linux-stable.git/arch/powerpc/kernel/entry_32.S, branch v5.3

powerpc: Wire up clone3 syscall

2019-07-28T23:34:27+00:00

Wire up the new clone3 syscall added in commit 7f192e3cd316 ("fork:
add clone3").

This requires a ppc_clone3 wrapper, in order to save the non-volatile
GPRs before calling into the generic syscall code. Otherwise we hit
the BUG_ON in CHECK_FULL_REGS in copy_thread().

Lightly tested using Christian's test code on a Power8 LE VM.

Signed-off-by: Michael Ellerman 
Acked-by: Christian Brauner 
Link: https://lore.kernel.org/r/20190724140259.23554-1-mpe@ellerman.id.au

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

powerpc/entry: Remove unneeded need_resched() loop

2019-05-02T16:54:57+00:00

Since the enabling and disabling of IRQs within preempt_schedule_irq()
is contained in a need_resched() loop, we don't need the outer arch
code loop.

Signed-off-by: Valentin Schneider 
[mpe: Rebase since CURRENT_THREAD_INFO() removal]
Signed-off-by: Michael Ellerman

powerpc/32: Don't add dummy frames when calling trace_hardirqs_on/off

2019-05-02T15:20:28+00:00

No need to add dummy frames when calling trace_hardirqs_on or
trace_hardirqs_off. GCC properly handles empty stacks.

In addition, powerpc doesn't set CONFIG_FRAME_POINTER, therefore
__builtin_return_address(1..) returns NULL at all time. So the
dummy frames are definitely unneeded here.

In the meantime, avoid reading memory for loading r1 with a value
we already know.

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

powerpc/32: don't do syscall stuff in transfer_to_handler

2019-05-02T15:20:27+00:00

As syscalls are now handled via a fast entry path, syscall related
actions can be removed from the generic transfer_to_handler path.

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

powerpc/32: implement fast entry for syscalls on BOOKE

2019-05-02T15:20:27+00:00

This patch implements a fast entry for syscalls.

Syscalls don't have to preserve non volatile registers except LR.

This patch then implement a fast entry for syscalls, where
volatile registers get clobbered.

As this entry is dedicated to syscall it always sets MSR_EE
and warns in case MSR_EE was previously off

It also assumes that the call is always from user, system calls are
unexpected from kernel.

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

powerpc/32: implement fast entry for syscalls on non BOOKE

2019-05-02T15:20:27+00:00

This patch implements a fast entry for syscalls.

Syscalls don't have to preserve non volatile registers except LR.

This patch then implement a fast entry for syscalls, where
volatile registers get clobbered.

As this entry is dedicated to syscall it always sets MSR_EE
and warns in case MSR_EE was previously off

It also assumes that the call is always from user, system calls are
unexpected from kernel.

The overall series improves null_syscall selftest by 12,5% on an 83xx
and by 17% on a 8xx.

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

powerpc: Fix 32-bit handling of MSR_EE on exceptions

2019-05-02T15:20:27+00:00

[text mostly copied from benh's RFC/WIP]

ppc32 are still doing something rather gothic and wrong on 32-bit
which we stopped doing on 64-bit a while ago.

We have that thing where some handlers "copy" the EE value from the
original stack frame into the new MSR before transferring to the
handler.

Thus for a number of exceptions, we enter the handlers with interrupts
enabled.

This is rather fishy, some of the stuff that handlers might do early
on such as irq_enter/exit or user_exit, context tracking, etc...
should be run with interrupts off afaik.

Generally our handlers know when to re-enable interrupts if needed.

The problem we were having is that we assumed these interrupts would
return with interrupts enabled. However that isn't the case.

Instead, this patch changes things so that we always enter exception
handlers with interrupts *off* with the notable exception of syscalls
which are special (and get a fast path).

Suggested-by: Benjamin Herrenschmidt 
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman

powerpc/32: move LOAD_MSR_KERNEL() into head_32.h and use it

2019-05-02T15:20:27+00:00

As preparation for using head_32.h for head_40x.S, move
LOAD_MSR_KERNEL() there and use it to load r10 with MSR_KERNEL value.

In the mean time, this patch modifies it so that it takes into account
the size of the passed value to determine if 'li' can be used or if
'lis/ori' is needed instead of using the size of MSR_KERNEL. This is
done by using gas macro.

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

powerpc/32s: Implement Kernel Userspace Execution Prevention.

2019-04-21T13:11:46+00:00

To implement Kernel Userspace Execution Prevention, this patch
sets NX bit on all user segments on kernel entry and clears NX bit
on all user segments on kernel exit.

Note that powerpc 601 doesn't have the NX bit, so KUEP will not
work on it. A warning is displayed at startup.

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