linux.git/arch/powerpc/kernel/head_32.S, branch v5.4.211

powerpc/603: Fix protection of user pages mapped with PROT_NONE

2021-03-17T16:03:33+00:00

commit c119565a15a628efdfa51352f9f6c5186e506a1c upstream.

On book3s/32, page protection is defined by the PP bits in the PTE
which provide the following protection depending on the access
keys defined in the matching segment register:
- PP 00 means RW with key 0 and N/A with key 1.
- PP 01 means RW with key 0 and RO with key 1.
- PP 10 means RW with both key 0 and key 1.
- PP 11 means RO with both key 0 and key 1.

Since the implementation of kernel userspace access protection,
PP bits have been set as follows:
- PP00 for pages without _PAGE_USER
- PP01 for pages with _PAGE_USER and _PAGE_RW
- PP11 for pages with _PAGE_USER and without _PAGE_RW

For kernelspace segments, kernel accesses are performed with key 0
and user accesses are performed with key 1. As PP00 is used for
non _PAGE_USER pages, user can't access kernel pages not flagged
_PAGE_USER while kernel can.

For userspace segments, both kernel and user accesses are performed
with key 0, therefore pages not flagged _PAGE_USER are still
accessible to the user.

This shouldn't be an issue, because userspace is expected to be
accessible to the user. But unlike most other architectures, powerpc
implements PROT_NONE protection by removing _PAGE_USER flag instead of
flagging the page as not valid. This means that pages in userspace
that are not flagged _PAGE_USER shall remain inaccessible.

To get the expected behaviour, just mimic other architectures in the
TLB miss handler by checking _PAGE_USER permission on userspace
accesses as if it was the _PAGE_PRESENT bit.

Note that this problem only is only for 603 cores. The 604+ have
an hash table, and hash_page() function already implement the
verification of _PAGE_USER permission on userspace pages.

Fixes: f342adca3afc ("powerpc/32s: Prepare Kernel Userspace Access Protection")
Cc: stable@vger.kernel.org # v5.2+
Reported-by: Christoph Plattner 
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/4a0c6e3bb8f0c162457bf54d9bc6fd8d7b55129f.1612160907.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman

powerpc/603: Always fault when _PAGE_ACCESSED is not set

2020-11-18T18:20:33+00:00

commit 11522448e641e8f1690c9db06e01985e8e19b401 upstream.

The kernel expects pte_young() to work regardless of CONFIG_SWAP.

Make sure a minor fault is taken to set _PAGE_ACCESSED when it
is not already set, regardless of the selection of CONFIG_SWAP.

Fixes: 84de6ab0e904 ("powerpc/603: don't handle PAGE_ACCESSED in TLB miss handlers.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/a44367744de54e2315b2f1a8cbbd7f88488072e0.1602342806.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman

powerpc/powermac: Fix low_sleep_handler with KUAP and KUEP

2020-11-05T10:43:31+00:00

commit 2c637d2df4ee4830e9d3eb2bd5412250522ce96e upstream.

low_sleep_handler() has an hardcoded restore of segment registers
that doesn't take KUAP and KUEP into account.

Use head_32's load_segment_registers() routine instead.

Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection")
Fixes: 31ed2b13c48d ("powerpc/32s: Implement Kernel Userspace Execution Prevention.")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/21b05f7298c1b18f73e6e5b4cd5005aafa24b6da.1599820109.git.christophe.leroy@csgroup.eu
Signed-off-by: Greg Kroah-Hartman

powerpc/32s: use CONFIG_PPC_BOOK3S_601 instead of reading PVR

2019-08-28T13:19:33+00:00

Use CONFIG_PPC_BOOK3S_601 instead of reading PVR to know if
it is a 601 or not.

Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/909c26db9facd7fe454695b303f952e019dd9eda.1566834712.git.christophe.leroy@c-s.fr

powerpc/603: Fix handling of the DIRTY flag

2019-08-20T11:22:21+00:00

If a page is already mapped RW without the DIRTY flag, the DIRTY
flag is never set and a TLB store miss exception is taken forever.

