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Lazy save and restore of FP/Altivec means that a userspace process can
be sent to userspace with FP or Altivec disabled and loaded only as
required (by way of an FP/Altivec unavailable exception). Transactional
Memory complicates this situation as a transaction could be started
without FP/Altivec being loaded up. This causes the hardware to
checkpoint incorrect registers. Handling FP/Altivec unavailable
exceptions while a thread is transactional requires a reclaim and
recheckpoint to ensure the CPU has correct state for both sets of
registers.
tm_reclaim() has optimisations to not always save the FP/Altivec
registers to the checkpointed save area. This was originally done
because the caller might have information that the checkpointed
registers aren't valid due to lazy save and restore. We've also been a
little vague as to how tm_reclaim() leaves the FP/Altivec state since it
doesn't necessarily always save it to the thread struct. This has lead
to an (incorrect) assumption that it leaves the checkpointed state on
the CPU.
tm_recheckpoint() has similar optimisations in reverse. It may not
always reload the checkpointed FP/Altivec registers from the thread
struct before the trecheckpoint. It is therefore quite unclear where it
expects to get the state from. This didn't help with the assumption
made about tm_reclaim().
These optimisations sit in what is by definition a slow path. If a
process has to go through a reclaim/recheckpoint then its transaction
will be doomed on returning to userspace. This mean that the process
will be unable to complete its transaction and be forced to its failure
handler. This is already an out if line case for userspace. Furthermore,
the cost of copying 64 times 128 bits from registers isn't very long[0]
(at all) on modern processors. As such it appears these optimisations
have only served to increase code complexity and are unlikely to have
had a measurable performance impact.
Our transactional memory handling has been riddled with bugs. A cause
of this has been difficulty in following the code flow, code complexity
has not been our friend here. It makes sense to remove these
optimisations in favour of a (hopefully) more stable implementation.
This patch does mean that some times the assembly will needlessly save
'junk' registers which will subsequently get overwritten with the
correct value by the C code which calls the assembly function. This
small inefficiency is far outweighed by the reduction in complexity for
general TM code, context switching paths, and transactional facility
unavailable exception handler.
0: I tried to measure it once for other work and found that it was
hiding in the noise of everything else I was working with. I find it
exceedingly likely this will be the case here.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Unfortunately userspace can construct a sigcontext which enables
suspend. Thus userspace can force Linux into a path where trechkpt is
executed.
This patch blocks this from happening on POWER9 by sanity checking
sigcontexts passed in.
ptrace doesn't have this problem as only MSR SE and BE can be changed
via ptrace.
This patch also adds a number of WARN_ON()s in case we ever enter
suspend when we shouldn't. This should not happen, but if it does the
symptoms are soft lockup warnings which are not obviously TM related,
so the WARN_ON()s should make it obvious what's happening.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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struct siginfo is a union and the kernel since 2.4 has been hiding a union
tag in the high 16bits of si_code using the values:
__SI_KILL
__SI_TIMER
__SI_POLL
__SI_FAULT
__SI_CHLD
__SI_RT
__SI_MESGQ
__SI_SYS
While this looks plausible on the surface, in practice this situation has
not worked well.
- Injected positive signals are not copied to user space properly
unless they have these magic high bits set.
- Injected positive signals are not reported properly by signalfd
unless they have these magic high bits set.
- These kernel internal values leaked to userspace via ptrace_peek_siginfo
- It was possible to inject these kernel internal values and cause the
the kernel to misbehave.
- Kernel developers got confused and expected these kernel internal values
in userspace in kernel self tests.
- Kernel developers got confused and set si_code to __SI_FAULT which
is SI_USER in userspace which causes userspace to think an ordinary user
sent the signal and that it was not kernel generated.
- The values make it impossible to reorganize the code to transform
siginfo_copy_to_user into a plain copy_to_user. As si_code must
be massaged before being passed to userspace.
So remove these kernel internal si codes and make the kernel code simpler
and more maintainable.
To replace these kernel internal magic si_codes introduce the helper
function siginfo_layout, that takes a signal number and an si_code and
computes which union member of siginfo is being used. Have
siginfo_layout return an enumeration so that gcc will have enough
information to warn if a switch statement does not handle all of union
members.
A couple of architectures have a messed up ABI that defines signal
specific duplications of SI_USER which causes more special cases in
siginfo_layout than I would like. The good news is only problem
architectures pay the cost.
Update all of the code that used the previous magic __SI_ values to
use the new SIL_ values and to call siginfo_layout to get those
values. Escept where not all of the cases are handled remove the
defaults in the switch statements so that if a new case is missed in
the future the lack will show up at compile time.
Modify the code that copies siginfo si_code to userspace to just copy
the value and not cast si_code to a short first. The high bits are no
longer used to hold a magic union member.
Fixup the siginfo header files to stop including the __SI_ values in
their constants and for the headers that were missing it to properly
update the number of si_codes for each signal type.
