From: Mark Rutland <mark.rutland@arm.com> To: Will Deacon <will.deacon@arm.com> Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, ard.biesheuvel@linaro.org, sboyd@codeaurora.org, dave.hansen@linux.intel.com, keescook@chromium.org, msalter@redhat.com, labbott@redhat.com, tglx@linutronix.de Subject: Re: [PATCH v3 18/20] perf: arm_spe: Fail device probe when arm64_kernel_unmapped_at_el0() Date: Wed, 6 Dec 2017 13:34:51 +0000 [thread overview] Message-ID: <20171206133450.7bcbyxnlyei3qgvl@lakrids.cambridge.arm.com> (raw) In-Reply-To: <1512563739-25239-19-git-send-email-will.deacon@arm.com> On Wed, Dec 06, 2017 at 12:35:37PM +0000, Will Deacon wrote: > When running with the kernel unmapped whilst at EL0, the virtually-addressed > SPE buffer is also unmapped, which can lead to buffer faults if userspace > profiling is enabled and potentially also when writing back kernel samples > unless an expensive drain operation is performed on exception return. > > For now, fail the SPE driver probe when arm64_kernel_unmapped_at_el0(). > > Signed-off-by: Will Deacon <will.deacon@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Mark. > --- > drivers/perf/arm_spe_pmu.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index 8ce262fc2561..51b40aecb776 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -1164,6 +1164,15 @@ static int arm_spe_pmu_device_dt_probe(struct platform_device *pdev) > struct arm_spe_pmu *spe_pmu; > struct device *dev = &pdev->dev; > > + /* > + * If kernelspace is unmapped when running at EL0, then the SPE > + * buffer will fault and prematurely terminate the AUX session. > + */ > + if (arm64_kernel_unmapped_at_el0()) { > + dev_warn_once(dev, "profiling buffer inaccessible. Try passing \"kpti=off\" on the kernel command line\n"); > + return -EPERM; > + } > + > spe_pmu = devm_kzalloc(dev, sizeof(*spe_pmu), GFP_KERNEL); > if (!spe_pmu) { > dev_err(dev, "failed to allocate spe_pmu\n"); > -- > 2.1.4 >
WARNING: multiple messages have this Message-ID (diff)
From: mark.rutland@arm.com (Mark Rutland) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v3 18/20] perf: arm_spe: Fail device probe when arm64_kernel_unmapped_at_el0() Date: Wed, 6 Dec 2017 13:34:51 +0000 [thread overview] Message-ID: <20171206133450.7bcbyxnlyei3qgvl@lakrids.cambridge.arm.com> (raw) In-Reply-To: <1512563739-25239-19-git-send-email-will.deacon@arm.com> On Wed, Dec 06, 2017 at 12:35:37PM +0000, Will Deacon wrote: > When running with the kernel unmapped whilst at EL0, the virtually-addressed > SPE buffer is also unmapped, which can lead to buffer faults if userspace > profiling is enabled and potentially also when writing back kernel samples > unless an expensive drain operation is performed on exception return. > > For now, fail the SPE driver probe when arm64_kernel_unmapped_at_el0(). > > Signed-off-by: Will Deacon <will.deacon@arm.com> Reviewed-by: Mark Rutland <mark.rutland@arm.com> Mark. > --- > drivers/perf/arm_spe_pmu.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c > index 8ce262fc2561..51b40aecb776 100644 > --- a/drivers/perf/arm_spe_pmu.c > +++ b/drivers/perf/arm_spe_pmu.c > @@ -1164,6 +1164,15 @@ static int arm_spe_pmu_device_dt_probe(struct platform_device *pdev) > struct arm_spe_pmu *spe_pmu; > struct device *dev = &pdev->dev; > > + /* > + * If kernelspace is unmapped when running at EL0, then the SPE > + * buffer will fault and prematurely terminate the AUX session. > + */ > + if (arm64_kernel_unmapped_at_el0()) { > + dev_warn_once(dev, "profiling buffer inaccessible. Try passing \"kpti=off\" on the kernel command line\n"); > + return -EPERM; > + } > + > spe_pmu = devm_kzalloc(dev, sizeof(*spe_pmu), GFP_KERNEL); > if (!spe_pmu) { > dev_err(dev, "failed to allocate spe_pmu\n"); > -- > 2.1.4 >
