From da97e18458fb42d7c00fac5fd1c56a3896ec666e Mon Sep 17 00:00:00 2001 From: "Joel Fernandes (Google)" Date: Mon, 14 Oct 2019 13:03:08 -0400 Subject: perf_event: Add support for LSM and SELinux checks In current mainline, the degree of access to perf_event_open(2) system call depends on the perf_event_paranoid sysctl. This has a number of limitations: 1. The sysctl is only a single value. Many types of accesses are controlled based on the single value thus making the control very limited and coarse grained. 2. The sysctl is global, so if the sysctl is changed, then that means all processes get access to perf_event_open(2) opening the door to security issues. This patch adds LSM and SELinux access checking which will be used in Android to access perf_event_open(2) for the purposes of attaching BPF programs to tracepoints, perf profiling and other operations from userspace. These operations are intended for production systems. 5 new LSM hooks are added: 1. perf_event_open: This controls access during the perf_event_open(2) syscall itself. The hook is called from all the places that the perf_event_paranoid sysctl is checked to keep it consistent with the systctl. The hook gets passed a 'type' argument which controls CPU, kernel and tracepoint accesses (in this context, CPU, kernel and tracepoint have the same semantics as the perf_event_paranoid sysctl). Additionally, I added an 'open' type which is similar to perf_event_paranoid sysctl == 3 patch carried in Android and several other distros but was rejected in mainline [1] in 2016. 2. perf_event_alloc: This allocates a new security object for the event which stores the current SID within the event. It will be useful when the perf event's FD is passed through IPC to another process which may try to read the FD. Appropriate security checks will limit access. 3. perf_event_free: Called when the event is closed. 4. perf_event_read: Called from the read(2) and mmap(2) syscalls for the event. 5. perf_event_write: Called from the ioctl(2) syscalls for the event. [1] https://lwn.net/Articles/696240/ Since Peter had suggest LSM hooks in 2016 [1], I am adding his Suggested-by tag below. To use this patch, we set the perf_event_paranoid sysctl to -1 and then apply selinux checking as appropriate (default deny everything, and then add policy rules to give access to domains that need it). In the future we can remove the perf_event_paranoid sysctl altogether. Suggested-by: Peter Zijlstra Co-developed-by: Peter Zijlstra Signed-off-by: Joel Fernandes (Google) Signed-off-by: Peter Zijlstra (Intel) Acked-by: James Morris Cc: Arnaldo Carvalho de Melo Cc: rostedt@goodmis.org Cc: Yonghong Song Cc: Kees Cook Cc: Ingo Molnar Cc: Alexei Starovoitov Cc: jeffv@google.com Cc: Jiri Olsa Cc: Daniel Borkmann Cc: primiano@google.com Cc: Song Liu Cc: rsavitski@google.com Cc: Namhyung Kim Cc: Matthew Garrett Link: https://lkml.kernel.org/r/20191014170308.70668-1-joel@joelfernandes.org --- kernel/events/core.c | 57 ++++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 46 insertions(+), 11 deletions(-) (limited to 'kernel/events') diff --git a/kernel/events/core.c b/kernel/events/core.c index 9ec0b0bfddbd..f9a5d4356562 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4229,8 +4229,9 @@ find_get_context(struct pmu *pmu, struct task_struct *task, if (!task) { /* Must be root to operate on a CPU event: */ - if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN)) - return ERR_PTR(-EACCES); + err = perf_allow_cpu(&event->attr); + if (err) + return ERR_PTR(err); cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu); ctx = &cpuctx->ctx; @@ -4539,6 +4540,8 @@ static void _free_event(struct perf_event *event) unaccount_event(event); + security_perf_event_free(event); + if (event->rb) { /* * Can happen when we close an event with re-directed output. @@ -4992,6 +4995,10 @@ perf_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) struct perf_event_context *ctx; int ret; + ret = security_perf_event_read(event); + if (ret) + return ret; + ctx = perf_event_ctx_lock(event); ret = __perf_read(event, buf, count); perf_event_ctx_unlock(event, ctx); @@ -5256,6 +5263,11 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) struct perf_event_context *ctx; long ret; + /* Treat ioctl like writes as it is likely a mutating operation. */ + ret = security_perf_event_write(event); + if (ret) + return ret; + ctx = perf_event_ctx_lock(event); ret = _perf_ioctl(event, cmd, arg); perf_event_ctx_unlock(event, ctx); @@ -5719,6 +5731,10 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) if (!