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  1. 22 Oct, 2017 2 commits
  3. 20 Oct, 2017 6 commits
    • Michael Neuling's avatar
      powerpc/tm: P9 disable transactionally suspended sigcontexts · 92fb8690
      Michael Neuling authored 
      Unfortunately userspace can construct a sigcontext which enables
suspend. Thus userspace can force Linux into a path where trechkpt is
executed.

This patch blocks this from happening on POWER9 by sanity checking
sigcontexts passed in.

ptrace doesn't have this problem as only MSR SE and BE can be changed
via ptrace.

This patch also adds a number of WARN_ON()s in case we ever enter
suspend when we shouldn't. This should not happen, but if it does the
symptoms are soft lockup warnings which are not obviously TM related,
so the WARN_ON()s should make it obvious what's happening.
Signed-off-by: default avatarMichael Neuling <mikey@neuling.org>
Signed-off-by: default avatarCyril Bur <cyrilbur@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      92fb8690
    • Michael Ellerman's avatar
      powerpc/powernv: Enable TM without suspend if possible · 54820530
      Michael Ellerman authored 
      Some Power9 revisions can run in a mode where TM operates without
suspended state. If we find ourself on a CPU that might be in this
mode, we query OPAL to check, and if so we reenable TM in CPU
features, and enable a new user feature to signal to userspace that we
are in this mode.

We do not enable the "normal" user feature, PPC_FEATURE2_HTM, but we
do enable PPC_FEATURE2_HTM_NOSC because that indicates to userspace
that the kernel will abort transactions on syscall entry, which is
true regardless of the suspend mode.
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      54820530
    • Michael Ellerman's avatar
      powerpc: Add PPC_FEATURE2_HTM_NO_SUSPEND · cba6ac48
      Michael Ellerman authored 
      Some CPUs can operate in a mode where TM (Transactional Memory) is
enabled but the suspended state of TM is disabled. In this mode
tsuspend does not enter suspended state, instead the transaction is
aborted. Similarly any other event that would lead to suspended state
instead aborts the transaction.

There is also an ABI change, in that in this mode processes are not
allowed to sigreturn with an MSR that would lead to suspended state,
Linux will instead return an error to the sigreturn syscall.
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      cba6ac48
    • Cyril Bur's avatar
      powerpc/tm: Add commandline option to disable hardware transactional memory · 07fd1761
      Cyril Bur authored 
      Currently the kernel relies on firmware to inform it whether or not the
CPU supports HTM and as long as the kernel was built with
CONFIG_PPC_TRANSACTIONAL_MEM=y then it will allow userspace to make
use of the facility.

There may be situations where it would be advantageous for the kernel
to not allow userspace to use HTM, currently the only way to achieve
this is to recompile the kernel with CONFIG_PPC_TRANSACTIONAL_MEM=n.

This patch adds a simple commandline option so that HTM can be
disabled at boot time.
Signed-off-by: default avatarCyril Bur <cyrilbur@gmail.com>
[mpe: Simplify to a bool, move to prom.c, put doco in the right place.
 Always disable, regardless of initial state, to avoid user confusion.]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      07fd1761
    • Michael Ellerman's avatar
      Merge branch 'topic/ppc-kvm' into next · ddd46ed2
      Michael Ellerman authored 
      Bring in some KVM commits we need (the TM one in particular).
      ddd46ed2
    • Michael Ellerman's avatar
      KVM: PPC: Tie KVM_CAP_PPC_HTM to the user-visible TM feature · 2a3d6553
      Michael Ellerman authored 
      Currently we use CPU_FTR_TM to decide if the CPU/kernel can support
TM (Transactional Memory), and if it's true we advertise that to
Qemu (or similar) via KVM_CAP_PPC_HTM.

PPC_FEATURE2_HTM is the user-visible feature bit, which indicates that
the CPU and kernel can support TM. Currently CPU_FTR_TM and
PPC_FEATURE2_HTM always have the same value, either true or false, so
using the former for KVM_CAP_PPC_HTM is correct.