The fixes to copy_siginfo_from_user32 implementations has the
interesting property that several of them perviously should never have
worked as the __SI_ values they depended up where kernel internal.
With that dependency gone those implementations should work much
better.
The idea of not passing the __SI_ values out to userspace and then
not reinserting them has been tested with criu and criu worked without
changes.
Ref: 2.4.0-test1
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Make the structures being used for checkpointed state named
consistently with the pt_regs/ckpt_regs.
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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There is currently an inconsistency as to how the entire CPU register
state is saved and restored when a thread uses transactional memory
(TM).
Using transactional memory results in the CPU having duplicated
(almost) all of its register state. This duplication results in a set
of registers which can be considered 'live', those being currently
modified by the instructions being executed and another set that is
frozen at a point in time.
On context switch, both sets of state have to be saved and (later)
restored. These two states are often called a variety of different
things. Common terms for the state which only exists after the CPU has
entered a transaction (performed a TBEGIN instruction) in hardware are
'transactional' or 'speculative'.
Between a TBEGIN and a TEND or TABORT (or an event that causes the
hardware to abort), regardless of the use of TSUSPEND the
transactional state can be referred to as the live state.
The second state is often to referred to as the 'checkpointed' state
and is a duplication of the live state when the TBEGIN instruction is
executed. This state is kept in the hardware and will be rolled back
to on transaction failure.
Currently all the registers stored in pt_regs are ALWAYS the live
registers, that is, when a thread has transactional registers their
values are stored in pt_regs and the checkpointed state is in
ckpt_regs. A strange opposite is true for fp_state/vr_state. When a
thread is non transactional fp_state/vr_state holds the live
registers. When a thread has initiated a transaction fp_state/vr_state
holds the checkpointed state and transact_fp/transact_vr become the
structure which holds the live state (at this point it is a
transactional state).
This method creates confusion as to where the live state is, in some
circumstances it requires extra work to determine where to put the
live state and prevents the use of common functions designed (probably
before TM) to save the live state.
With this patch pt_regs, fp_state and vr_state all represent the
same thing and the other structures [pending rename] are for
checkpointed state.
Acked-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Much of the signal code takes a pt_regs on which it operates. Over
time the signal code has needed to know more about the thread than
what pt_regs can supply, this information is obtained as needed by
using 'current'.
This approach is not strictly incorrect however it does mean that
there is now a hard requirement that the pt_regs being passed around
does belong to current, this is never checked. A safer approach is for
the majority of the signal functions to take a task_struct from which
they can obtain pt_regs and any other information they need. The
caveat that the task_struct they are passed must be current doesn't go
away but can more easily be checked for.
Functions called from outside powerpc signal code are passed a pt_regs
and they can confirm that the pt_regs is that of current and pass
current to other functions, furthurmore, powerpc signal functions can
check that the task_struct they are passed is the same as current
avoiding possible corruption of current (or the task they are passed)
if this assertion ever fails.
CC: paulus@samba.org
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Normally, when MSR[VSX/VR/SPE] bits == 1, the used_vsr/used_vr/used_spe
bit have already been set. However when loading a signal frame from user
space we need to explicitly set used_vsr/used_vr/used_spe to make them
consistent with the MSR bits from the signal frame.
For example, CRIU application, who utilizes sigreturn to restore
checkpointed process, will lead to the case where MSR[VSX] bit is active
in signal frame, but used_vsr bit is not set in the kernel. (the same
applies to VR/SPE).
This patch fixes this by always setting used_* bit when MSR related bits
are active in signal frame and we are doing sigreturn.
Based on a proposal by Benh.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
[mpe: Massage change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Another set of things that are only called from assembler and so need
prototypes to keep sparse happy.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Userspace can begin and suspend a transaction within the signal
handler which means they might enter sys_rt_sigreturn() with the
processor in suspended state.
sys_rt_sigreturn() wants to restore process context (which may have
been in a transaction before signal delivery). To do this it must
restore TM SPRS. To achieve this, any transaction initiated within the
signal frame must be discarded in order to be able to restore TM SPRs
as TM SPRs can only be manipulated non-transactionally..
>From the PowerPC ISA:
TM Bad Thing Exception [Category: Transactional Memory]
An attempt is made to execute a mtspr targeting a TM register in
other than Non-transactional state.
