PVR value of 0x0F000006 means we are arch v3.1 compliant (i.e.
POWER10). This is used by phyp and kvm when booting as a pseries guest
to detect the presence of new P10 features and to enable the
appropriate hwcap and facility bits.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Signed-off-by: NCédric Le Goater <clg@kaod.org>
[mpe: Fall through to __init_FSCR rather than duplicating it, drop
      hack to set current->thread.fscr now that is handled elsewhere.]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-8-alistair@popple.id.au

Matrix multiple assist (MMA) is a new feature added to ISAv3.1 and
POWER10. Support on powernv can be selected via a firmware CPU device
tree feature which enables it via a PCR bit.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-7-alistair@popple.id.au

Prefix instructions have their own FSCR bit which needs to be enabled
via a CPU feature. The kernel will save the FSCR for problem state but
it needs to be enabled initially.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-6-alistair@popple.id.au

On powernv hardware support for ISAv3.1 is advertised via a cpu feature
bit in the device tree. This patch enables the associated HWCAP bit if
the device tree indicates ISAv3.1 is available.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-4-alistair@popple.id.au

Newer ISA versions are enabled by clearing all bits in the PCR
associated with previous versions of the ISA. Enable ISA v3.1 support
by updating the PCR mask to include ISA v3.0. This ensures all PCR
bits corresponding to earlier architecture versions get cleared
thereby enabling ISA v3.1 if supported by the hardware.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-3-alistair@popple.id.au

POWER10 introduces two new architectural features - ISAv3.1 and matrix
multiply assist (MMA) instructions. Userspace detects the presence
of these features via two HWCAP bits introduced in this patch. These
bits have been agreed to by the compiler and binutils team.

According to ISAv3.1 MMA is an optional feature and software that makes
use of it should first check for availability via this HWCAP bit and use
alternate code paths if unavailable.
Signed-off-by: NAlistair Popple <alistair@popple.id.au>
Tested-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200521014341.29095-2-alistair@popple.id.au

Since the previous commit that saves the value of FSCR configured at
boot into init_task.thread.fscr, the static initialisation in
INIT_THREAD now no longer has any effect.

So remove it.

For non DT CPU features, the end result is the same, because
__init_FSCR() is called on all CPUs that have an FSCR (Power8,
Power9), and it sets FSCR_TAR & FSCR_EBB.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200527145843.2761782-4-mpe@ellerman.id.au

At boot the FSCR is initialised via one of two paths. On most systems
it's set to a hard coded value in __init_FSCR().

On newer skiboot systems we use the device tree CPU features binding,
where firmware can tell Linux what bits to set in FSCR (and HFSCR).

In both cases the value that's configured at boot is not propagated
into the init_task.thread.fscr value prior to the initial fork of init
(pid 1), which means the value is not used by any processes other than
swapper (the idle task).

For the __init_FSCR() case this is OK, because the value in
init_task.thread.fscr is initialised to something sensible. However it
does mean that the value set in __init_FSCR() is not used other than
for swapper, which is odd and confusing.

The bigger problem is for the device tree CPU features case it
prevents firmware from setting (or clearing) FSCR bits for use by user
space. This means all existing kernels can not have features
enabled/disabled by firmware if those features require
setting/clearing FSCR bits.

We can handle both cases by saving the FSCR value into
init_task.thread.fscr after we have initialised it at boot. This fixes
the bug for device tree CPU features, and will allow us to simplify
the initialisation for the __init_FSCR() case in a future patch.

Fixes: 5a61ef74 ("powerpc/64s: Support new device tree binding for discovering CPU features")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200527145843.2761782-3-mpe@ellerman.id.au

The device tree CPU features binding includes FSCR bit numbers which
Linux is instructed to set by firmware.

Whether that's a good idea or not, in the case of the DSCR the Linux
implementation has a hard requirement that the FSCR_DSCR bit not be
set by default. We use it to track when a process reads/writes to
DSCR, so it must be clear to begin with.

So if firmware tells us to set FSCR_DSCR we must ignore it.

