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The vdso code for the getcpu() and the clock_gettime() call use the access
register mode to access the per-CPU vdso data page with the current code.
An alternative to the complicated AR mode is to use the secondary space
mode. This makes the vdso faster and quite a bit simpler. The downside is
that the uaccess code has to be changed quite a bit.
Which instructions are used depends on the machine and what kind of uaccess
operation is requested. The instruction dictates which ASCE value needs
to be loaded into %cr1 and %cr7.
The different cases:
* User copy with MVCOS for z10 and newer machines
The MVCOS instruction can copy between the primary space (aka user) and
the home space (aka kernel) directly. For set_fs(KERNEL_DS) the kernel
ASCE is loaded into %cr1. For set_fs(USER_DS) the user space is already
loaded in %cr1.
* User copy with MVCP/MVCS for older machines
To be able to execute the MVCP/MVCS instructions the kernel needs to
switch to primary mode. The control register %cr1 has to be set to the
kernel ASCE and %cr7 to either the kernel ASCE or the user ASCE dependent
on set_fs(KERNEL_DS) vs set_fs(USER_DS).
* Data access in the user address space for strnlen / futex
To use "normal" instruction with data from the user address space the
secondary space mode is used. The kernel needs to switch to primary mode,
%cr1 has to contain the kernel ASCE and %cr7 either the user ASCE or the
kernel ASCE, dependent on set_fs.
To load a new value into %cr1 or %cr7 is an expensive operation, the kernel
tries to be lazy about it. E.g. for multiple user copies in a row with
MVCP/MVCS the replacement of the vdso ASCE in %cr7 with the user ASCE is
done only once. On return to user space a CPU bit is checked that loads the
vdso ASCE again.
To enable and disable the data access via the secondary space two new
functions are added, enable_sacf_uaccess and disable_sacf_uaccess. The fact
that a context is in secondary space uaccess mode is stored in the
mm_segment_t value for the task. The code of an interrupt may use set_fs
as long as it returns to the previous state it got with get_fs with another
call to set_fs. The code in finish_arch_post_lock_switch simply has to do a
set_fs with the current mm_segment_t value for the task.
For CPUs with MVCOS:
CPU running in | %cr1 ASCE | %cr7 ASCE |
--------------------------------------|-----------|-----------|
user space | user | vdso |
kernel, USER_DS, normal-mode | user | vdso |
kernel, USER_DS, normal-mode, lazy | user | user |
kernel, USER_DS, sacf-mode | kernel | user |
kernel, KERNEL_DS, normal-mode | kernel | vdso |
kernel, KERNEL_DS, normal-mode, lazy | kernel | kernel |
kernel, KERNEL_DS, sacf-mode | kernel | kernel |
For CPUs without MVCOS:
CPU running in | %cr1 ASCE | %cr7 ASCE |
--------------------------------------|-----------|-----------|
user space | user | vdso |
kernel, USER_DS, normal-mode | user | vdso |
kernel, USER_DS, normal-mode lazy | kernel | user |
kernel, USER_DS, sacf-mode | kernel | user |
kernel, KERNEL_DS, normal-mode | kernel | vdso |
kernel, KERNEL_DS, normal-mode, lazy | kernel | kernel |
kernel, KERNEL_DS, sacf-mode | kernel | kernel |
The lines with "lazy" refer to the state after a copy via the secondary
space with a delayed reload of %cr1 and %cr7.
There are three hardware address spaces that can cause a DAT exception,
primary, secondary and home space. The exception can be related to
four different fault types: user space fault, vdso fault, kernel fault,
and the gmap faults.
Dependent on the set_fs state and normal vs. sacf mode there are a number
of fault combinations:
1) user address space fault via the primary ASCE
2) gmap address space fault via the primary ASCE
3) kernel address space fault via the primary ASCE for machines with
MVCOS and set_fs(KERNEL_DS)
4) vdso address space faults via the secondary ASCE with an invalid
address while running in secondary space in problem state
5) user address space fault via the secondary ASCE for user-copy
based on the secondary space mode, e.g. futex_ops or strnlen_user
6) kernel address space fault via the secondary ASCE for user-copy
with secondary space mode with set_fs(KERNEL_DS)
7) kernel address space fault via the primary ASCE for user-copy
with secondary space mode with set_fs(USER_DS) on machines without
MVCOS.
