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A typical backtrace acquired from ftraced function currently looks like
the following (e.g. for "path_openat"):
arch_stack_walk+0x15c/0x2d8
stack_trace_save+0x50/0x68
stack_trace_call+0x15a/0x3b8
ftrace_graph_caller+0x0/0x1c
0x3e0007e3c98 <- ftraced function caller (should be do_filp_open+0x7c/0xe8)
do_open_execat+0x70/0x1b8
__do_execve_file.isra.0+0x7d8/0x860
__s390x_sys_execve+0x56/0x68
system_call+0xdc/0x2d8
Note random "0x3e0007e3c98" stack value as ftraced function caller. This
value causes either imprecise unwinder result or unwinding failure.
That "0x3e0007e3c98" comes from r14 of ftraced function stack frame, which
it haven't had a chance to initialize since the very first instruction
calls ftrace code ("ftrace_caller"). (ftraced function might never
save r14 as well). Nevertheless according to s390 ABI any function
is called with stack frame allocated for it and r14 contains return
address. "ftrace_caller" itself is called with "brasl %r0,ftrace_caller".
So, to fix this issue simply always save traced function caller onto
ftraced function stack frame.
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Consider reaching user mode pt_regs at the bottom of irq stack graceful
unwinder termination. This is the case when irq/mcck/ext interrupt arrives
while in user mode.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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the purgatory must not rely on functions from the "old" kernel,
so we must disable kasan and friends. We also need to have a
separate copy of string.c as the default does not build memcmp
with KASAN.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Since we link purgatory with -r aka we enable "incremental linking"
no checks for unresolved symbols are done while linking the purgatory.
This commit adds an extra check for unresolved symbols by calling ld
without -r before running objcopy to generate purgatory.ro.
This will help us catch missing symbols in the purgatory sooner.
Note this commit also removes --no-undefined from LDFLAGS_purgatory
as that has no effect.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/lkml/20191212205304.191610-1-hdegoede@redhat.com
Tested-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The following sequence triggers a kernel stack overflow on s390x:
mount -t tracefs tracefs /sys/kernel/tracing
cd /sys/kernel/tracing
echo function_graph > current_tracer
[crash]
This is because preempt_count_{add,sub} are in the list of traced
functions, which can be demonstrated by:
echo preempt_count_add >set_ftrace_filter
echo function_graph > current_tracer
[crash]
The stack overflow happens because get_tod_clock_monotonic() gets called
by ftrace but itself calls preempt_{disable,enable}(), which leads to a
endless recursion. Fix this by using preempt_{disable,enable}_notrace().
Fixes: 011620688a71 ("s390/time: ensure get_clock_monotonic() returns monotonic values")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Add KASAN_VMALLOC support which now enables vmalloc memory area access
checks as well as enables usage of VMAP_STACK under kasan.
KASAN_VMALLOC changes the way vmalloc and modules areas shadow memory
is handled. With this new approach only top level page tables are
pre-populated and lower levels are filled dynamically upon memory
allocation.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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diag 0x44 is a voluntary undirected yield of a virtual CPU. This has
caused a lot of performance issues in the past.
There is only one caller left, and that one is only executed if diag
0x9c (directed yield) is not present. Given that all hypervisors
implement diag 0x9c anyway, remove the last diag 0x44 to avoid that
more callers will be added.
Worst case that could happen now, if diag 0x9c is not present, is that
a virtual CPU would loop a bit instead of giving its time slice up.
diag 0x44 statistics in debugfs are kept and will always be zero, so
that user space can tell that there are no calls.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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ENOTSUP is just an internal kernel error and should never reach
userspace. The return value of the share function is not exported to
userspace, but to avoid giving bad examples let us use EOPNOTSUPP:
Suggested-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The s390 CPU Measurement sampling facility has an overflow condition
which fires when all entries in a SBD are used.
The measurement alert interrupt is triggered and reads out all samples
in this SDB. It then tests the successor SDB, if this SBD is not full,
the interrupt handler does not read any samples at all from this SDB
The design waits for the hardware to fill this SBD and then trigger
another meassurement alert interrupt.
This scheme works nicely until
an perf_event_overflow() function call discards the sample due to
a too high sampling rate.
The interrupt handler has logic to read out a partially filled SDB
when the perf event overflow condition in linux common code is met.
This causes the CPUM sampling measurement hardware and the PMU
device driver to operate on the same SBD's trailer entry.
This should not happen.
