- 14 Feb, 2023 2 commits
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Gerald Schaefer authored
RDP instruction allows to reset DAT-protection bit in a PTE, with less CPU synchronization overhead than IPTE instruction. In particular, IPTE can cause machine-wide synchronization overhead, and excessive IPTE usage can negatively impact machine performance. RDP can be used instead of IPTE, if the new PTE only differs in SW bits and _PAGE_PROTECT HW bit, for PTE protection changes from RO to RW. SW PTE bit changes are allowed, e.g. for dirty and young tracking, but none of the other HW-defined part of the PTE must change. This is because the architecture forbids such changes to an active and valid PTE, which is why invalidation with IPTE is always used first, before writing a new entry. The RDP optimization helps mainly for fault-driven SW dirty-bit tracking. Writable PTEs are initially always mapped with HW _PAGE_PROTECT bit set, to allow SW dirty-bit accounting on first write protection fault, where the DAT-protection would then be reset. The reset is now done with RDP instead of IPTE, if RDP instruction is available. RDP cannot always guarantee that the DAT-protection reset is propagated to all CPUs immediately. This means that spurious TLB protection faults on other CPUs can now occur. For this, common code provides a flush_tlb_fix_spurious_fault() handler, which will now be used to do a CPU-local TLB flush. However, this will clear the whole TLB of a CPU, and not just the affected entry. For more fine-grained flushing, by simply doing a (local) RDP again, flush_tlb_fix_spurious_fault() would need to also provide the PTE pointer. Note that spurious TLB protection faults cannot really be distinguished from racing pagetable updates, where another thread already installed the correct PTE. In such a case, the local TLB flush would be unnecessary overhead, but overall reduction of CPU synchronization overhead by not using IPTE is still expected to be beneficial. Reviewed-by:
Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by:
Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by:
Heiko Carstens <hca@linux.ibm.com>
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Peter Xu authored
The current definition already collapse with the generic definition of vm_fault_reason. Move the private definitions to allocate bits from the top of uint so they won't collapse anymore. Signed-off-by:
Peter Xu <peterx@redhat.com> Link: https://lore.kernel.org/r/20230205231704.909536-4-peterx@redhat.comSigned-off-by:
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- 10 Feb, 2023 4 commits
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Randy Dunlap authored
Correct spelling problems for Documentation/s390/ as reported by codespell. Signed-off-by:
Randy Dunlap <rdunlap@infradead.org> Acked-by:
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Halil Pasic authored
Since commit 159491f3 ("s390/ap: rework assembler functions to use unions for in/out register variables") the function ap_qact() tries to grab the status from the wrong part of the register. Thus we always end up with zeros. Which is wrong, among others, because we detect failures via status.response_code. Signed-off-by:
Halil Pasic <pasic@linux.ibm.com> Reported-by:
Harald Freudenberger <freude@linux.ibm.com> Fixes: 159491f3 ("s390/ap: rework assembler functions to use unions for in/out register variables") Reviewed-by:
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Halil Pasic authored
There function ap_aqic() tries to grab the status from the wrong part of the register. Thus we always end up with zeros. Which is wrong, among others, because we detect failures via status.response_code. Signed-off-by:
Janosch Frank <frankja@linux.ibm.com> Fixes: 159491f3 ("s390/ap: rework assembler functions to use unions for in/out register variables") Reviewed-by:
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Halil Pasic authored
The NIB is architecturally invalid if the address designates a storage location that is not installed or if it is zero. Signed-off-by:
Tony Krowiak <akrowiak@linux.ibm.com> Reviewed-by:
Pierre Morel <pmorel@linux.ibm.com> Signed-off-by:
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- 09 Feb, 2023 10 commits
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Heiko Carstens authored
This reverts commit cbc29f10. Get rid of the following smatch warnings: arch/s390/include/asm/mem_detect.h:86 get_mem_detect_end() error: uninitialized symbol 'end'. arch/s390/include/asm/mem_detect.h:86 get_mem_detect_end() error: uninitialized symbol 'end'. arch/s390/boot/vmem.c:256 setup_vmem() error: uninitialized symbol 'start'. arch/s390/boot/vmem.c:258 setup_vmem() error: uninitialized symbol 'end'. Note that there is no bug in the code. This is purely to silence smatch. Reported-by:
kernel test robot <lkp@intel.com> Reported-by:
Dan Carpenter <error27@gmail.com> Signed-off-by:
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Heiko Carstens authored
arch_cpu_idle_time() returns the idle time of any given cpu if it is in idle, or zero if not. All if this is racy and partially incorrect. Time stamps taken with store clock extended and store clock fast from different cpus are compared, while the architecture states that this is nothing which can be relied on (see Principles of Operation; Chapter 4, "Setting and Inspecting the Clock"). A more fundamental problem is that the timestamp when a cpu is leaving idle is taken early in the assembler part of the interrupt handler, and this value is only transferred many cycles later to the cpu's per-cpu idle data structure. This per cpu data structure is read by arch_cpu_idle() to tell for which period of time a remote cpu is idle: if only an idle_enter value is present, the assumed idle time of the cpu is calculated by taking a local timestamp and returning the difference of the local timestamp and the idle_enter value. This is potentially incorrect, since the remote cpu may have already left idle, but the taken timestamp may not have been transferred to the per-cpu data structure. This in turn means that too much idle time may be reported for a cpu, and a subsequent calculation of system idle time may result in a smaller value. Instead of coming up with even more complex code trying to fix this, just remove this code, and only account idle time of a cpu, after idle state is left. Another minor bug is that it is assumed that timestamps are non-zero, which is not necessarily the case for timestamps taken with store clock fast. This however is just a very minor problem, since this can only happen when the epoch increases. Reviewed-by:
Sven Schnelle <svens@linux.ibm.com> Signed-off-by:
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Heiko Carstens authored
Use simple assignments to access __vector128 members instead of hard to read casts. Signed-off-by: -
Heiko Carstens authored
Add 64 and 128 bit members to __vector128 struct in order to allow reading of the complete value, or the higher or lower part of vector register contents instead of having to use casts. Add an explicit __aligned(4) statement to avoid that the alignment of the structure changes from 4 to 8. This should make sure that no breakage happens because of this change. Reviewed-by:
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Heiko Carstens authored
The diag288_wdt watchdog driver is s390 specific. Document who is responsible for this driver. Signed-off-by: -
Vineeth Vijayan authored
Storage Class Memory driver support for s390 architecture has been there for a while. The original author of this work, Sebastian Ott has left IBM and I am taking over this module. Adding myself as the upstream maintainer for SCM on s390 architecture. Signed-off-by:
Vineeth Vijayan <vneethv@linux.ibm.com> Acked-by:
Peter Oberparleiter <oberpar@linux.ibm.com> Signed-off-by:
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Heiko Carstens authored
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:
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Heiko Carstens authored
linux-next commit ("cpuidle: tracing: Warn about !rcu_is_watching()") adds a new warning which hits on s390's arch_cpu_idle() function: RCU not on for: arch_cpu_idle+0x0/0x28 WARNING: CPU: 2 PID: 0 at include/linux/trace_recursion.h:162 arch_ftrace_ops_list_func+0x24c/0x258 Modules linked in: CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.2.0-rc6-next-20230202 #4 Hardware name: IBM 8561 T01 703 (z/VM 7.3.0) Krnl PSW : 0404d00180000000 00000000002b55c0 (arch_ftrace_ops_list_func+0x250/0x258) R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 RI:0 EA:3 Krnl GPRS: c0000000ffffbfff 0000000080000002 0000000000000026 0000000000000000 0000037ffffe3a28 0000037ffffe3a20 0000000000000000 0000000000000000 0000000000000000 0000000000f4acf6 00000000001044f0 0000037ffffe3cb0 0000000000000000 0000000000000000 00000000002b55bc 0000037ffffe3bb8 Krnl Code: 00000000002b55b0: c02000840051 larl %r2,0000000001335652 00000000002b55b6: c0e5fff512d1 brasl %r14,0000000000157b58 #00000000002b55bc: af000000 mc 0,0 >00000000002b55c0: a7f4ffe7 brc 15,00000000002b558e 00000000002b55c4: 0707 bcr 0,%r7 00000000002b55c6: 0707 bcr 0,%r7 00000000002b55c8: eb6ff0480024 stmg %r6,%r15,72(%r15) 00000000002b55ce: b90400ef lgr %r14,%r15 Call Trace: [<00000000002b55c0>] arch_ftrace_ops_list_func+0x250/0x258 ([<00000000002b55bc>] arch_ftrace_ops_list_func+0x24c/0x258) [<0000000000f5f0fc>] ftrace_common+0x1c/0x20 [<00000000001044f6>] arch_cpu_idle+0x6/0x28 [<0000000000f4acf6>] default_idle_call+0x76/0x128 [<00000000001cc374>] do_idle+0xf4/0x1b0 [<00000000001cc6ce>] cpu_startup_entry+0x36/0x40 [<0000000000119d00>] smp_start_secondary+0x140/0x150 [<0000000000f5d2ae>] restart_int_handler+0x6e/0x90 Mark arch_cpu_idle() noinstr like all other architectures with CONFIG_ARCH_WANTS_NO_INSTR (should) have it to fix this. Reviewed-by: -