8) kernel address space fault via the home space ASCE
Replace user_space_fault() with a new function get_fault_type() that
can distinguish all four different fault types.
With these changes the futex atomic ops from the kernel and the
strnlen_user will get a little bit slower, as well as the old style
uaccess with MVCP/MVCS. All user accesses based on MVCOS will be as
fast as before. On the positive side, the user space vdso code is a
lot faster and Linux ceases to use the complicated AR mode.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
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The identification of guest fault currently relies on the PF_VCPU flag.
This is set in guest_entry_irqoff and cleared in guest_exit_irqoff.
Both functions are called by __vcpu_run, the PF_VCPU flag is set for
quite a lot of kernel code outside of the guest execution.
Replace the PF_VCPU scheme with the PIF_GUEST_FAULT in the pt_regs and
make the program check handler code in entry.S set the bit only for
exception that occurred between the .Lsie_gmap and .Lsie_done labels.
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Heiko Carstens:
"Since Martin is on vacation you get the s390 pull request for the
v4.15 merge window this time from me.
Besides a lot of cleanups and bug fixes these are the most important
changes:
- a new regset for runtime instrumentation registers
- hardware accelerated AES-GCM support for the aes_s390 module
- support for the new CEX6S crypto cards
- support for FORTIFY_SOURCE
- addition of missing z13 and new z14 instructions to the in-kernel
disassembler
- generate opcode tables for the in-kernel disassembler out of a
simple text file instead of having to manually maintain those
tables
- fast memset16, memset32 and memset64 implementations
- removal of named saved segment support
- hardware counter support for z14
- queued spinlocks and queued rwlocks implementations for s390
- use the stack_depth tracking feature for s390 BPF JIT
- a new s390_sthyi system call which emulates the sthyi (store
hypervisor information) instruction
- removal of the old KVM virtio transport
- an s390 specific CPU alternatives implementation which is used in
the new spinlock code"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (88 commits)
MAINTAINERS: add virtio-ccw.h to virtio/s390 section
s390/noexec: execute kexec datamover without DAT
s390: fix transactional execution control register handling
s390/bpf: take advantage of stack_depth tracking
s390: simplify transactional execution elf hwcap handling
s390/zcrypt: Rework struct ap_qact_ap_info.
s390/virtio: remove unused header file kvm_virtio.h
s390: avoid undefined behaviour
s390/disassembler: generate opcode tables from text file
s390/disassembler: remove insn_to_mnemonic()
s390/dasd: avoid calling do_gettimeofday()
s390: vfio-ccw: Do not attempt to free no-op, test and tic cda.
s390: remove named saved segment support
s390/archrandom: Reconsider s390 arch random implementation
s390/pci: do not require AIS facility
s390/qdio: sanitize put_indicator
s390/qdio: use atomic_cmpxchg
s390/nmi: avoid using long-displacement facility
s390: pass endianness info to sparse
s390/decompressor: remove informational messages
...
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull initial SPDX identifiers from Greg KH:
"License cleanup: add SPDX license identifiers to some files
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the
'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally
binding shorthand, which can be used instead of the full boiler plate
text.
This patch is based on work done by Thomas Gleixner and Kate Stewart
and Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset
of the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to
license had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied
to a file was done in a spreadsheet of side by side results from of
the output of two independent scanners (ScanCode & Windriver)
producing SPDX tag:value files created by Philippe Ombredanne.
Philippe prepared the base worksheet, and did an initial spot review
of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537
files assessed. Kate Stewart did a file by file comparison of the
scanner results in the spreadsheet to determine which SPDX license
identifier(s) to be applied to the file. She confirmed any
determination that was not immediately clear with lawyers working with
the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained
>5 lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that
was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that
became the concluded license(s).
- when there was disagreement between the two scanners (one detected
a license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply
(and which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases,
confirmation by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.
The Windriver scanner is based on an older version of FOSSology in
part, so they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot
checks in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect
the correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial
patch version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch
license was not GPL-2.0 WITH Linux-syscall-note to ensure that the
applied SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>"
* tag 'spdx_identifiers-4.14-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
License cleanup: add SPDX license identifier to uapi header files with a license
License cleanup: add SPDX license identifier to uapi header files with no license
License cleanup: add SPDX GPL-2.0 license identifier to files with no license
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__LC_MCESAD is currently 4528 /* offsetof(struct lowcore, mcesad) */
that would require long-displacement facility for lg, which we don't
have on z900.
