linux.git/arch/powerpc/kernel/traps.c, branch v3.12.65 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git powerpc: Cleanup handling of the DSCR bit in the FSCR register 2013-08-27T05:05:22+00:00 Michael Neuling mikey@neuling.org 2013-08-26T03:55:57+00:00 bc683a7e51c5c838bc74316125bebec92af74f12 As suggested by paulus we can simplify the Data Stream Control Register (DSCR) Facility Status and Control Register (FSCR) handling. Firstly, we simplify the asm by using a rldimi. Secondly, we now use the FSCR only to control the DSCR facility, rather than both the FSCR and HFSCR. Users will see no functional change from this but will get a minor speedup as they will trap into the kernel only once (rather than twice) when they first touch the DSCR. Also, this changes removes a bunch of ugly FTR_SECTION code. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
As suggested by paulus we can simplify the Data Stream Control Register
(DSCR) Facility Status and Control Register (FSCR) handling.

Firstly, we simplify the asm by using a rldimi.

Secondly, we now use the FSCR only to control the DSCR facility, rather
than both the FSCR and HFSCR.  Users will see no functional change from
this but will get a minor speedup as they will trap into the kernel only
once (rather than twice) when they first touch the DSCR.  Also, this
changes removes a bunch of ugly FTR_SECTION code.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Merge branch 'merge' into next 2013-08-27T05:03:30+00:00 Benjamin Herrenschmidt benh@kernel.crashing.org 2013-08-27T05:03:30+00:00 3f1f4311881b330a7b5429dd101e676df191b159 Merge stuff that already went into Linus via "merge" which are pre-reqs for subsequent patches 
Merge stuff that already went into Linus via "merge" which
are pre-reqs for subsequent patches
powerpc: Skip emulating & leave interrupts off for kernel program checks 2013-08-27T04:45:09+00:00 Michael Ellerman michael@ellerman.id.au 2013-08-15T05:22:19+00:00 b3f6a45925232d29519007f1ba6687e1e790fb5d In the program check handler we handle some causes with interrupts off and others with interrupts on. We need to enable interrupts to handle the emulation cases, because they access userspace memory and might sleep. For faults in the kernel we don't want to do any emulation, and emulate_instruction() enforces that. do_mathemu() doesn't but probably should. The other disadvantage of enabling interrupts for kernel faults is that we may take another interrupt, and recurse. As seen below: --- Exception: e40 at c000000000004ee0 performance_monitor_relon_pSeries_1 [link register ] c00000000000f858 .arch_local_irq_restore+0x38/0x90 [c000000fb185dc10] 0000000000000000 (unreliable) [c000000fb185dc80] c0000000007d8558 .program_check_exception+0x298/0x2d0 [c000000fb185dd00] c000000000002f40 emulation_assist_common+0x140/0x180 --- Exception: e40 at c000000000004ee0 performance_monitor_relon_pSeries_1 [link register ] c00000000000f858 .arch_local_irq_restore+0x38/0x90 [c000000fb185dff0] 00000000008b9190 (unreliable) [c000000fb185e060] c0000000007d8558 .program_check_exception+0x298/0x2d0 So avoid both problems by checking if the fault was in the kernel and skipping the enable of interrupts and the emulation. Go straight to delivering the SIGILL, which for kernel faults calls die() and so on, dropping us in the debugger etc. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
In the program check handler we handle some causes with interrupts off
and others with interrupts on.

We need to enable interrupts to handle the emulation cases, because they
access userspace memory and might sleep.

For faults in the kernel we don't want to do any emulation, and
emulate_instruction() enforces that. do_mathemu() doesn't but probably
should.

The other disadvantage of enabling interrupts for kernel faults is that
we may take another interrupt, and recurse. As seen below:

  --- Exception: e40 at c000000000004ee0 performance_monitor_relon_pSeries_1
  [link register   ] c00000000000f858 .arch_local_irq_restore+0x38/0x90
  [c000000fb185dc10] 0000000000000000 (unreliable)
  [c000000fb185dc80] c0000000007d8558 .program_check_exception+0x298/0x2d0
  [c000000fb185dd00] c000000000002f40 emulation_assist_common+0x140/0x180
  --- Exception: e40 at c000000000004ee0 performance_monitor_relon_pSeries_1
  [link register   ] c00000000000f858 .arch_local_irq_restore+0x38/0x90
  [c000000fb185dff0] 00000000008b9190 (unreliable)
  [c000000fb185e060] c0000000007d8558 .program_check_exception+0x298/0x2d0

So avoid both problems by checking if the fault was in the kernel and
skipping the enable of interrupts and the emulation. Go straight to
delivering the SIGILL, which for kernel faults calls die() and so on,
dropping us in the debugger etc.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Emulate instructions in little endian mode 2013-08-14T05:33:35+00:00 Anton Blanchard anton@samba.org 2013-08-06T16:01:47+00:00 4288e343fb63cd74b35bf68c5d83551f867dba56 Alistair noticed we got a SIGILL on userspace mfpvr instructions. Remove the little endian check in the emulation code, it is probably there to protect against the old pseudo little endian implementations but doesn't make sense for real little endian. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
Alistair noticed we got a SIGILL on userspace mfpvr instructions.