Not doing so results in a TM Bad Thing:
[12045.221359] Kernel BUG at c000000000050a40 [verbose debug info unavailable]
[12045.221470] Unexpected TM Bad Thing exception at c000000000050a40 (msr 0x201033)
[12045.221540] Oops: Unrecoverable exception, sig: 6 [#1]
[12045.221586] SMP NR_CPUS=2048 NUMA PowerNV
[12045.221634] Modules linked in: xt_CHECKSUM iptable_mangle ipt_MASQUERADE
nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4
xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp bridge stp llc ebtable_filter
ebtables ip6table_filter ip6_tables iptable_filter ip_tables x_tables kvm_hv kvm
uio_pdrv_genirq ipmi_powernv uio powernv_rng ipmi_msghandler autofs4 ses enclosure
scsi_transport_sas bnx2x ipr mdio libcrc32c
[12045.222167] CPU: 68 PID: 6178 Comm: sigreturnpanic Not tainted 4.7.0 #34
[12045.222224] task: c0000000fce38600 ti: c0000000fceb4000 task.ti: c0000000fceb4000
[12045.222293] NIP: c000000000050a40 LR: c0000000000163bc CTR: 0000000000000000
[12045.222361] REGS: c0000000fceb7ac0 TRAP: 0700 Not tainted (4.7.0)
[12045.222418] MSR: 9000000300201033 <SF,HV,ME,IR,DR,RI,LE,TM[SE]> CR: 28444280 XER: 20000000
[12045.222625] CFAR: c0000000000163b8 SOFTE: 0 PACATMSCRATCH: 900000014280f033
GPR00: 01100000b8000001 c0000000fceb7d40 c00000000139c100 c0000000fce390d0
GPR04: 900000034280f033 0000000000000000 0000000000000000 0000000000000000
GPR08: 0000000000000000 b000000000001033 0000000000000001 0000000000000000
GPR12: 0000000000000000 c000000002926400 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR24: 0000000000000000 00003ffff98cadd0 00003ffff98cb470 0000000000000000
GPR28: 900000034280f033 c0000000fceb7ea0 0000000000000001 c0000000fce390d0
[12045.223535] NIP [c000000000050a40] tm_restore_sprs+0xc/0x1c
[12045.223584] LR [c0000000000163bc] tm_recheckpoint+0x5c/0xa0
[12045.223630] Call Trace:
[12045.223655] [c0000000fceb7d80] [c000000000026e74] sys_rt_sigreturn+0x494/0x6c0
[12045.223738] [c0000000fceb7e30] [c0000000000092e0] system_call+0x38/0x108
[12045.223806] Instruction dump:
[12045.223841] 7c800164 4e800020 7c0022a6 f80304a8 7c0222a6 f80304b0 7c0122a6 f80304b8
[12045.223955] 4e800020 e80304a8 7c0023a6 e80304b0 <7c0223a6> e80304b8 7c0123a6 4e800020
[12045.224074] ---[ end trace cb8002ee240bae76 ]---
It isn't clear exactly if there is really a use case for userspace
returning with a suspended transaction, however, doing so doesn't (on
its own) constitute a bad frame. As such, this patch simply discards
the transactional state of the context calling the sigreturn and
continues.
Reported-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Cyril Bur <cyrilbur@gmail.com>
Tested-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Reviewed-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Acked-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Merge the two TM fixes we merged in 4.4. We are about to merge selftests
for these, and without the fixes the selftests will oops.
powerpc fixes for 4.4 #2
- tm: Block signal return from setting invalid MSR state from Michael Neuling
- tm: Check for already reclaimed tasks from Michael Neuling
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Move the MSR modification into c. Removing it from the assembly
function will allow us to avoid costly MSR writes by batching them
up.
Check the FP and VMX bits before calling the relevant giveup_*()
function. This makes giveup_vsx() and flush_vsx_to_thread() perform
more like their sister functions, and allows us to use
flush_vsx_to_thread() in the signal code.
Move the check_if_tm_restore_required() check in.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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The UP only lazy floating point and vector optimisations were written
back when SMP was not common, and neither glibc nor gcc used vector
instructions. Now SMP is very common, glibc aggressively uses vector
instructions and gcc autovectorises.
We want to add new optimisations that apply to both UP and SMP, but
in preparation for that remove these UP only optimisations.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Currently we allow both the MSR T and S bits to be set by userspace on
a signal return. Unfortunately this is a reserved configuration and
will cause a TM Bad Thing exception if attempted (via rfid).
This patch checks for this case in both the 32 and 64 bit signals
code. If both T and S are set, we mark the context as invalid.
Found using a syscall fuzzer.
Fixes: 2b0a576d15e0 ("powerpc: Add new transactional memory state to the signal context")
Cc: stable@vger.kernel.org # v3.9+
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
- support "hybrid" iommu/direct DMA ops for coherent_mask < dma_mask
from Benjamin Herrenschmidt
- EEH fixes for SRIOV from Gavin
- introduce rtas_get_sensor_fast() for IRQ handlers from Thomas Huth
- use hardware RNG for arch_get_random_seed_* not arch_get_random_*
from Paul Mackerras
- seccomp filter support from Michael Ellerman
- opal_cec_reboot2() handling for HMIs & machine checks from Mahesh
Salgaonkar
- add powerpc timebase as a trace clock source from Naveen N. Rao
- misc cleanups in the xmon, signal & SLB code from Anshuman Khandual
- add an inline function to update POWER8 HID0 from Gautham R. Shenoy
- fix pte_pagesize_index() crash on 4K w/64K hash from Michael Ellerman
- drop support for 64K local store on 4K kernels from Michael Ellerman
- move dma_get_required_mask() from pnv_phb to pci_controller_ops from
Andrew Donnellan
- initialize distance lookup table from drconf path from Nikunj A
Dadhania
- enable RTC class support from Vaibhav Jain
- disable automatically blocked PCI config from Gavin Shan
- add LEDs driver for PowerNV platform from Vasant Hegde
- fix endianness issues in the HVSI driver from Laurent Dufour
- kexec endian fixes from Samuel Mendoza-Jonas
- fix corrupted pdn list from Gavin Shan
- fix fenced PHB caused by eeh_slot_error_detail() from Gavin Shan
- Freescale updates from Scott: Highlights include 32-bit memcpy/memset
optimizations, checksum optimizations, 85xx config fragments and
updates, device tree updates, e6500 fixes for non-SMP, and misc
cleanup and minor fixes.