Fixes: 3037a52f9846 ("s390/nmi: do register validation as early as possible")
Signed-off-by: Vasily Gorbik <gor@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The new detection code for guest machine checks added a check based
on %r11 to .Lcleanup_sie to distinguish between normal asynchronous
interrupts and machine checks. But the funtion is called from the
program check handler as well with an undefined value in %r11.
The effect is that all program exceptions pointing to the SIE instruction
will set the CIF_MCCK_GUEST bit. The bit stays set for the CPU until the
next machine check comes in which will incorrectly be interpreted as a
guest machine check.
The simplest fix is to stop using .Lcleanup_sie in the program check
handler and duplicate a few instructions.
Fixes: c929500d7a5a ("s390/nmi: s390: New low level handling for machine check happening in guest")
Cc: <stable@vger.kernel.org> # v4.13+
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The validation of the CPU registers in the machine check handler is
currently split into two parts. The first part is done at the start
of the low level mcck_int_handler function, this includes the CPU
timer register and the general purpose registers.
The second part is done a bit later in s390_do_machine_check for all
the other registers, including the control registers, floating pointer
control, vector or floating pointer registers, the access registers,
the guarded storage registers, the TOD programmable registers and the
clock comparator.
This is working fine to far but in theory a future extensions could
cause the C code to use registers that are not validated yet. A better
approach is to validate all CPU registers in "safe" assembler code
before any C function is called.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into features
Pull kvm patches from Christian Borntraeger:
"s390,kvm: provide plumbing for machines checks when running guests"
This provides the basic plumbing for handling machine checks when
running guests
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Add the logic to check if the machine check happens when the guest is
running. If yes, set the exit reason -EINTR in the machine check's
interrupt handler. Refactor s390_do_machine_check to avoid panicing
the host for some kinds of machine checks which happen
when guest is running.
Reinject the instruction processing damage's machine checks including
Delayed Access Exception instead of damaging the host if it happens
in the guest because it could be caused by improper update on TLB entry
or other software case and impacts the guest only.
Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
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The save_fpu_regs function is a general API that is supposed to be
usable for modules as well. Remove the #ifdef that hides the symbol
for CONFIG_KVM=n.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The system control vm.alloc_pgste is used to control the size of the
page tables, either 2K or 4K. The idea is that a KVM host sets the
vm.alloc_pgste control to 1 which causes *all* new processes to run
with 4K page tables. For a non-kvm system the control should stay off
to save on memory used for page tables.
Trouble is that distributions choose to set the control globally to
be able to run KVM guests. This wastes memory on non-KVM systems.
Introduce the PT_S390_PGSTE ELF segment type to "mark" the qemu
executable with it. All executables with this (empty) segment in
its ELF phdr array will be started with 4K page tables. Any executable
without PT_S390_PGSTE will run with the default 2K page tables.
This removes the need to set vm.alloc_pgste=1 for a KVM host and
minimizes the waste of memory for page tables.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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For most cases a protection exception in the host (e.g. copy
on write or dirty tracking) on the sie instruction will indicate
an instruction length of 4. Turns out that there are some corner
cases (e.g. runtime instrumentation) where this is not necessarily
true and the ILC is unpredictable.
Let's replace our 4 byte rewind_pad with 3 byte nops to prepare for
all possible ILCs.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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git commit c5328901aa1db134 "[S390] entry[64].S improvements" removed
the update of the exit_timer lowcore field from the critical section
cleanup of the .Lsysc_restore/.Lsysc_done and .Lio_restore/.Lio_done
blocks. If the PSW is updated by the critical section cleanup to point to
user space again, the interrupt entry code will do a vtime calculation
after the cleanup completed with an exit_timer value which has *not* been
updated. Due to this incorrect system time deltas are calculated.
If an interrupt occured with an old PSW between .Lsysc_restore/.Lsysc_done
or .Lio_restore/.Lio_done update __LC_EXIT_TIMER with the system entry
time of the interrupt.
