- 21 Jul, 2020 3 commits
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Aneesh Kumar K.V authored
With commit 4a4a5e5d ("powerpc/pkeys: key allocation/deallocation must not change pkey registers") we are not updating UAMOR on key allocation. So don't update the expected uamor value in the test. Fixes: 4a4a5e5d ("powerpc/pkeys: key allocation/deallocation must not change pkey registers") Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-23-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-22-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Rename variable to indicate that they are invalid values which we will use to test ptrace update of pkeys. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-21-aneesh.kumar@linux.ibm.com
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- 20 Jul, 2020 26 commits
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Aneesh Kumar K.V authored
UAMOR values are not application-specific. The kernel initializes its value based on different reserved keys. Remove the thread-specific UAMOR value and don't switch the UAMOR on context switch. Move UAMOR initialization to key initialization code and remove thread_struct.uamor because it is not used anymore. Before commit: 4a4a5e5d ("powerpc/pkeys: key allocation/deallocation must not change pkey registers") we used to update uamor based on key allocation and free. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-20-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
As we kexec across kernels that use AMR/IAMR for different purposes we need to ensure that new kernels get kexec'd with a reset value of AMR/IAMR. For ex: the new kernel can use key 0 for kernel mapping and the old AMR value prevents access to key 0. This patch also removes reset if IAMR and AMOR in kexec_sequence. Reset of AMOR is not needed and the IAMR reset is partial (it doesn't do the reset on secondary cpus) and is redundant with this patch. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-19-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-18-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Instead of pkey_disabled static key use mmu feature MMU_FTR_PKEY. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-17-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Use pkey_execute_disable_supported to check for execute key support instead of pkey_disabled. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-16-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
This will be used to enable/disable Kernel Userspace Execution Prevention (KUEP). Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-15-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Parse storage keys related device tree entry in early_init_devtree and enable MMU feature MMU_FTR_PKEY if pkeys are supported. MMU feature is used instead of CPU feature because this enables us to group MMU_FTR_KUAP and MMU_FTR_PKEY in asm feature fixup code. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-14-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
The hypervisor can return less than max allowed pkey (for ex: 31) instead of 32. We should mark all the pkeys above max allowed as reserved so that we avoid the allocation of the wrong pkey(for ex: key 31 in the above case) by userspace. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-13-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
initial_allocation_mask is not used outside this file. Also mark reserved_allocation_mask and initial_allocation_mask __ro_after_init; Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-12-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
num_pkey now represents max number of keys supported such that we return to userspace 0 - num_pkey - 1. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-11-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Make the default value FALSE (pkey enabled) and set to TRUE when we find the total number of keys supported to be zero. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-10-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
We don't use CPU_FTR_PKEY anymore. Remove the feature bit and mark it free. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-9-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Key 1 is marked reserved by ISA. Setup uamor to prevent userspace modification of the same. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-8-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Add documentation explaining the execute_only_key. The reservation and initialization mask details are also explained in this patch. No functional change in this patch. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-7-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
This explains the details w.r.t key 1. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-6-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