Currently this does not cause a bug in our DSCR handling because the
value of FSCR that the device tree CPU features code establishes is
only used by swapper. All other tasks use the value hard coded in
init_task.thread.fscr.

However we'd like to fix that in a future commit, at which point this
will become necessary.

Fixes: 5a61ef74 ("powerpc/64s: Support new device tree binding for discovering CPU features")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200527145843.2761782-2-mpe@ellerman.id.au

__init_FSCR() was added originally in commit 2468dcf6 ("powerpc:
Add support for context switching the TAR register") (Feb 2013), and
only set FSCR_TAR.

At that point FSCR (Facility Status and Control Register) was not
context switched, so the setting was permanent after boot.

Later we added initialisation of FSCR_DSCR to __init_FSCR(), in commit
54c9b225 ("powerpc: Set DSCR bit in FSCR setup") (Mar 2013), again
that was permanent after boot.

Then commit 2517617e ("powerpc: Fix context switch DSCR on
POWER8") (Aug 2013) added a limited context switch of FSCR, just the
FSCR_DSCR bit was context switched based on thread.dscr_inherit. That
commit said "This clears the H/FSCR DSCR bit initially", but it
didn't, it left the initialisation of FSCR_DSCR in __init_FSCR().
However the initial context switch from init_task to pid 1 would clear
FSCR_DSCR because thread.dscr_inherit was 0.

That commit also introduced the requirement that FSCR_DSCR be clear
for user processes, so that we can take the facility unavailable
interrupt in order to manage dscr_inherit.

Then in commit 152d523e ("powerpc: Create context switch helpers
save_sprs() and restore_sprs()") (Dec 2015) FSCR was added to
thread_struct. However it still wasn't fully context switched, we just
took the existing value and set FSCR_DSCR if the new thread had
dscr_inherit set. FSCR was still initialised at boot to FSCR_DSCR |
FSCR_TAR, but that value was not propagated into the thread_struct, so
the initial context switch set FSCR_DSCR back to 0.

Finally commit b57bd2de ("powerpc: Improve FSCR init and context
switching") (Jun 2016) added a full context switch of the FSCR, and
added an initialisation of init_task.thread.fscr to FSCR_TAR |
FSCR_EBB, but omitted FSCR_DSCR.

The end result is that swapper runs with FSCR_DSCR set because of the
initialisation in __init_FSCR(), but no other processes do, they use
the value from init_task.thread.fscr.

Having FSCR_DSCR set for swapper allows it to access SPR 3 from
userspace, but swapper never runs userspace, so it has no useful
effect. It's also confusing to have the value initialised in two
places to two different values.

So remove FSCR_DSCR from __init_FSCR(), this at least gets us to the
point where there's a single value of FSCR, even if it's still set in
two places.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Tested-by: NAlistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200527145843.2761782-1-mpe@ellerman.id.au

'thread' doesn't exist in kuap_check() macro.

Use 'current' instead.

Fixes: a68c31fc ("powerpc/32s: Implement Kernel Userspace Access Protection")
Cc: stable@vger.kernel.org
Reported-by: Nkbuild test robot <lkp@intel.com>
Signed-off-by: NChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b459e1600b969047a74e34251a84a3d6fdf1f312.1590858925.git.christophe.leroy@csgroup.eu

Since commit c55d7b5e ("powerpc: Remove STRICT_KERNEL_RWX
incompatibility with RELOCATABLE"), powerpc kernels with
-mprofile-kernel can crash in certain scenarios with a trace like below:

    BUG: Unable to handle kernel instruction fetch (NULL pointer?)
    Faulting instruction address: 0x00000000
    Oops: Kernel access of bad area, sig: 11 [#1]
    LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV
    <snip>
    NIP [0000000000000000] 0x0
    LR [c0080000102c0048] ext4_iomap_end+0x8/0x30 [ext4]
    Call Trace:
     iomap_apply+0x20c/0x920 (unreliable)
     iomap_bmap+0xfc/0x160
     ext4_bmap+0xa4/0x180 [ext4]
     bmap+0x4c/0x80
     jbd2_journal_init_inode+0x44/0x1a0 [jbd2]
     ext4_load_journal+0x440/0x860 [ext4]
     ext4_fill_super+0x342c/0x3ab0 [ext4]
     mount_bdev+0x25c/0x290
     ext4_mount+0x28/0x50 [ext4]
     legacy_get_tree+0x4c/0xb0
     vfs_get_tree+0x4c/0x130
     do_mount+0xa18/0xc50
     sys_mount+0x158/0x180
     system_call+0x5c/0x68