- a ton of cxl updates & fixes:
- add explicit precision specifiers from Rasmus Villemoes
- use more common format specifier from Rasmus Villemoes
- destroy cxl_adapter_idr on module_exit from Johannes Thumshirn
- destroy afu->contexts_idr on release of an afu from Johannes
Thumshirn
- compile with -Werror from Daniel Axtens
- EEH support from Daniel Axtens
- plug irq_bitmap getting leaked in cxl_context from Vaibhav Jain
- add alternate MMIO error handling from Ian Munsie
- allow release of contexts which have been OPENED but not STARTED
from Andrew Donnellan
- remove use of macro DEFINE_PCI_DEVICE_TABLE from Vaishali Thakkar
- release irqs if memory allocation fails from Vaibhav Jain
- remove racy attempt to force EEH invocation in reset from Daniel
Axtens
- fix + cleanup error paths in cxl_dev_context_init from Ian Munsie
- fix force unmapping mmaps of contexts allocated through the kernel
api from Ian Munsie
- set up and enable PSL Timebase from Philippe Bergheaud
* tag 'powerpc-4.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (140 commits)
cxl: Set up and enable PSL Timebase
cxl: Fix force unmapping mmaps of contexts allocated through the kernel api
cxl: Fix + cleanup error paths in cxl_dev_context_init
powerpc/eeh: Fix fenced PHB caused by eeh_slot_error_detail()
powerpc/pseries: Cleanup on pci_dn_reconfig_notifier()
powerpc/pseries: Fix corrupted pdn list
powerpc/powernv: Enable LEDS support
powerpc/iommu: Set default DMA offset in dma_dev_setup
cxl: Remove racy attempt to force EEH invocation in reset
cxl: Release irqs if memory allocation fails
cxl: Remove use of macro DEFINE_PCI_DEVICE_TABLE
powerpc/powernv: Fix mis-merge of OPAL support for LEDS driver
powerpc/powernv: Reset HILE before kexec_sequence()
powerpc/kexec: Reset secondary cpu endianness before kexec
powerpc/hvsi: Fix endianness issues in the HVSI driver
leds/powernv: Add driver for PowerNV platform
powerpc/powernv: Create LED platform device
powerpc/powernv: Add OPAL interfaces for accessing and modifying system LED states
powerpc/powernv: Fix the log message when disabling VF
cxl: Allow release of contexts which have been OPENED but not STARTED
...
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This function can leak kernel stack data when the user siginfo_t has a
positive si_code value. The top 16 bits of si_code descibe which fields
in the siginfo_t union are active, but they are treated inconsistently
between copy_siginfo_from_user32, copy_siginfo_to_user32 and
copy_siginfo_to_user.
copy_siginfo_from_user32 is called from rt_sigqueueinfo and
rt_tgsigqueueinfo in which the user has full control overthe top 16 bits
of si_code.
This fixes the following information leaks:
x86: 8 bytes leaked when sending a signal from a 32-bit process to
itself. This leak grows to 16 bytes if the process uses x32.
(si_code = __SI_CHLD)
x86: 100 bytes leaked when sending a signal from a 32-bit process to
a 64-bit process. (si_code = -1)
sparc: 4 bytes leaked when sending a signal from a 32-bit process to a
64-bit process. (si_code = any)
parsic and s390 have similar bugs, but they are not vulnerable because
rt_[tg]sigqueueinfo have checks that prevent sending a positive si_code
to a different process. These bugs are also fixed for consistency.
Signed-off-by: Amanieu d'Antras <amanieu@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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SIG_SYS was added in commit a0727e8ce513 "signal, x86: add SIGSYS info
and make it synchronous."
Because we use the asm-generic struct siginfo, we got support for
SIG_SYS for free as part of that commit.
However there was no compat handling added for powerpc. That means we've
been advertising the existence of signfo._sifields._sigsys to compat
tasks, but not actually filling in the fields correctly.
Luckily it looks like no one has noticed, presumably because the only
user of SIGSYS in the kernel is seccomp filter, which we don't support
yet.
