| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <5af3f1ab-b139-2c41-3218-1cba5ee3803e@linux.vnet.ibm.com>
Date: Tue, 29 Aug 2017 17:05:15 +0530
From: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
To: kan.liang@...el.com, peterz@...radead.org, mingo@...hat.com,
linux-kernel@...r.kernel.org
Cc: acme@...nel.org, jolsa@...hat.com, tglx@...utronix.de,
eranian@...gle.com, ak@...ux.intel.com, mpe@...erman.id.au
Subject: Re: [PATCH V8] perf: Add PERF_SAMPLE_PHYS_ADDR
On Tuesday 29 August 2017 06:22 AM, kan.liang@...el.com wrote:
> From: Kan Liang <kan.liang@...el.com>
>
> For understanding how the workload maps to memory channels and hardware
> behavior, it's very important to collect address maps with physical
> addresses. For example, 3D XPoint access can only be found by filtering
> the physical address.
>
> Add a new sample type for physical address.
>
> perf already has a facility to collect data virtual address. This patch
> introduces a function to convert the virtual address to physical address.
> The function is quite generic and can be extended to any architecture as
> long as a virtual address is provided.
> - For kernel direct mapping addresses, virt_to_phys is used to convert
> the virtual addresses 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.
>
> The new sample type requires collecting the virtual address. The
> virtual address will not be output unless SAMPLE_ADDR is applied.
>
> For security, the physical address can only be exposed to root or
> privileged user.
Tested-by: Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>
>
> Signed-off-by: Kan Liang <kan.liang@...el.com>
> ---
>
> This patch is kernel patch.
> The user space patch can be found here.
> https://urldefense.proofpoint.com/v2/url?u=https-3A__www.spinics.net_lists_kernel_msg2587093.html&d=DwIBaQ&c=jf_iaSHvJObTbx-siA1ZOg&r=3f2W2m24mqGnx1C8qDsVjM_Sd89MwbaDB37IJVL-h7w&m=bL7qsJKf8aRpvBVr07ODZxoQhPgxffpGFgN9A4iyACw&s=R1OMYJt1szqNhPZu8QQDDRCnQgHZiQzcCPzofF6FIF8&e=
>
> Changes since V7
> - Fix virt_addr_valid compile warning for MIPS architecture (LKP)
>
> arch/powerpc/perf/core-book3s.c | 3 ++-
> arch/x86/events/intel/ds.c | 2 +-
> arch/x86/events/perf_event.h | 2 +-
> include/linux/perf_event.h | 2 ++
> include/uapi/linux/perf_event.h | 4 +++-
> kernel/events/core.c | 47 +++++++++++++++++++++++++++++++++++++++++
> 6 files changed, 56 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
> index 6c2d416..2e3eb74 100644
> --- a/arch/powerpc/perf/core-book3s.c
> +++ b/arch/powerpc/perf/core-book3s.c
> @@ -2039,7 +2039,8 @@ static void record_and_restart(struct perf_event *event, unsigned long val,
>
> perf_sample_data_init(&data, ~0ULL, event->hw.last_period);
>
> - if (event->attr.sample_type & PERF_SAMPLE_ADDR)
> + if (event->attr.sample_type &
> + (PERF_SAMPLE_ADDR | PERF_SAMPLE_PHYS_ADDR))
> perf_get_data_addr(regs, &data.addr);
>
> if (event->attr.sample_type & PERF_SAMPLE_BRANCH_STACK) {
> diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
> index a322fed..0516f78 100644
> --- a/arch/x86/events/intel/ds.c
> +++ b/arch/x86/events/intel/ds.c
> @@ -1175,7 +1175,7 @@ static void setup_pebs_sample_data(struct perf_event *event,
> else
> regs->flags &= ~PERF_EFLAGS_EXACT;
>
> - if ((sample_type & PERF_SAMPLE_ADDR) &&
> + if ((sample_type & (PERF_SAMPLE_ADDR | PERF_SAMPLE_PHYS_ADDR)) &&
> x86_pmu.intel_cap.pebs_format >= 1)
> data->addr = pebs->dla;
>
> diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
> index 476aec3..65bb91e 100644
> --- a/arch/x86/events/perf_event.h
> +++ b/arch/x86/events/perf_event.h
> @@ -91,7 +91,7 @@ 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/include/linux/perf_event.h b/include/linux/perf_event.h
> index b14095b..74fb87e 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -944,6 +944,8 @@ struct perf_sample_data {
>
> struct perf_regs regs_intr;
> u64 stack_user_size;
> +
> + u64 phys_addr;
> } ____cacheline_aligned;
>
> /* default value for data source */
> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
> index 642db5f..cbea02f 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 */
> };
>
> /*
> @@ -814,6 +815,7 @@ 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
> * };
> */
> PERF_RECORD_SAMPLE = 9,
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index d704e23..e8d5c5d 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -1570,6 +1570,9 @@ 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;
> }
>
> @@ -6012,6 +6015,9 @@ void perf_output_sample(struct perf_output_handle *handle,
> }
> }
>
> + if (sample_type & PERF_SAMPLE_PHYS_ADDR)
> + perf_output_put(handle, data->phys_addr);
> +
> if (!event->attr.watermark) {
> int wakeup_events = event->attr.wakeup_events;
>
> @@ -6027,6 +6033,38 @@ void perf_output_sample(struct perf_output_handle *handle,
> }
> }
>
> +static u64 perf_virt_to_phys(u64 virt)
> +{
> + u64 phys_addr = 0;
> + struct page *p = NULL;
> +
> + if (!virt)
> + return 0;
> +
> + if (virt >= TASK_SIZE) {
> + /* If it's vmalloc()d memory, leave phys_addr as 0 */
> + if (virt_addr_valid((void *)(uintptr_t)virt) &&
> + !(virt >= VMALLOC_START && virt < VMALLOC_END))
> + phys_addr = (u64)virt_to_phys((void *)(uintptr_t)virt);
> + } 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(virt, 1, 0, &p) == 1))
> + phys_addr = page_to_phys(p) + virt % PAGE_SIZE;
> +
> + if (p)
> + put_page(p);
> + }
> +
> + return phys_addr;
> +}
> +
> void perf_prepare_sample(struct perf_event_header *header,
> struct perf_sample_data *data,
> struct perf_event *event,
> @@ -6145,6 +6183,9 @@ void perf_prepare_sample(struct perf_event_header *header,
>
> header->size += size;
> }
> +
> + if (sample_type & PERF_SAMPLE_PHYS_ADDR)
> + data->phys_addr = perf_virt_to_phys(data->addr);
> }
>
> static void __always_inline
> @@ -9892,6 +9933,12 @@ SYSCALL_DEFINE5(perf_event_open,
> return -EINVAL;
> }
>
> + /* Only privileged users can get kernel addresses */
> + if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR) &&
> + perf_paranoid_kernel() &&
> + !capable(CAP_SYS_ADMIN))
> + return -EACCES;
> +
> if (!attr.sample_max_stack)
> attr.sample_max_stack = sysctl_perf_event_max_stack;
>
Powered by blists - more mailing lists