The NIP points to NULL, or a random location (data even), while the LR
always points to the LEP of a function (with an offset of 8), indicating
that something went wrong with ftrace. However, ftrace is not
necessarily active when such crashes occur.

The kernel OOPS sometimes follows a warning from ftrace indicating that
some module functions could not be patched with a nop. Other times, if a
module is loaded early during boot, instruction patching can fail due to
a separate bug, but the error is not reported due to missing error
reporting.

In all the above cases when instruction patching fails, ftrace will be
disabled but certain kernel module functions will be left with default
calls to _mcount(). This is not a problem with ELFv1. However, with
-mprofile-kernel, the default stub is problematic since it depends on a
valid module TOC in r2. If the kernel (or a different module) calls into
a function that does not use the TOC, the function won't have a prologue
to setup the module TOC. When that function calls into _mcount(), we
will end up in the relocation stub that will use the previous TOC, and
end up trying to jump into a random location. From the above trace:

	iomap_apply+0x20c/0x920 [kernel TOC]
			|
			V
	ext4_iomap_end+0x8/0x30 [no GEP == kernel TOC]
			|
			V
		_mcount() stub
	[uses kernel TOC -> random entry]

To address this, let's change over to using the special stub that is
used for ftrace_[regs_]caller() for _mcount(). This ensures that we are
not dependent on a valid module TOC in r2 for default _mcount()
handling.
Reported-by: NQian Cai <cai@lca.pw>
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Tested-by: NQian Cai <cai@lca.pw>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8affd4298d22099bbd82544fab8185700a6222b1.1587488954.git.naveen.n.rao@linux.vnet.ibm.com

For -mprofile-kernel, we need special handling when generating stubs for
ftrace calls such as _mcount(). To faciliate this, we check if a
R_PPC64_REL24 relocation is for a symbol named "_mcount()" along with
also checking the instruction sequence. The latter is not really
required since "_mcount()" is an exported symbol and kernel modules
cannot use it. As such, drop the additional checking and simplify the
code. This helps unify stub creation for ftrace stubs with
-mprofile-kernel and aids in code reuse.

Also rename is_mprofile_mcount_callsite() to is_mprofile_ftrace_call()
to reflect the checking being done.
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7d9c316adfa1fb787ad268bb4691e7e4059ff2d5.1587488954.git.naveen.n.rao@linux.vnet.ibm.com

module_trampoline_target() is only used by ftrace. Move the prototype
within the appropriate #ifdef in the header. Also, move the function
body to the end of module_64.c so as to consolidate all ftrace code in
one place.

No functional changes.
Signed-off-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2527351f65c53c5866068ae130dc34c5d4ee8ad9.1587488954.git.naveen.n.rao@linux.vnet.ibm.com

Mapping of early shadow area is implemented by using a single static
page table having all entries pointing to the same early shadow page.
The shadow area must therefore occupy full PGD entries.

The shadow area has a size of 128MB starting at 0xf8000000.
With 4k pages, a PGD entry is 4MB
With 16k pages, a PGD entry is 64MB
With 64k pages, a PGD entry is 1GB which is too big.

Until we rework the early shadow mapping, disable KASAN when the page
size is too big.

Fixes: 2edb16ef ("powerpc/32: Add KASAN support")
Cc: stable@vger.kernel.org # v5.2+
Reported-by: Nkbuild test robot <lkp@intel.com>
Signed-off-by: NChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7195fcde7314ccbf7a081b356084a69d421b10d4.1590660977.git.christophe.leroy@csgroup.eu

On book3s/32, KUEP is an heavy process as it requires to
set/unset the NX bit in each of the 12 user segments
everytime the kernel is entered/exited from/to user space.

