linux.git/arch/powerpc/kernel/exceptions-64e.S, branch v5.1

powerpc/fsl: Fix the flush of branch predictor.

2019-02-27T11:52:38+00:00

The commit identified below adds MC_BTB_FLUSH macro only when
CONFIG_PPC_FSL_BOOK3E is defined. This results in the following error
on some configs (seen several times with kisskb randconfig_defconfig)

arch/powerpc/kernel/exceptions-64e.S:576: Error: Unrecognized opcode: `mc_btb_flush'
make[3]: *** [scripts/Makefile.build:367: arch/powerpc/kernel/exceptions-64e.o] Error 1
make[2]: *** [scripts/Makefile.build:492: arch/powerpc/kernel] Error 2
make[1]: *** [Makefile:1043: arch/powerpc] Error 2
make: *** [Makefile:152: sub-make] Error 2

This patch adds a blank definition of MC_BTB_FLUSH for other cases.

Fixes: 10c5e83afd4a ("powerpc/fsl: Flush the branch predictor at each kernel entry (64bit)")
Cc: Diana Craciun 
Signed-off-by: Christophe Leroy 
Reviewed-by: Daniel Axtens 
Reviewed-by: Diana Craciun 
Signed-off-by: Michael Ellerman

powerpc/64: Replace CURRENT_THREAD_INFO with PACA_THREAD_INFO

2019-02-23T11:31:40+00:00

Now that current_thread_info is located at the beginning of 'current'
task struct, CURRENT_THREAD_INFO macro is not really needed any more.

This patch replaces it by loads of the value at PACA_THREAD_INFO(r13).

Signed-off-by: Christophe Leroy 
[mpe: Add PACA_THREAD_INFO rather than using PACACURRENT]
Signed-off-by: Michael Ellerman

powerpc: Activate CONFIG_THREAD_INFO_IN_TASK

2019-02-23T11:31:40+00:00

This patch activates CONFIG_THREAD_INFO_IN_TASK which
moves the thread_info into task_struct.

Moving thread_info into task_struct has the following advantages:
  - It protects thread_info from corruption in the case of stack
    overflows.
  - Its address is harder to determine if stack addresses are leaked,
    making a number of attacks more difficult.

This has the following consequences:
  - thread_info is now located at the beginning of task_struct.
  - The 'cpu' field is now in task_struct, and only exists when
    CONFIG_SMP is active.
  - thread_info doesn't have anymore the 'task' field.

This patch:
  - Removes all recopy of thread_info struct when the stack changes.
  - Changes the CURRENT_THREAD_INFO() macro to point to current.
  - Selects CONFIG_THREAD_INFO_IN_TASK.
  - Modifies raw_smp_processor_id() to get ->cpu from current without
    including linux/sched.h to avoid circular inclusion and without
    including asm/asm-offsets.h to avoid symbol names duplication
    between ASM constants and C constants.
  - Modifies klp_init_thread_info() to take a task_struct pointer
    argument.

Signed-off-by: Christophe Leroy 
Reviewed-by: Nicholas Piggin 
[mpe: Add task_stack.h to livepatch.h to fix build fails]
Signed-off-by: Michael Ellerman

powerpc/fsl: Flush the branch predictor at each kernel entry (64bit)

2018-12-20T11:59:03+00:00

In order to protect against speculation attacks on
indirect branches, the branch predictor is flushed at
kernel entry to protect for the following situations:
- userspace process attacking another userspace process
- userspace process attacking the kernel
Basically when the privillege level change (i.e. the
kernel is entered), the branch predictor state is flushed.

Signed-off-by: Diana Craciun 
Signed-off-by: Michael Ellerman

powerpc: clean inclusions of asm/feature-fixups.h

2018-07-30T12:48:17+00:00

files not using feature fixup don't need asm/feature-fixups.h
files using feature fixup need asm/feature-fixups.h

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman

powerpc/64s: make PACA_IRQ_HARD_DIS track MSR[EE] closely

2018-07-24T12:03:14+00:00

When the masked interrupt handler clears MSR[EE] for an interrupt in
the PACA_IRQ_MUST_HARD_MASK set, it does not set PACA_IRQ_HARD_DIS.
This makes them get out of synch.

With that taken into account, it's only low level irq manipulation
(and interrupt entry before reconcile) where they can be out of synch.
This makes the code less surprising.

