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Use bitop functions to implement cpu flag helper functions. This way
it is guaranteed that bits cannot get lost if modified in different
contexts on a cpu.
E.g. if process context is interrupted in the middle of a
read-modify-write sequence while modifying cpu flags, and within
interrupt context cpu flags are also modified, bits can get lost.
There is currently no code which is doing this, however upcoming code
could potentially run into this problem.
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use asm_inline for all inline assemblies which make use of the EX_TABLE or
ALTERNATIVE macros.
These macros expand to many lines and the compiler assumes the number of
lines within an inline assembly is the same as the number of instructions
within an inline assembly. This has an effect on inlining and loop
unrolling decisions.
In order to avoid incorrect assumptions use asm_inline, which tells the
compiler that an inline assembly has the smallest possible size.
In order to avoid confusion when asm_inline should be used or not, since a
couple of inline assemblies are quite large: the rule is to always use
asm_inline whenever the EX_TABLE or ALTERNATIVE macro is used. In specific
cases there may be reasons to not follow this guideline, but that should
be documented with the corresponding code.
Using the inline qualifier everywhere has only a small effect on the kernel
image size:
add/remove: 0/10 grow/shrink: 19/8 up/down: 1492/-1858 (-366)
The only location where this seems to matter is load_unaligned_zeropad()
from word-at-a-time.h where the compiler inlines more functions within the
dcache code, which is indeed code where performance matters.
Suggested-by: Juergen Christ <jchrist@linux.ibm.com>
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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exrl is present in all machines currently supported, therefore prefer
it over ex. This saves one instruction and doesn't need an additional
register to hold the address of the target instruction.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Any program interrupt that happens in the host during the execution of
a KVM guest will now short circuit the fault handler and return to KVM
immediately. Guest fault handling (including pfault) will happen
entirely inside KVM.
When sie64a() returns zero, current->thread.gmap_int_code will contain
the program interrupt number that caused the exit, or zero if the exit
was not caused by a host program interrupt.
KVM will now take care of handling all guest faults in vcpu_post_run().
Since gmap faults will not be visible by the rest of the kernel, remove
GMAP_FAULT, the linux fault handlers for secure execution faults, the
exception table entries for the sie instruction, the nop padding after
the sie instruction, and all other references to guest faults from the
s390 code.
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Co-developed-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20241022120601.167009-6-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Linux scheduler allows architectures to assign capacity values to
individual CPUs. This hints scheduler the performance difference between
CPUs and allows more efficient task distribution them. Implement
helper methods to set and get CPU capacities for s390. This is
particularly helpful in vertical polarization configurations of LPARs.
On vertical polarization an LPARs CPUs can get different polarization
values depending on the CEC configuration. CPUs with different
polarization values can perform different from each other, using CPU
capacities this can be reflected to linux scheduler.
Acked-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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CIF_SIE indicates if a thread is running in SIE context. This is the
state of a thread and not the CPU. Therefore move this indicator to
thread info.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The nospec implementation is deeply integrated into the alternatives
code: only for nospec an alternative facility list is implemented and
used by the alternative code, while it is modified by nospec specific
needs.
Push down the nospec alternative handling into the nospec by
introducing a new alternative type and a specific nospec callback to
decide if alternatives should be applied.
Also introduce a new global nobp variable which together with facility
82 can be used to decide if nobp is enabled or not.
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Rework alternatives to allow for callbacks. With this every
alternative entry has additional data encoded:
- When (aka context) an alternative is supposed to be applied
- The type of an alternative, which allows for type specific handling
and callbacks
- Extra type specific payload (patch information), which can be passed
to callbacks in order to decide if an alternative should be applied
or not
With this only the "late" context is implemented, which means there is
no change to the previous behaviour. All code is just converted to the
more generic new infrastructure.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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To allow testing flags for offline CPUs, move the CIF flags
to struct pcpu. To avoid having to calculate the array index
for each access, add a pointer to the pcpu member for the current
cpu to lowcore.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Replace all S390_lowcore usages in arch/s390/ by get_lowcore().