(vma->vm_flags & VM_SHARED)) return -EINVAL; + ret = security_perf_event_read(event); + if (ret) + return ret; + vma_size = vma->vm_end - vma->vm_start; if (vma->vm_pgoff == 0) { @@ -5844,7 +5860,7 @@ accounting: lock_limit >>= PAGE_SHIFT; locked = atomic64_read(&vma->vm_mm->pinned_vm) + extra; - if ((locked > lock_limit) && perf_paranoid_tracepoint_raw() && + if ((locked > lock_limit) && perf_is_paranoid() && !capable(CAP_IPC_LOCK)) { ret = -EPERM; goto unlock; @@ -10578,11 +10594,20 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, } } + err = security_perf_event_alloc(event); + if (err) + goto err_callchain_buffer; + /* symmetric to unaccount_event() in _free_event() */ account_event(event); return event; +err_callchain_buffer: + if (!event->parent) { + if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) + put_callchain_buffers(); + } err_addr_filters: kfree(event->addr_filter_ranges); @@ -10671,9 +10696,11 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr, attr->branch_sample_type = mask; } /* privileged levels capture (kernel, hv): check permissions */ - if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM) - && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) - return -EACCES; + if (mask & PERF_SAMPLE_BRANCH_PERM_PLM) { + ret = perf_allow_kernel(attr); + if (ret) + return ret; + } } if (attr->sample_type & PERF_SAMPLE_REGS_USER) { @@ -10886,13 +10913,19 @@ SYSCALL_DEFINE5(perf_event_open, if (flags & ~PERF_FLAG_ALL) return -EINVAL; + /* Do we allow access to perf_event_open(2) ? */ + err = security_perf_event_open(&attr, PERF_SECURITY_OPEN); + if (err) + return err; + err = perf_copy_attr(attr_uptr, &attr); if (err) return err; if (!attr.exclude_kernel) { - if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) - return -EACCES; + err = perf_allow_kernel(&attr); + if (err) + return err; } if (attr.namespaces) { @@ -10909,9 +10942,11 @@ SYSCALL_DEFINE5(perf_event_open, } /* Only privileged users can get physical addresses */ - if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR) && - perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) - return -EACCES; + if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR)) { + err = perf_allow_kernel(&attr); + if (err) + return err; + } err = security_locked_down(LOCKDOWN_PERF); if (err && (attr.sample_type & PERF_SAMPLE_REGS_INTR)) -- cgit v1.2.3-58-ga151 From 8a9f91c51ea72b126864e0db616b1bac12261200 Mon Sep 17 00:00:00 2001 From: Yunfeng Ye Date: Mon, 14 Oct 2019 16:14:59 +0800 Subject: perf/ring_buffer: Modify the parameter type of perf_mmap_free_page() In perf_mmap_free_page(), the unsigned long type is converted to the pointer type, but where the call is made, the pointer type is converted to the unsigned long type. There is no need to do these operations. Modify the parameter type of perf_mmap_free_page() to pointer type. Signed-off-by: Yunfeng Ye Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Cc: Cc: Cc: Cc: Link: https://lkml.kernel.org/r/e6ae3f0c-d04c-50f9-544a-aee3b30330cd@huawei.com --- kernel/events/ring_buffer.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/events') diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index ffb59a4ef4ff..abc145cbfedf 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -799,9 +799,9 @@ fail: return NULL; } -static void perf_mmap_free_page(unsigned long addr) +static void perf_mmap_free_page(void *addr) { - struct page *page = virt_to_page((void *)addr); + struct page *page = virt_to_page(addr); page->mapping = NULL; __free_page(page); @@ -811,9 +811,9 @@ void rb_free(struct ring_buffer *rb) { int i; - perf_mmap_free_page((unsigned long)rb->user_page); + perf_mmap_free_page(rb->user_page); for (i = 0; i < rb->nr_pages; i++) - perf_mmap_free_page((unsigned long)rb->data_pages[i]); + perf_mmap_free_page(rb->data_pages[i]); kfree(rb); } -- cgit v1.2.3-58-ga151 From d7e78706e43107fa269fe34b1a69e653f5ec9f2c Mon Sep 17 00:00:00 2001 From: Yunfeng Ye Date: Mon, 14 Oct 2019 16:15:57 +0800 Subject: perf/ring_buffer: Matching the memory allocate and free, in rb_alloc() Currently perf_mmap_alloc_page() is used to allocate memory in rb_alloc(), but using free_page() to free memory in the failure path. It's better to use perf_mmap_free_page() instead. Signed-off-by: Yunfeng Ye Signed-off-by: Peter Zijlstra (Intel) Cc: Cc: Cc: Cc: Cc: Cc: Link: https://lkml.kernel.org/r/575c7e8c-90c7-4e3a-b41d-f894d8cdbd7f@huawei.com --- kernel/events/ring_buffer.