Cc: stable@vger.kernel.org # 3.3+
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching
Pull livepatch updates from Jiri Kosina:
- a per-task consistency model is being added for architectures that
support reliable stack dumping (extending this, currently rather
trivial set, is currently in the works).
This extends the nature of the types of patches that can be applied
by live patching infrastructure. The code stems from the design
proposal made [1] back in November 2014. It's a hybrid of SUSE's
kGraft and RH's kpatch, combining advantages of both: it uses
kGraft's per-task consistency and syscall barrier switching combined
with kpatch's stack trace switching. There are also a number of
fallback options which make it quite flexible.
Most of the heavy lifting done by Josh Poimboeuf with help from
Miroslav Benes and Petr Mladek
[1] https://lkml.kernel.org/r/20141107140458.GA21774@suse.cz
- module load time patch optimization from Zhou Chengming
- a few assorted small fixes
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching:
livepatch: add missing printk newlines
livepatch: Cancel transition a safe way for immediate patches
livepatch: Reduce the time of finding module symbols
livepatch: make klp_mutex proper part of API
livepatch: allow removal of a disabled patch
livepatch: add /proc/<pid>/patch_state
livepatch: change to a per-task consistency model
livepatch: store function sizes
livepatch: use kstrtobool() in enabled_store()
livepatch: move patching functions into patch.c
livepatch: remove unnecessary object loaded check
livepatch: separate enabled and patched states
livepatch/s390: add TIF_PATCH_PENDING thread flag
livepatch/s390: reorganize TIF thread flag bits
livepatch/powerpc: add TIF_PATCH_PENDING thread flag
livepatch/x86: add TIF_PATCH_PENDING thread flag
livepatch: create temporary klp_update_patch_state() stub
x86/entry: define _TIF_ALLWORK_MASK flags explicitly
stacktrace/x86: add function for detecting reliable stack traces
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There are three different code levels in regard to the identification
of guest samples. They differ in the way the LPP instruction is used.
1) Old kernels without the LPP instruction. The guest program parameter
is always zero.
2) Newer kernels load the process pid into the program parameter with LPP.
The guest program parameter is non-zero if the guest executes in a
process != idle.
3) The latest kernels load ((1UL << 31) | pid) with LPP to make the value
non-zero even for the idle task. The guest program parameter is non-zero
if the guest is running.
All kernels load the process pid to CR4 on context switch. The CPU sampling
code uses the value in CR4 to decide between guest and host samples in case
the guest program parameter is zero. The three cases:
1) CR4==pid, gpp==0
2) CR4==pid, gpp==pid
3) CR4==pid, gpp==((1UL << 31) | pid)
The load-control instruction to load the pid into CR4 is expensive and the
goal is to remove it. To distinguish the host CR4 from the guest pid for
the idle process the maximum value 0xffff for the PASN is used.
This adds a fourth case for a guest OS with an updated kernel:
4) CR4==0xffff, gpp=((1UL << 31) | pid)
The host kernel will have CR4==0xffff and will use (gpp!=0 || CR4!==0xffff)
to identify guest samples. This works nicely with all 4 cases, the only
possible issue would be a guest with an old kernel (gpp==0) and a process
pid of 0xffff. Well, don't do that..
Suggested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The 32-bit lctl instruction is quite a bit slower than the 64-bit
counter part lctlg. Use the faster instruction.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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This adds a new system call to enable the use of guarded storage for
user space processes. The system call takes two arguments, a command
and pointer to a guarded storage control block:
s390_guarded_storage(int command, struct gs_cb *gs_cb);
The second argument is relevant only for the GS_SET_BC_CB command.
The commands in detail:
0 - GS_ENABLE
Enable the guarded storage facility for the current task. The
initial content of the guarded storage control block will be
all zeros. After the enablement the user space code can use
load-guarded-storage-controls instruction (LGSC) to load an
arbitrary control block. While a task is enabled the kernel
will save and restore the current content of the guarded
storage registers on context switch.
1 - GS_DISABLE
Disables the use of the guarded storage facility for the current
task. The kernel will cease to save and restore the content of
the guarded storage registers, the task specific content of
these registers is lost.
