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- 16 Mar, 2021 3 commits
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Ondrej Mosnacek authored
Currently, the lockdown state is queried unconditionally, even though its result is used only if the PERF_SAMPLE_REGS_INTR bit is set in attr.sample_type. While that doesn't matter in case of the Lockdown LSM, it causes trouble with the SELinux's lockdown hook implementation. SELinux implements the locked_down hook with a check whether the current task's type has the corresponding "lockdown" class permission ("integrity" or "confidentiality") allowed in the policy. This means that calling the hook when the access control decision would be ignored generates a bogus permission check and audit record. Fix this by checking sample_type first and only calling the hook when its result would be honored. Fixes: b0c8fdc7 ("lockdown: Lock down perf when in confidentiality mode") Signed-off-by:Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by:
Paul Moore <paul@paul-moore.com> Link: https://lkml.kernel.org/r/20210224215628.192519-1-omosnace@redhat.com
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Namhyung Kim authored
For cpu events, it'd better allocating them in the corresponding node memory as they would be mostly accessed by the target cpu. Although perf tools sets the cpu affinity before calling perf_event_open, there are places it doesn't (notably perf record) and we should consider other external users too. Signed-off-by:
Namhyung Kim <namhyung@kernel.org> Signed-off-by:
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Namhyung Kim authored
The kernel can allocate a lot of struct perf_event when profiling. For example, 256 cpu x 8 events x 20 cgroups = 40K instances of the struct would be allocated on a large system. The size of struct perf_event in my setup is 1152 byte. As it's allocated by kmalloc, the actual allocation size would be rounded up to 2K. Then there's 896 byte (~43%) of waste per instance resulting in total ~35MB with 40K instances. We can create a dedicated kmem_cache to avoid such a big unnecessary memory consumption. With this change, I can see below (note this machine has 112 cpus). # grep perf_event /proc/slabinfo perf_event 224 784 1152 7 2 : tunables 24 12 8 : slabdata 112 112 0 The sixth column is pages-per-slab which is 2, and the fifth column is obj-per-slab which is 7. Thus actually it can use 1152 x 7 = 8064 byte in the 8K, and wasted memory is (8192 - 8064) / 7 = ~18 byte per instance. Signed-off-by:
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- 06 Mar, 2021 1 commit
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Kan Liang authored
Sometimes the PMU internal buffers have to be flushed for per-CPU events during a context switch, e.g., large PEBS. Otherwise, the perf tool may report samples in locations that do not belong to the process where the samples are processed in, because PEBS does not tag samples with PID/TID. The current code only flush the buffers for a per-task event. It doesn't check a per-CPU event. Add a new event state flag, PERF_ATTACH_SCHED_CB, to indicate that the PMU internal buffers have to be flushed for this event during a context switch. Add sched_cb_entry and perf_sched_cb_usages back to track the PMU/cpuctx which is required to be flushed. Only need to invoke the sched_task() for per-CPU events in this patch. The per-task events have been handled in perf_event_context_sched_in/out already. Fixes: 9c964efa ("perf/x86/intel: Drain the PEBS buffer during context switches") Reported-by:
Gabriel Marin <gmx@google.com> Originally-by:
Kan Liang <kan.liang@linux.intel.com> Signed-off-by:
Ingo Molnar <mingo@kernel.org> Link: https://lkml.kernel.org/r/20201130193842.10569-1-kan.liang@linux.intel.com
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- 26 Feb, 2021 1 commit
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Randy Dunlap authored
Drop repeated words in kernel/events/. {if, the, that, with, time} Drop repeated words in kernel/locking/. {it, no, the} Drop repeated words in kernel/sched/. {in, not} Link: https://lkml.kernel.org/r/20210127023412.26292-1-rdunlap@infradead.orgSigned-off-by:Randy Dunlap <rdunlap@infradead.org> Acked-by: Will Deacon <will@kernel.org> [kernel/locking/] Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Will Deacon <will@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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- 17 Feb, 2021 1 commit
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Peter Zijlstra authored
Reduce rbtree boiler plate by using the new helpers. One noteworthy change is unification of the various (partial) compare functions. We construct a subtree match by forcing the sub-order to always match, see __group_cmp(). Due to 'const' we had to touch cgroup_id(). Signed-off-by:
Tejun Heo <tj@kernel.org> Acked-by:
Davidlohr Bueso <dbueso@suse.de>
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- 01 Feb, 2021 1 commit