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) (limited to 'kernel/events') diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index abc145cbfedf..246c83ac5643 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -754,6 +754,14 @@ static void *perf_mmap_alloc_page(int cpu) return page_address(page); } +static void perf_mmap_free_page(void *addr) +{ + struct page *page = virt_to_page(addr); + + page->mapping = NULL; + __free_page(page); +} + struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags) { struct ring_buffer *rb; @@ -788,9 +796,9 @@ struct ring_buffer *rb_alloc(int nr_pages, long watermark, int cpu, int flags) fail_data_pages: for (i--; i >= 0; i--) - free_page((unsigned long)rb->data_pages[i]); + perf_mmap_free_page(rb->data_pages[i]); - free_page((unsigned long)rb->user_page); + perf_mmap_free_page(rb->user_page); fail_user_page: kfree(rb); @@ -799,14 +807,6 @@ fail: return NULL; } -static void perf_mmap_free_page(void *addr) -{ - struct page *page = virt_to_page(addr); - - page->mapping = NULL; - __free_page(page); -} - void rb_free(struct ring_buffer *rb) { int i; -- cgit v1.2.3-58-ga151 From c2b98a8661514f29a44ebd0925cf4b1503beb48c Mon Sep 17 00:00:00 2001 From: Alexey Budankov Date: Wed, 23 Oct 2019 10:13:56 +0300 Subject: perf/x86: Synchronize PMU task contexts on optimized context switches Install Intel specific PMU task context synchronization adapter and extend optimized context switch path with PMU specific task context synchronization to fix LBR callstack virtualization on context switches. Signed-off-by: Alexey Budankov Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Arnaldo Carvalho de Melo Cc: Ian Rogers Cc: Jiri Olsa Cc: Kan Liang Cc: Linus Torvalds Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Song Liu Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Link: https://lkml.kernel.org/r/9c6445a9-bdba-ef03-3859-f1f91198f27a@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/events/intel/core.c | 7 +++++++ kernel/events/core.c | 13 ++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-) (limited to 'kernel/events') diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index bbf6588d47ee..dc64b16e6b71 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3820,6 +3820,12 @@ static void intel_pmu_sched_task(struct perf_event_context *ctx, intel_pmu_lbr_sched_task(ctx, sched_in); } +static void intel_pmu_swap_task_ctx(struct perf_event_context *prev, + struct perf_event_context *next) +{ + intel_pmu_lbr_swap_task_ctx(prev, next); +} + static int intel_pmu_check_period(struct perf_event *event, u64 value) { return intel_pmu_has_bts_period(event, value) ? -EINVAL : 0; @@ -3955,6 +3961,7 @@ static __initconst const struct x86_pmu intel_pmu = { .guest_get_msrs = intel_guest_get_msrs, .sched_task = intel_pmu_sched_task, + .swap_task_ctx = intel_pmu_swap_task_ctx, .check_period = intel_pmu_check_period, diff --git a/kernel/events/core.c b/kernel/events/core.c index 0940c8810be0..f48d38b55e7b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3204,10 +3204,21 @@ static void perf_event_context_sched_out(struct task_struct *task, int ctxn, raw_spin_lock(&ctx->lock); raw_spin_lock_nested(&next_ctx->lock, SINGLE_DEPTH_NESTING); if (context_equiv(ctx, next_ctx)) { + struct pmu *pmu = ctx->pmu; + WRITE_ONCE(ctx->task, next); WRITE_ONCE(next_ctx->task, task); - swap(ctx->task_ctx_data, next_ctx->task_ctx_data); + /* + * PMU specific parts of task perf context can require + * additional synchronization. As an example of such + * synchronization see implementation details of Intel + * LBR call stack data profiling; + */ + if (pmu->swap_task_ctx) + pmu->swap_task_ctx(ctx, next_ctx); + else + swap(ctx->task_ctx_data, next_ctx->task_ctx_data); /* * RCU_INIT_POINTER here is safe because we've not -- cgit v1.2.3-58-ga151 From db0503e4f6751f2c719d002ba1becd1811633e6e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 21 Oct 2019 16:02:39 +0200 Subject: perf/core: Optimize perf_install_in_event() Andi reported that when creating a lot of events, a lot of time is spent in IPIs and asked if it would be possible to elide some of that. Now when, as for example the perf-tool always does, events are created disabled, then these events will not need to be scheduled when added to the context (they're still disable) and therefore the IPI is not required -- except for the very first event, that will need to set ctx->is_active. ( It might be possible to set ctx->is_active remotely for cpu_ctx, but we really need the IPI for task_ctx, so lets not make that distinction. ) Also use __perf_effective_state() since group events depend on the state of the leader, if the leader is OFF, the whole group is OFF. So when sibling events are created enabled (XXX check tool) then we only need a single IPI to create and enable the whole group (+ that initial IPI to initialize the context). Suggested-by: Andi Kleen Reported-by: Andi Kleen Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: acme@kernel.org Cc: kan.liang@linux.intel.