To keep things simple, all the pkey related bits are kept together in linux page table for 64K config with hash translation. With hash-4k kernel requires 4 bits to store slots details. This is done by overloading some of the RPN bits for storing the slot details. Due to this PKEY_BIT0 on the 4K config is used for storing hash slot details. 64K before |....|RSV1| RSV2| RSV3 | RSV4 | RPN44| RPN43 |.... | RSV5| |....| P4 | P3 | P2 | P1 | Busy | HASHPTE |.... | P0 | after |....|RSV1| RSV2| RSV3 | RSV4 | RPN44 | RPN43 |.... | RSV5 | |....| P4 | P3 | P2 | P1 | P0 | HASHPTE |.... | Busy | 4k before |....| RSV1 | RSV2 | RSV3 | RSV4 | RPN44| RPN43.... | RSV5| |....| Busy | HASHPTE | P2 | P1 | F_SEC| F_GIX.... | P0 | after |....| RSV1 | RSV2| RSV3 | RSV4 | Free | RPN43.... | RSV5 | |....| HASHPTE | P2 | P1 | P0 | F_SEC| F_GIX.... | BUSY | Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-5-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-4-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
This number the pkey bit such that it is easy to follow. PKEY_BIT0 is the lower order bit. This makes further changes easy to follow. No functional change in this patch other than linux page table for hash translation now maps pkeys differently. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-3-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
We are wrongly using CPU_FTRS_POWER8 to check for P8 support. Instead, we should use PVR value. Now considering we are using CPU_FTRS_POWER8, that implies we returned true for P9 with older firmware. Keep the same behavior by checking for P9 PVR value. Fixes: cf43d3b2 ("powerpc: Enable pkey subsystem") Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709032946.881753-2-aneesh.kumar@linux.ibm.com
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Santosh Sivaraj authored
Subscribe to the MCE notification and add the physical address which generated a memory error to nvdimm bad range. Signed-off-by: Santosh Sivaraj <santosh@fossix.org> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709135142.721504-2-santosh@fossix.org
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Santosh Sivaraj authored
Introduce notification chain which lets us know about uncorrected memory errors(UE). This would help prospective users in pmem or nvdimm subsystem to track bad blocks for better handling of persistent memory allocations. Signed-off-by: Santosh Sivaraj <santosh@fossix.org> Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709135142.721504-1-santosh@fossix.org
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Aneesh Kumar K.V authored
To enable memory unplug without splitting kernel page table mapping, we force the max mapping size to the LMB size. LMB size is the unit in which hypervisor will do memory add/remove operation. Pseries systems supports max LMB size of 256MB. Hence on pseries, we now end up mapping memory with 2M page size instead of 1G. To improve that we want hypervisor to hint the kernel about the hotplug memory range. That was added that as part of commit b6eca183 ("powerpc/kernel: Enables memory hot-remove after reboot on pseries guests") But PowerVM doesn't provide that hint yet. Once we get PowerVM updated, we can then force the 2M mapping only to hot-pluggable memory region using memblock_is_hotpluggable(). Till then let's depend on LMB size for finding the mapping page size for linear range. With this change KVM guest will also be doing linear mapping with 2M page size. The actual TLB benefit of mapping guest page table entries with hugepage size can only be materialized if the partition scoped entries are also using the same or higher page size. A guest using 1G hugetlbfs backing guest memory can have a performance impact with the above change. Signed-off-by: Bharata B Rao <bharata@linux.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> [mpe: Fold in fix from Aneesh spotted by lkp@intel.com] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709131925.922266-5-aneesh.kumar@linux.ibm.com
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Bharata B Rao authored
We split the page table mapping on memory unplug if the linear range was mapped with huge page mapping (for ex: 1G) The page table splitting code has a few issues: 1. Recursive locking -------------------- Memory unplug path takes cpu_hotplug_lock and calls stop_machine() for splitting the mappings. However stop_machine() takes cpu_hotplug_lock again causing deadlock. 2. BUG: sleeping function called from in_atomic() context --------------------------------------------------------- Memory unplug path (remove_pagetable) takes init_mm.page_table_lock spinlock and later calls stop_machine() which does wait_for_completion() 3. Bad unlock unbalance ----------------------- Memory unplug path takes init_mm.page_table_lock spinlock and calls stop_machine(). The stop_machine thread function runs in a different thread context (migration thread) which tries to release and reaquire ptl. Releasing ptl from a different thread than which acquired it causes bad unlock unbalance. These problems can be avoided if we avoid mapping hot-plugged memory with 1G mapping, thereby removing the need for splitting them during unplug. The kernel always make sure the minimum unplug request is SUBSECTION_SIZE for device memory and SECTION_SIZE for regular memory. In preparation for such a change remove page table splitting support. This essentially is a revert of commit 4dd5f8a9 ("powerpc/mm/radix: Split linear mapping on hot-unplug") Signed-off-by: Bharata B Rao <bharata@linux.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709131925.922266-4-aneesh.kumar@linux.ibm.com
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Bharata B Rao authored