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Without __unitialized, the following code is generated when
INIT_STACK_ALL_ZERO is enabled:
86: d7 0f f0 a0 f0 a0 xc 160(16,%r15), 160(%r15)
8c: e3 40 f0 a0 00 24 stg %r4, 160(%r15)
92: c0 10 00 00 00 08 larl %r1, 0xa2
98: e3 10 f0 a8 00 24 stg %r1, 168(%r15)
9e: b2 b2 f0 a0 lpswe 160(%r15)
The xc is not adding any security because psw is fully initialized
with the following instructions. Add __unitialized to the psw
definitiation to avoid the superfluous clearing of psw.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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To ease maintenance and further enhancements, convert
the psw_idle() function to C.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Clear the backchain of the extra stack frame added by the vdso user wrapper
code. This allows the user stack walker to detect and skip the non-standard
stack frame. Without this an incorrect instruction pointer would be added
to stack traces, and stack frame walking would be continued with a more or
less random back chain.
Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support")
Reviewed-by: Jens Remus <jremus@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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When a program check, interrupt or machine check is triggered, the
PSW address is compared to a certain range of the sie64a() function
to figure out whether SIE was interrupted and a cleanup of SIE is
needed.
This doesn't work with kprobes: If kprobes probes an instruction, it
copies the instruction to the kprobes instruction page and overwrites the
original instruction with an undefind instruction (Opcode 00). When this
instruction is hit later, kprobes single-steps the instruction on the
kprobes_instruction page.
However, if this instruction is a relative branch instruction it will now
point to a different location in memory due to being moved to the kprobes
instruction page. If the new branch target points into sie64a() the kernel
assumes it interrupted SIE when processing the breakpoint and will crash
trying to access the SIE control block.
Instead of comparing the address, introduce a new CIF_SIE flag which
indicates whether SIE was interrupted.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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The first invocation of kernel_fpu_begin() after switching from user to
kernel context will save all vector registers, even if only parts of the
vector registers are used within the kernel fpu context. Given that save
and restore of all vector registers is quite expensive change the current
approach in several ways:
- Instead of saving and restoring all user registers limit this to those
registers which are actually used within an kernel fpu context.
- On context switch save all remaining user fpu registers, so they can be
restored when the task is rescheduled.
- Saving user registers within kernel_fpu_begin() is done without disabling
and enabling interrupts - which also slightly reduces runtime. In worst
case (e.g. interrupt context uses the same registers) this may lead to
the situation that registers are saved several times, however the
assumption is that this will not happen frequently, so that the new
method is faster in nearly all cases.
- save_user_fpu_regs() can still be called from all contexts and saves all
(or all remaining) user registers to a tasks ufpu user fpu save area.
Overall this reduces the time required to save and restore the user fpu
context for nearly all cases.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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KVM was the only user which modified the regs pointer in struct fpu. Remove
the pointer and convert the rest of the core fpu code to directly access
the save area embedded within struct fpu.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Make the kernel fpu context preemptible. Add another fpu structure to the
thread_struct, and use it to save and restore the kernel fpu context if its
task uses fpu registers when it is preempted.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Rename save_fpu_regs(), load_fpu_regs(), and struct thread_struct's fpu
member to save_user_fpu_regs(), load_user_fpu_regs(), and ufpu. This way
the function and variable names reflect for which context they are supposed
to be used.
This large and trivial conversion is a prerequisite for making the kernel
fpu usage preemptible.
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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The FPU state, as represented by the CIF_FPU flag reflects the FPU state of
a task, not the CPU it is running on. Therefore convert the flag to a
regular TIF flag.
This removes the magic in switch_to() where a save_fpu_regs() call for the
currently (previous) running task sets the per-cpu CIF_FPU flag, which is
required to restore FPU register contents of the next task, when it returns
to user space.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Move, rename, and merge the fpu and vx header files. This way fpu header
files have a consistent naming scheme (fpu*.h).
Also get rid of the fpu subdirectory and move header files to asm
directory, so that all fpu and vx header files can be found at the same
location.
Merge internal.h header file into other header files, since the internal
helpers are used at many locations. so those helper functions are really
not internal.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Alexander Gordeev:
- Add machine variable capacity information to /proc/sysinfo.
- Limit the waste of page tables and always align vmalloc area size and
base address on segment boundary.
- Fix a memory leak when an attempt to register interruption sub class
(ISC) for the adjunct-processor (AP) guest failed.