This can be seen here using this trace:
cpumsf_pmu_add: tear:0xb5286000
hw_perf_event_update: sdbt 0xb5286000 full 1 over 0 flush_all:0
hw_perf_event_update: sdbt 0xb5286008 full 0 over 0 flush_all:0
above shows 1. interrupt
hw_perf_event_update: sdbt 0xb5286008 full 1 over 0 flush_all:0
hw_perf_event_update: sdbt 0xb5286008 full 0 over 0 flush_all:0
above shows 2. interrupt
... this goes on fine until...
hw_perf_event_update: sdbt 0xb5286068 full 1 over 0 flush_all:0
perf_push_sample1: overflow
one or more samples read from the IRQ handler are rejected by
perf_event_overflow() and the IRQ handler advances to the next SDB
and modifies the trailer entry of a partially filled SDB.
hw_perf_event_update: sdbt 0xb5286070 full 0 over 0 flush_all:1
timestamp: 14:32:52.519953
Next time the IRQ handler is called for this SDB the trailer entry shows
an overflow count of 19 missed entries.
hw_perf_event_update: sdbt 0xb5286070 full 1 over 19 flush_all:1
timestamp: 14:32:52.970058
Remove access to a follow on SDB when event overflow happened.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Function perf_event_ever_overflow() and perf_event_account_interrupt()
are called every time samples are processed by the interrupt handler.
However function perf_event_account_interrupt() has checks to avoid being
flooded with interrupts (more then 1000 samples are received per
task_tick). Samples are then dropped and a PERF_RECORD_THROTTLED is
added to the perf data. The perf subsystem limit calculation is:
maximum sample frequency := 100000 --> 1 samples per 10 us
task_tick = 10ms = 10000us --> 1000 samples per task_tick
The work flow is
measurement_alert() uses SDBT head and each SBDT points to 511
SDB pages, each with 126 sample entries. After processing 8 SBDs
and for each valid sample calling:
perf_event_overflow()
perf_event_account_interrupts()
there is a considerable amount of samples being dropped, especially when
the sample frequency is very high and near the 100000 limit.
To avoid the high amount of samples being dropped near the end of a
task_tick time frame, increment the sampling interval in case of
dropped events. The CPU Measurement sampling facility on the s390
supports only intervals, specifiing how many CPU cycles have to be
executed before a sample is generated. Increase the interval when the
samples being generated hit the task_tick limit.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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There is a spelling mistake in a pr_info message. Fix it.
Link: https://lkml.kernel.org/r/20191202090215.28766-1-colin.king@canonical.com
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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arch_spin_lock_wait does not take steal time into consideration.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull more powerpc updates from Michael Ellerman:
"A few commits splitting the KASAN instrumented bitops header in three,
to match the split of the asm-generic bitops headers.
This is needed on powerpc because we use the generic bitops for the
non-atomic case only, whereas the existing KASAN instrumented bitops
assume all the underlying operations are provided by the arch as
arch_foo() versions.
Thanks to: Daniel Axtens & Christophe Leroy"
* tag 'powerpc-5.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
docs/core-api: Remove possibly confusing sub-headings from Bit Operations
powerpc: support KASAN instrumentation of bitops
kasan: support instrumented bitops combined with generic bitops
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Userspace cannot compile <asm/ipcbuf.h> due to some missing type
definitions. For example, building it for x86 fails as follows:
CC usr/include/asm/ipcbuf.h.s
In file included from usr/include/asm/ipcbuf.h:1:0,
from <command-line>:32:
usr/include/asm-generic/ipcbuf.h:21:2: error: unknown type name `__kernel_key_t'
__kernel_key_t key;
^~~~~~~~~~~~~~
usr/include/asm-generic/ipcbuf.h:22:2: error: unknown type name `__kernel_uid32_t'
__kernel_uid32_t uid;
^~~~~~~~~~~~~~~~
usr/include/asm-generic/ipcbuf.h:23:2: error: unknown type name `__kernel_gid32_t'
__kernel_gid32_t gid;
^~~~~~~~~~~~~~~~
usr/include/asm-generic/ipcbuf.h:24:2: error: unknown type name `__kernel_uid32_t'
__kernel_uid32_t cuid;
^~~~~~~~~~~~~~~~
usr/include/asm-generic/ipcbuf.h:25:2: error: unknown type name `__kernel_gid32_t'
__kernel_gid32_t cgid;
^~~~~~~~~~~~~~~~
usr/include/asm-generic/ipcbuf.h:26:2: error: unknown type name `__kernel_mode_t'
__kernel_mode_t mode;
^~~~~~~~~~~~~~~
usr/include/asm-generic/ipcbuf.h:28:35: error: `__kernel_mode_t' undeclared here (not in a function)
unsigned char __pad1[4 - sizeof(__kernel_mode_t)];
^~~~~~~~~~~~~~~
usr/include/asm-generic/ipcbuf.h:31:2: error: unknown type name `__kernel_ulong_t'
__kernel_ulong_t __unused1;
^~~~~~~~~~~~~~~~
usr/include/asm-generic/ipcbuf.h:32:2: error: unknown type name `__kernel_ulong_t'
__kernel_ulong_t __unused2;
^~~~~~~~~~~~~~~~
It is just a matter of missing include directive.
Include <linux/posix_types.h> to make it self-contained, and add it to
the compile-test coverage.
