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thread_info is not anymore in the stack, so the entire stack
can now be used.
There is also no risk anymore of corrupting task_cpu(p) with a
stack overflow so the patch removes the test.
When doing this, an explicit test for NULL stack pointer is
needed in validate_sp() as it is not anymore implicitely covered
by the sizeof(thread_info) gap.
In the meantime, with the previous patch all pointers to the stacks
are not anymore pointers to thread_info so this patch changes them
to void*
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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When we enable THREAD_INFO_IN_TASK we will remove our definition of
current_thread_info(). Instead it will come from linux/thread_info.h
So switch processor.h to include the latter, so that it can continue
to find current_thread_info().
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Split out of larger patch]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Currently INIT_SP_LIMIT uses sizeof(init_thread_info), but that symbol
won't exist when we enable THREAD_INFO_IN_TASK. So just use the sizeof
the type which is the same value but will continue to work.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Split out of larger patch]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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When activating CONFIG_THREAD_INFO_IN_TASK, linux/sched.h includes
asm/current.h. This generates a circular dependency. To avoid that,
asm/processor.h shall not be included in mmu-hash.h.
In order to do that, this patch moves into a new header called
asm/task_size_64/32.h all the TASK_SIZE related constants, which can
then be included in mmu-hash.h directly.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Split out all the TASK_SIZE constants not just 64-bit ones]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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When calling RTAS, the stack pointer is stored in SPRN_SPRG2
in order to be able to restore it in case of machine check in RTAS.
As machine check is not a perfomance critical path, this patch
frees SPRN_SPRG2 by using a field in thread struct instead.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Prefer _THIS_IP_ defined in linux/kernel.h.
Most definitions of current_text_addr were the same as _THIS_IP_, but
a few archs had inline assembly instead.
This patch removes the final call site of current_text_addr, making all
of the definitions dead code.
[akpm@linux-foundation.org: fix arch/csky/include/asm/processor.h]
Link: http://lkml.kernel.org/r/20180911182413.180715-1-ndesaulniers@google.com
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When switching processes, currently all user SLBEs are cleared, and a
few (exec_base, pc, and stack) are preloaded. In trivial testing with
small apps, this tends to miss the heap and low 256MB segments, and it
will also miss commonly accessed segments on large memory workloads.
Add a simple round-robin preload cache that just inserts the last SLB
miss into the head of the cache and preloads those at context switch
time. Every 256 context switches, the oldest entry is removed from the
cache to shrink the cache and require fewer slbmte if they are unused.
Much more could go into this, including into the SLB entry reclaim
side to track some LRU information etc, which would require a study of
large memory workloads. But this is a simple thing we can do now that
is an obvious win for common workloads.
With the full series, process switching speed on the context_switch
benchmark on POWER9/hash (with kernel speculation security masures
disabled) increases from 140K/s to 178K/s (27%).
POWER8 does not change much (within 1%), it's unclear why it does not
see a big gain like POWER9.
Booting to busybox init with 256MB segments has SLB misses go down
from 945 to 69, and with 1T segments 900 to 21. These could almost all
be eliminated by preloading a bit more carefully with ELF binary
loading.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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PPR is the odd register out when it comes to interrupt handling, it is
saved in current->thread.ppr while all others are saved on the stack.
The difficulty with this is that accessing thread.ppr can cause a SLB
fault, but the SLB fault handler implementation in C change had
assumed the normal exception entry handlers would not cause an SLB
fault.
Fix this by allocating room in the interrupt stack to save PPR.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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This reverts commits:
5e46e29e6a97 ("powerpc/64s/hash: convert SLB miss handlers to C")
8fed04d0f6ae ("powerpc/64s/hash: remove user SLB data from the paca")
655deecf67b2 ("powerpc/64s/hash: SLB allocation status bitmaps")
2e1626744e8d ("powerpc/64s/hash: provide arch_setup_exec hooks for hash slice setup")
89ca4e126a3f ("powerpc/64s/hash: Add a SLB preload cache")
This series had a few bugs, and the fixes are not all trivial. So
revert most of it for now.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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When switching processes, currently all user SLBEs are cleared, and a
few (exec_base, pc, and stack) are preloaded. In trivial testing with
small apps, this tends to miss the heap and low 256MB segments, and it
will also miss commonly accessed segments on large memory workloads.