- Reset response code AP_RESPONSE_INVALID_GISA to understandable by
guest AP_RESPONSE_INVALID_ADDRESS in response to a failed
interruption sub class (ISC) registration attempt.
- Improve reaction to adjunct-processor (AP)
AP_RESPONSE_OTHERWISE_CHANGED response code when enabling interrupts
on behalf of a guest.
- Fix incorrect sysfs 'status' attribute of adjunct-processor (AP)
queue device bound to the vfio_ap device driver when the mediated
device is attached to a guest, but the queue device is not passed
through.
- Rework struct ap_card to hold the whole adjunct-processor (AP) card
hardware information. As result, all the ugly bit checks are replaced
by simple evaluations of the required bit fields.
- Improve handling of some weird scenarios between service element (SE)
host and SE guest with adjunct-processor (AP) pass-through support.
- Change local_ctl_set_bit() and local_ctl_clear_bit() so they return
the previous value of the to be changed control register. This is
useful if a bit is only changed temporarily and the previous content
needs to be restored.
- The kernel starts with machine checks disabled and is expected to
enable it once trap_init() is called. However the implementation
allows machine checks early. Consistently enable it in trap_init()
only.
- local_mcck_disable() and local_mcck_enable() assume that machine
checks are always enabled. Instead implement and use
local_mcck_save() and local_mcck_restore() to disable machine checks
and restore the previous state.
- Modification of floating point control (FPC) register of a traced
process using ptrace interface may lead to corruption of the FPC
register of the tracing process. Fix this.
- kvm_arch_vcpu_ioctl_set_fpu() allows to set the floating point
control (FPC) register in vCPU, but may lead to corruption of the FPC
register of the host process. Fix this.
- Use READ_ONCE() to read a vCPU floating point register value from the
memory mapped area. This avoids that, depending on code generation, a
different value is tested for validity than the one that is used.
- Get rid of test_fp_ctl(), since it is quite subtle to use it
correctly. Instead copy a new floating point control register value
into its save area and test the validity of the new value when
loading it.
- Remove superfluous save_fpu_regs() call.
- Remove s390 support for ARCH_WANTS_DYNAMIC_TASK_STRUCT. All machines
provide the vector facility since many years and the need to make the
task structure size dependent on the vector facility does not exist.
- Remove the "novx" kernel command line option, as the vector code runs
without any problems since many years.
- Add the vector facility to the z13 architecture level set (ALS). All
hypervisors support the vector facility since many years. This allows
compile time optimizations of the kernel.
- Get rid of MACHINE_HAS_VX and replace it with cpu_has_vx(). As
result, the compiled code will have less runtime checks and less
code.
- Convert pgste_get_lock() and pgste_set_unlock() ASM inlines to C.
- Convert the struct subchannel spinlock from pointer to member.
* tag 's390-6.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (24 commits)
Revert "s390: update defconfigs"
s390/cio: make sch->lock spinlock pointer a member
s390: update defconfigs
s390/mm: convert pgste locking functions to C
s390/fpu: get rid of MACHINE_HAS_VX
s390/als: add vector facility to z13 architecture level set
s390/fpu: remove "novx" option
s390/fpu: remove ARCH_WANTS_DYNAMIC_TASK_STRUCT support
KVM: s390: remove superfluous save_fpu_regs() call
s390/fpu: get rid of test_fp_ctl()
KVM: s390: use READ_ONCE() to read fpc register value
KVM: s390: fix setting of fpc register
s390/ptrace: handle setting of fpc register correctly
s390/nmi: implement and use local_mcck_save() / local_mcck_restore()
s390/nmi: consistently enable machine checks in trap_init()
s390/ctlreg: return old register contents when changing bits
s390/ap: handle outband SE bind state change
s390/ap: store TAPQ hwinfo in struct ap_card
s390/vfio-ap: fix sysfs status attribute for AP queue devices
s390/vfio-ap: improve reaction to response code 07 from PQAP(AQIC) command
...
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s390 selects ARCH_WANTS_DYNAMIC_TASK_STRUCT in order to make the size of
the task structure dependent on the availability of the vector
facility. This doesn't make sense anymore because since many years all
machines provide the vector facility.
Therefore simplify the code a bit and remove s390 support for
ARCH_WANTS_DYNAMIC_TASK_STRUCT.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Instead of using local_mcck_disable() / local_mcck_enable() implement and
use local_mcck_save() / local_mcck_restore() to disable machine checks, and
restoring the previous state.