Link: http://lkml.kernel.org/r/20191030063855.9989-1-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci
Pull PCI updates from Bjorn Helgaas:
"Enumeration:
- Warn if a host bridge has no NUMA info (Yunsheng Lin)
- Add PCI_STD_NUM_BARS for the number of standard BARs (Denis
Efremov)
Resource management:
- Fix boot-time Embedded Controller GPE storm caused by incorrect
resource assignment after ACPI Bus Check Notification (Mika
Westerberg)
- Protect pci_reassign_bridge_resources() against concurrent
addition/removal (Benjamin Herrenschmidt)
- Fix bridge dma_ranges resource list cleanup (Rob Herring)
- Add "pci=hpmmiosize" and "pci=hpmmioprefsize" parameters to control
the MMIO and prefetchable MMIO window sizes of hotplug bridges
independently (Nicholas Johnson)
- Fix MMIO/MMIO_PREF window assignment that assigned more space than
desired (Nicholas Johnson)
- Only enforce bus numbers from bridge EA if the bridge has EA
devices downstream (Subbaraya Sundeep)
- Consolidate DT "dma-ranges" parsing and convert all host drivers to
use shared parsing (Rob Herring)
Error reporting:
- Restore AER capability after resume (Mayurkumar Patel)
- Add PoisonTLPBlocked AER counter (Rajat Jain)
- Use for_each_set_bit() to simplify AER code (Andy Shevchenko)
- Fix AER kernel-doc (Andy Shevchenko)
- Add "pcie_ports=dpc-native" parameter to allow native use of DPC
even if platform didn't grant control over AER (Olof Johansson)
Hotplug:
- Avoid returning prematurely from sysfs requests to enable or
disable a PCIe hotplug slot (Lukas Wunner)
- Don't disable interrupts twice when suspending hotplug ports (Mika
Westerberg)
- Fix deadlocks when PCIe ports are hot-removed while suspended (Mika
Westerberg)
Power management:
- Remove unnecessary ASPM locking (Bjorn Helgaas)
- Add support for disabling L1 PM Substates (Heiner Kallweit)
- Allow re-enabling Clock PM after it has been disabled (Heiner
Kallweit)
- Add sysfs attributes for controlling ASPM link states (Heiner
Kallweit)
- Remove CONFIG_PCIEASPM_DEBUG, including "link_state" and "clk_ctl"
sysfs files (Heiner Kallweit)
- Avoid AMD FCH XHCI USB PME# from D0 defect that prevents wakeup on
USB 2.0 or 1.1 connect events (Kai-Heng Feng)
- Move power state check out of pci_msi_supported() (Bjorn Helgaas)
- Fix incorrect MSI-X masking on resume and revert related nvme quirk
for Kingston NVME SSD running FW E8FK11.T (Jian-Hong Pan)
- Always return devices to D0 when thawing to fix hibernation with
drivers like mlx4 that used legacy power management (previously we
only did it for drivers with new power management ops) (Dexuan Cui)
- Clear PCIe PME Status even for legacy power management (Bjorn
Helgaas)
- Fix PCI PM documentation errors (Bjorn Helgaas)
- Use dev_printk() for more power management messages (Bjorn Helgaas)
- Apply D2 delay as milliseconds, not microseconds (Bjorn Helgaas)
- Convert xen-platform from legacy to generic power management (Bjorn
Helgaas)
- Removed unused .resume_early() and .suspend_late() legacy power
management hooks (Bjorn Helgaas)
- Rearrange power management code for clarity (Rafael J. Wysocki)
- Decode power states more clearly ("4" or "D4" really refers to
"D3cold") (Bjorn Helgaas)
- Notice when reading PM Control register returns an error (~0)
instead of interpreting it as being in D3hot (Bjorn Helgaas)
- Add missing link delays required by the PCIe spec (Mika Westerberg)
Virtualization:
- Move pci_prg_resp_pasid_required() to CONFIG_PCI_PRI (Bjorn
Helgaas)
- Allow VFs to use PRI (the PF PRI is shared by the VFs, but the code
previously didn't recognize that) (Kuppuswamy Sathyanarayanan)
- Allow VFs to use PASID (the PF PASID capability is shared by the
VFs, but the code previously didn't recognize that) (Kuppuswamy
Sathyanarayanan)
- Disconnect PF and VF ATS enablement, since ATS in PFs and
associated VFs can be enabled independently (Kuppuswamy
Sathyanarayanan)
- Cache PRI and PASID capability offsets (Kuppuswamy Sathyanarayanan)
- Cache the PRI PRG Response PASID Required bit (Bjorn Helgaas)
- Consolidate ATS declarations in linux/pci-ats.h (Krzysztof
Wilczynski)
- Remove unused PRI and PASID stubs (Bjorn Helgaas)
- Removed unnecessary EXPORT_SYMBOL_GPL() from ATS, PRI, and PASID
interfaces that are only used by built-in IOMMU drivers (Bjorn
Helgaas)
- Hide PRI and PASID state restoration functions used only inside the
PCI core (Bjorn Helgaas)
- Add a DMA alias quirk for the Intel VCA NTB (Slawomir Pawlowski)
- Serialize sysfs sriov_numvfs reads vs writes (Pierre Crégut)
- Update Cavium ACS quirk for ThunderX2 and ThunderX3 (George
Cherian)
- Fix the UPDCR register address in the Intel ACS quirk (Steffen
