Messages in this thread | | | Date | Wed, 6 Jan 2016 11:21:37 -0800 | Subject | Re: [PATCH 1/8] perf: Add PERF_SAMPLE_PHYS_ADDR | From | Stephane Eranian <> |
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On Wed, Jan 6, 2016 at 3:04 AM, <kan.liang@intel.com> wrote: > From: Kan Liang <kan.liang@intel.com> > > For understanding how the workload maps to memory channels and hardware > behavior, it's useful to collect address maps with physical addresses. > This is not intended for detecting page sharing (which can be already > done using the mmap inode), but for lower level hardware behavior > studies. > Perf supports load latency/DLA which can only collect virtual addresses. > This patch add a new sample type PERF_SAMPLE_PHYS_ADDR to expose the > physical addresses. > For kernel direct mapping addresses, the patch uses virt_to_phys to > convert the virtual addresses from DLA to physical address. > For user virtual addresses, __get_user_pages_fast is used to walk the > pages tables for user physical address. > This does not work for vmalloc addresses. Right now these are not > resolved, but code to do that could be added. > For security, the physical address can only be exposed to root or > privileged user. > > Signed-off-by: Kan Liang <kan.liang@intel.com> > --- > arch/x86/kernel/cpu/perf_event.h | 2 +- > arch/x86/kernel/cpu/perf_event_intel_ds.c | 23 +++++++++++++++++++++++ > include/linux/perf_event.h | 3 +++ > include/uapi/linux/perf_event.h | 4 +++- > kernel/events/core.c | 11 +++++++++++ > 5 files changed, 41 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/cpu/perf_event.h b/arch/x86/kernel/cpu/perf_event.h > index 799e6bd..164de68 100644 > --- a/arch/x86/kernel/cpu/perf_event.h > +++ b/arch/x86/kernel/cpu/perf_event.h > @@ -90,7 +90,7 @@ struct amd_nb { > (PERF_SAMPLE_IP | PERF_SAMPLE_TID | PERF_SAMPLE_ADDR | \ > PERF_SAMPLE_ID | PERF_SAMPLE_CPU | PERF_SAMPLE_STREAM_ID | \ > PERF_SAMPLE_DATA_SRC | PERF_SAMPLE_IDENTIFIER | \ > - PERF_SAMPLE_TRANSACTION) > + PERF_SAMPLE_TRANSACTION | PERF_SAMPLE_PHYS_ADDR) > > /* > * A debug store configuration. > diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c > index 5db1c77..2e333dc 100644 > --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c > +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c > @@ -986,6 +986,7 @@ static void setup_pebs_sample_data(struct perf_event *event, > u64 sample_type; > int fll, fst, dsrc; > int fl = event->hw.flags; > + struct page *p = NULL; > > if (pebs == NULL) > return; > @@ -1071,6 +1072,28 @@ static void setup_pebs_sample_data(struct perf_event *event, > x86_pmu.intel_cap.pebs_format >= 1) > data->addr = pebs->dla; > > + if ((sample_type & PERF_SAMPLE_PHYS_ADDR) && (data->addr != 0)) { > + if (data->addr >= TASK_SIZE) { > + /* If it's vmalloc()d memory, leave phys_addr as 0 */ > + if (virt_addr_valid(data->addr) && > + !(data->addr >= VMALLOC_START && data->addr < VMALLOC_END)) > + data->phys_addr = (u64)virt_to_phys((void *)data->addr); > + } else { > + /* > + * Walking the pages tables for user address. > + * Interrupts are disabled, so it prevents any tear down > + * of the page tables. > + * Try IRQ-safe __get_user_pages_fast first. > + * If failed, leave phys_addr as 0. > + */ > + if ((current->mm != NULL) && > + (__get_user_pages_fast(data->addr, 1, 0, &p) == 1)) > + data->phys_addr = page_to_phys(p) + data->addr % PAGE_SIZE; > + > + if (p) > + put_page(p); > + } > + } > if (x86_pmu.intel_cap.pebs_format >= 2) { > /* Only set the TSX weight when no memory weight. */ > if ((sample_type & PERF_SAMPLE_WEIGHT) && !fll) > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index f9828a4..d9c0527 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -795,6 +795,8 @@ struct perf_sample_data { > > struct perf_regs regs_intr; > u64 stack_user_size; > + > + u64 phys_addr; > } ____cacheline_aligned; > > /* default value for data source */ > @@ -815,6 +817,7 @@ static inline void perf_sample_data_init(struct perf_sample_data *data, > data->weight = 0; > data->data_src.val = PERF_MEM_NA; > data->txn = 0; > + data->phys_addr = 0; > } > > extern void perf_output_sample(struct perf_output_handle *handle, > diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h > index 1afe962..5afc572 100644 > --- a/include/uapi/linux/perf_event.h > +++ b/include/uapi/linux/perf_event.h > @@ -139,8 +139,9 @@ enum perf_event_sample_format { > PERF_SAMPLE_IDENTIFIER = 1U << 16, > PERF_SAMPLE_TRANSACTION = 1U << 17, > PERF_SAMPLE_REGS_INTR = 1U << 18, > + PERF_SAMPLE_PHYS_ADDR = 1U << 19, > > - PERF_SAMPLE_MAX = 1U << 19, /* non-ABI */ > + PERF_SAMPLE_MAX = 1U << 20, /* non-ABI */ > }; > > /* > @@ -767,6 +768,7 @@ enum perf_event_type { > * { u64 transaction; } && PERF_SAMPLE_TRANSACTION > * { u64 abi; # enum perf_sample_regs_abi > * u64 regs[weight(mask)]; } && PERF_SAMPLE_REGS_INTR > + * { u64 phys_addr;} && PERF_SAMPLE_PHYS_ADDR
If you say, PHYS_ADDR appears after SAMPLE_REGS_INTR then you have do respect that order in the perf_output_sample() routine, otherwise the tool cannot parse the record correctly.
> * }; > */ > PERF_RECORD_SAMPLE = 9, > diff --git a/kernel/events/core.c b/kernel/events/core.c > index a627f36..9a922a2 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -1334,6 +1334,9 @@ static void __perf_event_header_size(struct perf_event *event, u64 sample_type) > if (sample_type & PERF_SAMPLE_TRANSACTION) > size += sizeof(data->txn); > > + if (sample_type & PERF_SAMPLE_PHYS_ADDR) > + size += sizeof(data->phys_addr); > + > event->header_size = size; > } > > @@ -5432,6 +5435,9 @@ void perf_output_sample(struct perf_output_handle *handle, > if (sample_type & PERF_SAMPLE_DATA_SRC) > perf_output_put(handle, data->data_src.val); > > + if (sample_type & PERF_SAMPLE_PHYS_ADDR) > + perf_output_put(handle, data->phys_addr); > + Need to order the put calls according to the order you define in the header file, unless this logic has changed recently.
> if (sample_type & PERF_SAMPLE_TRANSACTION) > perf_output_put(handle, data->txn); > > @@ -8269,6 +8275,11 @@ SYSCALL_DEFINE5(perf_event_open, > return -EINVAL; > } > > + /* Only privileged users can get kernel addresses */ > + if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR) && > + !capable(CAP_SYS_ADMIN)) > + return -EACCES; > + > /* > * In cgroup mode, the pid argument is used to pass the fd > * opened to the cgroup directory in cgroupfs. The cpu argument > -- > 1.8.3.1 >
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