresponds to [PATCH] x86: Use the new schedule_user API on userspace preemption commit 0430499ce9d78691f3985962021b16bf8f8a8048 Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Saw this warning again, and this time from the ret_from_fork path. It seems we could clear the back chain earlier in copy_thread(), which could cover both path, and also fix potential lockdep usage in schedule_tail(), or exception occurred before we clear the back chain. Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Pull audit changes from Eric Paris: "Al used to send pull requests every couple of years but he told me to just start pushing them to you directly. Our touching outside of core audit code is pretty straight forward. A couple of interface changes which hit net/. A simple argument bug calling audit functions in namei.c and the removal of some assembly branch prediction code on ppc" * git://git.infradead.org/users/eparis/audit: (31 commits) audit: fix message spacing printing auid Revert "audit: move kaudit thread start from auditd registration to kaudit init" audit: vfs: fix audit_inode call in O_CREAT case of do_last audit: Make testing for a valid loginuid explicit. audit: fix event coverage of AUDIT_ANOM_LINK audit: use spin_lock in audit_receive_msg to process tty logging audit: do not needlessly take a lock in tty_audit_exit audit: do not needlessly take a spinlock in copy_signal audit: add an option to control logging of passwords with pam_tty_audit audit: use spin_lock_irqsave/restore in audit tty code helper for some session id stuff audit: use a consistent audit helper to log lsm information audit: push loginuid and sessionid processing down audit: stop pushing loginid, uid, sessionid as arguments audit: remove the old depricated kernel interface audit: make validity checking generic audit: allow checking the type of audit message in the user filter audit: fix build break when AUDIT_DEBUG == 2 audit: remove duplicate export of audit_enabled Audit: do not print error when LSMs disabled ...