Liebergeld)
- Unify ACS quirk implementations (Bjorn Helgaas)
Amlogic Meson host bridge driver:
- Fix meson PERST# GPIO polarity problem (Remi Pommarel)
- Add DT bindings for Amlogic Meson G12A (Neil Armstrong)
- Fix meson clock names to match DT bindings (Neil Armstrong)
- Add meson support for Amlogic G12A SoC with separate shared PHY
(Neil Armstrong)
- Add meson extended PCIe PHY functions for Amlogic G12A USB3+PCIe
combo PHY (Neil Armstrong)
- Add arm64 DT for Amlogic G12A PCIe controller node (Neil Armstrong)
- Add commented-out description of VIM3 USB3/PCIe mux in arm64 DT
(Neil Armstrong)
Broadcom iProc host bridge driver:
- Invalidate iProc PAXB address mapping before programming it
(Abhishek Shah)
- Fix iproc-msi and mvebu __iomem annotations (Ben Dooks)
Cadence host bridge driver:
- Refactor Cadence PCIe host controller to use as a library for both
host and endpoint (Tom Joseph)
Freescale Layerscape host bridge driver:
- Add layerscape LS1028a support (Xiaowei Bao)
Intel VMD host bridge driver:
- Add VMD bus 224-255 restriction decode (Jon Derrick)
- Add VMD 8086:9A0B device ID (Jon Derrick)
- Remove Keith from VMD maintainer list (Keith Busch)
Marvell ARMADA 3700 / Aardvark host bridge driver:
- Use LTSSM state to build link training flag since Aardvark doesn't
implement the Link Training bit (Remi Pommarel)
- Delay before training Aardvark link in case PERST# was asserted
before the driver probe (Remi Pommarel)
- Fix Aardvark issues with Root Control reads and writes (Remi
Pommarel)
- Don't rely on jiffies in Aardvark config access path since
interrupts may be disabled (Remi Pommarel)
- Fix Aardvark big-endian support (Grzegorz Jaszczyk)
Marvell ARMADA 370 / XP host bridge driver:
- Make mvebu_pci_bridge_emul_ops static (Ben Dooks)
Microsoft Hyper-V host bridge driver:
- Add hibernation support for Hyper-V virtual PCI devices (Dexuan
Cui)
- Track Hyper-V pci_protocol_version per-hbus, not globally (Dexuan
Cui)
- Avoid kmemleak false positive on hv hbus buffer (Dexuan Cui)
Mobiveil host bridge driver:
- Change mobiveil csr_read()/write() function names that conflict
with riscv arch functions (Kefeng Wang)
NVIDIA Tegra host bridge driver:
- Fix Tegra CLKREQ dependency programming (Vidya Sagar)
Renesas R-Car host bridge driver:
- Remove unnecessary header include from rcar (Andrew Murray)
- Tighten register index checking for rcar inbound range programming
(Marek Vasut)
- Fix rcar inbound range alignment calculation to improve packing of
multiple entries (Marek Vasut)
- Update rcar MACCTLR setting to match documentation (Yoshihiro
Shimoda)
- Clear bit 0 of MACCTLR before PCIETCTLR.CFINIT per manual
(Yoshihiro Shimoda)
- Add Marek Vasut and Yoshihiro Shimoda as R-Car maintainers (Simon
Horman)
Rockchip host bridge driver:
- Make rockchip 0V9 and 1V8 power regulators non-optional (Robin
Murphy)
Socionext UniPhier host bridge driver:
- Set uniphier to host (RC) mode always (Kunihiko Hayashi)
Endpoint drivers:
- Fix endpoint driver sign extension problem when shifting page
number to phys_addr_t (Alan Mikhak)
Misc:
- Add NumaChip SPDX header (Krzysztof Wilczynski)
- Replace EXTRA_CFLAGS with ccflags-y (Krzysztof Wilczynski)
- Remove unused includes (Krzysztof Wilczynski)
- Removed unused sysfs attribute groups (Ben Dooks)
- Remove PTM and ASPM dependencies on PCIEPORTBUS (Bjorn Helgaas)
- Add PCIe Link Control 2 register field definitions to replace magic
numbers in AMDGPU and Radeon CIK/SI (Bjorn Helgaas)
- Fix incorrect Link Control 2 Transmit Margin usage in AMDGPU and
Radeon CIK/SI PCIe Gen3 link training (Bjorn Helgaas)
- Use pcie_capability_read_word() instead of pci_read_config_word()
in AMDGPU and Radeon CIK/SI (Frederick Lawler)
- Remove unused pci_irq_get_node() Greg Kroah-Hartman)
- Make asm/msi.h mandatory and simplify PCI_MSI_IRQ_DOMAIN Kconfig
(Palmer Dabbelt, Michal Simek)
- Read all 64 bits of Switchtec part_event_bitmap (Logan Gunthorpe)
- Fix erroneous intel-iommu dependency on CONFIG_AMD_IOMMU (Bjorn
Helgaas)
- Fix bridge emulation big-endian support (Grzegorz Jaszczyk)
- Fix dwc find_next_bit() usage (Niklas Cassel)
- Fix pcitest.c fd leak (Hewenliang)
- Fix typos and comments (Bjorn Helgaas)
- Fix Kconfig whitespace errors (Krzysztof Kozlowski)"
* tag 'pci-v5.5-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (160 commits)
PCI: Remove PCI_MSI_IRQ_DOMAIN architecture whitelist
asm-generic: Make msi.h a mandatory include/asm header
Revert "nvme: Add quirk for Kingston NVME SSD running FW E8FK11.T"
PCI/MSI: Fix incorrect MSI-X masking on resume
PCI/MSI: Move power state check out of pci_msi_supported()