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'kernel/events') diff --git a/kernel/events/core.c b/kernel/events/core.c index f48d38b55e7b..ea70ca614987 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -2666,6 +2666,25 @@ perf_install_in_context(struct perf_event_context *ctx, */ smp_store_release(&event->ctx, ctx); + /* + * perf_event_attr::disabled events will not run and can be initialized + * without IPI. Except when this is the first event for the context, in + * that case we need the magic of the IPI to set ctx->is_active. + * + * The IOC_ENABLE that is sure to follow the creation of a disabled + * event will issue the IPI and reprogram the hardware. + */ + if (__perf_effective_state(event) == PERF_EVENT_STATE_OFF && ctx->nr_events) { + raw_spin_lock_irq(&ctx->lock); + if (ctx->task == TASK_TOMBSTONE) { + raw_spin_unlock_irq(&ctx->lock); + return; + } + add_event_to_ctx(event, ctx); + raw_spin_unlock_irq(&ctx->lock); + return; + } + if (!task) { cpu_function_call(cpu, __perf_install_in_context, event); return; -- cgit v1.2.3-58-ga151 From 66d258c5b048840991de49697264af75f5b09def Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 17 Oct 2019 20:31:03 +0200 Subject: perf/core: Optimize perf_init_event() Andi reported that he was hitting the linear search in perf_init_event() a lot. Make more agressive use of the IDR lookup to avoid hitting the linear search. With exception of PERF_TYPE_SOFTWARE (which relies on a hideous hack), we can put everything in the IDR. On top of that, we can alias TYPE_HARDWARE and TYPE_HW_CACHE to TYPE_RAW on the lookup side. This greatly reduces the chances of hitting the linear search. Reported-by: Andi Kleen Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Kan Cc: Linus Torvalds Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Signed-off-by: Ingo Molnar --- kernel/events/core.c | 41 ++++++++++++++++++++++++++++++----------- 1 file changed, 30 insertions(+), 11 deletions(-) (limited to 'kernel/events') diff --git a/kernel/events/core.c b/kernel/events/core.c index ea70ca614987..4d67c5d35c13 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10080,7 +10080,7 @@ static struct lock_class_key cpuctx_lock; int perf_pmu_register(struct pmu *pmu, const char *name, int type) { - int cpu, ret; + int cpu, ret, max = PERF_TYPE_MAX; mutex_lock(&pmus_lock); ret = -ENOMEM; @@ -10093,12 +10093,17 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type) goto skip_type; pmu->name = name; - if (type < 0) { - type = idr_alloc(&pmu_idr, pmu, PERF_TYPE_MAX, 0, GFP_KERNEL); - if (type < 0) { - ret = type; + if (type != PERF_TYPE_SOFTWARE) { + if (type >= 0) + max = type; + + ret = idr_alloc(&pmu_idr, pmu, max, 0, GFP_KERNEL); + if (ret < 0) goto free_pdc; - } + + WARN_ON(type >= 0 && ret != type); + + type = ret; } pmu->type = type; @@ -10188,7 +10193,7 @@ free_dev: put_device(pmu->dev); free_idr: - if (pmu->type >= PERF_TYPE_MAX) + if (pmu->type != PERF_TYPE_SOFTWARE) idr_remove(&pmu_idr, pmu->type); free_pdc: @@ -10210,7 +10215,7 @@ void perf_pmu_unregister(struct pmu *pmu) synchronize_rcu(); free_percpu(pmu->pmu_disable_count); - if (pmu->type >= PERF_TYPE_MAX) + if (pmu->type != PERF_TYPE_SOFTWARE) idr_remove(&pmu_idr, pmu->type); if (pmu_bus_running) { if (pmu->nr_addr_filters) @@ -10280,9 +10285,8 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) static struct pmu *perf_init_event(struct perf_event *event) { + int idx, type, ret; struct pmu *pmu; - int idx; - int ret; idx = srcu_read_lock(&pmus_srcu); @@ -10295,12 +10299,27 @@ static struct pmu *perf_init_event(struct perf_event *event) } rcu_read_lock(); - pmu = idr_find(&pmu_idr, event->attr.type); + /* + * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE + * are often aliases for PERF_TYPE_RAW. + */ + type = event->attr.type; + if (type == PERF_TYPE_HARDWARE || type == PERF_TYPE_HW_CACHE) + type = PERF_TYPE_RAW; + +again: + pmu = idr_find(&pmu_idr, type); rcu_read_unlock(); if (pmu) { ret = perf_try_init_event(pmu, event); + if (ret == -ENOENT && event->attr.type != type) { + type = event->attr.type; + goto again; + } + if (ret) pmu = ERR_PTR(ret); + goto unlock; } -- cgit v1.2.3-58-ga151 From d44f821b0e13275735e8f3fe4db8703b45f05d52 Mon Sep 17 00:00:00 2001 From: "Liang, Kan" Date: Tue, 22 Oct 2019 11:13:09 +0200 Subject: perf/core: Optimize perf_init_event() for TYPE_SOFTWARE Andi reported that he was hitting the linear search in perf_init_event() a lot. Now that all !TYPE_SOFTWARE events should hit the IDR, make sure the TYPE_SOFTWARE events are at the head of the list such that we'll quickly find the right PMU (provided a valid event was given). Signed-off-by: Liang, Kan Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Signed-off-by: Ingo Molnar --- kernel/events/core.