remove_pagetable() isn't freeing PUD table. This causes memory leak during memory unplug. Fix this. Fixes: 4b5d62ca ("powerpc/mm: add radix__remove_section_mapping()") Signed-off-by: Bharata B Rao <bharata@linux.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709131925.922266-3-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
We can hit the following BUG_ON during memory unplug: kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:342! Oops: Exception in kernel mode, sig: 5 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries NIP [c000000000093308] pmd_fragment_free+0x48/0xc0 LR [c00000000147bfec] remove_pagetable+0x578/0x60c Call Trace: 0xc000008050000000 (unreliable) remove_pagetable+0x384/0x60c radix__remove_section_mapping+0x18/0x2c remove_section_mapping+0x1c/0x3c arch_remove_memory+0x11c/0x180 try_remove_memory+0x120/0x1b0 __remove_memory+0x20/0x40 dlpar_remove_lmb+0xc0/0x114 dlpar_memory+0x8b0/0xb20 handle_dlpar_errorlog+0xc0/0x190 pseries_hp_work_fn+0x2c/0x60 process_one_work+0x30c/0x810 worker_thread+0x98/0x540 kthread+0x1c4/0x1d0 ret_from_kernel_thread+0x5c/0x74 This occurs when unplug is attempted for such memory which has been mapped using memblock pages as part of early kernel page table setup. We wouldn't have initialized the PMD or PTE fragment count for those PMD or PTE pages. This can be fixed by allocating memory in PAGE_SIZE granularity during early page table allocation. This makes sure a specific page is not shared for another memblock allocation and we can free them correctly on removing page-table pages. Since we now do PAGE_SIZE allocations for both PUD table and PMD table (Note that PTE table allocation is already of PAGE_SIZE), we end up allocating more memory for the same amount of system RAM. Here is a comparision of how much more we need for a 64T and 2G system after this patch: 1. 64T system ------------- 64T RAM would need 64G for vmemmap with struct page size being 64B. 128 PUD tables for 64T memory (1G mappings) 1 PUD table and 64 PMD tables for 64G vmemmap (2M mappings) With default PUD[PMD]_TABLE_SIZE(4K), (128+1+64)*4K=772K With PAGE_SIZE(64K) table allocations, (128+1+64)*64K=12352K 2. 2G system ------------ 2G RAM would need 2M for vmemmap with struct page size being 64B. 1 PUD table for 2G memory (1G mapping) 1 PUD table and 1 PMD table for 2M vmemmap (2M mappings) With default PUD[PMD]_TABLE_SIZE(4K), (1+1+1)*4K=12K With new PAGE_SIZE(64K) table allocations, (1+1+1)*64K=192K Signed-off-by: Bharata B Rao <bharata@linux.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200709131925.922266-2-aneesh.kumar@linux.ibm.com
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Nicholas Piggin authored
When '029ab30b ("powerpc/mm: Enable radix GTSE only if supported.")' made GTSE an MMU feature, it was enabled by default in powerpc-cpu-features but was missed in pa-features. This causes random memory corruption during boot of PowerNV kernels where CONFIG_PPC_DT_CPU_FTRS isn't enabled. Fixes: 029ab30b ("powerpc/mm: Enable radix GTSE only if supported.") Reported-by: Qian Cai <cai@lca.pw> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Bharata B Rao <bharata@linux.ibm.com> [mpe: Unwrap long line] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200720044258.863574-1-bharata@linux.ibm.com
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- 18 Jul, 2020 1 commit
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Michael Ellerman authored
Merge our fixes branch, primarily to bring in the ebb selftests build fix and the pkey fix, which is a dependency for some future work.
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- 16 Jul, 2020 10 commits
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Nayna Jain authored
The device-tree properties to check secure and trusted boot state are different for guests (pseries) compared to baremetal (powernv). This patch updates the existing is_ppc_secureboot_enabled() and is_ppc_trustedboot_enabled() functions to add support for pseries. For pseries the secureboot and trustedboot state are exposed via device-tree properties /ibm,secure-boot and /ibm,trusted-boot. The values of ibm,secure-boot under pseries are interpreted as: 0 - Disabled 1 - Enabled in Log-only mode. This patch interprets this value as disabled, since audit mode is currently not supported for Linux. 2 - Enabled and enforced. 3-9 - Enabled and enforcing; requirements are at the discretion of the operating system. The values of ibm,trusted-boot under pseries are interpreted as: 0 - Disabled 1 - Enabled Signed-off-by: Nayna Jain <nayna@linux.ibm.com> Reviewed-by: Daniel Axtens <dja@axtens.net> Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> [mpe: Drop machdep.h inclusion, tweak change log slightly] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1594813921-12425-1-git-send-email-nayna@linux.ibm.com
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Milton Miller authored
The code in vdso_cpu_init that exposes the cpu and numa node to userspace via SPRG_VDSO incorrctly masks the cpu to 12 bits. This means that any kernel running on a box with more than 4096 threads (NR_CPUS advertises a limit of of 8192 cpus) would expose userspace to two cpu contexts running at the same time with the same cpu number. Note: I'm not aware of any distro shipping a kernel with support for more than 4096 threads today, nor of any system image that currently exceeds 4096 threads. Found via code browsing. Fixes: 18ad51dd ("powerpc: Add VDSO version of getcpu") Signed-off-by: Milton Miller <miltonm@us.ibm.com> Signed-off-by: Anton Blanchard <anton@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200715233704.1352257-1-anton@ozlabs.org