So before we enable seccomp filter, add compat handling for SIGSYS.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
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If an attacker can cause a controlled kernel stack overflow, overwriting
the restart block is a very juicy exploit target. This is because the
restart_block is held in the same memory allocation as the kernel stack.
Moving the restart block to struct task_struct prevents this exploit by
making the restart_block harder to locate.
Note that there are other fields in thread_info that are also easy
targets, at least on some architectures.
It's also a decent simplification, since the restart code is more or less
identical on all architectures.
[james.hogan@imgtec.com: metag: align thread_info::supervisor_stack]
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: David Miller <davem@davemloft.net>
Acked-by: Richard Weinberger <richard@nod.at>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Cc: Steven Miao <realmz6@gmail.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Aurelien Jacquiot <a-jacquiot@ti.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Tested-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Use sigsp() instead of the open coded variant.
Signed-off-by: Richard Weinberger <richard@nod.at>
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Use the more generic functions get_signal() signal_setup_done()
for signal delivery.
This inverts also the return codes of setup_*frame() to follow the
kernel convention.
Signed-off-by: Richard Weinberger <richard@nod.at>
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We have some compile-time disabled debug code in signal_xx.c. It's from
some ancient time BG, almost certainly part of the original port, given
the very similar code on other arches.
The show_unhandled_signal logic, added in d0c3d534a438 (2.6.24) is
cleaner and prints more useful information, so drop the debug code.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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We can't take an IRQ when we're about to do a trechkpt as our GPR state is set
to user GPR values.
We've hit this when running some IBM Java stress tests in the lab resulting in
the following dump:
cpu 0x3f: Vector: 700 (Program Check) at [c000000007eb3d40]
pc: c000000000050074: restore_gprs+0xc0/0x148
lr: 00000000b52a8184
sp: ac57d360
msr: 8000000100201030
current = 0xc00000002c500000
paca = 0xc000000007dbfc00 softe: 0 irq_happened: 0x00
pid = 34535, comm = Pooled Thread #
R00 = 00000000b52a8184 R16 = 00000000b3e48fda
R01 = 00000000ac57d360 R17 = 00000000ade79bd8
R02 = 00000000ac586930 R18 = 000000000fac9bcc
R03 = 00000000ade60000 R19 = 00000000ac57f930
R04 = 00000000f6624918 R20 = 00000000ade79be8
R05 = 00000000f663f238 R21 = 00000000ac218a54
R06 = 0000000000000002 R22 = 000000000f956280
R07 = 0000000000000008 R23 = 000000000000007e
R08 = 000000000000000a R24 = 000000000000000c
R09 = 00000000b6e69160 R25 = 00000000b424cf00
R10 = 0000000000000181 R26 = 00000000f66256d4
R11 = 000000000f365ec0 R27 = 00000000b6fdcdd0
R12 = 00000000f66400f0 R28 = 0000000000000001
R13 = 00000000ada71900 R29 = 00000000ade5a300
R14 = 00000000ac2185a8 R30 = 00000000f663f238
R15 = 0000000000000004 R31 = 00000000f6624918
pc = c000000000050074 restore_gprs+0xc0/0x148
cfar= c00000000004fe28 dont_restore_vec+0x1c/0x1a4
lr = 00000000b52a8184
msr = 8000000100201030 cr = 24804888
ctr = 0000000000000000 xer = 0000000000000000 trap = 700
This moves tm_recheckpoint to a C function and moves the tm_restore_sprs into
that function. It then adds IRQ disabling over the trechkpt critical section.
It also sets the TEXASR FS in the signals code to ensure this is never set now
that we explictly write the TM sprs in tm_recheckpoint.
Signed-off-by: Michael Neuling <mikey@neuling.org>
cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Commit d31626f70b61 ("powerpc: Don't corrupt transactional state when
using FP/VMX in kernel") introduced a bug where the uc_link and uc_regs
fields of the ucontext_t that is created to hold the transactional
values of the registers in a 32-bit signal frame didn't get set
correctly. The reason is that we now clear the MSR_TS bits in the MSR
in save_tm_user_regs(), before the code that sets uc_link and uc_regs.
To fix this, we move the setting of uc_link and uc_regs into the same
if statement that selects whether to call save_tm_user_regs() or
save_user_regs().
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Currently, when we have a process using the transactional memory
facilities on POWER8 (that is, the processor is in transactional
or suspended state), and the process enters the kernel and the
kernel then uses the floating-point or vector (VMX/Altivec) facility,
we end up corrupting the user-visible FP/VMX/VSX state. This
happens, for example, if a page fault causes a copy-on-write
operation, because the copy_page function will use VMX to do the
copy on POWER8. The test program below demonstrates the bug.