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'kernel/events') diff --git a/kernel/events/core.c b/kernel/events/core.c index 4d67c5d35c13..cfd89b4a02d8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10180,7 +10180,16 @@ got_cpu_context: if (!pmu->event_idx) pmu->event_idx = perf_event_idx_default; - list_add_rcu(&pmu->entry, &pmus); + /* + * Ensure the TYPE_SOFTWARE PMUs are at the head of the list, + * since these cannot be in the IDR. This way the linear search + * is fast, provided a valid software event is provided. + */ + if (type == PERF_TYPE_SOFTWARE || !name) + list_add_rcu(&pmu->entry, &pmus); + else + list_add_tail_rcu(&pmu->entry, &pmus); + atomic_set(&pmu->exclusive_cnt, 0); ret = 0; unlock: -- cgit v1.2.3-58-ga151 From deb0c3c29d552ab81ecd5481bb83bf2f4e41927d Mon Sep 17 00:00:00 2001 From: Qian Cai Date: Wed, 6 Nov 2019 00:29:35 -0500 Subject: perf/core: Fix unlock balance in perf_init_event() Commit: 66d258c5b048 ("perf/core: Optimize perf_init_event()") introduced an unlock imbalance in perf_init_event() where it calls "goto again" and then only repeat rcu_read_unlock(). Signed-off-by: Qian Cai Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: David Ahern Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mark Rutland Cc: Namhyung Kim Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Fixes: 66d258c5b048 ("perf/core: Optimize perf_init_event()") Link: https://lkml.kernel.org/r/20191106052935.8352-1-cai@lca.pw Signed-off-by: Ingo Molnar --- kernel/events/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel/events') diff --git a/kernel/events/core.c b/kernel/events/core.c index 6cb6d685191d..8d65e03b98f2 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -10307,7 +10307,6 @@ static struct pmu *perf_init_event(struct perf_event *event) goto unlock; } - rcu_read_lock(); /* * PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE * are often aliases for PERF_TYPE_RAW. @@ -10317,6 +10316,7 @@ static struct pmu *perf_init_event(struct perf_event *event) type = PERF_TYPE_RAW; again: + rcu_read_lock(); pmu = idr_find(&pmu_idr, type); rcu_read_unlock(); if (pmu) { -- cgit v1.2.3-58-ga151 From a4faf00d994c40e64f656805ac375c65e324eefb Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Fri, 25 Oct 2019 17:08:33 +0300 Subject: perf/aux: Allow using AUX data in perf samples AUX data can be used to annotate perf events such as performance counters or tracepoints/breakpoints by including it in sample records when PERF_SAMPLE_AUX flag is set. Such samples would be instrumental in debugging and profiling by providing, for example, a history of instruction flow leading up to the event's overflow. The implementation makes use of grouping an AUX event with all the events that wish to take samples of the AUX data, such that the former is the group leader. The samplees should also specify the desired size of the AUX sample via attr.aux_sample_size. AUX capable PMUs need to explicitly add support for sampling, because it relies on a new callback to take a snapshot of the buffer without touching the event states. Signed-off-by: Alexander Shishkin Signed-off-by: Peter Zijlstra (Intel) Cc: Arnaldo Carvalho de Melo Cc: David Ahern Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mark Rutland Cc: Namhyung Kim Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: adrian.hunter@intel.com Cc: mathieu.poirier@linaro.org Link: https://lkml.kernel.org/r/20191025140835.53665-2-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- include/linux/perf_event.h | 19 +++++ include/uapi/linux/perf_event.h | 10 ++- kernel/events/core.c | 173 +++++++++++++++++++++++++++++++++++++++- kernel/events/internal.h | 1 + kernel/events/ring_buffer.c | 36 +++++++++ 5 files changed, 234 insertions(+), 5 deletions(-) (limited to 'kernel/events') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 011dcbdbccc2..34c7c6910026 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -249,6 +249,8 @@ struct perf_event; #define PERF_PMU_CAP_NO_EXCLUDE 0x80 #define PERF_PMU_CAP_AUX_OUTPUT 0x100 +struct perf_output_handle; + /** * struct pmu - generic performance monitoring unit */ @@ -432,6 +434,19 @@ struct pmu { */ void (*free_aux) (void *aux); /* optional */ + /* + * Take