Heiko Carstens authored
There is no reason to do idle time accounting in arch_cpu_idle(). Do idle time accounting in account_idle_time_irq(), where it belongs to. The accounted values don't change between account_idle_time_irq() and arch_cpu_idle(); so the result is the same. Reviewed-by:
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Heiko Carstens authored
Signed-off-by:
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- 06 Feb, 2023 23 commits
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Alexander Egorenkov authored
Change naming of the internal diag288 helper functions to improve overall readability and reduce confusion: * Rename __diag288() to diag288(). * Get rid of the misnamed helper __diag288_lpar() that was used not only on LPARs but also zVM and KVM systems. * Rename __diag288_vm() to diag288_str(). Reviewed-by:
Alexander Egorenkov <egorenar@linux.ibm.com> Reviewed-by:
Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20230203073958.1585738-6-egorenar@linux.ibm.comSigned-off-by:
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Alexander Egorenkov authored
Call diag_stat_inc() from __diag288() to reduce code duplication. Reviewed-by:
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Alexander Egorenkov authored
Simplify and de-duplicate code by introducing a common single command buffer allocated once at initialization. Moreover, simplify the interface of __diag288_vm() by accepting ASCII strings as the command parameter and converting it to the EBCDIC format within the function itself. Reviewed-by:
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Alexander Egorenkov authored
Remove power management because s390 no longer supports hibernation since commit 39421627 ("s390: remove broken hibernate / power management support"). Reviewed-by:
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Alexander Egorenkov authored
Using register asm statements has been proven to be very error prone, especially when using code instrumentation where gcc may add function calls, which clobbers register contents in an unexpected way. Therefore, get rid of register asm statements in watchdog code, and make sure this bug class cannot happen. Moreover, remove the register r1 from the clobber list because this register is not changed by DIAG 288. Reviewed-by:
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Heiko Carstens authored
Signed-off-by: -
Vasily Gorbik authored
Fixes: bb1520d5 ("s390/mm: start kernel with DAT enabled") Reviewed-by:
Vasily Gorbik <gor@linux.ibm.com> Signed-off-by:
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Vasily Gorbik authored
Facilities setup has to be done after "facilities" command line option parsing, it might set extra or remove existing facilities bits for testing purposes. Fixes: bb1520d5 ("s390/mm: start kernel with DAT enabled") Reviewed-by:
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Vasily Gorbik authored
KASAN common code is able to handle memory hotplug and create KASAN shadow memory on a fly. Online memory ranges are available from mem_detect, use this information to avoid mapping KASAN shadow for standby memory. Reviewed-by:
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Vasily Gorbik authored
If kernel is build without KASAN support there is a chance that kernel image is going to be positioned by KASLR code to overlap with identity mapping page tables. When kernel is build with KASAN support enabled memory which is potentially going to be used for page tables and KASAN shadow mapping is accounted for in KASLR with the use of kasan_estimate_memory_needs(). Split this function and introduce vmem_estimate_memory_needs() to cover decompressor's vmem identity mapping page tables. Fixes: bb1520d5 ("s390/mm: start kernel with DAT enabled") Reviewed-by:
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Vasily Gorbik authored
Add a function to get online memory in total. It is supposed to be used in the decompressor as well as during early kernel startup. Reviewed-by:
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Vasily Gorbik authored
Introduce mem_detect_truncate() to cut any online memory ranges above established identity mapping size, so that mem_detect users wouldn't have to do it over and over again. Suggested-by:
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Vasily Gorbik authored