The bug happens because when FP/VMX state for a transactional process
is stored in the thread_struct, we store the checkpointed state in
.fp_state/.vr_state and the transactional (current) state in
.transact_fp/.transact_vr. However, when the kernel wants to use
FP/VMX, it calls enable_kernel_fp() or enable_kernel_altivec(),
which saves the current state in .fp_state/.vr_state. Furthermore,
when we return to the user process we return with FP/VMX/VSX
disabled. The next time the process uses FP/VMX/VSX, we don't know
which set of state (the current register values, .fp_state/.vr_state,
or .transact_fp/.transact_vr) we should be using, since we have no
way to tell if we are still in the same transaction, and if not,
whether the previous transaction succeeded or failed.
Thus it is necessary to strictly adhere to the rule that if FP has
been enabled at any point in a transaction, we must keep FP enabled
for the user process with the current transactional state in the
FP registers, until we detect that it is no longer in a transaction.
Similarly for VMX; once enabled it must stay enabled until the
process is no longer transactional.
In order to keep this rule, we add a new thread_info flag which we
test when returning from the kernel to userspace, called TIF_RESTORE_TM.
This flag indicates that there is FP/VMX/VSX state to be restored
before entering userspace, and when it is set the .tm_orig_msr field
in the thread_struct indicates what state needs to be restored.
The restoration is done by restore_tm_state(). The TIF_RESTORE_TM
bit is set by new giveup_fpu/altivec_maybe_transactional helpers,
which are called from enable_kernel_fp/altivec, giveup_vsx, and
flush_fp/altivec_to_thread instead of giveup_fpu/altivec.
The other thing to be done is to get the transactional FP/VMX/VSX
state from .fp_state/.vr_state when doing reclaim, if that state
has been saved there by giveup_fpu/altivec_maybe_transactional.
Having done this, we set the FP/VMX bit in the thread's MSR after
reclaim to indicate that that part of the state is now valid
(having been reclaimed from the processor's checkpointed state).
Finally, in the signal handling code, we move the clearing of the
transactional state bits in the thread's MSR a bit earlier, before
calling flush_fp_to_thread(), so that we don't unnecessarily set
the TIF_RESTORE_TM bit.
This is the test program:
/* Michael Neuling 4/12/2013
*
* See if the altivec state is leaked out of an aborted transaction due to
* kernel vmx copy loops.
*
* gcc -m64 htm_vmxcopy.c -o htm_vmxcopy
*
*/
/* We don't use all of these, but for reference: */
int main(int argc, char *argv[])
{
long double vecin = 1.3;
long double vecout;
unsigned long pgsize = getpagesize();
int i;
int fd;
int size = pgsize*16;
char tmpfile[] = "/tmp/page_faultXXXXXX";
char buf[pgsize];
char *a;
uint64_t aborted = 0;
fd = mkstemp(tmpfile);
assert(fd >= 0);
memset(buf, 0, pgsize);
for (i = 0; i < size; i += pgsize)
assert(write(fd, buf, pgsize) == pgsize);
unlink(tmpfile);
a = mmap(NULL, size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
assert(a != MAP_FAILED);
asm __volatile__(
"lxvd2x 40,0,%[vecinptr] ; " // set 40 to initial value
TBEGIN
"beq 3f ;"
TSUSPEND
"xxlxor 40,40,40 ; " // set 40 to 0
"std 5, 0(%[map]) ;" // cause kernel vmx copy page
TABORT
TRESUME
TEND
"li %[res], 0 ;"
"b 5f ;"
"3: ;" // Abort handler
"li %[res], 1 ;"
"5: ;"
"stxvd2x 40,0,%[vecoutptr] ; "
: [res]"=r"(aborted)
: [vecinptr]"r"(&vecin),
[vecoutptr]"r"(&vecout),
[map]"r"(a)
: "memory", "r0", "r3", "r4", "r5", "r6", "r7");
if (aborted && (vecin != vecout)){
printf("FAILED: vector state leaked on abort %f != %f\n",
(double)vecin, (double)vecout);
exit(1);
}
munmap(a, size);
close(fd);
printf("PASSED!\n");
return 0;
}
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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In a recent patch:
commit c13f20ac48328b05cd3b8c19e31ed6c132b44b42
Author: Michael Neuling <mikey@neuling.org>
powerpc/signals: Mark VSX not saved with small contexts
We fixed an issue but an improved solution was later discussed after the patch
was merged.
Firstly, this patch doesn't handle the 64bit signals case, which could also hit
this issue (but has never been reported).
Secondly, the original patch isn't clear what MSR VSX should be set to. The
new approach below always clears the MSR VSX bit (to indicate no VSX is in the
context) and sets it only in the specific case where VSX is available (ie. when
VSX has been used and the signal context passed has space to provide the
state).
This reverts the original patch and replaces it with the improved solution. It
also adds a 64 bit version.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The VSX MSR bit in the user context indicates if the context contains VSX
state. Currently we set this when the process has touched VSX at any stage.
Unfortunately, if the user has not provided enough space to save the VSX state,
we can't save it but we currently still set the MSR VSX bit.