a snapshot of the AUX buffer without touching the event + * state, so that preempting ->start()/->stop() callbacks does + * not interfere with their logic. Called in PMI context. + * + * Returns the size of AUX data copied to the output handle. + * + * Optional. + */ + long (*snapshot_aux) (struct perf_event *event, + struct perf_output_handle *handle, + unsigned long size); + /* * Validate address range filters: make sure the HW supports the * requested configuration and number of filters; return 0 if the @@ -973,6 +988,7 @@ struct perf_sample_data { u32 reserved; } cpu_entry; struct perf_callchain_entry *callchain; + u64 aux_size; /* * regs_user may point to task_pt_regs or to regs_user_copy, depending @@ -1362,6 +1378,9 @@ extern unsigned int perf_output_copy(struct perf_output_handle *handle, const void *buf, unsigned int len); extern unsigned int perf_output_skip(struct perf_output_handle *handle, unsigned int len); +extern long perf_output_copy_aux(struct perf_output_handle *aux_handle, + struct perf_output_handle *handle, + unsigned long from, unsigned long to); extern int perf_swevent_get_recursion_context(void); extern void perf_swevent_put_recursion_context(int rctx); extern u64 perf_swevent_set_period(struct perf_event *event); diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index bb7b271397a6..377d794d3105 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -141,8 +141,9 @@ enum perf_event_sample_format { PERF_SAMPLE_TRANSACTION = 1U << 17, PERF_SAMPLE_REGS_INTR = 1U << 18, PERF_SAMPLE_PHYS_ADDR = 1U << 19, + PERF_SAMPLE_AUX = 1U << 20, - PERF_SAMPLE_MAX = 1U << 20, /* non-ABI */ + PERF_SAMPLE_MAX = 1U << 21, /* non-ABI */ __PERF_SAMPLE_CALLCHAIN_EARLY = 1ULL << 63, /* non-ABI; internal use */ }; @@ -300,6 +301,7 @@ enum perf_event_read_format { /* add: sample_stack_user */ #define PERF_ATTR_SIZE_VER4 104 /* add: sample_regs_intr */ #define PERF_ATTR_SIZE_VER5 112 /* add: aux_watermark */ +#define PERF_ATTR_SIZE_VER6 120 /* add: aux_sample_size */ /* * Hardware event_id to monitor via a performance monitoring event: @@ -424,7 +426,9 @@ struct perf_event_attr { */ __u32 aux_watermark; __u16 sample_max_stack; - __u16 __reserved_2; /* align to __u64 */ + __u16 __reserved_2; + __u32 aux_sample_size; + __u32 __reserved_3; }; /* @@ -864,6 +868,8 @@ enum perf_event_type { * { u64 abi; # enum perf_sample_regs_abi * u64 regs[weight(mask)]; } && PERF_SAMPLE_REGS_INTR * { u64 phys_addr;} && PERF_SAMPLE_PHYS_ADDR + * { u64 size; + * char data[size]; } && PERF_SAMPLE_AUX * }; */ PERF_RECORD_SAMPLE = 9, diff --git a/kernel/events/core.c b/kernel/events/core.c index 8d65e03b98f2..16d80ad8d6d7 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1941,6 +1941,11 @@ static void perf_put_aux_event(struct perf_event *event) } } +static bool perf_need_aux_event(struct perf_event *event) +{ + return !!event->attr.aux_output || !!event->attr.aux_sample_size; +} + static int perf_get_aux_event(struct perf_event *event, struct perf_event *group_leader) { @@ -1953,7 +1958,17 @@ static int perf_get_aux_event(struct perf_event *event, if (!group_leader) return 0; - if (!perf_aux_output_match(event, group_leader)) + /* + * aux_output and aux_sample_size are mutually exclusive. + */ + if (event->attr.aux_output && event->attr.aux_sample_size) + return 0; + + if (event->attr.aux_output && + !perf_aux_output_match(event, group_leader)) + return 0; + + if (event->attr.aux_sample_size && !group_leader->pmu->snapshot_aux) return 0; if (!atomic_long_inc_not_zero(&group_leader->refcount)) @@ -6222,6 +6237,122 @@ perf_output_sample_ustack(struct perf_output_handle *handle, u64 dump_size, } } +static unsigned long perf_prepare_sample_aux(struct perf_event *event, + struct perf_sample_data *data, + size_t size) +{ + struct perf_event *sampler = event->aux_event; + struct ring_buffer *rb; + + data->aux_size = 0; + + if (!sampler) + goto out; + + if (WARN_ON_ONCE(READ_ONCE(sampler->state) != PERF_EVENT_STATE_ACTIVE)) + goto out; + + if (WARN_ON_ONCE(READ_ONCE(sampler->oncpu) != smp_processor_id())) + goto out; + + rb = ring_buffer_get(sampler->parent ? sampler->parent : sampler); + if (!rb) + goto out; + + /* + * If this is an NMI hit inside sampling code, don't take + * the sample. See also perf_aux_sample_output(). + */ + if (READ_ONCE(rb->aux_in_sampling)) { + data->aux_size = 0; + } else { + size = min_t(size_t, size, perf_aux_size(rb)); + data->aux_size = ALIGN(size, sizeof(u64)); + } + ring_buffer_put(rb); + +out: + return data->aux_size; +} + +long perf_pmu_snapshot_aux(struct ring_buffer *rb, + struct perf_event *event, + struct perf_output_handle *handle, + unsigned long size) +{ + unsigned long flags; + long ret; + + /* + * Normal ->start()/->stop() callbacks run in IRQ mode in scheduler + * paths. If we start calling them in NMI context, they may race with + * the IRQ ones, that is, for example, re-starting an event that's just + * been stopped, which is why we're using a separate callback that + * doesn't change the event state. + * + * IRQs need to be disabled to prevent IPIs from racing with us. + */ + local_irq_save(flags); + /* + * Guard against NMI hits inside the critical section; + * see also perf_prepare_sample_aux(). + */ + WRITE_ONCE(rb->aux_in_sampling, 1); + barrier(); + + ret = event->pmu->snapshot_aux(event, handle, size); + + barrier(); + WRITE_ONCE(rb->aux_in_sampling, 0); + local_irq_restore(flags); + + return ret; +} + +static void perf_aux_sample_output(struct perf_event *event, + struct perf_output_handle *handle, + struct perf_sample_data *data) +{ + struct perf_event *sampler = event->aux_event; + unsigned long pad; + struct ring_buffer *rb; + long size; + + if (WARN_ON_ONCE(!sampler || !data->aux_size)) + return; + + rb = ring_buffer_get(sampler->parent ? sampler->parent : sampler); + if (!rb) + return; + + size = perf_pmu_snapshot_aux(rb, sampler, handle, data->aux_size); + + /* + * An error here means that perf_output_copy() failed (returned a + * non-zero surplus that it didn't copy), which in its current + * enlightened implementation is not possible. If that changes, we'd + * like to know. + */ + if (WARN_ON_ONCE(size < 0)) + goto out_put; + + /* + * The pad comes from ALIGN()ing data->aux_size up to u64 in + * perf_prepare_sample_aux(), so should not be more than that. + */ + pad = data->aux_size - size; + if (WARN_ON_ONCE(pad >= sizeof(u64))) + pad = 8; + + if (pad) { + u64 zero = 0; + perf_output_copy(handle, &zero, pad); + } + +out_put: + ring_buffer_put(rb); +} + static void __perf_event_header__init_id(struct perf_event_header *header, struct perf_sample_data *data, struct perf_event *event) @@ -6541,6 +6672,13 @@ void perf_output_sample(struct perf_output_handle *handle, if (sample_type & PERF_SAMPLE_PHYS_ADDR) perf_output_put(handle, data->phys_addr); + if (sample_type & PERF_SAMPLE_AUX) { + perf_output_put(handle, data->aux_size); + + if (data->aux_size) + perf_aux_sample_output(event, handle, data); + } + if (!event->attr.watermark) { int wakeup_events = event->attr.wakeup_events; @@ -6729,6 +6867,35 @@ void perf_prepare_sample(struct perf_event_header *header, if (sample_type & PERF_SAMPLE_PHYS_ADDR) data->phys_addr = perf_virt_to_phys(data->addr); + + if (sample_type & PERF_SAMPLE_AUX) { + u64 size; + + header->size += sizeof(u64); /* size */ + + /* + * Given the 16bit nature of header::size, an AUX sample can + * easily overflow it, what with all the preceding sample bits. + * Make sure this doesn't happen by using up to U16_MAX bytes + * per sample in total (rounded down to 8 byte boundary). + */ + size = min_t(size_t, U16_MAX - header->size, + event->attr.aux_sample_size); + size = rounddown(size, 8); + size = perf_prepare_sample_aux(event, data, size); + + WARN_ON_ONCE(size + header->size > U16_MAX); + header->size += size; + } + /* + * If you're adding more sample types here, you likely need to do + * something about the overflowing header::size, like repurpose the + * lowest 3 bits of size, which should be always zero at the moment. + * This raises a more important question, do we really need 512k sized + * samples and why, so good argumentation is in order for whatever you + * do here next. + */ + WARN_ON_ONCE(header->size & 7); } static __always_inline int @@ -10727,7 +10894,7 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr, attr->size = size; - if (attr->__reserved_1 || attr->__reserved_2) + if (attr->__reserved_1 || attr->__reserved_2 || attr->__reserved_3) return -EINVAL; if (attr->sample_type & ~(PERF_SAMPLE_MAX-1)) @@ -11277,7 +11444,7 @@ SYSCALL_DEFINE5(perf_event_open, } } - if (event->attr.aux_output && !perf_get_aux_event(event, group_leader)) + if (perf_need_aux_event(event) && !perf_get_aux_event(event, group_leader)) goto err_locked; /* diff --git a/kernel/events/internal.h b/kernel/events/internal.h index 3aef4191798c..747d67f130cb 100644 --- a/kernel/events/internal.h +++ b/kernel/events/internal.h @@ -50,6 +50,7 @@ struct ring_buffer { unsigned long aux_mmap_locked; void (*free_aux)(void *); refcount_t aux_refcount; + int aux_in_sampling; void **aux_pages; void *aux_priv; diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 246c83ac5643..7ffd5c763f93 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -562,6 +562,42 @@ void *perf_get_aux(struct perf_output_handle *handle) } EXPORT_SYMBOL_GPL(perf_get_aux); +/* + * Copy out AUX data from an AUX handle. + */ +long perf_output_copy_aux(struct perf_output_handle *aux_handle, + struct perf_output_handle *handle, + unsigned long from, unsigned long to) +{ + unsigned long tocopy, remainder, len = 0; + struct ring_buffer *rb = aux_handle->rb; + void *addr; + + from &= (rb->aux_nr_pages << PAGE_SHIFT) - 1; + to &= (rb->aux_nr_pages << PAGE_SHIFT) - 1; + + do { + tocopy = PAGE_SIZE - offset_in_page(from); + if (to > from) + tocopy = min(tocopy, to - from); + if (!tocopy) + break; + + addr = rb->aux_pages[from >> PAGE_SHIFT]; + addr += offset_in_page(from); + + remainder = perf_output_copy(handle, addr, tocopy); + if (remainder) + return -EFAULT; + + len += tocopy; + from += tocopy; + from &= (rb->aux_nr_pages << PAGE_SHIFT) - 1; + } while (to != from); + + return len; +} + #define PERF_AUX_GFP (GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_NORETRY) static struct page *rb_alloc_aux_page(int node, int order) -- cgit v1.2.3-58-ga151 From 36b3db03b4741b8935b68fffc7e69951d8d70a89 Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Fri, 15 Nov 2019 18:08:18 +0200 Subject: perf/core: Fix the mlock accounting, again Commit: 5e6c3c7b1ec2 ("perf/aux: Fix tracking of auxiliary trace buffer allocation") tried to guess the correct combination of arithmetic operations that would undo the AUX buffer's mlock accounting, and failed, leaking the bottom part when an allocation needs to be charged partially to both user->locked_vm and mm->pinned_vm, eventually leaving the user with no locked bonus: $ perf record -e intel_pt//u -m1,128 uname [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.061 MB perf.data ] $ perf record -e intel_pt//u -m1,128 uname Permission error mapping pages. Consider increasing /proc/sys/kernel/perf_event_mlock_kb, or try again with a smaller value of -m/--mmap_pages. (current value: 1,128) Fix this by subtracting both locked and pinned counts when AUX buffer is unmapped. Reported-by: Thomas Richter Tested-by: Thomas Richter Signed-off-by: Alexander Shishkin Acked-by: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Mark Rutland Cc: Namhyung Kim Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Signed-off-by: Ingo Molnar --- kernel/events/core.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'kernel/events') diff --git a/kernel/events/core.c b/kernel/events/core.c index 00a014670ed0..8f66a4833ded 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5607,10 +5607,8 @@ static void perf_mmap_close(struct vm_area_struct *vma) perf_pmu_output_stop(event); /* now it's safe to free the pages */ - if (!rb->aux_mmap_locked) - atomic_long_sub(rb->aux_nr_pages, &mmap_user->locked_vm); - else - atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm); + atomic_long_sub(rb->aux_nr_pages - rb->aux_mmap_locked, &mmap_user->locked_vm); + atomic64_sub(rb->aux_mmap_locked, &vma->vm_mm->pinned_vm); /* this has to be the last one */ rb_free_aux(rb); -- cgit v1.2.3-58-ga151 From c4b75479741c9c3a4f0abff5baa5013d27640ac1 Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Wed, 20 Nov 2019 19:06:40 +0200 Subject: perf/core: Make the mlock accounting simple again Commit: d44248a41337 ("perf/core: Rework memory accounting in perf_mmap()") does a lot of things to the mlock accounting arithmetics, while the only thing that actually needed to happen is subtracting the part that is charged to the mm from the part that is charged to the user, so that the former isn't charged twice. Signed-off-by: Alexander Shishkin Acked-by: Song Liu Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Peter Zijlstra Cc: Wanpeng Li Cc: Yauheni Kaliuta Cc: songliubraving@fb.com Link: https://lkml.kernel.org/r/20191120170640.54123-1-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- kernel/events/core.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) (limited to 'kernel/events') diff --git a/kernel/events/core.c b/kernel/events/core.c index 8f66a4833ded..7e8980d0b997 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5825,13 +5825,7 @@ accounting: user_locked = atomic_long_read(&user->locked_vm) + user_extra; - if (user_locked <= user_lock_limit) { - /* charge all to locked_vm */ - } else if (atomic_long_read(&user->locked_vm) >= user_lock_limit) { - /* charge all to pinned_vm */ - extra = user_extra; - user_extra = 0; - } else { + if (user_locked > user_lock_limit) { /* * charge locked_vm until it hits user_lock_limit; * charge the rest from pinned_vm -- cgit v1.2.3-58-ga151