The problem with using local_mcck_disable() / local_mcck_enable() is that
there is an assumption that machine checks are always enabled. While this
is currently the case the code still looks quite odd, readers need to
double check if the code is correct.
In order to increase readability save and then restore the old machine
check mask bit, instead of assuming that it must have been enabled.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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In the meantime hopefully most people got used to forward
declarations, therefore remove the explanation.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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Provide an s390 specific __stackleak_poison() implementation which is
faster than the generic variant.
For the original implementation with an enforced 4kb stackframe for the
getpid() system call the system call overhead increases by a factor of 3 if
the stackleak feature is enabled. Using the s390 mvc based variant this is
reduced to an increase of 25% instead.
This is within the expected area, since the mvc based implementation is
more or less a memset64() variant which comes with similar results. See
commit 0b77d6701cf8 ("s390: implement memset16, memset32 & memset64").
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20230405130841.1350565-3-hca@linux.ibm.com
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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As preparation for the stackleak feature move on_thread_stack() to
processor.h like x86.
Also make it __always_inline, and slightly optimize it by reading
current task's kernel stack pointer from lowcore.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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There is no point in changing branch prediction state of a cpu shortly
before it enters stop state. Therefore remove __bpon().
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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s390_isolate_bp_guest() is unused. Remove it.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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TIF_ISOLATE_BP is unused since it was introduced with commit 6b73044b2b00
("s390: run user space and KVM guests with modified branch prediction").
Given that there is no use case remove it again.
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Add test_and_set_cpu_flag() and test_and_clear_cpu_flag() helper functions.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Let cpu helper functions return boolean values. This also allows to
make the code a bit simpler by getting rid of the "!!" construct.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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arch_cpu_idle() is marked noinstr and therefore must only call functions
which are also not instrumented.
Make sure that cpu flag helper functions are always inlined to avoid that
the compiler generates an out-of-line function for e.g. the call within
arch_cpu_idle().
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Commit 30de14b1884b ("s390: current_stack_pointer shouldn't be a
function") made current_stack_pointer a global register variable like
on many other architectures. Unfortunately on s390 it uncovers old
gcc bug which is fixed only since gcc-9.1 [gcc commit 3ad7fed1cc87
("S/390: Fix PR89775. Stackpointer save/restore instructions removed")]
and backported to gcc-8.4 and later. Due to this bug gcc versions prior
to 8.4 generate broken code which leads to stack corruptions.
Current minimal gcc version required to build the kernel is declared
as 5.1. It is not possible to fix all old gcc versions, so work
around this problem by avoiding using global register variable for
current_stack_pointer.
Fixes: 30de14b1884b ("s390: current_stack_pointer shouldn't be a function")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- hfs and hfsplus kmap API modernization (Fabio Francesco)
- make crash-kexec work properly when invoked from an NMI-time panic
(Valentin Schneider)
- ntfs bugfixes (Hawkins Jiawei)
- improve IPC msg scalability by replacing atomic_t's with percpu
counters (Jiebin Sun)
- nilfs2 cleanups (Minghao Chi)
- lots of other single patches all over the tree!
* tag 'mm-nonmm-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (71 commits)
include/linux/entry-common.h: remove has_signal comment of arch_do_signal_or_restart() prototype
proc: test how it holds up with mapping'less process
mailmap: update Frank Rowand email address
ia64: mca: use strscpy() is more robust and safer
init/Kconfig: fix unmet direct dependencies
ia64: update config files
nilfs2: replace WARN_ONs by nilfs_error for checkpoint acquisition failure
fork: remove duplicate included header files
init/main.c: remove unnecessary (void*) conversions
proc: mark more files as permanent
nilfs2: remove the unneeded result variable
nilfs2: delete unnecessary checks before brelse()
checkpatch: warn for non-standard fixes tag style
usr/gen_init_cpio.c: remove unnecessary -1 values from int file
ipc/msg: mitigate the lock contention with percpu counter
percpu: add percpu_counter_add_local and percpu_counter_sub_local
fs/ocfs2: fix repeated words in comments
relay: use kvcalloc to alloc page array in relay_alloc_page_array
proc: make config PROC_CHILDREN depend on PROC_FS
fs: uninline inode_maybe_inc_iversion()
...