Allocation of mem_detect extended area was not considered neither in commit 9641b8cc ("s390/ipl: read IPL report at early boot") nor in commit b2d24b97 ("s390/kernel: add support for kernel address space layout randomization (KASLR)"). As a result mem_detect extended theoretically may overlap with ipl report or randomized kernel image position. But as mem_detect code will allocate extended area only upon exceeding 255 online regions (which should alternate with offline memory regions) it is not seen in practice. To make sure mem_detect extended area does not overlap with ipl report or randomized kernel position extend usage of "safe_addr". Make initrd handling and mem_detect extended area allocation code move it further right and make KASLR takes in into consideration as well. Fixes: 9641b8cc ("s390/ipl: read IPL report at early boot") Fixes: b2d24b97 ("s390/kernel: add support for kernel address space layout randomization (KASLR)") Reviewed-by:
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Vasily Gorbik authored
In case sclp_early_get_memsize() fails but diag260() succeeds make sure some sane value is returned. This error scenario is highly unlikely, but this change makes system able to boot in such case. Suggested-by:
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Heiko Carstens authored
Get rid of this sparse warning: arch/s390/kernel/diag.c:69:29: warning: symbol '__diag8c_tmp_amode31' was not declared. Should it be static? Fixes: fbaee746 ("s390/tty3270: add support for diag 8c") Signed-off-by:
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Heiko Carstens authored
Compiling the kernel with CONFIG_KPROBES disabled, but CONFIG_RETHOOK enabled, results in this sparse warning: arch/s390/kernel/rethook.c:26:15: warning: no previous prototype for 'arch_rethook_trampoline_callback' [-Wmissing-prototypes] 26 | unsigned long arch_rethook_trampoline_callback(struct pt_regs *regs) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Add a local rethook header file similar to riscv to address this. Reported-by: -
Vasily Gorbik authored
Kasan shadow memory area has been moved to the end of kernel address space since commit 9a39abb7 ("s390/boot: simplify and fix kernel memory layout setup"), therefore skipping any memory ranges above VMALLOC_START in empty page tables cleanup code already handles KASAN shadow memory intersection case and explicit checks could be removed. Reviewed-by:
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Vasily Gorbik authored
Commit b9ff8100 ("s390/vmem: cleanup empty page tables") introduced empty page tables cleanup in vmem code, but when the kernel is built with KASAN enabled the code has no effect due to wrong KASAN shadow memory intersection condition, which effectively ignores any memory range below KASAN shadow. Fix intersection condition to make code work as anticipated. Fixes: b9ff8100 ("s390/vmem: cleanup empty page tables") Reviewed-by:
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Vasily Gorbik authored
Kasan shadow memory area has been moved to the end of kernel address space since commit 9a39abb7 ("s390/boot: simplify and fix kernel memory layout setup"). Change kasan memory layout note accordingly. Reviewed-by:
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Vasily Gorbik authored
Currently if for some reason sclp_early_read_info() fails, sclp_early_get_memsize() will not set max_physmem_end and it will stay uninitialized. Any garbage value other than 0 will lead to detect_memory() taking wrong path or returning a garbage value as max_physmem_end. To avoid that simply initialize max_physmem_end. Fixes: 73045a08 ("s390: unify identity mapping limits handling") Reported-by:
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Heiko Carstens authored
Given that strlcpy() is deprecated use strscpy() instead. Signed-off-by: -
Sven Schnelle authored
commit 87fd22e0 ("s390/ipl: add eckd support") missed to add the loadparm attribute to the new eckd ipl/reipl data. Fixes: 87fd22e0 ("s390/ipl: add eckd support") Cc: <stable@vger.kernel.org> Signed-off-by:
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Sven Schnelle authored
In the current code each reipl type implements its own pair of loadparm show/store functions. Add a macro to deduplicate the code a bit. Reviewed-by:
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- 31 Jan, 2023 1 commit
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Alexander Gordeev authored
Function __get_mem_detect_block() resets start and end output parameters in case of invalid mem_detect array index is provided. That violates the rule of sparing the output on fail path and leads e.g to a below anomaly: for_each_mem_detect_block(i, &start, &end) continue; One would expect start and end contain addresses of the last memory block (if available), but in fact the two will be reset to zeroes. That is not how an iterator is expected to work. Reviewed-by:
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