PCI/MSI: Remove unused pci_irq_get_node()
PCI: hv: Avoid a kmemleak false positive caused by the hbus buffer
PCI: hv: Change pci_protocol_version to per-hbus
PCI: hv: Add hibernation support
PCI: hv: Reorganize the code in preparation of hibernation
MAINTAINERS: Remove Keith from VMD maintainer
PCI/ASPM: Remove PCIEASPM_DEBUG Kconfig option and related code
PCI/ASPM: Add sysfs attributes for controlling ASPM link states
PCI: Fix indentation
drm/radeon: Prefer pcie_capability_read_word()
drm/radeon: Replace numbers with PCI_EXP_LNKCTL2 definitions
drm/radeon: Correct Transmit Margin masks
drm/amdgpu: Prefer pcie_capability_read_word()
PCI: uniphier: Set mode register to host mode
drm/amdgpu: Replace numbers with PCI_EXP_LNKCTL2 definitions
...
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull more s390 updates from Vasily Gorbik:
- Make stack unwinder reliable and suitable for livepatching. Add
unwinder testing module.
- Fixes for CALL_ON_STACK helper used for stack switching.
- Fix unwinding from bpf code.
- Fix getcpu and remove compat support in vdso code.
- Fix address space control registers initialization.
- Save KASLR offset for early dumps.
- Handle new FILTERED_BY_HYPERVISOR reply code in crypto code.
- Minor perf code cleanup and potential memory leak fix.
- Add couple of error messages for corner cases during PCI device
creation.
* tag 's390-5.5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (33 commits)
s390: remove compat vdso code
s390/livepatch: Implement reliable stack tracing for the consistency model
s390/unwind: add stack pointer alignment sanity checks
s390/unwind: filter out unreliable bogus %r14
s390/unwind: start unwinding from reliable state
s390/test_unwind: add program check context tests
s390/test_unwind: add irq context tests
s390/test_unwind: print verbose unwinding results
s390/test_unwind: add CALL_ON_STACK tests
s390: fix register clobbering in CALL_ON_STACK
s390/test_unwind: require that unwinding ended successfully
s390/unwind: add a test for the internal API
s390/unwind: always inline get_stack_pointer
s390/pci: add error message on device number limit
s390/pci: add error message for UID collision
s390/cpum_sf: Check for SDBT and SDB consistency
s390/cpum_sf: Use TEAR_REG macro consistantly
s390/cpum_sf: Remove unnecessary check for pending SDBs
s390/cpum_sf: Replace function name in debug statements
s390/kaslr: store KASLR offset for early dumps
...
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Remove compat vdso code, since there is hardly any compat user space
left. Still existing compat user space will have to use system calls
instead.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull seccomp updates from Kees Cook:
"Mostly this is implementing the new flag SECCOMP_USER_NOTIF_FLAG_CONTINUE,
but there are cleanups as well.
- implement SECCOMP_USER_NOTIF_FLAG_CONTINUE (Christian Brauner)
- fixes to selftests (Christian Brauner)
- remove secure_computing() argument (Christian Brauner)"
* tag 'seccomp-v5.5-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
seccomp: rework define for SECCOMP_USER_NOTIF_FLAG_CONTINUE
seccomp: fix SECCOMP_USER_NOTIF_FLAG_CONTINUE test
seccomp: simplify secure_computing()
seccomp: test SECCOMP_USER_NOTIF_FLAG_CONTINUE
seccomp: add SECCOMP_USER_NOTIF_FLAG_CONTINUE
seccomp: avoid overflow in implicit constant conversion
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The livepatch consistency model requires reliable stack tracing
architecture support in order to work properly. In order to achieve
this, two main issues have to be solved. First, reliable and consistent
call chain backtracing has to be ensured. Second, the unwinder needs to
be able to detect stack corruptions and return errors.
The "zSeries ELF Application Binary Interface Supplement" says:
"The stack pointer points to the first word of the lowest allocated
stack frame. If the "back chain" is implemented this word will point to
the previously allocated stack frame (towards higher addresses), except
for the first stack frame, which shall have a back chain of zero (NULL).
The stack shall grow downwards, in other words towards lower addresses."
"back chain" is optional. GCC option -mbackchain enables it. Quoting
Martin Schwidefsky [1]:
"The compiler is called with the -mbackchain option, all normal C
function will store the backchain in the function prologue. All
functions written in assembler code should do the same, if you find one
that does not we should fix that. The end result is that a task that
*voluntarily* called schedule() should have a proper backchain at all
times.