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Function memcpy_real() is an univeral data mover that does not
require DAT mode to be able reading from a physical address.
Its advantage is an ability to read from any address, even
those for which no kernel virtual mapping exists.
Although memcpy_real() is interrupt-safe, there are no handlers
that make use of this function. The compiler instrumentation
have to be disabled and separate no-DAT stack used to allow
execution of the function once DAT mode is disabled.
Rework memcpy_real() to overcome these shortcomings. As result,
data copying (which is primarily reading out a crashed system
memory by a user process) is executed on a regular stack with
enabled interrupts. Also, use of memcpy_real_buf swap buffer
becomes unnecessary and the swapping is eliminated.
The above is achieved by using a fixed virtual address range
that spans a single page and remaps that page repeatedly when
memcpy_real() is called for a particular physical address.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Temporary unsetting of the prefix page in memcpy_absolute() routine
poses a risk of executing code path with unexpectedly disabled prefix
page. This rework avoids the prefix page uninstalling and disabling
of normal and machine check interrupts when accessing the absolute
zero memory.
Although memcpy_absolute() routine can access the whole memory, it is
only used to update the absolute zero lowcore. This rework therefore
introduces a new mechanism for the absolute zero lowcore access and
scraps memcpy_absolute() routine for good.
Instead, an area is reserved in the virtual memory that is used for
the absolute lowcore access only. That area holds an array of 8KB
virtual mappings - one per CPU. Whenever a CPU is brought online, the
corresponding item is mapped to the real address of the previously
installed prefix page.
The absolute zero lowcore access works like this: a CPU calls the
new primitive get_abs_lowcore() to obtain its 8KB mapping as a
pointer to the struct lowcore. Virtual address references to that
pointer get translated to the real addresses of the prefix page,
which in turn gets swapped with the absolute zero memory addresses
due to prefixing. Once the pointer is not needed it must be released
with put_abs_lowcore() primitive:
struct lowcore *abs_lc;
unsigned long flags;
abs_lc = get_abs_lowcore(&flags);
abs_lc->... = ...;
put_abs_lowcore(abs_lc, flags);
To ensure the described mechanism works large segment- and region-
table entries must be avoided for the 8KB mappings. Failure to do
so results in usage of Region-Frame Absolute Address (RFAA) or
Segment-Frame Absolute Address (SFAA) large page fields. In that
case absolute addresses would be used to address the prefix page
instead of the real ones and the prefixing would get bypassed.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Only x86 has own release_thread(), introduce a new weak release_thread()
function to clean empty definitions in other ARCHs.
Link: https://lkml.kernel.org/r/20220819014406.32266-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Guo Ren <guoren@kernel.org> [csky]
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Brian Cain <bcain@quicinc.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Acked-by: Stafford Horne <shorne@gmail.com> [openrisc]
Acked-by: Catalin Marinas <catalin.marinas@arm.com> [arm64]
Acked-by: Huacai Chen <chenhuacai@kernel.org> [LoongArch]
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Guo Ren <guoren@kernel.org> [csky]
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Xuerui Wang <kernel@xen0n.name>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Due to historic reasons the base program check handler calls a
configurable function. Given that there is only the early program
check handler left, simplify the code by directly calling that
function.
The only other user was removed with commit d485235b0054 ("s390:
assume diag308 set always works").
Also rename all functions and the asm file to reflect this.
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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In the current code vdso is mapped below the stack. This is
problematic when programs mapped to the top of the address space
are allocating a lot of memory, because the heap will clash with
the vdso. To avoid this map the vdso above the stack and move
STACK_TOP so that it all fits into three level paging.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
|
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This is a preparation patch for adding vdso randomization to s390.
It adds a function vdso_size(), which will be used later in calculating
the STACK_TOP value. It also moves the vdso mapping into a new function
vdso_map(), to keep the code similar to other architectures.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
|
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s390 defines current_stack_pointer as function while all other
architectures use 'register unsigned long asm("<stackptr reg>").
This make codes like the following from check_stack_object() fail:
if (IS_ENABLED(CONFIG_STACK_GROWSUP)) {
if ((void *)current_stack_pointer < obj + len)
return BAD_STACK;
} else {
if (obj < (void *)current_stack_pointer)
return BAD_STACK;
}
because this would compare the address of current_stack_pointer() and
not the stackpointer value.