Add a simple round-robin preload cache that just inserts the last SLB
miss into the head of the cache and preloads those at context switch
time. Every 256 context switches, the oldest entry is removed from the
cache to shrink the cache and require fewer slbmte if they are unused.
Much more could go into this, including into the SLB entry reclaim
side to track some LRU information etc, which would require a study of
large memory workloads. But this is a simple thing we can do now that
is an obvious win for common workloads.
With the full series, process switching speed on the context_switch
benchmark on POWER9/hash (with kernel speculation security masures
disabled) increases from 140K/s to 178K/s (27%).
POWER8 does not change much (within 1%), it's unclear why it does not
see a big gain like POWER9.
Booting to busybox init with 256MB segments has SLB misses go down
from 945 to 69, and with 1T segments 900 to 21. These could almost all
be eliminated by preloading a bit more carefully with ELF binary
loading.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Remove superflous includes and add missing ones
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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It's called 'fs' for historical reasons, it's named after the x86 'FS'
register. But we don't have to use that name for the member of
thread_struct, and in fact arch/x86 doesn't even call it 'fs' anymore.
So rename it to 'addr_limit', which better reflects what it's used
for, and is also the name used on other arches.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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These fields are only written to.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Implement a new function to invoke stop, power9_offline_stop, which is
like power9_idle_stop but used by the cpu hotplug code.
Move KVM secondary state manipulation code to the offline case.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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This patch increases the max virtual (effective) address value to 4PB.
With 4K page size config we continue to limit ourself to 64TB.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[mpe: Keep the H_PGTABLE_RANGE test, update it to work]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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For addresses above 512TB we allocate additional mmu contexts. To make
it all easy, addresses above 512TB are handled with IR/DR=1 and with
stack frame setup.
The mmu_context_t is also updated to track the new extended_ids. To
support upto 4PB we need a total 8 contexts.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
[mpe: Minor formatting tweaks and comment wording, switch BUG to WARN
in get_ea_context().]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Store and restore the AMR, IAMR and UAMOR register state of the task
before scheduling out and after scheduling in, respectively.
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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A CP_ABORT instruction is required in processes that have mapped a VAS
"paste address" with the intention of using COPY/PASTE instructions.
But since CP_ABORT is expensive, we want to restrict it to only
processes that use/intend to use COPY/PASTE.
Define an interface, set_thread_uses_vas(), that VAS can use to
indicate that the current process opened a send window. During context
switch, issue CP_ABORT only for processes that have the flag set.
Thanks for input from Nick Piggin, Michael Ellerman.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
[mpe: Fix to not use new_thread after _switch() returns]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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We need the SPRN_TIDR to be set for use with fast thread-wakeup (core-
to-core wakeup) and also with CAPI.
Each thread in a process needs to have a unique id within the process.
But for now, we assign globally unique thread ids to all threads in
the system.
Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
[mpe: Simplify tidr clearing on fork() and ctx switch code]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"Highlights include:
- Support for STRICT_KERNEL_RWX on 64-bit server CPUs.
- Platform support for FSP2 (476fpe) board
- Enable ZONE_DEVICE on 64-bit server CPUs.
- Generic & powerpc spin loop primitives to optimise busy waiting
- Convert VDSO update function to use new update_vsyscall() interface
- Optimisations to hypercall/syscall/context-switch paths
- Improvements to the CPU idle code on Power8 and Power9.
As well as many other fixes and improvements.
Thanks to: Akshay Adiga, Andrew Donnellan, Andrew Jeffery, Anshuman
Khandual, Anton Blanchard, Balbir Singh, Benjamin Herrenschmidt,
Christophe Leroy, Christophe Lombard, Colin Ian King, Dan Carpenter,
Gautham R. Shenoy, Hari Bathini, Ian Munsie, Ivan Mikhaylov, Javier
Martinez Canillas, Madhavan Srinivasan, Masahiro Yamada, Matt Brown,
Michael Neuling, Michal Suchanek, Murilo Opsfelder Araujo, Naveen N.