It also allows the IRQ replay code to rely on the IRQ_HARD_DIS value
and not have to mtmsrd again in this case (e.g., for an external
interrupt that has been masked). The bigger benefit might just be
that there is not such an element of surprise in these two bits of
state.

Signed-off-by: Nicholas Piggin 
Signed-off-by: Michael Ellerman

powerpc/64s: Fix may_hard_irq_enable() for PMI soft masking

2018-02-08T12:56:10+00:00

The soft IRQ masking code has to hard-disable interrupts in cases
where the exception is not cleared by the masked handler. External
interrupts used this approach for soft masking. Now recently PMU
interrupts do the same thing.

The soft IRQ masking code additionally allowed for interrupt handlers
to hard-enable interrupts after soft-disabling them. The idea is to
allow PMU interrupts through to profile interrupt handlers.

So when interrupts are being replayed when there is a pending
interrupt that requires hard-disabling, there is a test to prevent
those handlers from hard-enabling them if there is a pending external
interrupt. may_hard_irq_enable() handles this.

After f442d00480 ("powerpc/64s: Add support to mask perf interrupts
and replay them"), may_hard_irq_enable() could prematurely enable
MSR[EE] when a PMU exception exists, which would result in the
interrupt firing again while masked, and MSR[EE] being disabled again.

I haven't seen that this could cause a serious problem, but it's
more consistent to handle these soft-masked interrupts in the same
way. So introduce a define for all types of interrupts that require
MSR[EE] masking in their soft-disable handlers, and use that in
may_hard_irq_enable().

Fixes: f442d004806e ("powerpc/64s: Add support to mask perf interrupts and replay them")
Signed-off-by: Nicholas Piggin 
Reviewed-by: Madhavan Srinivasan 
Signed-off-by: Michael Ellerman

powerpc/64: Rename soft_enabled to irq_soft_mask

2018-01-19T11:37:01+00:00

Rename the paca->soft_enabled to paca->irq_soft_mask as it is no
longer used as a flag for interrupt state, but a mask.

Signed-off-by: Madhavan Srinivasan 
Signed-off-by: Michael Ellerman

powerpc/64: Change soft_enabled from flag to bitmask

2018-01-19T11:37:00+00:00

"paca->soft_enabled" is used as a flag to mask some of interrupts.
Currently supported flags values and their details:

soft_enabled    MSR[EE]

0               0       Disabled (PMI and HMI not masked)
1               1       Enabled

"paca->soft_enabled" is initialized to 1 to make the interripts as
enabled. arch_local_irq_disable() will toggle the value when
interrupts needs to disbled. At this point, the interrupts are not
actually disabled, instead, interrupt vector has code to check for the
flag and mask it when it occurs. By "mask it", it update interrupt
paca->irq_happened and return. arch_local_irq_restore() is called to
re-enable interrupts, which checks and replays interrupts if any
occured.

Now, as mentioned, current logic doesnot mask "performance monitoring
interrupts" and PMIs are implemented as NMI. But this patchset depends
on local_irq_* for a successful local_* update. Meaning, mask all
possible interrupts during local_* update and replay them after the
update.

So the idea here is to reserve the "paca->soft_enabled" logic. New
values and details:

soft_enabled    MSR[EE]

1               0       Disabled  (PMI and HMI not masked)
0               1       Enabled

Reason for the this change is to create foundation for a third mask
value "0x2" for "soft_enabled" to add support to mask PMIs. When
->soft_enabled is set to a value "3", PMI interrupts are mask and when
set to a value of "1", PMI are not mask. With this patch also extends
soft_enabled as interrupt disable mask.

Current flags are renamed from IRQ_[EN?DIS}ABLED to
IRQS_ENABLED and IRQS_DISABLED.

Patch also fixes the ptrace call to force the user to see the softe
value to be alway 1. Reason being, even though userspace has no
business knowing about softe, it is part of pt_regs. Like-wise in
signal context.

Signed-off-by: Madhavan Srinivasan 
Signed-off-by: Michael Ellerman

powerpc/64: Add #defines for paca->soft_enabled flags

2018-01-19T11:36:56+00:00

Two #defines IRQS_ENABLED and IRQS_DISABLED are added to be used when
updating paca->soft_enabled. Replace the hardcoded values used when
updating paca->soft_enabled with IRQ_(EN|DIS)ABLED #define. No logic
change.

Reviewed-by: Nicholas Piggin 
Signed-off-by: Madhavan Srinivasan 
Signed-off-by: Michael Ellerman