Don't select KUEP by default on book3s/32.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1492bb150c1aaa53d99a604b49992e60ea20cd5f.1586962582.git.christophe.leroy@c-s.fr

On book3s/32, KUAP is an heavy process as it requires to
determine which segments are impacted and unlock/lock
each of them.

And since the implementation of user_access_begin/end, it
is even worth for the time being because unlike __get_user(),
user_access_begin doesn't make difference between read and write
and unlocks access also for read allthought that's unneeded
on book3s/32.

As shown by the size of a kernel built with KUAP and one without,
the overhead is 64k bytes of code. As a comparison a similar
build on an 8xx has an overhead of only 8k bytes of code.

   text	   data	    bss	    dec	    hex	filename
7230416	1425868	 837376	9493660	 90dc9c	vmlinux.kuap6xx
7165012	1425548	 837376	9427936	 8fdbe0	vmlinux.nokuap6xx
6519796	1960028	 477464	8957288	 88ad68	vmlinux.kuap8xx
6511664	1959864	 477464	8948992	 888d00	vmlinux.nokuap8xx

Until a more optimised KUAP is implemented on book3s/32,
don't select it by default.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/154a99399317b096ac1f04827b9f8d7a9179ddc1.1586962586.git.christophe.leroy@c-s.fr

To enable/disable kernel access to user space, the 8xx has to
modify the properties of access group 1. This is done by writing
predefined values into SPRN_Mx_AP registers.

As of today, a __put_user() gives:

00000d64 <my_test>:
 d64:	3d 20 4f ff 	lis     r9,20479
 d68:	61 29 ff ff 	ori     r9,r9,65535
 d6c:	7d 3a c3 a6 	mtspr   794,r9
 d70:	39 20 00 00 	li      r9,0
 d74:	90 83 00 00 	stw     r4,0(r3)
 d78:	3d 20 6f ff 	lis     r9,28671
 d7c:	61 29 ff ff 	ori     r9,r9,65535
 d80:	7d 3a c3 a6 	mtspr   794,r9
 d84:	4e 80 00 20 	blr

Because only groups 0 and 1 are used, the definition of
groups 2 to 15 doesn't matter.
By setting unused bits to 0 instead on 1, one instruction is
removed for each lock and unlock action:

00000d5c <my_test>:
 d5c:	3d 20 40 00 	lis     r9,16384
 d60:	7d 3a c3 a6 	mtspr   794,r9
 d64:	39 20 00 00 	li      r9,0
 d68:	90 83 00 00 	stw     r4,0(r3)
 d6c:	3d 20 60 00 	lis     r9,24576
 d70:	7d 3a c3 a6 	mtspr   794,r9
 d74:	4e 80 00 20 	blr
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/57425c33dd72f292b1a23570244b81419072a7aa.1586945153.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode.

The very last part of exception exits cannot support a trap.
Blacklist them from kprobe.

While we are at it, remove exc_exit_start symbol which is not
used to avoid having to blacklist it.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/098b0fd3f6299aa1bd692bd576bd7012c84608de.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode.

The very last part of syscall cannot support a trap.
Add a symbol syscall_exit_finish to identify that part and
blacklist it from kprobe.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/23eddf49abb03d1359fa0be4206998eb3800f42c.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode.

As exception entry points are running with MMU disabled,
blacklist them.

The handling of TLF_NAPPING and TLF_SLEEPING is moved before the
CONFIG_TRACE_IRQFLAGS which contains 'reenable_mmu' because from there
kprobe will be possible as the kernel will run with MMU enabled.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f61ac599855e674ebb592464d0ea32a3ba9c6644.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode, all
functions running with MMU disabled have to be blacklisted.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3bf57066d05518644dee0840af69d36ab5086729.1585670437.git.christophe.leroy@c-s.fr

machine_check_in_rtas() is just a trap.

Do the trap directly in the machine check exception handler.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/78899f40f89cb3c4f69bdff7f04eb6ec7cb753d5.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode, all
functions running with MMU disabled have to be blacklisted.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/dabed523c1b8955dd425152ce260b390053e727a.1585670437.git.christophe.leroy@c-s.fr

In hash_low.S, a lot of named local symbols are used instead of
numbers to ease code readability. However, they don't need to be
visible.

