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111 lines
3.9 KiB
Diff
111 lines
3.9 KiB
Diff
From e429817b401f095ac483fcb02524b01faf45dad6 Mon Sep 17 00:00:00 2001
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From: "Suzuki K. Poulose" <suzuki.poulose@arm.com>
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Date: Tue, 17 Mar 2015 18:14:58 +0000
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Subject: ARM: perf: reject groups spanning multiple hardware PMUs
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The perf core implicitly rejects events spanning multiple HW PMUs, as in
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these cases the event->ctx will differ. However this validation is
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performed after pmu::event_init() is called in perf_init_event(), and
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thus pmu::event_init() may be called with a group leader from a
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different HW PMU.
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The ARM PMU driver does not take this fact into account, and when
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validating groups assumes that it can call to_arm_pmu(event->pmu) for
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any HW event. When the event in question is from another HW PMU this is
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wrong, and results in dereferencing garbage.
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This patch updates the ARM PMU driver to first test for and reject
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events from other PMUs, moving the to_arm_pmu and related logic after
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this test. Fixes a crash triggered by perf_fuzzer on Linux-4.0-rc2, with
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a CCI PMU present:
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---
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CPU: 0 PID: 1527 Comm: perf_fuzzer Not tainted 4.0.0-rc2 #57
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Hardware name: ARM-Versatile Express
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task: bd8484c0 ti: be676000 task.ti: be676000
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PC is at 0xbf1bbc90
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LR is at validate_event+0x34/0x5c
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pc : [<bf1bbc90>] lr : [<80016060>] psr: 00000013
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...
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[<80016060>] (validate_event) from [<80016198>] (validate_group+0x28/0x90)
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[<80016198>] (validate_group) from [<80016398>] (armpmu_event_init+0x150/0x218)
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[<80016398>] (armpmu_event_init) from [<800882e4>] (perf_try_init_event+0x30/0x48)
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[<800882e4>] (perf_try_init_event) from [<8008f544>] (perf_init_event+0x5c/0xf4)
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[<8008f544>] (perf_init_event) from [<8008f8a8>] (perf_event_alloc+0x2cc/0x35c)
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[<8008f8a8>] (perf_event_alloc) from [<8009015c>] (SyS_perf_event_open+0x498/0xa70)
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[<8009015c>] (SyS_perf_event_open) from [<8000e420>] (ret_fast_syscall+0x0/0x34)
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Code: bf1be000 bf1bb380 802a2664 00000000 (00000002)
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---[ end trace 01aff0ff00926a0a ]---
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Also cleans up the code to use the arm_pmu only when we know that
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we are dealing with an arm pmu event.
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Cc: Will Deacon <will.deacon@arm.com>
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Acked-by: Mark Rutland <mark.rutland@arm.com>
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Acked-by: Peter Ziljstra (Intel) <peterz@infradead.org>
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Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
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Signed-off-by: Will Deacon <will.deacon@arm.com>
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---
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arch/arm/kernel/perf_event.c | 21 +++++++++++++++------
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1 file changed, 15 insertions(+), 6 deletions(-)
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diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
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index 557e128..4a86a01 100644
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--- a/arch/arm/kernel/perf_event.c
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+++ b/arch/arm/kernel/perf_event.c
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@@ -259,20 +259,29 @@ out:
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}
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static int
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-validate_event(struct pmu_hw_events *hw_events,
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- struct perf_event *event)
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+validate_event(struct pmu *pmu, struct pmu_hw_events *hw_events,
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+ struct perf_event *event)
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{
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- struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
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+ struct arm_pmu *armpmu;
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if (is_software_event(event))
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return 1;
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+ /*
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+ * Reject groups spanning multiple HW PMUs (e.g. CPU + CCI). The
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+ * core perf code won't check that the pmu->ctx == leader->ctx
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+ * until after pmu->event_init(event).
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+ */
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+ if (event->pmu != pmu)
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+ return 0;
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+
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if (event->state < PERF_EVENT_STATE_OFF)
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return 1;
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if (event->state == PERF_EVENT_STATE_OFF && !event->attr.enable_on_exec)
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return 1;
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+ armpmu = to_arm_pmu(event->pmu);
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return armpmu->get_event_idx(hw_events, event) >= 0;
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}
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@@ -288,15 +297,15 @@ validate_group(struct perf_event *event)
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*/
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memset(&fake_pmu.used_mask, 0, sizeof(fake_pmu.used_mask));
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- if (!validate_event(&fake_pmu, leader))
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+ if (!validate_event(event->pmu, &fake_pmu, leader))
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return -EINVAL;
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list_for_each_entry(sibling, &leader->sibling_list, group_entry) {
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- if (!validate_event(&fake_pmu, sibling))
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+ if (!validate_event(event->pmu, &fake_pmu, sibling))
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return -EINVAL;
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}
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- if (!validate_event(&fake_pmu, event))
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+ if (!validate_event(event->pmu, &fake_pmu, event))
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return -EINVAL;
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return 0;
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--
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cgit v1.1
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