This patch changes this to clear the MSR VSX bit when the user doesn't provide
enough space. This indicates that there is no valid VSX state in the user
context.
This is needed to support get/set/make/swapcontext for applications that use
VSX but only provide a small context. For example, getcontext in glibc
provides a smaller context since the VSX registers don't need to be saved over
the glibc function call. But since the program calling getcontext may have
used VSX, the kernel currently says the VSX state is valid when it's not. If
the returned context is then used in setcontext (ie. a small context without
VSX but with MSR VSX set), the kernel will refuse the context. This situation
has been reported by the glibc community.
Based on patch from Carlos O'Donell.
Tested-by: Haren Myneni <haren@linux.vnet.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
"All kinds of stuff this time around; some more notable parts:
- RCU'd vfsmounts handling
- new primitives for coredump handling
- files_lock is gone
- Bruce's delegations handling series
- exportfs fixes
plus misc stuff all over the place"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (101 commits)
ecryptfs: ->f_op is never NULL
locks: break delegations on any attribute modification
locks: break delegations on link
locks: break delegations on rename
locks: helper functions for delegation breaking
locks: break delegations on unlink
namei: minor vfs_unlink cleanup
locks: implement delegations
locks: introduce new FL_DELEG lock flag
vfs: take i_mutex on renamed file
vfs: rename I_MUTEX_QUOTA now that it's not used for quotas
vfs: don't use PARENT/CHILD lock classes for non-directories
vfs: pull ext4's double-i_mutex-locking into common code
exportfs: fix quadratic behavior in filehandle lookup
exportfs: better variable name
exportfs: move most of reconnect_path to helper function
exportfs: eliminate unused "noprogress" counter
exportfs: stop retrying once we race with rename/remove
exportfs: clear DISCONNECTED on all parents sooner
exportfs: more detailed comment for path_reconnect
...
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This way we can use same data type struct with KVM and
also help in using other debug related function.
Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
Acked-by: Michael Neuling <mikey@neuling.org>
[scottwood@freescale.com: removed obvious debug_reg comment]
Signed-off-by: Scott Wood <scottwood@freescale.com>
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Topic branch for commits that the KVM tree might want to pull
in separately.
Hand merged a few files due to conflicts with the LE stuff
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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This creates new 'thread_fp_state' and 'thread_vr_state' structures
to store FP/VSX state (including FPSCR) and Altivec/VSX state
(including VSCR), and uses them in the thread_struct. In the
thread_fp_state, the FPRs and VSRs are represented as u64 rather
than double, since we rarely perform floating-point computations
on the values, and this will enable the structures to be used
in KVM code as well. Similarly FPSCR is now a u64 rather than
a structure of two 32-bit values.
This takes the offsets out of the macros such as SAVE_32FPRS,
REST_32FPRS, etc. This enables the same macros to be used for normal
and transactional state, enabling us to delete the transactional
versions of the macros. This also removes the unused do_load_up_fpu
and do_load_up_altivec, which were in fact buggy since they didn't
create large enough stack frames to account for the fact that
load_up_fpu and load_up_altivec are not designed to be called from C
and assume that their caller's stack frame is an interrupt frame.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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We always take signals in big endian which is wrong. Signals
should be taken in native endian.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Since 2002, the kernel has not saved VRSAVE on exception entry and
restored it on exit; rather, VRSAVE gets context-switched in _switch.
This means that when executing in process context in the kernel, the
userspace VRSAVE value is live in the VRSAVE register.
However, the signal code assumes that current->thread.vrsave holds
the current VRSAVE value, which is incorrect. Therefore, this
commit changes it to use the actual VRSAVE register instead. (It
still uses current->thread.vrsave as a temporary location to store
it in, as __get_user and __put_user can only transfer to/from a
variable, not an SPR.)
This also modifies the transactional memory code to save and restore
VRSAVE regardless of whether VMX is enabled in the MSR. This is
because accesses to VRSAVE are not controlled by the MSR.VEC bit,
but can happen at any time.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Currently we only restore signals which are transactionally suspended but it's
possible that the transaction can be restored even when it's active. Most
likely this will result in a transactional rollback by the hardware as the
transaction will have been doomed by an earlier treclaim.
The current code is a legacy of earlier kernel implementations which did
software rollback of active transactions in the kernel. That code has now gone
but we didn't correctly fix up this part of the signals code which still makes
assumptions based on having software rollback.
This changes the signal return code to always restore both contexts on 32 bit
rt signal return.
Signed-off-by: Michael Neuling <mikey@neuling.org>
cc: stable@vger.kernel.org (v3.9+)
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Currently we clear out the MSR TM bits on signal return assuming that the
signal should never return to an active transaction.
This is bogus as the user may do this. It's most likely the transaction will
be doomed due to a treclaim but that's a problem for the HW not the kernel.
The current code is a legacy of earlier kernel implementations which did
software rollback of active transactions in the kernel. That code has now gone
but we didn't correctly fix up this part of the signals code which still makes
the assumption that it must be returning to a suspended transaction.