However some Power9 CPUs can operate in a mode where TM is enabled but
TM suspended state is disabled. In this mode CPU_FTR_TM is true, but
PPC_FEATURE2_HTM is false. Instead a different PPC_FEATURE2 bit is
set, to indicate that this different mode of TM is available.

It is not safe to let guests use TM as-is, when the CPU is in this
mode. So to prevent that from happening, use PPC_FEATURE2_HTM to
determine the value of KVM_CAP_PPC_HTM.
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      2a3d6553
  5. 19 Oct, 2017 1 commit
  7. 16 Oct, 2017 9 commits
  9. 13 Oct, 2017 3 commits
  11. 10 Oct, 2017 1 commit
  13. 06 Oct, 2017 7 commits
  15. 05 Oct, 2017 2 commits
    • Naveen N. Rao's avatar
      powerpc/jprobes: Validate break handler invocation as being due to a jprobe_return() · 3368f569
      Naveen N. Rao authored 
      Fix a circa 2005 FIXME by implementing a check to ensure that we
actually got into the jprobe break handler() due to the trap in
jprobe_return().
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      3368f569
    • Naveen N. Rao's avatar
      powerpc/jprobes: Disable preemption when triggered through ftrace · 6baea433
      Naveen N. Rao authored 
      KPROBES_SANITY_TEST throws the below splat when CONFIG_PREEMPT is
enabled:

  Kprobe smoke test: started
  DEBUG_LOCKS_WARN_ON(val > preempt_count())
  ------------[ cut here ]------------
  WARNING: CPU: 19 PID: 1 at kernel/sched/core.c:3094 preempt_count_sub+0xcc/0x140
  Modules linked in:
  CPU: 19 PID: 1 Comm: swapper/0 Not tainted 4.13.0-rc7-nnr+ #97
  task: c0000000fea80000 task.stack: c0000000feb00000
  NIP:  c00000000011d3dc LR: c00000000011d3d8 CTR: c000000000a090d0
  REGS: c0000000feb03400 TRAP: 0700   Not tainted  (4.13.0-rc7-nnr+)
  MSR:  8000000000021033 <SF,ME,IR,DR,RI,LE>  CR: 28000282  XER: 00000000
  CFAR: c00000000015aa18 SOFTE: 0
  <snip>
  NIP preempt_count_sub+0xcc/0x140
  LR  preempt_count_sub+0xc8/0x140
  Call Trace:
    preempt_count_sub+0xc8/0x140 (unreliable)
    kprobe_handler+0x228/0x4b0
    program_check_exception+0x58/0x3b0
    program_check_common+0x16c/0x170
    --- interrupt: 0 at kprobe_target+0x8/0x20
                     LR = init_test_probes+0x248/0x7d0
    kp+0x0/0x80 (unreliable)
    livepatch_handler+0x38/0x74
    init_kprobes+0x1d8/0x208
    do_one_initcall+0x68/0x1d0
    kernel_init_freeable+0x298/0x374
    kernel_init+0x24/0x160
    ret_from_kernel_thread+0x5c/0x70
  Instruction dump:
  419effdc 3d22001b 39299240 81290000 2f890000 409effc8 3c82ffcb 3c62ffcb
  3884bc68 3863bc18 4803d5fd 60000000 <0fe00000> 4bffffa8 60000000 60000000
  ---[ end trace 432dd46b4ce3d29f ]---
  Kprobe smoke test: passed successfully

The issue is that we aren't disabling preemption in
kprobe_ftrace_handler(). Disable it.