In order to ease blacklisting of functions running with MMU
disabled for kprobe, rename the symbols to .Lsymbols in order
to hide them as if they were numbered labels.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/90c430d9e0f7af772a58aaeaf17bcc6321265340.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode, all
functions running with MMU disabled have to be blacklisted.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/eaab3bff961c3bfe149f1d0bd3593291ef939dcc.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode, all
functions running with MMU disabled have to be blacklisted.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/6316e8883753499073f47301857e4e88b73c3ddd.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode, all
functions running with MMU disabled have to be blacklisted.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3ac4ab8dd7008b9706d9228a60645a1756fa84bf.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode, all
functions running with MMU disabled have to be blacklisted.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/5dca36682383577a3c2b2bca4d577e8654944461.1585670437.git.christophe.leroy@c-s.fr

kprobe does not handle events happening in real mode, all
functions running with MMU disabled have to be blacklisted.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Acked-by: NNaveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1ae02b6637b87fc5aaa1d5012c3e2cb30e62b4a3.1585670437.git.christophe.leroy@c-s.fr

In order to avoid Oopses, use probe_address() to read the
instruction at the address where the trap happened.
Signed-off-by: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7f24b5961a6839ff01df792816807f74ff236bf6.1582567319.git.christophe.leroy@c-s.fr

This gives us OF_PMEM which is useful in mambo.

This adds 153K to the text of ppc64le_defconfig which 0.8% of the
total text.

  LIBNVDIMM text     data    bss     dec      hex
  Without   18574833 5518150 1539240 25632223 1871ddf
  With      18727834 5546206 1539368 25813408 189e1a0
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200519043009.3081885-1-mikey@neuling.org

Implement rtas_call_reentrant() for reentrant rtas-calls:
"ibm,int-on", "ibm,int-off",ibm,get-xive" and  "ibm,set-xive".

On LoPAPR Version 1.1 (March 24, 2016), from 7.3.10.1 to 7.3.10.4,
items 2 and 3 say:

2 - For the PowerPC External Interrupt option: The * call must be
reentrant to the number of processors on the platform.
3 - For the PowerPC External Interrupt option: The * argument call
buffer for each simultaneous call must be physically unique.

So, these rtas-calls can be called in a lockless way, if using
a different buffer for each cpu doing such rtas call.

For this, it was suggested to add the buffer (struct rtas_args)
in the PACA struct, so each cpu can have it's own buffer.
The PACA struct received a pointer to rtas buffer, which is
allocated in the memory range available to rtas 32-bit.

Reentrant rtas calls are useful to avoid deadlocks in crashing,
where rtas-calls are needed, but some other thread crashed holding
the rtas.lock.

This is a backtrace of a deadlock from a kdump testing environment:

  #0 arch_spin_lock
  #1  lock_rtas ()
  #2  rtas_call (token=8204, nargs=1, nret=1, outputs=0x0)
  #3  ics_rtas_mask_real_irq (hw_irq=4100)
  #4  machine_kexec_mask_interrupts
  #5  default_machine_crash_shutdown
  #6  machine_crash_shutdown
  #7  __crash_kexec
  #8  crash_kexec
  #9  oops_end
Signed-off-by: NLeonardo Bras <leobras.c@gmail.com>
[mpe: Move under #ifdef PSERIES to avoid build breakage]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200518234245.200672-3-leobras.c@gmail.com

In order to get any rtas* struct into other headers, including rtas.h
may cause a lot of errors, regarding include dependency needed for
inline functions.

Create rtas-types.h and move there all type/struct definitions
from rtas.h, then include rtas-types.h into rtas.h.

Also, as suggested by checkpath.pl, replace uint8_t for u8.
Signed-off-by: NLeonardo Bras <leobras.c@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200518234245.200672-2-leobras.c@gmail.com

Currently, if printk lock (logbuf_lock) is held by other thread during
crash, there is a chance of deadlocking the crash on next printk, and
blocking a possibly desired kdump.