Rao, Nicholas Piggin, Oliver O'Halloran, Paul Mackerras, Pavel Machek,
Russell Currey, Santosh Sivaraj, Stephen Rothwell, Thiago Jung
Bauermann, Yang Li"
* tag 'powerpc-4.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (158 commits)
powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs
powerpc/mm/radix: Implement STRICT_RWX/mark_rodata_ro() for Radix
powerpc/mm/hash: Implement mark_rodata_ro() for hash
powerpc/vmlinux.lds: Align __init_begin to 16M
powerpc/lib/code-patching: Use alternate map for patch_instruction()
powerpc/xmon: Add patch_instruction() support for xmon
powerpc/kprobes/optprobes: Use patch_instruction()
powerpc/kprobes: Move kprobes over to patch_instruction()
powerpc/mm/radix: Fix execute permissions for interrupt_vectors
powerpc/pseries: Fix passing of pp0 in updatepp() and updateboltedpp()
powerpc/64s: Blacklist rtas entry/exit from kprobes
powerpc/64s: Blacklist functions invoked on a trap
powerpc/64s: Un-blacklist system_call() from kprobes
powerpc/64s: Move system_call() symbol to just after setting MSR_EE
powerpc/64s: Blacklist system_call() and system_call_common() from kprobes
powerpc/64s: Convert .L__replay_interrupt_return to a local label
powerpc64/elfv1: Only dereference function descriptor for non-text symbols
cxl: Export library to support IBM XSL
powerpc/dts: Use #include "..." to include local DT
powerpc/perf/hv-24x7: Aggregate result elements on POWER9 SMT8
...
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Merge our fixes branch, a few of them are tripping people up while
working on top of next, and we also have a dependency between the CXL
fixes and new CXL code we want to merge into next.
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Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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The only user of thread_saved_pc() in non-arch-specific code was removed
in commit 8243d5597793 ("sched/core: Remove pointless printout in
sched_show_task()"). Remove the implementations as well.
Some architectures use thread_saved_pc() in their arch-specific code.
Leave their thread_saved_pc() intact.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This simplifies the asm and fixes irq-off tracing over sleep
instructions.
Also move powersave_nap check for POWER8 into C code, and move
PSSCR register value calculation for POWER9 into C.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Supporting 512TB requires us to do a order 3 allocation for level 1 page
table (pgd). This results in page allocation failures with certain workloads.
For now limit 4k linux page size config to 64TB.
Fixes: f6eedbba7a26 ("powerpc/mm/hash: Increase VA range to 128TB")
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Commit f4ea6dcb08ea ("powerpc/mm: Enable mappings above 128TB") increased
the task size on book3s, and introduced a mechanism to dynamically
control whether a task uses these larger addresses. While the change to
the task size itself was ifdef-protected to only apply on book3s, the
change to STACK_TOP_USER64 was not. On book3e, this had the effect of
trying to use addresses up to 128TiB for the stack despite a 64TiB task
size limit -- which broke 64-bit userspace producing the following errors:
Starting init: /sbin/init exists but couldn't execute it (error -14)
Starting init: /bin/sh exists but couldn't execute it (error -14)
Kernel panic - not syncing: No working init found. Try passing init= option to kernel. See Linux Documentation/admin-guide/init.rst for guidance.
Fixes: f4ea6dcb08ea ("powerpc/mm: Enable mappings above 128TB")
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Scott Wood <oss@buserror.net>
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Not all user space application is ready to handle wide addresses. It's
known that at least some JIT compilers use higher bits in pointers to
encode their information. It collides with valid pointers with 512TB
addresses and leads to crashes.
To mitigate this, we are not going to allocate virtual address space
above 128TB by default.
But userspace can ask for allocation from full address space by
specifying hint address (with or without MAP_FIXED) above 128TB.