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Kan Liang authored
Current PERF_SAMPLE_WEIGHT sample type is very useful to expresses the cost of an action represented by the sample. This allows the profiler to scale the samples to be more informative to the programmer. It could also help to locate a hotspot, e.g., when profiling by memory latencies, the expensive load appear higher up in the histograms. But current PERF_SAMPLE_WEIGHT sample type is solely determined by one factor. This could be a problem, if users want two or more factors to contribute to the weight. For example, Golden Cove core PMU can provide both the instruction latency and the cache Latency information as factors for the memory profiling. For current X86 platforms, although meminfo::latency is defined as a u64, only the lower 32 bits include the valid data in practice (No memory access could last than 4G cycles). The higher 32 bits can be used to store new factors. Add a new sample type, PERF_SAMPLE_WEIGHT_STRUCT, to indicate the new sample weight structure. It shares the same space as the PERF_SAMPLE_WEIGHT sample type. Users can apply either the PERF_SAMPLE_WEIGHT sample type or the PERF_SAMPLE_WEIGHT_STRUCT sample type to retrieve the sample weight, but they cannot apply both sample types simultaneously. Currently, only X86 and PowerPC use the PERF_SAMPLE_WEIGHT sample type. - For PowerPC, there is nothing changed for the PERF_SAMPLE_WEIGHT sample type. There is no effect for the new PERF_SAMPLE_WEIGHT_STRUCT sample type. PowerPC can re-struct the weight field similarly later. - For X86, the same value will be dumped for the PERF_SAMPLE_WEIGHT sample type or the PERF_SAMPLE_WEIGHT_STRUCT sample type for now. The following patches will apply the new factors for the PERF_SAMPLE_WEIGHT_STRUCT sample type. The field in the union perf_sample_weight should be shared among different architectures. A generic name is required, but it's hard to abstract a name that applies to all architectures. For example, on X86, the fields are to store all kinds of latency. While on PowerPC, it stores MMCRA[TECX/TECM], which should not be latency. So a general name prefix 'var$NUM' is used here. Suggested-by:
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- 15 Jan, 2021 1 commit
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Jiri Olsa authored
Adding support to carry build id data in mmap2 event. The build id data replaces maj/min/ino/ino_generation fields, which are also used to identify map's binary, so it's ok to replace them with build id data: union { struct { u32 maj; u32 min; u64 ino; u64 ino_generation; }; struct { u8 build_id_size; u8 __reserved_1; u16 __reserved_2; u8 build_id[20]; }; }; Replaced maj/min/ino/ino_generation fields give us size of 24 bytes. We use 20 bytes for build id data, 1 byte for size and rest is unused. There's new misc bit for mmap2 to signal there's build id data in it: #define PERF_RECORD_MISC_MMAP_BUILD_ID (1 << 14) Signed-off-by:Jiri Olsa <jolsa@kernel.org> Signed-off-by:
Alexei Starovoitov <ast@kernel.org> Acked-by:
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- 10 Dec, 2020 1 commit
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Eric W. Biederman authored
Recently syzbot reported[0] that there is a deadlock amongst the users of exec_update_mutex. The problematic lock ordering found by lockdep was: perf_event_open (exec_update_mutex -> ovl_i_mutex) chown (ovl_i_mutex -> sb_writes) sendfile (sb_writes -> p->lock) by reading from a proc file and writing to overlayfs proc_pid_syscall (p->lock -> exec_update_mutex) While looking at possible solutions it occured to me that all of the users and possible users involved only wanted to state of the given process to remain the same. They are all readers. The only writer is exec. There is no reason for readers to block on each other. So fix this deadlock by transforming exec_update_mutex into a rw_semaphore named exec_update_lock that only exec takes for writing. Cc: Jann Horn <jannh@google.com> Cc: Vasiliy Kulikov <segoon@openwall.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Bernd Edlinger <bernd.edlinger@hotmail.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Christopher Yeoh <cyeoh@au1.ibm.com> Cc: Cyrill Gorcunov <gorcunov@gmail.com> Cc: Sargun Dhillon <sargun@sargun.me> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Fixes: eea96732 ("exec: Add exec_update_mutex to replace cred_guard_mutex") [0] https://lkml.kernel.org/r/00000000000063640c05ade8e3de@google.com Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com Link: https://lkml.kernel.org/r/87ft4mbqen.fsf@x220.int.ebiederm.orgSigned-off-by:Eric W. Biederman <ebiederm@xmission.com>
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- 09 Dec, 2020 1 commit
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peterz@infradead.org authored