Fixes: ead514d5 ("powerpc/kprobes: Add support for KPROBES_ON_FTRACE")
Acked-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
[mpe: Trim oops a little for formatting]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      6baea433
  17. 04 Oct, 2017 9 commits
    • Naveen N. Rao's avatar
      powerpc/kprobes: Fix warnings from __this_cpu_read() on preempt kernels · c179ea27
      Naveen N. Rao authored 
      Kamalesh pointed out that we are getting the below call traces with
livepatched functions when we enable CONFIG_PREEMPT:

[  495.470721] BUG: using __this_cpu_read() in preemptible [00000000] code: cat/8394
[  495.471167] caller is is_current_kprobe_addr+0x30/0x90
[  495.471171] CPU: 4 PID: 8394 Comm: cat Tainted: G              K 4.13.0-rc7-nnr+ #95
[  495.471173] Call Trace:
[  495.471178] [c00000008fd9b960] [c0000000009f039c] dump_stack+0xec/0x160 (unreliable)
[  495.471184] [c00000008fd9b9a0] [c00000000059169c] check_preemption_disabled+0x15c/0x170
[  495.471187] [c00000008fd9ba30] [c000000000046460] is_current_kprobe_addr+0x30/0x90
[  495.471191] [c00000008fd9ba60] [c00000000004e9a0] ftrace_call+0x1c/0xb8
[  495.471195] [c00000008fd9bc30] [c000000000376fd8] seq_read+0x238/0x5c0
[  495.471199] [c00000008fd9bcd0] [c0000000003cfd78] proc_reg_read+0x88/0xd0
[  495.471203] [c00000008fd9bd00] [c00000000033e5d4] __vfs_read+0x44/0x1b0
[  495.471206] [c00000008fd9bd90] [c0000000003402ec] vfs_read+0xbc/0x1b0
[  495.471210] [c00000008fd9bde0] [c000000000342138] SyS_read+0x68/0x110
[  495.471214] [c00000008fd9be30] [c00000000000bc6c] system_call+0x58/0x6c

Commit c05b8c44 ("powerpc/kprobes: Skip livepatch_handler() for
jprobes") introduced a helper is_current_kprobe_addr() to help determine
if the current function has been livepatched or if it has a jprobe
installed, both of which modify the NIP. This was subsequently renamed
to __is_active_jprobe().

In the case of a jprobe, kprobe_ftrace_handler() disables pre-emption
before calling into setjmp_pre_handler() which returns without disabling
pre-emption. This is done to ensure that the jprobe handler won't
disappear beneath us if the jprobe is unregistered between the
setjmp_pre_handler() and the subsequent longjmp_break_handler() called
from the jprobe handler. Due to this, we can use __this_cpu_read() in
__is_active_jprobe() with the pre-emption check as we know that
pre-emption will be disabled.

However, if this function has been livepatched, we are still doing this
check and when we do so, pre-emption won't necessarily be disabled. This
results in the call trace shown above.

Fix this by only invoking __is_active_jprobe() when pre-emption is
disabled. And since we now guard this within a pre-emption check, we can
instead use raw_cpu_read() to get the current_kprobe value skipping the
check done by __this_cpu_read().