Dependent on the use case this may or may not be enough. Asynchronous
interrupts may stop the CPU at the beginning of a function, if kernel
preemption is enabled we can end up with a broken backchain. The
production kernels for IBM Z are all compiled *without* kernel
preemption. So yes, we might get away without the objtool support.
On a side-note, we do have a line item to implement the ORC unwinder for
the kernel, that includes the objtool support. Once we have that we can
drop the -mbackchain option for the kernel build. That gives us a nice
little performance benefit. I hope that the change from backchain to the
ORC unwinder will not be too hard to implement in the livepatch tools."
Since -mbackchain is enabled by default when the kernel is compiled, the
call chain backtracing should be currently ensured and objtool should
not be necessary for livepatch purposes.
Regarding the second issue, stack corruptions and non-reliable states
have to be recognized by the unwinder. Mainly it means to detect
preemption or page faults, the end of the task stack must be reached,
return addresses must be valid text addresses and hacks like function
graph tracing and kretprobes must be properly detected.
Unwinding a running task's stack is not a problem, because there is a
livepatch requirement that every checked task is blocked, except for the
current task. Due to that, the implementation can be much simpler
compared to the existing non-reliable infrastructure. We can consider a
task's kernel/thread stack only and skip the other stacks.
[1] 20180912121106.31ffa97c@mschwideX1 [not archived on lore.kernel.org]
Link: https://lkml.kernel.org/r/20191106095601.29986-5-mbenes@suse.cz
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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ABI requires SP to be aligned 8 bytes, report unwinding error otherwise.
Link: https://lkml.kernel.org/r/20191106095601.29986-5-mbenes@suse.cz
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Tested-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Currently unwinder unconditionally returns %r14 from the first frame
pointed by %r15 from pt_regs. A task could be interrupted when a function
already allocated this frame (if it needs it) for its callees or to
store local variables. In that case this frame would contain random
values from stack or values stored there by a callee. As we are only
interested in %r14 to get potential return address, skip bogus return
addresses which doesn't belong to kernel text.
This helps to avoid duplicating filtering logic in unwider users, most
of which use unwind_get_return_address() and would choke on bogus 0
address returned by it otherwise.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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A comment in arch/s390/include/asm/unwind.h says:
> If 'first_frame' is not zero unwind_start skips unwind frames until it
> reaches the specified stack pointer.
> The end of the unwinding is indicated with unwind_done, this can be true
> right after unwind_start, e.g. with first_frame!=0 that can not be found.
> unwind_next_frame skips to the next frame.
> Once the unwind is completed unwind_error() can be used to check if there
> has been a situation where the unwinder could not correctly understand
> the tasks call chain.
With this change backchain unwinder now comply with behaviour
described. As well as matches orc unwinder implementation. Now unwinder
starts from reliable state, i.e. __unwind_start own stack frame is
taken or stack frame generated by __switch_to (ksp) - both known to be
valid. In case of pt_regs %r15 is better match for pt_regs psw, than
sometimes random "sp" caller passed.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Add unwinding from program check handler tests. Unwinder should be able
to unwind through pt_regs stored by program check handler on task stack.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Add unwinding from irq context tests. Unwinder should be able to unwind
through irq stack to task stack up to task pt_regs.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Add stack name, sp and reliable information into test unwinding
results. Also consider ip outside of kernel text as failure if the
state is reported reliable.
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Add CALL_ON_STACK helper testing. Tests make sure that we can unwind from
switched stack to original one up to task pt_regs (nodat -> task stack).
UWM_SWITCH_STACK could not be used together with UWM_THREAD because
get_stack_info explicitly restricts unwinding to task stack if
task != current.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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CALL_ON_STACK defines and initializes register variables. Inline
assembly which follows might trigger compiler to generate memory access
for "stack" argument (e.g. in case of S390_lowcore.nodat_stack). This
memory access produces a function call under kasan with outline
instrumentation which clobbers registers.
Switch "stack" argument in CALL_ON_STACK helper to use memory reference
constraint and perform load instead.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Currently unwinder test passes if unwinding results contain unwindme_func2
and unwindme_func1 functions.
Now that unwinder reports success upon reaching task pt_regs, check
that unwinding ended successfully in every test.
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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unwind_for_each_frame can take at least 8 different sets of parameters.
Add a test to make sure they all are handled in a sane way.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Co-developed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Always inline get_stack_pointer() to avoid potential problems
due to compiler inlining decisions, i.e. getting stack pointer of
get_stack_pointer() itself which is later reused.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The config option CONFIG_PCI_NR_FUNCTIONS sets a limit on the number of
PCI functions we can support. Previously on reaching this limit there
was no indication why newly attached devices are not recognized by Linux
which could be quite confusing. Thus this patch adds a pr_err() for this
case.
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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When UID checking was turned off during runtime in the underlying
hypervisor, a PCI device may be attached with the same UID. This is
already detected but happens silently. Add an error message so it can
more easily be understood why a device was not added.