Syzbot reported a lock inversion involving perf. The sore point being perf holding exec_update_mutex() for a very long time, specifically across a whole bunch of filesystem ops in pmu::event_init() (uprobes) and anon_inode_getfile(). This then inverts against procfs code trying to take exec_update_mutex. Move the permission checks later, such that we need to hold the mutex over less code. Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com Signed-off-by:
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- 03 Dec, 2020 1 commit
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Peter Zijlstra authored
The (new) page-table walker in arch_perf_get_page_size() is broken in various ways. Specifically while it is used in a lockless manner, it doesn't depend on CONFIG_HAVE_FAST_GUP nor uses the proper _lockless offset methods, nor is careful to only read each entry only once. Also the hugetlb support is broken due to calling pte_page() without first checking pte_special(). Rewrite the whole thing to be a proper lockless page-table walker and employ the new pXX_leaf_size() pgtable functions to determine the pagetable size without looking at the page-frames. Fixes: 51b646b2 ("perf,mm: Handle non-page-table-aligned hugetlbfs") Fixes: 8d97e718 ("perf/core: Add PERF_SAMPLE_DATA_PAGE_SIZE") Signed-off-by:
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- 09 Nov, 2020 6 commits
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Peter Zijlstra authored
Currently perf_event_attr::exclusive can be used to ensure an event(group) is the sole group scheduled on the PMU. One consequence is that when you have a pinned event (say the watchdog) you can no longer have regular exclusive event(group)s. Inspired by the fact that !pinned events are considered less strict, allow !pinned,exclusive events to share the PMU with pinned,!exclusive events. Pinned,exclusive is still fully exclusive. Signed-off-by:
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Peter Zijlstra authored
Commit 9e630205 ("perf: Use hrtimers for event multiplexing") placed the hrtimer (re)start call in the wrong place. Instead of capturing all scheduling failures, it only considered the PMU failure. The result is that groups using perf_event_attr::exclusive are no longer rotated. Fixes: 9e630205 ("perf: Use hrtimers for event multiplexing") Reported-by:
Andi Kleen <ak@linux.intel.com> Signed-off-by:
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Peter Zijlstra authored
Collate the error paths. Code duplication only leads to divergence and extra bugs. Signed-off-by:
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Peter Zijlstra authored
Since event_sched_out() clears cpuctx->exclusive upon removal of an exclusive event (and only group leaders can be exclusive), there is no point in group_sched_out() trying to do it too. It is impossible for cpuctx->exclusive to still be set here. Signed-off-by:
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Peter Zijlstra authored
struct perf_sample_data lives on-stack, we should be careful about it's size. Furthermore, the pt_regs copy in there is only because x86_64 is a trainwreck, solve it differently. Reported-by:
Thomas Gleixner <tglx@linutronix.de> Signed-off-by:
Steven Rostedt <rostedt@goodmis.org> Link: https://lkml.kernel.org/r/20201030151955.258178461@infradead.org
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Peter Zijlstra authored
__perf_output_begin() has an on-stack struct perf_sample_data in the unlikely case it needs to generate a LOST record. However, every call to perf_output_begin() must already have a perf_sample_data on-stack. Reported-by:
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- 07 Nov, 2020 1 commit
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kiyin(尹亮) authored
As shown through runtime testing, the "filename" allocation is not always freed in perf_event_parse_addr_filter(). There are three possible ways that this could happen: - It could be allocated twice on subsequent iterations through the loop, - or leaked on the success path, - or on the failure path. Clean up the code flow to make it obvious that 'filename' is always freed in the reallocation path and in the two return paths as well. We rely on the fact that kfree(NULL) is NOP and filename is initialized with NULL. This fixes the leak. No other side effects expected. [ Dan Carpenter: cleaned up the code flow & added a changelog. ] [ Ingo Molnar: updated the changelog some more. ] Fixes: 375637bc ("perf/core: Introduce address range filtering") Signed-off-by:
"kiyin(尹亮)" <kiyin@tencent.com> Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by:
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- 29 Oct, 2020 3 commits
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Peter Zijlstra authored
A limited nunmber of architectures support hugetlbfs sizes that do not align with the page-tables (ARM64, Power, Sparc64). Add support for this to the generic perf_get_page_size() implementation, and also allow an architecture to override this implementation. This latter is only needed when it uses non-page-table aligned huge pages in its kernel map. Signed-off-by: -