At the start of default_machine_crash_shutdown, make printk enter
NMI context, as it will use per-cpu buffers to store the message,
and avoid locking logbuf_lock.
Suggested-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NLeonardo Bras <leobras.c@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200512214533.93878-1-leobras.c@gmail.com

While providing guests, it's desirable to resize it's memory on demand.

By now, it's possible to do so by creating a guest with a small base
memory, hot-plugging all the rest, and using 'movable_node' kernel
command-line parameter, which puts all hot-plugged memory in
ZONE_MOVABLE, allowing it to be removed whenever needed.

But there is an issue regarding guest reboot:
If memory is hot-plugged, and then the guest is rebooted, all hot-plugged
memory goes to ZONE_NORMAL, which offers no guaranteed hot-removal.
It usually prevents this memory to be hot-removed from the guest.

It's possible to use device-tree information to fix that behavior, as
it stores flags for LMB ranges on ibm,dynamic-memory-vN.
It involves marking each memblock with the correct flags as hotpluggable
memory, which mm/memblock.c puts in ZONE_MOVABLE during boot if
'movable_node' is passed.

For carrying such information, the new flag DRCONF_MEM_HOTREMOVABLE was
proposed and accepted into Power Architecture documentation.
This flag should be:
- true (b=1) if the hypervisor may want to hot-remove it later, and
- false (b=0) if it does not care.

During boot, guest kernel reads the device-tree, early_init_drmem_lmb()
is called for every added LMBs. Here, checking for this new flag and
marking memblocks as hotplugable memory is enough to get the desirable
behavior.

This should cause no change if 'movable_node' parameter is not passed
in kernel command-line.
Signed-off-by: NLeonardo Bras <leonardo@linux.ibm.com>
Reviewed-by: NBharata B Rao <bharata@linux.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200402195156.626430-1-leonardo@linux.ibm.com

Show the address of the tasks regs in the process listing in xmon. The
regs should always be on the stack page that we also print the address
of, but it's still helpful not to have to find them by hand.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200520111740.953679-1-mpe@ellerman.id.au

This adds the CPU or thread number to printk messages. This helps a
lot when deciphering concurrent oopses that have been interleaved.

Example output, of PID1 (T1) triggering a warning:

  [    1.581678][    T1] WARNING: CPU: 0 PID: 1 at crypto/rsa-pkcs1pad.c:539 pkcs1pad_verify+0x38/0x140
  [    1.581681][    T1] Modules linked in:
  [    1.581693][    T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc5-gcc-8.2.0-00121-gf84c2e595927-dirty #1515
  [    1.581700][    T1] NIP:  c000000000207d64 LR: c000000000207d3c CTR: c000000000207d2c
  [    1.581708][    T1] REGS: c0000000fd2e7560 TRAP: 0700   Not tainted  (5.5.0-rc5-gcc-8.2.0-00121-gf84c2e595927-dirty)
  [    1.581712][    T1] MSR:  9000000000029033 <SF,HV,EE,ME,IR,DR,RI,LE>  CR: 44000222  XER: 00040000
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200520121257.961112-1-mpe@ellerman.id.au

Currently when we boot on a big core system, we get this print:
  [    0.040500] Using small cores at SMT level

This is misleading as we've actually detected big cores.

This patch clears up the print to say we've detect big cores but are
using small cores for scheduling.
Signed-off-by: NMichael Neuling <mikey@neuling.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200528230731.1235752-1-mikey@neuling.org

If the memory chunk found for reserving memory overshoots the memory
limit imposed, do not proceed with reserving memory. Default behavior
was this until commit 140777a3 ("powerpc/fadump: consider reserved
ranges while reserving memory") changed it unwittingly.

Fixes: 140777a3 ("powerpc/fadump: consider reserved ranges while reserving memory")
Cc: stable@vger.kernel.org
Reported-by: Nkbuild test robot <lkp@intel.com>
Signed-off-by: NHari Bathini <hbathini@linux.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/159057266320.22331.6571453892066907320.stgit@hbathini.in.ibm.com