Reported-by: Karsten Graul <kgraul@linux.ibm.com>
Fixes: 2792d84e6da5 ("usercopy: Check valid lifetime via stack depth")
Cc: Kees Cook <keescook@chromium.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
|
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Macro mem_assign_absolute() is able to access the whole memory, but
is only used and makes sense when updating the absolute lowcore.
Instead, introduce get_abs_lowcore() and put_abs_lowcore() macros
that limit access to absolute lowcore addresses only.
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
|
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With z10 as minimum supported machine generation many ".insn" encodings
could be now converted to instruction names. There are couple of exceptions
- stfle is used from the als code built for z900 and cannot be converted
- few ".insn" directives encode unsupported instruction formats
The generated code is identical before/after this change.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
|
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Pass pt_regs to early program check handler like it is done for every
other interrupt and exception handler.
Also the passed pt_regs can be changed by the called function and the
changes register contents and psw contents will be taken into account
when returning. In addition the return psw will not be copied to the
program check old psw in lowcore, but to the usual return psw
location, like it is also done by the regular program check handler.
This allows also to get rid of the code that disabled lowcore
protection when changing the return address.
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
|
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There is a confusion with regard to the source address of
memcpy_real() and calling functions. While the declared
type for a source assumes a virtual address, in fact it
always called with physical address of the source.
This confusion led to bugs in copy_oldmem_kernel() and
copy_oldmem_user() functions, where __pa() macro applied
mistakenly to physical addresses. It does not lead to a
real issue, since virtual and physical addresses are
currently the same.
Fix both the bugs and memcpy_real() prototype by making
type of source address consistent to the function name
and the way it actually used.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
|
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This macro isn't used in Linux sched, now. Delete in
include/linux/sched.h and arch's include/asm.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20211228064730.2882351-6-guoren@kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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Having a stable wchan means the process must be blocked and for it to
stay that way while performing stack unwinding.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> [arm]
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Link: https://lkml.kernel.org/r/20211008111626.332092234@infradead.org
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The restart interrupt is triggered whenever a secondary CPU is
brought online, a remote function call dispatched from another
CPU or a manual PSW restart is initiated and causes the system
to kdump. The handling routine is always called with DAT turned
off. It then initializes the stack frame and invokes a callback.
The existing callbacks handle DAT as follows:
* __do_restart() and __machine_kexec() turn in on upon entry;
* __ipl_run(), __reipl_run() and __dump_run() do not turn it
right away, but all of them call diag308() - which turns DAT
on, but only if kasan is enabled;
In addition to the described complexity all callbacks (and the
functions they call) should avoid kasan instrumentation while
DAT is off.
This update enables DAT in the assembler restart handler and
relieves any callbacks (which are mostly C functions) from
dealing with DAT altogether.
There are four types of CPU restart that initialize control
registers in different ways:
1. Start of secondary CPU on boot - control registers are
inherited from the IPL CPU;
2. Restart of online CPU - control registers of the CPU being
restarted are kept;
3. Hotplug of offline CPU - control registers are inherited
from the starting CPU;
4. Start of offline CPU triggered by manual PSW restart -
the control registers are read from the absolute lowcore
and contain the boot time IPL CPU values updated with all
follow-up calls of smp_ctl_set_bit() and smp_ctl_clear_bit()
routines;
In first three cases contents of the control registers is the
most recent. In the latter case control registers are good
enough to facilitate successful completion of kdump operation.
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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s390 is the only architecture which makes use of the __no_kasan_or_inline
attribute for two functions. Given that both stap() and __load_psw_mask()
are very small functions they can and should be always inlined anyway.
Therefore get rid of __no_kasan_or_inline and always inline these
functions.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
|
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gcc-11 warns:
arch/s390/kernel/traps.c: In function __do_pgm_check:
arch/s390/kernel/traps.c:319:17: warning: memcpy reading 256 bytes from a region of size 0 [-Wstringop-overread]
319 | memcpy(¤t->thread.trap_tdb, &S390_lowcore.pgm_tdb, 256);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fix this by adding a struct pgm_tdb to struct lowcore and copy that.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
|