Stephane Eranian authored
When studying code layout, it is useful to capture the page size of the sampled code address. Add a new sample type for code page size. The new sample type requires collecting the ip. The code page size can be calculated from the NMI-safe perf_get_page_size(). For large PEBS, it's very unlikely that the mapping is gone for the earlier PEBS records. Enable the feature for the large PEBS. The worst case is that page-size '0' is returned. Signed-off-by:
Stephane Eranian <eranian@google.com> Signed-off-by:
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Kan Liang authored
Current perf can report both virtual addresses and physical addresses, but not the MMU page size. Without the MMU page size information of the utilized page, users cannot decide whether to promote/demote large pages to optimize memory usage. Add a new sample type for the data MMU page size. Current perf already has a facility to collect data virtual addresses. A page walker is required to walk the pages tables and calculate the MMU page size from a given virtual address. On some platforms, e.g., X86, the page walker is invoked in an NMI handler. So the page walker must be NMI-safe and low overhead. Besides, the page walker should work for both user and kernel virtual address. The existing generic page walker, e.g., walk_page_range_novma(), is a little bit complex and doesn't guarantee the NMI-safe. The follow_page() is only for user-virtual address. Add a new function perf_get_page_size() to walk the page tables and calculate the MMU page size. In the function: - Interrupts have to be disabled to prevent any teardown of the page tables. - For user space threads, the current->mm is used for the page walker. For kernel threads and the like, the current->mm is NULL. The init_mm is used for the page walker. The active_mm is not used here, because it can be NULL. Quote from Peter Zijlstra, "context_switch() can set prev->active_mm to NULL when it transfers it to @next. It does this before @current is updated. So an NMI that comes in between this active_mm swizzling and updating @current will see !active_mm." - The MMU page size is calculated from the page table level. The method should work for all architectures, but it has only been verified on X86. Should there be some architectures, which support perf, where the method doesn't work, it can be fixed later separately. Reporting the wrong page size would not be fatal for the architecture. Some under discussion features may impact the method in the future. Quote from Dave Hansen, "There are lots of weird things folks are trying to do with the page tables, like Address Space Isolation. For instance, if you get a perf NMI when running userspace, current->mm->pgd is *different* than the PGD that was in use when userspace was running. It's close enough today, but it might not stay that way." If the case happens later, lots of consecutive page walk errors will happen. The worst case is that lots of page-size '0' are returned, which would not be fatal. In the perf tool, a check is implemented to detect this case. Once it happens, a kernel patch could be implemented accordingly then. Suggested-by:
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- 12 Oct, 2020 1 commit
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Jiri Olsa authored
There's a possible race in perf_mmap_close() when checking ring buffer's mmap_count refcount value. The problem is that the mmap_count check is not atomic because we call atomic_dec() and atomic_read() separately. perf_mmap_close: ... atomic_dec(&rb->mmap_count); ... if (atomic_read(&rb->mmap_count)) goto out_put; <ring buffer detach> free_uid out_put: ring_buffer_put(rb); /* could be last */ The race can happen when we have two (or more) events sharing same ring buffer and they go through atomic_dec() and then they both see 0 as refcount value later in atomic_read(). Then both will go on and execute code which is meant to be run just once. The code that detaches ring buffer is probably fine to be executed more than once, but the problem is in calling free_uid(), which will later on demonstrate in related crashes and refcount warnings, like: refcount_t: addition on 0; use-after-free. ... RIP: 0010:refcount_warn_saturate+0x6d/0xf ... Call Trace: prepare_creds+0x190/0x1e0 copy_creds+0x35/0x172 copy_process+0x471/0x1a80 _do_fork+0x83/0x3a0 __do_sys_wait4+0x83/0x90 __do_sys_clone+0x85/0xa0 do_syscall_64+0x5b/0x1e0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Using atomic decrease and check instead of separated calls. Tested-by:Michael Petlan <mpetlan@redhat.com> Signed-off-by:
Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by:
Wade Mealing <wmealing@redhat.com> Fixes: 9bb5d40c ("perf: Fix mmap() accounting hole"); Link: https://lore.kernel.org/r/20200916115311.GE2301783@krava