This pulls out both MSR TM bits from the user supplied context rather than just
setting TM suspend. We pull out only the bits needed to ensure the user can't
do anything dangerous to the MSR.
Signed-off-by: Michael Neuling <mikey@neuling.org>
cc: stable@vger.kernel.org (v3.9+)
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Currently sys_sigreturn() is TM unaware. Therefore, if we take a 32 bit signal
without SIGINFO (non RT) inside a transaction, on signal return we don't
restore the signal frame correctly.
This checks if the signal frame being restoring is an active transaction, and
if so, it copies the additional state to ptregs so it can be restored.
Signed-off-by: Michael Neuling <mikey@neuling.org>
cc: stable@vger.kernel.org (v3.9+)
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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The MSR TM controls are in the top 32 bits of the MSR hence on 32 bit signals,
we stick the top half of the MSR in the checkpointed signal context so that the
user can access it.
Unfortunately, we don't currently write anything to the checkpointed signal
context when coming in a from a non transactional process and hence the top MSR
bits can contain junk.
This updates the 32 bit signal handling code to always write something to the
top MSR bits so that users know if the process is transactional or not and the
kernel can use it on signal return.
Signed-off-by: Michael Neuling <mikey@neuling.org>
cc: stable@vger.kernel.org (v3.9+)
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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transactions
When in an active transaction that takes a signal, we need to be careful with
the stack. It's possible that the stack has moved back up after the tbegin.
The obvious case here is when the tbegin is called inside a function that
returns before a tend. In this case, the stack is part of the checkpointed
transactional memory state. If we write over this non transactionally or in
suspend, we are in trouble because if we get a tm abort, the program counter
and stack pointer will be back at the tbegin but our in memory stack won't be
valid anymore.
To avoid this, when taking a signal in an active transaction, we need to use
the stack pointer from the checkpointed state, rather than the speculated
state. This ensures that the signal context (written tm suspended) will be
written below the stack required for the rollback. The transaction is aborted
becuase of the treclaim, so any memory written between the tbegin and the
signal will be rolled back anyway.
For signals taken in non-TM or suspended mode, we use the
normal/non-checkpointed stack pointer.
Tested with 64 and 32 bit signals
Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: <stable@vger.kernel.org> # v3.9
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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We can't compile a kernel with CONFIG_ALTIVEC=n when
CONFIG_PPC_TRANSACTIONAL_MEM=y. We currently get:
arch/powerpc/kernel/tm.S:320: Error: unsupported relocation against THREAD_VSCR
arch/powerpc/kernel/tm.S:323: Error: unsupported relocation against THREAD_VR0
arch/powerpc/kernel/tm.S:323: Error: unsupported relocation against THREAD_VR0
etc.
The below fixes this with a sprinkling of #ifdefs.
This was found by mpe with kisskb:
http://kisskb.ellerman.id.au/kisskb/buildresult/8539442/
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal
Pull signal handling cleanups from Al Viro:
"This is the first pile; another one will come a bit later and will
contain SYSCALL_DEFINE-related patches.
- a bunch of signal-related syscalls (both native and compat)
unified.
- a bunch of compat syscalls switched to COMPAT_SYSCALL_DEFINE
(fixing several potential problems with missing argument
validation, while we are at it)
- a lot of now-pointless wrappers killed
- a couple of architectures (cris and hexagon) forgot to save
altstack settings into sigframe, even though they used the
(uninitialized) values in sigreturn; fixed.
- microblaze fixes for delivery of multiple signals arriving at once
- saner set of helpers for signal delivery introduced, several
architectures switched to using those."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal: (143 commits)
x86: convert to ksignal
sparc: convert to ksignal
arm: switch to struct ksignal * passing
alpha: pass k_sigaction and siginfo_t using ksignal pointer
burying unused conditionals
make do_sigaltstack() static
arm64: switch to generic old sigaction() (compat-only)
arm64: switch to generic compat rt_sigaction()
arm64: switch compat to generic old sigsuspend
arm64: switch to generic compat rt_sigqueueinfo()
arm64: switch to generic compat rt_sigpending()
arm64: switch to generic compat rt_sigprocmask()
arm64: switch to generic sigaltstack
sparc: switch to generic old sigsuspend
sparc: COMPAT_SYSCALL_DEFINE does all sign-extension as well as SYSCALL_DEFINE
sparc: kill sign-extending wrappers for native syscalls
kill sparc32_open()
sparc: switch to use of generic old sigaction
sparc: switch sys_compat_rt_sigaction() to COMPAT_SYSCALL_DEFINE
mips: switch to generic sys_fork() and sys_clone()
...
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This adds the new transactional memory archtected state to the signal context
in both 32 and 64 bit.
Signed-off-by: Matt Evans <matt@ozlabs.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This include is no longer needed.
(seems to be a leftover from try_to_freeze())
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
|