If hint address set above 128TB, but MAP_FIXED is not specified, we try
to look for unmapped area by specified address. If it's already
occupied, we look for unmapped area in *full* address space, rather than
from 128TB window.
This approach helps to easily make application's memory allocator aware
about large address space without manually tracking allocated virtual
address space.
This is going to be a per mmap decision. ie, we can have some mmaps with
larger addresses and other that do not.
A sample memory layout looks like:
10000000-10010000 r-xp 00000000 fc:00 9057045 /home/max_addr_512TB
10010000-10020000 r--p 00000000 fc:00 9057045 /home/max_addr_512TB
10020000-10030000 rw-p 00010000 fc:00 9057045 /home/max_addr_512TB
10029630000-10029660000 rw-p 00000000 00:00 0 [heap]
7fff834a0000-7fff834b0000 rw-p 00000000 00:00 0
7fff834b0000-7fff83670000 r-xp 00000000 fc:00 9177190 /lib/powerpc64le-linux-gnu/libc-2.23.so
7fff83670000-7fff83680000 r--p 001b0000 fc:00 9177190 /lib/powerpc64le-linux-gnu/libc-2.23.so
7fff83680000-7fff83690000 rw-p 001c0000 fc:00 9177190 /lib/powerpc64le-linux-gnu/libc-2.23.so
7fff83690000-7fff836a0000 rw-p 00000000 00:00 0
7fff836a0000-7fff836c0000 r-xp 00000000 00:00 0 [vdso]
7fff836c0000-7fff83700000 r-xp 00000000 fc:00 9177193 /lib/powerpc64le-linux-gnu/ld-2.23.so
7fff83700000-7fff83710000 r--p 00030000 fc:00 9177193 /lib/powerpc64le-linux-gnu/ld-2.23.so
7fff83710000-7fff83720000 rw-p 00040000 fc:00 9177193 /lib/powerpc64le-linux-gnu/ld-2.23.so
7fffdccf0000-7fffdcd20000 rw-p 00000000 00:00 0 [stack]
1000000000000-1000000010000 rw-p 00000000 00:00 0
1ffff83710000-1ffff83720000 rw-p 00000000 00:00 0
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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We update the hash linux page table layout such that we can support
512TB. But we limit the TASK_SIZE to 128TB. We can switch to 128TB by
default without conditional because that is the max virtual address
supported by other architectures. We will later add a mechanism to
on-demand increase the application's effective address range to 512TB.
Having the page table layout changed to accommodate 512TB makes testing
large memory configuration easier with less code changes to kernel
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux into next
Freescale updates from Scott:
"Highlights include 8xx breakpoints and perf, t1042rdb display support,
and board updates."
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The power9_idle_stop method currently takes only the requested stop
level as a parameter and picks up the rest of the PSSCR bits from a
hand-coded macro. This is not a very flexible design, especially when
the firmware has the capability to communicate the psscr value and the
mask associated with a particular stop state via device tree.
This patch modifies the power9_idle_stop API to take as parameters the
PSSCR value and the PSSCR mask corresponding to the stop state that
needs to be set. These PSSCR value and mask are respectively obtained
by parsing the "ibm,cpu-idle-state-psscr" and
"ibm,cpu-idle-state-psscr-mask" fields from the device tree.
In addition to this, the patch adds support for handling stop states
for which ESL and EC bits in the PSSCR are zero. As per the
architecture, a wakeup from these stop states resumes execution from
the subsequent instruction as opposed to waking up at the System
Vector.
The older firmware sets only the Requested Level (RL) field in the
psscr and psscr-mask exposed in the device tree. For older firmware
where psscr-mask=0xf, this patch will set the default sane values that
the set for for remaining PSSCR fields (i.e PSLL, MTL, ESL, EC, and
TR). For the new firmware, the patch will validate that the invariants
required by the ISA for the psscr values are maintained by the
firmware.