This is easily reproduced with the following app:

void main(void)
{
	volatile char *ptr = mmap(0, 4096, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);

	*ptr = *ptr;
}

When DIRTY flag is not set, bail out of TLB miss handler and take
a minor page fault which will set the DIRTY flag.

Fixes: f8b58c64eaef ("powerpc/603: let's handle PAGE_DIRTY directly")
Cc: stable@vger.kernel.org # v5.1+
Reported-by: Doug Crawford 
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/80432f71194d7ee75b2f5043ecf1501cf1cca1f3.1566196646.git.christophe.leroy@c-s.fr

powerpc/32s: Fix boot failure with DEBUG_PAGEALLOC without KASAN.

2019-08-20T11:22:13+00:00

When KASAN is selected, the definitive hash table has to be
set up later, but there is already an early temporary one.

When KASAN is not selected, there is no early hash table,
so the setup of the definitive hash table cannot be delayed.

Fixes: 72f208c6a8f7 ("powerpc/32s: move hash code patching out of MMU_init_hw()")
Cc: stable@vger.kernel.org # v5.2+
Reported-by: Jonathan Neuschafer 
Tested-by: Jonathan Neuschafer 
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman 
Link: https://lore.kernel.org/r/b7860c5e1e784d6b96ba67edf47dd6cbc2e78ab6.1565776892.git.christophe.leroy@c-s.fr

Merge tag 'powerpc-5.2-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2019-06-22T16:09:42+00:00

Pull powerpc fixes from Michael Ellerman:
 "This is a frustratingly large batch at rc5. Some of these were sent
  earlier but were missed by me due to being distracted by other things,
  and some took a while to track down due to needing manual bisection on
  old hardware. But still we clearly need to improve our testing of KVM,
  and of 32-bit, so that we catch these earlier.

  Summary: seven fixes, all for bugs introduced this cycle.

   - The commit to add KASAN support broke booting on 32-bit SMP
     machines, due to a refactoring that moved some setup out of the
     secondary CPU path.

   - A fix for another 32-bit SMP bug introduced by the fast syscall
     entry implementation for 32-bit BOOKE. And a build fix for the same
     commit.

   - Our change to allow the DAWR to be force enabled on Power9
     introduced a bug in KVM, where we clobber r3 leading to a host
     crash.

   - The same commit also exposed a previously unreachable bug in the
     nested KVM handling of DAWR, which could lead to an oops in a
     nested host.

   - One of the DMA reworks broke the b43legacy WiFi driver on some
     people's powermacs, fix it by enabling a 30-bit ZONE_DMA on 32-bit.

   - A fix for TLB flushing in KVM introduced a new bug, as it neglected
     to also flush the ERAT, this could lead to memory corruption in the
     guest.

  Thanks to: Aaro Koskinen, Christoph Hellwig, Christophe Leroy, Larry
  Finger, Michael Neuling, Suraj Jitindar Singh"

* tag 'powerpc-5.2-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  KVM: PPC: Book3S HV: Invalidate ERAT when flushing guest TLB entries
  powerpc: enable a 30-bit ZONE_DMA for 32-bit pmac
  KVM: PPC: Book3S HV: Only write DAWR[X] when handling h_set_dawr in real mode
  KVM: PPC: Book3S HV: Fix r3 corruption in h_set_dabr()
  powerpc/32: fix build failure on book3e with KVM
  powerpc/booke: fix fast syscall entry on SMP
  powerpc/32s: fix initial setup of segment registers on secondary CPU

powerpc/32s: fix initial setup of segment registers on secondary CPU

2019-06-15T13:43:54+00:00

The patch referenced below moved the loading of segment registers
out of load_up_mmu() in order to do it earlier in the boot sequence.
However, the secondary CPU still needs it to be done when loading up
the MMU.

Reported-by: Erhard F. 
Fixes: 215b823707ce ("powerpc/32s: set up an early static hash table for KASAN")
Signed-off-by: Christophe Leroy 
Signed-off-by: Michael Ellerman

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/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