Remove the little endian check in the emulation code, it is
probably there to protect against the old pseudo little endian
implementations but doesn't make sense for real little endian.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Introduce function emulate_math() 2013-08-14T04:59:12+00:00 Kevin Hao haokexin@gmail.com 2013-07-14T08:40:07+00:00 3a3b5aa63fad4911e239055c2c0a89ce2dac62ce There are two invocations of do_mathemu() in traps.c. And the codes in these two places are almost the same. Introduce a locale function to eliminate the duplication. With this change we can also make sure that in program_check_exception() the PPC_WARN_EMULATED is invoked for the correctly emulated math instructions. Signed-off-by: Kevin Hao <haokexin@gmail.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
There are two invocations of do_mathemu() in traps.c. And the codes
in these two places are almost the same. Introduce a locale function
to eliminate the duplication. With this change we can also make sure
that in program_check_exception() the PPC_WARN_EMULATED is invoked for
the correctly emulated math instructions.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc/math-emu: Move the flush FPU state function into do_mathemu 2013-08-14T04:59:06+00:00 Kevin Hao haokexin@gmail.com 2013-07-14T08:40:06+00:00 6761ee3d7e139ec8728e1515bfc5fdcaf3be317e By doing this we can make sure that the FPU state is only flushed to the thread struct when it is really needed. Signed-off-by: Kevin Hao <haokexin@gmail.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
By doing this we can make sure that the FPU state is only flushed to
the thread struct when it is really needed.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Fix context switch DSCR on POWER8 2013-08-09T08:07:05+00:00 Michael Neuling mikey@neuling.org 2013-08-09T07:29:29+00:00 2517617e0de65f8f7cfe75cae745d06b1fa98586 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> 
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>
powerpc/85xx: Add machine check handler to fix PCIe erratum on mpc85xx 2013-07-30T20:50:07+00:00 Hongtao Jia hongtao.jia@freescale.com 2013-04-28T05:20:08+00:00 4e0e3435b50285eafe5898124ce02f7577f6803a A PCIe erratum of mpc85xx may causes a core hang when a link of PCIe goes down. when the link goes down, Non-posted transactions issued via the ATMU requiring completion result in an instruction stall. At the same time a machine-check exception is generated to the core to allow further processing by the handler. We implements the handler which skips the instruction caused the stall. This patch depends on patch: powerpc/85xx: Add platform_device declaration to fsl_pci.h Signed-off-by: Zhao Chenhui <b35336@freescale.com> Signed-off-by: Li Yang <leoli@freescale.com> Signed-off-by: Liu Shuo <soniccat.liu@gmail.com> Signed-off-by: Jia Hongtao <hongtao.jia@freescale.com> Signed-off-by: Scott Wood <scottwood@freescale.com> 
A PCIe erratum of mpc85xx may causes a core hang when a link of PCIe
goes down. when the link goes down, Non-posted transactions issued
via the ATMU requiring completion result in an instruction stall.
At the same time a machine-check exception is generated to the core
to allow further processing by the handler. We implements the handler
which skips the instruction caused the stall.

This patch depends on patch:
powerpc/85xx: Add platform_device declaration to fsl_pci.h

Signed-off-by: Zhao Chenhui <b35336@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Liu Shuo <soniccat.liu@gmail.com>
Signed-off-by: Jia Hongtao <hongtao.jia@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
Merge tag 'v3.10' into next 2013-07-01T07:57:25+00:00 Benjamin Herrenschmidt benh@kernel.crashing.org 2013-07-01T07:57:25+00:00 24a72acac155576d630cf4304fa9cefb9b62ea1f Merge 3.10 in order to get some of the last minute powerpc changes, resolve conflicts and add additional fixes on top of them. 
Merge 3.10 in order to get some of the last minute powerpc
changes, resolve conflicts and add additional fixes on top
of them.
powerpc: Wire up the HV facility unavailable exception 2013-07-01T01:49:47+00:00 Michael Ellerman michael@ellerman.id.au 2013-06-25T07:47:57+00:00 b14b6260efeee6eb8942c6e6420e31281892acb6 Similar to the facility unavailble exception, except the facilities are controlled by HFSCR. Adapt the facility_unavailable_exception() so it can be called for either the regular or Hypervisor facility unavailable exceptions. Signed-off-by: Michael Ellerman <michael@ellerman.id.au> CC: <stable@vger.kernel.org> [v3.10] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
Similar to the facility unavailble exception, except the facilities are
controlled by HFSCR.

Adapt the facility_unavailable_exception() so it can be called for
either the regular or Hypervisor facility unavailable exceptions.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
CC: <stable@vger.kernel.org> [v3.10]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>