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- 09 Oct, 2020 1 commit
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Kajol Jain authored
The error handling introduced by commit: 2ed6edd3 ("perf: Add cond_resched() to task_function_call()") looses any return value from smp_call_function_single() that is not {0, -EINVAL}. This is a problem because it will return -EXNIO when the target CPU is offline. Worse, in that case it'll turn into an infinite loop. Fixes: 2ed6edd3 ("perf: Add cond_resched() to task_function_call()") Reported-by:
Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by:
Kajol Jain <kjain@linux.ibm.com> Signed-off-by:
Barret Rhoden <brho@google.com> Tested-by:
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- 10 Sep, 2020 2 commits
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Kan Liang authored
The pmu::sched_task() is a context switch callback. It passes the cpuctx->task_ctx as a parameter to the lower code. To find the cpuctx->task_ctx, the current code iterates a cpuctx list. The same context will iterated in perf_event_context_sched_out() soon. Share the cpuctx->task_ctx can avoid the unnecessary iteration of the cpuctx list. The pmu::sched_task() is also required for the optimization case for equivalent contexts. The task_ctx_sched_out() will eventually disable and reenable the PMU when schedule out events. Add perf_pmu_disable() and perf_pmu_enable() around task_ctx_sched_out() don't break anything. Drop the cpuctx->ctx.lock for the pmu::sched_task(). The lock is for per-CPU context, which is not necessary for the per-task context schedule. No one uses sched_cb_entry, perf_sched_cb_usages, sched_cb_list, and perf_pmu_sched_task() any more. Suggested-by:
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Kan Liang authored
The pmu::sched_task() is a context switch callback. It passes the cpuctx->task_ctx as a parameter to the lower code. To find the cpuctx->task_ctx, the current code iterates a cpuctx list. The same context was just iterated in perf_event_context_sched_in(), which is invoked right before the pmu::sched_task(). Reuse the cpuctx->task_ctx from perf_event_context_sched_in() can avoid the unnecessary iteration of the cpuctx list. Both pmu::sched_task and perf_event_context_sched_in() have to disable PMU. Pull the pmu::sched_task into perf_event_context_sched_in() can also save the overhead from the PMU disable and reenable. The new and old tasks may have equivalent contexts. The current code optimize this case by swapping the context, which avoids the scheduling. For this case, pmu::sched_task() is still required, e.g., restore the LBR content. Suggested-by:
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- 23 Aug, 2020 1 commit
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Gustavo A. R. Silva authored
Replace the existing /* fall through */ comments and its variants with the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary fall-through markings when it is the case. [1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-throughSigned-off-by:
Gustavo A. R. Silva <gustavoars@kernel.org>
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- 18 Aug, 2020 1 commit
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Kan Liang authored
Current perf assumes that events in a group are independent. Close an event doesn't impact the value of the other events in the same group. If the closed event is a member, after the event closure, other events are still running like a group. If the closed event is a leader, other events are running as singleton events. Add PERF_EV_CAP_SIBLING to allow events to indicate they require being part of a group, and when the leader dies they cannot exist independently. Suggested-by:
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- 12 Aug, 2020 1 commit
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Christoph Hellwig authored
Add helpers to wrap the get_fs/set_fs magic for undoing any damange done by set_fs(KERNEL_DS). There is no real functional benefit, but this documents the intent of these calls better, and will allow stubbing the functions out easily for kernels builds that do not allow address space overrides in the future. [hch@lst.de: drop two incorrect hunks, fix a commit log typo] Link: http://lkml.kernel.org/r/20200714105505.935079-6-hch@lst.deSigned-off-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
Mark Rutland <mark.rutland@arm.com> Acked-by:
Greentime Hu <green.hu@gmail.com> Acked-by:
Geert Uytterhoeven <geert@linux-m68k.org> Cc: Nick Hu <nickhu@andestech.com> Cc: Vincent Chen <deanbo422@gmail.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Link: http://lkml.kernel.org/r/20200710135706.537715-6-hch@lst.deSigned-off-by:
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- 06 Aug, 2020 1 commit
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Alexey Budankov authored