2 - GS_SET_BC_CB
Set a broadcast guarded storage control block. This is called
per thread and stores a specific guarded storage control block
in the task struct of the current task. This control block will
be used for the broadcast event GS_BROADCAST.
3 - GS_CLEAR_BC_CB
Clears the broadcast guarded storage control block. The guarded-
storage control block is removed from the task struct that was
established by GS_SET_BC_CB.
4 - GS_BROADCAST
Sends a broadcast to all thread siblings of the current task.
Every sibling that has established a broadcast guarded storage
control block will load this control block and will be enabled
for guarded storage. The broadcast guarded storage control block
is used up, a second broadcast without a refresh of the stored
control block with GS_SET_BC_CB will not have any effect.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Update a task's patch state when returning from a system call or user
space interrupt, or after handling a signal.
This greatly increases the chances of a patch operation succeeding. If
a task is I/O bound, it can be patched when returning from a system
call. If a task is CPU bound, it can be patched when returning from an
interrupt. If a task is sleeping on a to-be-patched function, the user
can send SIGSTOP and SIGCONT to force it to switch.
Since there are two ways the syscall can be restarted on return from a
signal handling process, it is important to clear the flag before
do_signal() is called. Otherwise we could miss the migration if we used
SIGSTOP/SIGCONT procedure or fake signal to migrate patching blocking
tasks. If we place our hook to sysc_work label in entry before
TIF_SIGPENDING is evaluated we kill two birds with one stone. The task
is correctly migrated in all return paths from a syscall.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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A program check inside the kernel takes a slightly different path in
entry.S compare to a normal user fault. A recent change moved the store
of the breaking event address into the path taken for in-kernel program
checks as well, but %r14 has not been setup to point to the correct
location. A wild store is the consequence.
Move the store of the breaking event address to the code path for
user space faults.
Fixes: 34525e1f7e8d ("s390: store breaking event address only for program checks")
Reported-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Unbalanced set_fs usages (e.g. early exit from a function and a
forgotten set_fs(USER_DS) call) may lead to a situation where the
secondary asce is the kernel space asce when returning to user
space. This would allow user space to modify kernel space at will.
This would only be possible with the above mentioned kernel bug,
however we can detect this and fix the secondary asce before returning
to user space.
Therefore a new TIF_ASCE_SECONDARY which is used within set_fs. When
returning to user space check if TIF_ASCE_SECONDARY is set, which
would indicate a bug. If it is set print a message to the console,
fixup the secondary asce, and then return to user space.
This is similar to what is being discussed for x86 and arm:
"[RFC] syscalls: Restore address limit after a syscall".
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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This is just a preparation patch in order to keep the "restore address
space after syscall" patch small.
Rename CIF_ASCE to CIF_ASCE_PRIMARY to be unique and specific when
introducing a second CIF_ASCE_SECONDARY CIF flag.
Suggested-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Fix PER tracing of system calls after git commit 34525e1f7e8dc478
"s390: store breaking event address only for program checks"
broke it.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Bit 0x100 of a page table, segment table of region table entry
can be used to disallow code execution for the virtual addresses
associated with the entry.
There is one tricky bit, the system call to return from a signal
is part of the signal frame written to the user stack. With a
non-executable stack this would stop working. To avoid breaking
things the protection fault handler checks the opcode that caused
the fault for 0x0a77 (sys_sigreturn) and 0x0aad (sys_rt_sigreturn)
and injects a system call. This is preferable to the alternative
solution with a stub function in the vdso because it works for
vdso=off and statically linked binaries as well.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The principles of operations specifies that the breaking event address
is stored to the address 0x110 in the prefix page only for program checks.
The last branch in user space is lost as soon as a branch in kernel space
is executed after e.g. an svc. This makes it impossible to accurately
maintain the breaking event address for a user space process.
Simplify the code, just copy the current breaking event address from
0x110 to the task structure for program checks from user space.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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For system damage machine checks or machine checks due to invalid PSW
fields the system will be stopped. In order to get an oops message out
before killing the system the machine check handler branches to
.Lmcck_panic, switches to the panic stack and then does the usual
machine check handling.
The switch to the panic stack is incomplete, the stack pointer in %r15
is replaced, but the pt_regs pointer in %r11 is not. The result is
a program check which will kill the system in a slightly different way.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The LAST_BREAK macro in entry.S uses a different instruction sequence
for CONFIG_MARCH_Z900 builds. The branch target offset to skip the
store of the last breaking event address needs to take the different
length of the code block into account.