This skiboot patch that exports fully populated PSSCR values and the
mask for all the stop states can be found here:
https://lists.ozlabs.org/pipermail/skiboot/2016-September/004869.html
[Optimize the number of instructions before entering STOP with
ESL=EC=0, validate the PSSCR values provided by the firimware
maintains the invariants required as per the ISA suggested by Balbir
Singh]
Acked-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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BOOK3S also has DABR register and capability to handle data
breakpoints, so this patch enable it on all BOOK3S, not only 64 bits.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"Highlights include:
- Support for the kexec_file_load() syscall, which is a prereq for
secure and trusted boot.
- Prevent kernel execution of userspace on P9 Radix (similar to
SMEP/PXN).
- Sort the exception tables at build time, to save time at boot, and
store them as relative offsets to save space in the kernel image &
memory.
- Allow building the kernel with thin archives, which should allow us
to build an allyesconfig once some other fixes land.
- Build fixes to allow us to correctly rebuild when changing the
kernel endian from big to little or vice versa.
- Plumbing so that we can avoid doing a full mm TLB flush on P9
Radix.
- Initial stack protector support (-fstack-protector).
- Support for dumping the radix (aka. Linux) and hash page tables via
debugfs.
- Fix an oops in cxl coredump generation when cxl_get_fd() is used.
- Freescale updates from Scott: "Highlights include 8xx hugepage
support, qbman fixes/cleanup, device tree updates, and some misc
cleanup."
- Many and varied fixes and minor enhancements as always.
Thanks to:
Alexey Kardashevskiy, Andrew Donnellan, Aneesh Kumar K.V, Anshuman
Khandual, Anton Blanchard, Balbir Singh, Bartlomiej Zolnierkiewicz,
Christophe Jaillet, Christophe Leroy, Denis Kirjanov, Elimar
Riesebieter, Frederic Barrat, Gautham R. Shenoy, Geliang Tang, Geoff
Levand, Jack Miller, Johan Hovold, Lars-Peter Clausen, Libin,
Madhavan Srinivasan, Michael Neuling, Nathan Fontenot, Naveen N.
Rao, Nicholas Piggin, Pan Xinhui, Peter Senna Tschudin, Rashmica
Gupta, Rui Teng, Russell Currey, Scott Wood, Simon Guo, Suraj
Jitindar Singh, Thiago Jung Bauermann, Tobias Klauser, Vaibhav Jain"
[ And thanks to Michael, who took time off from a new baby to get this
pull request done. - Linus ]
* tag 'powerpc-4.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (174 commits)
powerpc/fsl/dts: add FMan node for t1042d4rdb
powerpc/fsl/dts: add sg_2500_aqr105_phy4 alias on t1024rdb
powerpc/fsl/dts: add QMan and BMan nodes on t1024
powerpc/fsl/dts: add QMan and BMan nodes on t1023
soc/fsl/qman: test: use DEFINE_SPINLOCK()
powerpc/fsl-lbc: use DEFINE_SPINLOCK()
powerpc/8xx: Implement support of hugepages
powerpc: get hugetlbpage handling more generic
powerpc: port 64 bits pgtable_cache to 32 bits
powerpc/boot: Request no dynamic linker for boot wrapper
soc/fsl/bman: Use resource_size instead of computation
soc/fsl/qe: use builtin_platform_driver
powerpc/fsl_pmc: use builtin_platform_driver
powerpc/83xx/suspend: use builtin_platform_driver
powerpc/ftrace: Fix the comments for ftrace_modify_code
powerpc/perf: macros for power9 format encoding
powerpc/perf: power9 raw event format encoding
powerpc/perf: update attribute_group data structure
powerpc/perf: factor out the event format field
powerpc/mm/iommu, vfio/spapr: Put pages on VFIO container shutdown
...
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No need to duplicate the same define everywhere. Since
the only user is stop-machine and the only provider is
s390, we can use a default implementation of cpu_relax_yield()
in sched.h.
Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-s390 <linux-s390@vger.kernel.org>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: sparclinux@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1479298985-191589-1-git-send-email-borntraeger@de.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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As there are no users left, we can remove cpu_relax_lowlatency()
implementations from every architecture.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Cc: <linux-arch@vger.kernel.org>
Link: http://lkml.kernel.org/r/1477386195-32736-6-git-send-email-borntraeger@de.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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For spinning loops people do often use barrier() or cpu_relax().