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Each SBDT is located at a 4KB page and contains 512 entries.
Each entry of a SDBT points to a SDB, a 4KB page containing
sampled data. The last entry is a link to another SDBT page.
When an event is created the function sequence executed is:
__hw_perf_event_init()
+--> allocate_buffers()
+--> realloc_sampling_buffers()
+---> alloc_sample_data_block()
Both functions realloc_sampling_buffers() and
alloc_sample_data_block() allocate pages and the allocation
can fail. This is handled correctly and all allocated
pages are freed and error -ENOMEM is returned to the
top calling function. Finally the event is not created.
Once the event has been created, the amount of initially
allocated SDBT and SDB can be too low. This is detected
during measurement interrupt handling, where the amount
of lost samples is calculated. If the number of lost samples
is too high considering sampling frequency and already allocated
SBDs, the number of SDBs is enlarged during the next execution
of cpumsf_pmu_enable().
If more SBDs need to be allocated, functions
realloc_sampling_buffers()
+---> alloc-sample_data_block()
are called to allocate more pages. Page allocation may fail
and the returned error is ignored. A SDBT and SDB setup
already exists.
However the modified SDBTs and SDBs might end up in a situation
where the first entry of an SDBT does not point to an SDB,
but another SDBT, basicly an SBDT without payload.
This can not be handled by the interrupt handler, where an SDBT
must have at least one entry pointing to an SBD.
Add a check to avoid SDBTs with out payload (SDBs) when enlarging
the buffer setup.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The macro TEAR_REG() saves the last used SDBT address
in the perf_hw_event structure. This is also done
by function hw_reset_registers() which is a one-liner
and simply uses macro TEAR_REG(). Remove function
hw_reset_registers(), which is only used one time and use
macro TEAR_REG() instead. This macro is used throughout
the code anyway.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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In interrupt handling the function extend_sampling_buffer()
is called after checking for a possibly extension.
This check is not necessary as the called function itself
performs this check again.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Replace hard coded function names in debug statements
by the "%s ...", __func__ construct suggested by checkpatch.pl
script. Use consistent debug print format of the form variable
blank value. Also add leading 0x for all hex values.
Print allocated page addresses consistantly as hex numbers
with leading 0x.
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The KASLR offset is added to vmcoreinfo in arch_crash_save_vmcoreinfo(),
so that it can be found by crash when processing kernel dumps.
However, arch_crash_save_vmcoreinfo() is called during a subsys_initcall,
so if the kernel crashes before that, we have no vmcoreinfo and no KASLR
offset.
Fix this by storing the KASLR offset in the lowcore, where the vmcore_info
pointer will be stored, and where it can be found by crash. In order to
make it distinguishable from a real vmcore_info pointer, mark it as uneven
(KASLR offset itself is aligned to THREAD_SIZE).
When arch_crash_save_vmcoreinfo() stores the real vmcore_info pointer in
the lowcore, it overwrites the KASLR offset. At that point, the KASLR
offset is not yet added to vmcoreinfo, so we also need to move the
mem_assign_absolute() behind the vmcoreinfo_append_str().
Fixes: b2d24b97b2a9 ("s390/kernel: add support for kernel address space layout randomization (KASLR)")
Cc: <stable@vger.kernel.org> # v5.2+
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Consider reaching task pt_regs graceful unwinder termination. Task
pt_regs itself never contains a valid state to which a task might return
within the kernel context (user task pt_regs is a special case). Since
we already avoid printing user task pt_regs and in most cases we don't
even bother filling task pt_regs psw and r15 with something reasonable
simply skip task pt_regs altogether. With this change unwind_error() now
accurately represent whether unwinder reached task pt_regs successfully
or failed along the way.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Add missing allocation of pt_regs at the bottom of the stack. This
makes it consistent with other stack setup cases and also what stack
unwinder expects.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Currently unwinder yields 2 entries when pt_regs are met:
sp="address of pt_regs itself" ip=pt_regs->psw
sp=pt_regs->gprs[15] ip="r14 from stack frame pointed by pt_regs->gprs[15]"
And neither of those 2 states (combination of sp and ip) ever happened.
reuse_sp has been introduced by commit a1d863ac3e10 ("s390/unwind: fix
mixing regs and sp"). reuse_sp=true makes unwinder keen to produce the
following result, when pt_regs are given (as an arg to unwind_start):
sp=pt_regs->gprs[15] ip=pt_regs->psw
sp=pt_regs->gprs[15] ip="r14 from stack frame pointed by pt_regs->gprs[15]"
The first state is an actual state in which a task was when pt_regs were
collected. The second state is marked unreliable and is for debugging
purposes to cover the case when a task has been interrupted in between
stack frame allocation and writing back_chain - in this case r14 might
show an actual caller.
Make unwinder behaviour enabled via reuse_sp=true default and drop the
special case handling.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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If unwinder is looking at pt_regs which is not on stack then something
went wrong and an error has to be reported rather than successful
unwinding termination.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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CALL_ON_STACK is intended to be used for temporary stack switching with
potential return to the caller.