Fixes: f8fc82b47149e344 ("s390: move sys_call_table and last_break from thread_info to thread_struct")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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We have the s390 specific THREAD_ORDER define and the THREAD_SIZE_ORDER
define which is also used in common code. Both have exactly the same
semantics. Therefore get rid of THREAD_ORDER and always use
THREAD_SIZE_ORDER instead.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Move the last two architecture specific fields from the thread_info
structure to the thread_struct. All that is left in thread_info is
the flags field.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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This is the s390 variant of commit 15f4eae70d36 ("x86: Move
thread_info into task_struct").
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Convert s390 to use a field in the struct lowcore for the CPU
preemption count. It is a bit cheaper to access a lowcore field
compared to a thread_info variable and it removes the depencency
on a task related structure.
bloat-o-meter on the vmlinux image for the default configuration
(CONFIG_PREEMPT_NONE=y) reports a small reduction in text size:
add/remove: 0/0 grow/shrink: 18/578 up/down: 228/-5448 (-5220)
A larger improvement is achieved with the default configuration
but with CONFIG_PREEMPT=y and CONFIG_DEBUG_PREEMPT=n:
add/remove: 2/6 grow/shrink: 59/4477 up/down: 1618/-228762 (-227144)
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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After linking there are several symbols for the same address that the
__switch_to symbol points to. E.g.:
000000000089b9c0 T __kprobes_text_start
000000000089b9c0 T __lock_text_end
000000000089b9c0 T __lock_text_start
000000000089b9c0 T __sched_text_end
000000000089b9c0 T __switch_to
When disassembling with "objdump -d" this results in a missing
__switch_to function. It would be named __kprobes_text_start
instead. To unconfuse objdump add a nop in front of the kprobes text
section. That way __switch_to appears again.
Obviously this solution is sort of a hack, since it also depends on
link order if this works or not. However it is the best I can come up
with for now.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Remove a leftover from the code that transferred a couple of TIF bits
from the previous task to the next task.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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There is a tricky interaction between the machine check handler
and the critical sections of load_fpu_regs and save_fpu_regs
functions. If the machine check interrupts one of the two
functions the critical section cleanup will complete the function
before the machine check handler s390_do_machine_check is called.
Trouble is that the machine check handler needs to validate the
floating point registers *before* and not *after* the completion
of load_fpu_regs/save_fpu_regs.
The simplest solution is to rewind the PSW to the start of the
load_fpu_regs/save_fpu_regs and retry the function after the
return from the machine check handler.
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: <stable@vger.kernel.org> # 4.3+
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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commit e22cf8ca6f75 ("s390/cpumf: rework program parameter setting
to detect guest samples") requires guest changes to get proper
guest/host. We can do better: We can use the primary asn value,
which is set on all Linux variants to compare this with the host
pp value.
We now have the following cases:
1. Guest using PP
host sample: gpp == 0, asn == hpp --> host
guest sample: gpp != 0 --> guest
2. Guest not using PP
host sample: gpp == 0, asn == hpp --> host
guest sample: gpp == 0, asn != hpp --> guest
As soon as the host no longer sets CR4, we must back out
this heuristics - let's add a comment in switch_to.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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It does not make sense to try to relinquish the time slice with diag 0x9c
to a CPU in a state that does not allow to schedule the CPU. The scenario
where this can happen is a CPU waiting in udelay/mdelay while holding a
spin-lock.
Add a CIF bit to tag a CPU in enabled wait and use it to detect that the
yield of a CPU will not be successful and skip the diagnose call.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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When using systemtap it was observed that our udelay implementation is
rather suboptimal if being called from a kprobe handler installed by
systemtap.
The problem observed when a kprobe was installed on lock_acquired().
When the probe was hit the kprobe handler did call udelay, which set
up an (internal) timer and reenabled interrupts (only the clock comparator
interrupt) and waited for the interrupt.
This is an optimization to avoid that the cpu is busy looping while waiting
that enough time passes. The problem is that the interrupt handler still
does call irq_enter()/irq_exit() which then again can lead to a deadlock,
since some accounting functions may take locks as well.