For most architectures cpu_relax and barrier are the same, but on
some architectures cpu_relax can add some latency.
For example on power,sparc64 and arc, cpu_relax can shift the CPU
towards other hardware threads in an SMT environment.
On s390 cpu_relax does even more, it uses an hypercall to the
hypervisor to give up the timeslice.
In contrast to the SMT yielding this can result in larger latencies.
In some places this latency is unwanted, so another variant
"cpu_relax_lowlatency" was introduced. Before this is used in more
and more places, lets revert the logic and provide a cpu_relax_yield
that can be called in places where yielding is more important than
latency. By default this is the same as cpu_relax on all architectures.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Noam Camus <noamc@ezchip.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1477386195-32736-2-git-send-email-borntraeger@de.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Load monitored is no longer supported on POWER9 so let's remove the
code.
This reverts commit bd3ea317fddf ("powerpc: Load Monitor Register
Support").
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Currently the MSR TM bit is always set if the hardware is TM capable.
This adds extra overhead as it means the TM SPRS (TFHAR, TEXASR and
TFAIR) must be swapped for each process regardless of if they use TM.
For processes that don't use TM the TM MSR bit can be turned off
allowing the kernel to avoid the expensive swap of the TM registers.
A TM unavailable exception will occur if a thread does use TM and the
kernel will enable MSR_TM and leave it so for some time afterwards.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Make the structures being used for checkpointed state named
consistently with the pt_regs/ckpt_regs.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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There is currently an inconsistency as to how the entire CPU register
state is saved and restored when a thread uses transactional memory
(TM).
Using transactional memory results in the CPU having duplicated
(almost) all of its register state. This duplication results in a set
of registers which can be considered 'live', those being currently
modified by the instructions being executed and another set that is
frozen at a point in time.
On context switch, both sets of state have to be saved and (later)
restored. These two states are often called a variety of different
things. Common terms for the state which only exists after the CPU has
entered a transaction (performed a TBEGIN instruction) in hardware are
'transactional' or 'speculative'.
Between a TBEGIN and a TEND or TABORT (or an event that causes the
hardware to abort), regardless of the use of TSUSPEND the
transactional state can be referred to as the live state.
The second state is often to referred to as the 'checkpointed' state
and is a duplication of the live state when the TBEGIN instruction is
executed. This state is kept in the hardware and will be rolled back
to on transaction failure.
Currently all the registers stored in pt_regs are ALWAYS the live
registers, that is, when a thread has transactional registers their
values are stored in pt_regs and the checkpointed state is in
ckpt_regs. A strange opposite is true for fp_state/vr_state. When a
thread is non transactional fp_state/vr_state holds the live
registers. When a thread has initiated a transaction fp_state/vr_state
holds the checkpointed state and transact_fp/transact_vr become the
structure which holds the live state (at this point it is a
transactional state).
This method creates confusion as to where the live state is, in some
circumstances it requires extra work to determine where to put the
live state and prevents the use of common functions designed (probably
before TM) to save the live state.
With this patch pt_regs, fp_state and vr_state all represent the
same thing and the other structures [pending rename] are for
checkpointed state.
Acked-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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POWER ISA v3 defines a new idle processor core mechanism. In summary,
a) new instruction named stop is added. This instruction replaces
instructions like nap, sleep, rvwinkle.
b) new per thread SPR named Processor Stop Status and Control Register
(PSSCR) is added which controls the behavior of stop instruction.
PSSCR layout:
----------------------------------------------------------
| PLS | /// | SD | ESL | EC | PSLL | /// | TR | MTL | RL |
----------------------------------------------------------
0 4 41 42 43 44 48 54 56 60
PSSCR key fields:
Bits 0:3 - Power-Saving Level Status. This field indicates the lowest
power-saving state the thread entered since stop instruction was last
executed.
Bit 42 - Enable State Loss
0 - No state is lost irrespective of other fields
1 - Allows state loss
Bits 44:47 - Power-Saving Level Limit
This limits the power-saving level that can be entered into.