When CALL_ON_STACK is misused to switch from nodat stack to task stack
back_chain information would later lead stack unwinder from task stack into
(per cpu) nodat stack which is reused for other purposes. This would
yield confusing unwinding result or errors.
To avoid that introduce CALL_ON_STACK_NORETURN to be used instead. It
makes sure that back_chain is zeroed and unwinder finishes gracefully
ending up at task pt_regs.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Currently CALL_ON_STACK saves r15 as back_chain in the first stack frame of
the stack we about to switch to. But if a function which uses CALL_ON_STACK
calls other function it allocates a stack frame for a callee. In this
case r15 is pointing to a callee stack frame and not a stack frame of
function itself. This results in dummy unwinding entry with random
sp and ip values.
Introduce and utilize current_frame_address macro to get an address of
actual function stack frame.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Avoid mixture of task == NULL and task == current meaning the same
thing and simply always initialize task with current in unwind_start.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Make sure preemption is disabled when temporary switching to nodat
stack with CALL_ON_STACK helper, because nodat stack is per cpu.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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disabled_wait uses _THIS_IP_ and assumes that compiler would inline it.
Make sure this assumption is always correct by utilizing __always_inline.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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getcpu reads the required values for cpu and node with two
instructions. This might lead to an inconsistent result if user space
gets preempted and migrated to a different CPU between the two
instructions.
Fix this by using just a single instruction to read both values at
once.
This is currently rather a theoretical bug, since there is no real
NUMA support available (except for NUMA emulation).
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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When a secondary CPU is brought up it must initialize its control
registers. CPU A which triggers that a secondary CPU B is brought up
stores its control register contents into the lowcore of new CPU B,
which then loads these values on startup.
This is problematic in various ways: the control register which
contains the home space ASCE will correctly contain the kernel ASCE;
however control registers for primary and secondary ASCEs are
initialized with whatever values were present in CPU A.
Typically:
- the primary ASCE will contain the user process ASCE of the process
that triggered onlining of CPU B.
- the secondary ASCE will contain the percpu VDSO ASCE of CPU A.
Due to lazy ASCE handling we may also end up with other combinations.
When then CPU B switches to a different process (!= idle) it will
fixup the primary ASCE. However the problem is that the (wrong) ASCE
from CPU A was loaded into control register 1: as soon as an ASCE is
attached (aka loaded) a CPU is free to generate TLB entries using that
address space.
Even though it is very unlikey that CPU B will actually generate such
entries, this could result in TLB entries of the address space of the
process that ran on CPU A. These entries shouldn't exist at all and
could cause problems later on.
Furthermore the secondary ASCE of CPU B will not be updated correctly.
This means that processes may see wrong results or even crash if they
access VDSO data on CPU B. The correct VDSO ASCE will eventually be
loaded on return to user space as soon as the kernel executed a call
to strnlen_user or an atomic futex operation on CPU B.
Fix both issues by intializing the to be loaded control register
contents with the correct ASCEs and also enforce (re-)loading of the
ASCEs upon first context switch and return to user space.
Fixes: 0aaba41b58bc ("s390: remove all code using the access register mode")
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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On s390 bpf_get_stack_raw_tp() returns 0 entries for both kernel and
user stacks. While there is no practical unwinding solution for userspace
on s390 at this moment, there certainly is a kernel unwinder. However,
it is not properly integrated with BPF.
In order to start unwinding, bpf_get_stack_raw_tp() obtains the current
kernel register values using perf_fetch_caller_regs(), which is not
implemented for s390. The actual unwinding then happens by passing those
registers to perf_callchain_kernel().
Implement perf_arch_fetch_caller_regs() for s390, where
__builtin_frame_address(0) points to back_chain.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Pull generic ioremap support from Christoph Hellwig:
"This adds the remaining bits for an entirely generic ioremap and
iounmap to lib/ioremap.c. To facilitate that, it cleans up the giant
mess of weird ioremap variants we had with no users outside the arch
code.
For now just the three newest ports use the code, but there is more
than a handful others that can be converted without too much work.
Summary:
- clean up various obsolete ioremap and iounmap variants
- add a new generic ioremap implementation and switch csky, nds32 and
riscv over to it"
* tag 'ioremap-5.5' of git://git.infradead.org/users/hch/ioremap: (21 commits)
nds32: use generic ioremap
csky: use generic ioremap
csky: remove ioremap_cache
riscv: use the generic ioremap code
lib: provide a simple generic ioremap implementation
sh: remove __iounmap
nios2: remove __iounmap
hexagon: remove __iounmap
m68k: rename __iounmap and mark it static
arch: rely on asm-generic/io.h for default ioremap_* definitions
asm-generic: don't provide ioremap for CONFIG_MMU
asm-generic: ioremap_uc should behave the same with and without MMU
xtensa: clean up ioremap
x86: Clean up ioremap()
parisc: remove __ioremap
nios2: remove __ioremap
alpha: remove the unused __ioremap wrapper
hexagon: clean up ioremap
ia64: rename ioremap_nocache to ioremap_uc
unicore32: remove ioremap_cached
...
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