If one of these locks is the same, which caused lock_acquired() to be
called, we have a nice deadlock.
This patch reworks the udelay code for the interrupts disabled case to
immediately leave the low level interrupt handler when the clock
comparator interrupt happens. That way no C code is being called and the
deadlock cannot happen anymore.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The program parameter can be used to mark hardware samples with
some token. Previously, it was used to mark guest samples only.
Improve the program parameter doubleword by combining two parts,
the leftmost LPP part and the rightmost PID part. Set the PID
part for processes by using the task PID.
To distinguish host and guest samples for the kernel (PID part
is zero), the guest must always set the program paramater to a
non-zero value. Use the leftmost bit in the LPP part of the
program parameter to be able to detect guest kernel samples.
[brueckner@linux.vnet.ibm.com]: Split __LC_CURRENT and introduced
__LC_LPP. Corrected __LC_CURRENT users and adjusted assembler parts.
And updated the commit message accordingly.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Various functions in entry.S perform test-under-mask instructions
to test for particular bits in memory. Because test-under-mask uses
a mask value of one byte, the mask value and the offset into the
memory must be calculated manually. This easily introduces errors
and is hard to review and read.
Introduce the TSTMSK assembler macro to specify a mask constant and
let the macro calculate the offset and the byte mask to generate a
test-under-mask instruction. The benefit is that existing symbolic
constants can now be used for tests. Also the macro checks for
zero mask values and mask values that consist of multiple bytes.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Previously, the init task did not have an allocated FPU save area and
saving an FPU state was not possible. Now if the vector extension is
always enabled, provide a static FPU save area to save FPU states of
vector instructions that can be executed quite early.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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If the kernel detects that the s390 hardware supports the vector
facility, it is enabled by default at an early stage. To force
it off, use the novx kernel parameter. Note that there is a small
time window, where the vector facility is enabled before it is
forced to be off.
With enabling the vector facility by default, the FPU save and
restore functions can be improved. They do not longer require
to manage expensive control register updates to enable or disable
the vector enablement control for particular processes.
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The calculation for the SMT scaling factor for a hardware thread
which has been partially idle needs to disregard the cycles spent
by the other threads of the core while the thread is idle.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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The critical section cleanup code misses to add the offset of the
thread_struct to the task address.
Therefore, if the critical section code gets executed, it may corrupt
the task struct or restore the contents of the floating point registers
from the wrong memory location.
Fixes d0164ee20d "s390/kernel: remove save_fpu_regs() parameter and use
__LC_CURRENT instead".
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Right now we use the address of the sie control block as tag for
the sampling data. This is hard to get for users. Let's just use
the PID of the cpu thread to mark the hardware samples.
Reviewed-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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All calls to save_fpu_regs() specify the fpu structure of the current task
pointer as parameter. The task pointer of the current task can also be
retrieved from the CPU lowcore directly. Remove the parameter definition,
load the __LC_CURRENT task pointer from the CPU lowcore, and rebase the FPU
structure onto the task structure. Apply the same approach for the
load_fpu_regs() function.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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If a machine checks is received while the CPU is in the kernel, only
the s390_do_machine_check function will be called. The call to
s390_handle_mcck is postponed until the CPU returns to user space.
Because of this it is safe to use the asynchronous stack for machine
checks even if the CPU is already handling an interrupt.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Reorder the instructions of UPDATE_VTIME to improve superscalar execution,
remove duplicate checks for problem-state from the asynchronous interrupt
handlers, and move the check for problem-state from the synchronous
exit path to the program check path as it is only needed for program
checks inside the kernel.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Currently there are two mechanisms to deal with cleanup work due to
interrupts. The HANDLE_SIE_INTERCEPT macro is used to undo the changes
required to enter SIE in sie64a. If the SIE instruction causes a program
check, or an asynchronous interrupt is received the HANDLE_SIE_INTERCEPT
code forwards the program execution to sie_exit.
All the other critical sections in entry.S are handled by the code in
cleanup_critical that is called by the SWITCH_ASYNC macro.
Move the sie64a function to the beginning of the critical section and
add the code from HANDLE_SIE_INTERCEPT to cleanup_critical. Add a special
case for the sie64a cleanup to the program check handler.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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