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Anju T Sudhakar authored
IMC trace-mode record has MSR[HV PR] bits added in the third DW. These bits can be used to set the cpumode for the instruction pointer captured in each sample. Add support in kernel to use these bits to set the cpumode for each sample. Signed-off-by: Anju T Sudhakar <anju@linux.vnet.ibm.com> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200713144623.508695-1-maddy@linux.ibm.com
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Alexander A. Klimov authored
Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200713192656.37443-1-grandmaster@al2klimov.de
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Alexander A. Klimov authored
Rationale: Reduces attack surface on kernel devs opening the links for MITM as HTTPS traffic is much harder to manipulate. Deterministic algorithm: For each file: If not .svg: For each line: If doesn't contain `\bxmlns\b`: For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`: If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`: If both the HTTP and HTTPS versions return 200 OK and serve the same content: Replace HTTP with HTTPS. Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de> Acked-by: Andrew Donnellan <ajd@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200713175506.36676-1-grandmaster@al2klimov.de
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Wei Yongjun authored
The sparse tool complains as follows: drivers/cpuidle/cpuidle-pseries.c:25:23: warning: symbol 'pseries_idle_driver' was not declared. Should it be static? 'pseries_idle_driver' is not used outside of this file, so marks it static. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200714142424.66648-1-weiyongjun1@huawei.com
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Anton Blanchard authored
Booting with a 4GB LMB size causes us to panic: qemu-system-ppc64: OS terminated: OS panic: Memory block size not suitable: 0x0 Fix pseries_memory_block_size() to handle 64 bit LMBs. Cc: stable@vger.kernel.org Signed-off-by: Anton Blanchard <anton@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200715000820.1255764-1-anton@ozlabs.org
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YueHaibing authored
commit e27e0a94 ("powerpc/xive: Remove xive_kexec_teardown_cpu()") left behind this, remove it. Signed-off-by: YueHaibing <yuehaibing@huawei.com> Reviewed-by: Greg Kurz <groug@kaod.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200715025040.33952-1-yuehaibing@huawei.com
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Sourabh Jain authored
When we enter into fadump crash path via system reset we fail to update the pstore. On the system reset path we first update the pstore then we go for fadump crash. But the problem here is when all the CPUs try to get the pstore lock to initiate the pstore write, only one CPUs will acquire the lock and proceed with the pstore write. Since it in NMI context CPUs that fail to get lock do not wait for their turn to write to the pstore and simply proceed with the next operation which is fadump crash. One of the CPU who proceeded with fadump crash path triggers the crash and does not wait for the CPU who gets the pstore lock to complete the pstore update. Timeline diagram to depicts the sequence of events that leads to an unsuccessful pstore update when we hit fadump crash path via system reset. 1 2 3 ... n CPU Threads | | | | | | | | Reached to -->|--->|---->| ----------->| system reset | | | | path | | | | | | | | Try to -->|--->|---->|------------>| acquire the | | | | pstore lock | | | | | | | | | | | | Got the -->| +->| | |<-+ pstore lock | | | | | |--> Didn't get the | --------------------------+ lock and moving | | | | ahead on fadump | | | | crash path | | | | Begins the -->| | | | process to | | | |<-- Got the chance to update the | | | | trigger the crash pstore | -> | | ... <- | | | | | | | | | | | | |<-- Triggers the | | | | | | crash | | | | | | ^ | | | | | | | Writing to -->| | | | | | | pstore | | | | | | | | | | ^ |__________________| | | CPU Relax | | | +-----------------------------------------+ | v Race: crash triggered before pstore update completes To avoid this race condition a barrier is added on crash_fadump path, it prevents the CPU to trigger the crash until all the online CPUs completes their task. A barrier is added to make sure all the secondary CPUs hit the crash_fadump function before we initiates the crash. A timeout is kept to ensure the primary CPU (one who initiates the crash) do not wait for secondary CPUs indefinitely. Signed-off-by: Sourabh Jain <sourabhjain@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200713052435.183750-1-sourabhjain@linux.ibm.com
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Anton Blanchard authored
Generic code has a wrapper to implement cputime_to_nsecs() on top of cputime_to_usecs() but we can easily return the full nanosecond resolution directly. Signed-off-by: Anton Blanchard <anton@ozlabs.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200713083601.1103978-1-anton@ozlabs.org
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