Fixes: c05b8c44 ("powerpc/kprobes: Skip livepatch_handler() for jprobes")
Reported-by: default avatarKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Tested-by: default avatarKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      c179ea27
    • Naveen N. Rao's avatar
      powerpc/kprobes: Clean up jprobe detection in livepatch handler · bf3a9125
      Naveen N. Rao authored 
      In commit c05b8c44 ("powerpc/kprobes: Skip livepatch_handler() for
jprobes"), we added a helper is_current_kprobe_addr() to help detect if
the modified regs->nip was due to a jprobe or livepatch. Masami felt
that the function name was not quite clear. To that end, this patch
renames is_current_kprobe_addr() to __is_active_jprobe() and adds a
comment to (hopefully) better clarify the purpose of this helper. The
helper has also now been moved to kprobes-ftrace.c so that it is only
available for KPROBES_ON_FTRACE.
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      bf3a9125
    • Naveen N. Rao's avatar
      powerpc/kprobes: Do not suppress instruction emulation if a single run failed · a7b44038
      Naveen N. Rao authored 
      Currently, we disable instruction emulation if emulate_step() fails for
any reason. However, such failures could be transient and specific to a
particular run. Instead, only disable instruction emulation if we have
never been able to emulate this. If we had emulated this instruction
successfully at least once, then we single step only this probe hit and
continue to try emulating the instruction in subsequent probe hits.
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      a7b44038
    • Naveen N. Rao's avatar
      powerpc/kprobes: Some cosmetic updates to try_to_emulate() · 22085337
      Naveen N. Rao authored 
      1. This is only used in kprobes.c, so make it static.
2. Remove the un-necessary (ret == 0) comparison in the else clause.
Reviewed-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: default avatarKamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      22085337
    • Joel Stanley's avatar
      powerpc/configs: Add Skiroot defconfig · c3dda4b0
      Joel Stanley authored 
      This configuration is used by the OpenPower firmware for it's
Linux-as-bootloader implementation. Also known as the Petitboot
kernel, this configuration broke in 4.12 (CPU_HOTPLUG=n), so add it to
the upstream tree in order to get better coverage.
Signed-off-by: default avatarJoel Stanley <joel@jms.id.au>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      c3dda4b0
    • Sandipan Das's avatar
      powerpc/lib/sstep: Fix fixed-point shift instructions that set CA32 · 0a75aff1
      Sandipan Das authored 
      This fixes the emulated behaviour of existing fixed-point shift right
algebraic instructions that are supposed to set both the CA and CA32
bits of XER when running on a system that is compliant with POWER ISA
v3.0 independent of whether the system is executing in 32-bit mode or
64-bit mode. The following instructions are affected:
  * Shift Right Algebraic Word Immediate (srawi[.])
  * Shift Right Algebraic Word (sraw[.])
  * Shift Right Algebraic Doubleword Immediate (sradi[.])
  * Shift Right Algebraic Doubleword (srad[.])

Fixes: 0016a4cf ("powerpc: Emulate most Book I instructions in emulate_step()")
Signed-off-by: default avatarSandipan Das <sandipan@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      0a75aff1
    • Sandipan Das's avatar
      powerpc/lib/sstep: Fix fixed-point arithmetic instructions that set CA32 · dc39c1d6
      Sandipan Das authored 
      There are existing fixed-point arithmetic instructions that always set the
CA bit of XER to reflect the carry out of bit 0 in 64-bit mode and out of
bit 32 in 32-bit mode. In ISA v3.0, these instructions also always set the
CA32 bit of XER to reflect the carry out of bit 32.

This fixes the emulated behaviour of such instructions when running on a
system that is compliant with POWER ISA v3.0. The following instructions
are affected:
  * Add Immediate Carrying (addic)
  * Add Immediate Carrying and Record (addic.)
  * Subtract From Immediate Carrying (subfic)
  * Add Carrying (addc[.])
  * Subtract From Carrying (subfc[.])
  * Add Extended (adde[.])
  * Subtract From Extended (subfe[.])
  * Add to Minus One Extended (addme[.])
  * Subtract From Minus One Extended (subfme[.])
  * Add to Zero Extended (addze[.])
  * Subtract From Zero Extended (subfze[.])

Fixes: 0016a4cf ("powerpc: Emulate most Book I instructions in emulate_step()")
Signed-off-by: default avatarSandipan Das <sandipan@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      dc39c1d6
    • Sandipan Das's avatar
      powerpc/lib/sstep: Add XER bits introduced in POWER ISA v3.0 · 924c8feb
      Sandipan Das authored 
      This adds definitions for the OV32 and CA32 bits of XER that
were introduced in POWER ISA v3.0. There are some existing
instructions that currently set the OV and CA bits based on
certain conditions.

The emulation behaviour of all these instructions needs to
be updated to set these new bits accordingly.
Signed-off-by: default avatarSandipan Das <sandipan@linux.vnet.ibm.com>
Acked-by: default avatarNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      924c8feb
    • Allen Pais's avatar
      powerpc/powermac: Use setup_timer() helper · 01451ad4
      Allen Pais authored 
      Use setup_timer function instead of initializing timer with the
function and data fields.
Signed-off-by: default avatarAllen Pais <allen.lkml@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
      01451ad4
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