Open access to per-process monitoring for CAP_PERFMON only privileged processes [1]. Extend ptrace_may_access() check in perf_events subsystem with perfmon_capable() to simplify user experience and make monitoring more secure by reducing attack surface. [1] https://lore.kernel.org/lkml/7776fa40-6c65-2aa6-1322-eb3a01201000@linux.intel.com/Signed-off-by:
Alexey Budankov <alexey.budankov@linux.intel.com> Signed-off-by:
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- 26 Jul, 2020 1 commit
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Song Liu authored
bpf_get_[stack|stackid] on perf_events with precise_ip uses callchain attached to perf_sample_data. If this callchain is not presented, do not allow attaching BPF program that calls bpf_get_[stack|stackid] to this event. In the error case, -EPROTO is returned so that libbpf can identify this error and print proper hint message. Signed-off-by:
Song Liu <songliubraving@fb.com> Signed-off-by:
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- 16 Jul, 2020 1 commit
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Kees Cook authored
Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var\(([^\)]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by:
Kees Cook <keescook@chromium.org>
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- 08 Jul, 2020 3 commits
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Kan Liang authored
A new kmem_cache method has replaced the kzalloc() to allocate the PMU specific data. The task_ctx_size is not required anymore. Signed-off-by:
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Kan Liang authored
Currently, the PMU specific data task_ctx_data is allocated by the function kzalloc() in the perf generic code. When there is no specific alignment requirement for the task_ctx_data, the method works well for now. However, there will be a problem once a specific alignment requirement is introduced in future features, e.g., the Architecture LBR XSAVE feature requires 64-byte alignment. If the specific alignment requirement is not fulfilled, the XSAVE family of instructions will fail to save/restore the xstate to/from the task_ctx_data. The function kzalloc() itself only guarantees a natural alignment. A new method to allocate the task_ctx_data has to be introduced, which has to meet the requirements as below: - must be a generic method can be used by different architectures, because the allocation of the task_ctx_data is implemented in the perf generic code; - must be an alignment-guarantee method (The alignment requirement is not changed after the boot); - must be able to allocate/free a buffer (smaller than a page size) dynamically; - should not cause extra CPU overhead or space overhead. Several options were considered as below: - One option is to allocate a larger buffer for task_ctx_data. E.g., ptr = kmalloc(size + alignment, GFP_KERNEL); ptr &= ~(alignment - 1); This option causes space overhead. - Another option is to allocate the task_ctx_data in the PMU specific code. To do so, several function pointers have to be added. As a result, both the generic structure and the PMU specific structure will become bigger. Besides, extra function calls are added when allocating/freeing the buffer. This option will increase both the space overhead and CPU overhead. - The third option is to use a kmem_cache to allocate a buffer for the task_ctx_data. The kmem_cache can be created with a specific alignment requirement by the PMU at boot time. A new pointer for kmem_cache has to be added in the generic struct pmu, which would be used to dynamically allocate a buffer for the task_ctx_data at run time. Although the new pointer is added to the struct pmu, the existing variable task_ctx_size is not required anymore. The size of the generic structure is kept the same. The third option which meets all the aforementioned requirements is used to replace kzalloc() for the PMU specific data allocation. A later patch will remove the kzalloc() method and the related variables. Signed-off-by: -
Kan Liang authored
The method to allocate/free the task_ctx_data is going to be changed in the following patch. Currently, the task_ctx_data is allocated/freed in several different places. To avoid repeatedly modifying the same codes in several different places, alloc_task_ctx_data() and free_task_ctx_data() are factored out to allocate/free the task_ctx_data. The modification only needs to be applied once. Signed-off-by:
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- 15 Jun, 2020 1 commit
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Adrian Hunter authored