Bits 60:63 - Requested Level
Used to specify which power-saving level must be entered on executing
stop instruction
This patch adds support for stop instruction and PSSCR handling.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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This enables new registers, LMRR and LMSER, that can trigger an EBB in
userspace code when a monitored load (via the new ldmx instruction)
loads memory from a monitored space. This facility is controlled by a
new FSCR bit, LM.
This patch disables the FSCR LM control bit on task init and enables
that bit when a load monitor facility unavailable exception is taken
for using it. On context switch, this bit is then used to determine
whether the two relevant registers are saved and restored. This is
done lazily for performance reasons.
Signed-off-by: Jack Miller <jack@codezen.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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This fixes a few issues with FSCR init and switching.
In commit 152d523e6307 ("powerpc: Create context switch helpers
save_sprs() and restore_sprs()") we moved the setting of the FSCR
register from inside an CPU_FTR_ARCH_207S section to inside just a
CPU_FTR_ARCH_DSCR section. Hence we are setting FSCR on POWER6/7 where
the FSCR doesn't exist. This is harmless but we shouldn't do it.
Also, we can simplify the FSCR context switch. We don't need to go
through the calculation involving dscr_inherit. We can just restore
what we saved last time.
We also set an initial value in INIT_THREAD, so that pid 1 which is
cloned from that gets a sane value.
Based on patch by Jack Miller.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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The used_vsr flag is set if process has used VSX registers, not Altivec
registers. But the comment says otherwise, correct the comment.
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Currently the FPU, VEC and VSX facilities are lazily loaded. This is not
a problem unless a process is using these facilities.
Modern versions of GCC are very good at automatically vectorising code,
new and modernised workloads make use of floating point and vector
facilities, even the kernel makes use of vectorised memcpy.
All this combined greatly increases the cost of a syscall since the
kernel uses the facilities sometimes even in syscall fast-path making it
increasingly common for a thread to take an *_unavailable exception soon
after a syscall, not to mention potentially taking all three.
The obvious overcompensation to this problem is to simply always load
all the facilities on every exit to userspace. Loading up all FPU, VEC
and VSX registers every time can be expensive and if a workload does
avoid using them, it should not be forced to incur this penalty.
An 8bit counter is used to detect if the registers have been used in the
past and the registers are always loaded until the value wraps to back
to zero.
Several versions of the assembly in entry_64.S were tested:
1. Always calling C.
2. Performing a common case check and then calling C.
3. A complex check in asm.
After some benchmarking it was determined that avoiding C in the common
case is a performance benefit (option 2). The full check in asm (option
3) greatly complicated that codepath for a negligible performance gain
and the trade-off was deemed not worth it.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
[mpe: Move load_vec in the struct to fill an existing hole, reword change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
fixup
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More consolidation of our MSR available bit handling.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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The UP only lazy floating point and vector optimisations were written
back when SMP was not common, and neither glibc nor gcc used vector
instructions. Now SMP is very common, glibc aggressively uses vector
instructions and gcc autovectorises.
We want to add new optimisations that apply to both UP and SMP, but
in preparation for that remove these UP only optimisations.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Move all our context switch SPR save and restore code into two
helpers. We do a few optimisations:
- Group all mfsprs and all mtsprs. In many cases an mtspr sets a
scoreboarding bit that an mfspr waits on, so the current practise of
mfspr A; mtspr A; mfpsr B; mtspr B is the worst scheduling we can
do.
- SPR writes are slow, so check that the value is changing before
writing it.
A context switch microbenchmark using yield():
http://ozlabs.org/~anton/junkcode/context_switch2.c
./context_switch2 --test=yield 0 0
shows an improvement of almost 10% on POWER8.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Currently tm_orig_msr is getting used during process context switch only.
Then there is ckpt_regs which saves the checkpointed userspace context
The MSR slot contained in ckpt_regs structure can be used during process
context switch instead of tm_orig_msr, thus allowing us to drop it from
thread_struct structure. This patch does that change.
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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This patch adds some in-code documentation to the DSCR related code to
make it more readable without having any functional change to it.
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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