Record (single instruction) changes to the kernel text (i.e. self-modifying code) in order to support tracers like Intel PT and ARM CoreSight. A copy of the running kernel code is needed as a reference point (e.g. from /proc/kcore). The text poke event records the old bytes and the new bytes so that the event can be processed forwards or backwards. The basic problem is recording the modified instruction in an unambiguous manner given SMP instruction cache (in)coherence. That is, when modifying an instruction concurrently any solution with one or multiple timestamps is not sufficient: CPU0 CPU1 0 1 write insn A 2 execute insn A 3 sync-I$ 4 Due to I$, CPU1 might execute either the old or new A. No matter where we record tracepoints on CPU0, one simply cannot tell what CPU1 will have observed, except that at 0 it must be the old one and at 4 it must be the new one. To solve this, take inspiration from x86 text poking, which has to solve this exact problem due to variable length instruction encoding and I-fetch windows. 1) overwrite the instruction with a breakpoint and sync I$ This guarantees that that code flow will never hit the target instruction anymore, on any CPU (or rather, it will cause an exception). 2) issue the TEXT_POKE event 3) overwrite the breakpoint with the new instruction and sync I$ Now we know that any execution after the TEXT_POKE event will either observe the breakpoint (and hit the exception) or the new instruction. So by guarding the TEXT_POKE event with an exception on either side; we can now tell, without doubt, which instruction another CPU will have observed. Signed-off-by:
Adrian Hunter <adrian.hunter@intel.com> Signed-off-by:
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- 09 Jun, 2020 2 commits
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Michel Lespinasse authored
Convert comments that reference mmap_sem to reference mmap_lock instead. [akpm@linux-foundation.org: fix up linux-next leftovers] [akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil] [akpm@linux-foundation.org: more linux-next fixups, per Michel] Signed-off-by:
Michel Lespinasse <walken@google.com> Signed-off-by:
Vlastimil Babka <vbabka@suse.cz> Reviewed-by:
Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Davidlohr Bueso <dbueso@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Laurent Dufour <ldufour@linux.ibm.com> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ying Han <yinghan@google.com> Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.comSigned-off-by:
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Michel Lespinasse authored
This change converts the existing mmap_sem rwsem calls to use the new mmap locking API instead. The change is generated using coccinelle with the following rule: // spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir . @@ expression mm; @@ ( -init_rwsem +mmap_init_lock | -down_write +mmap_write_lock | -down_write_killable +mmap_write_lock_killable | -down_write_trylock +mmap_write_trylock | -up_write +mmap_write_unlock | -downgrade_write +mmap_write_downgrade | -down_read +mmap_read_lock | -down_read_killable +mmap_read_lock_killable | -down_read_trylock +mmap_read_trylock | -up_read +mmap_read_unlock ) -(&mm->mmap_sem) +(mm) Signed-off-by:
Laurent Dufour <ldufour@linux.ibm.com> Reviewed-by:
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- 08 Jun, 2020 1 commit
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Souptick Joarder authored
API __get_user_pages_fast() renamed to get_user_pages_fast_only() to align with pin_user_pages_fast_only(). As part of this we will get rid of write parameter. Instead caller will pass FOLL_WRITE to get_user_pages_fast_only(). This will not change any existing functionality of the API. All the callers are changed to pass FOLL_WRITE. Also introduce get_user_page_fast_only(), and use it in a few places that hard-code nr_pages to 1. Updated the documentation of the API. Signed-off-by:
Souptick Joarder <jrdr.linux@gmail.com> Signed-off-by:
John Hubbard <jhubbard@nvidia.com> Reviewed-by: Paul Mackerras <paulus@ozlabs.org> [arch/powerpc/kvm] Cc: Matthew Wilcox <willy@infradead.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Michal Suchanek <msuchanek@suse.de> Link: http://lkml.kernel.org/r/1590396812-31277-1-git-send-email-jrdr.linux@gmail.comSigned-off-by:
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- 07 May, 2020 1 commit
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Eric W. Biederman authored
The two functions are now always called one right after the other so merge them together to make future maintenance easier. Reviewed-by:
Greg Ungerer <gerg@linux-m68k.org> Signed-off-by:
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- 30 Apr, 2020 1 commit
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Barret Rhoden authored
Under rare circumstances, task_function_call() can repeatedly fail and cause a soft lockup. There is a slight race where the process is no longer running on the cpu we targeted by the time remote_function() runs. The code will simply try again. If we are very unlucky, this will continue to fail, until a watchdog fires. This can happen in a heavily loaded, multi-core virtual machine. Reported-by: syzbot+bb4935a5c09b5ff79940@syzkaller.appspotmail.com Signed-off-by:
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