next prev parent reply other threads:[~2017-12-06 13:34 UTC|newest] Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-12-06 12:35 [PATCH v3 00/20] arm64: Unmap the kernel whilst running in userspace (KPTI) Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 01/20] arm64: mm: Use non-global mappings for kernel space Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 02/20] arm64: mm: Temporarily disable ARM64_SW_TTBR0_PAN Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 03/20] arm64: mm: Move ASID from TTBR0 to TTBR1 Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 04/20] arm64: mm: Remove pre_ttbr0_update_workaround for Falkor erratum #E1003 Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 05/20] arm64: mm: Rename post_ttbr0_update_workaround Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 06/20] arm64: mm: Fix and re-enable ARM64_SW_TTBR0_PAN Will Deacon 2017-12-06 12:35 ` Will Deacon 2018-01-17 2:58 ` Yisheng Xie 2018-01-17 2:58 ` Yisheng Xie 2017-12-06 12:35 ` [PATCH v3 07/20] arm64: mm: Allocate ASIDs in pairs Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 08/20] arm64: mm: Add arm64_kernel_unmapped_at_el0 helper Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 09/20] arm64: mm: Invalidate both kernel and user ASIDs when performing TLBI Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 10/20] arm64: entry: Add exception trampoline page for exceptions from EL0 Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 11/20] arm64: mm: Map entry trampoline into trampoline and kernel page tables Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 14:32 ` Mark Rutland 2017-12-06 14:32 ` Mark Rutland 2018-01-23 8:28 ` Yisheng Xie 2018-01-23 8:28 ` Yisheng Xie 2018-01-23 10:04 ` Will Deacon 2018-01-23 10:04 ` Will Deacon 2018-01-23 10:43 ` Yisheng Xie 2018-01-23 10:43 ` Yisheng Xie 2017-12-06 12:35 ` [PATCH v3 12/20] arm64: entry: Explicitly pass exception level to kernel_ventry macro Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 13/20] arm64: entry: Hook up entry trampoline to exception vectors Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 14/20] arm64: erratum: Work around Falkor erratum #E1003 in trampoline code Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 15/20] arm64: tls: Avoid unconditional zeroing of tpidrro_el0 for native tasks Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 16/20] arm64: entry: Add fake CPU feature for unmapping the kernel at EL0 Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 14:11 ` Mark Rutland 2017-12-06 14:11 ` Mark Rutland 2017-12-06 12:35 ` [PATCH v3 17/20] arm64: Kconfig: Add CONFIG_UNMAP_KERNEL_AT_EL0 Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:35 ` [PATCH v3 18/20] perf: arm_spe: Fail device probe when arm64_kernel_unmapped_at_el0() Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 13:34 ` Mark Rutland [this message] 2017-12-06 13:34 ` Mark Rutland 2017-12-06 12:35 ` [PATCH v3 19/20] arm64: mm: Introduce TTBR_ASID_MASK for getting at the ASID in the TTBR Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 14:12 ` Mark Rutland 2017-12-06 14:12 ` Mark Rutland 2017-12-06 12:35 ` [PATCH v3 20/20] arm64: kaslr: Put kernel vectors address in separate data page Will Deacon 2017-12-06 12:35 ` Will Deacon 2017-12-06 12:59 ` Ard Biesheuvel 2017-12-06 12:59 ` Ard Biesheuvel 2017-12-06 13:27 ` Will Deacon 2017-12-06 13:27 ` Will Deacon 2017-12-06 14:03 ` Ard Biesheuvel 2017-12-06 14:03 ` Ard Biesheuvel 2017-12-08 0:40 ` [PATCH v3 00/20] arm64: Unmap the kernel whilst running in userspace (KPTI) Laura Abbott 2017-12-08 0:40 ` Laura Abbott 2017-12-11 13:23 ` Will Deacon 2017-12-11 13:23 ` Will Deacon 2017-12-11 17:59 ` Catalin Marinas 2017-12-11 17:59 ` Catalin Marinas 2018-01-04 5:17 ` Florian Fainelli 2018-01-04 5:17 ` Florian Fainelli 2018-01-04 6:50 ` Greg Kroah-Hartman 2018-01-04 6:50 ` Greg Kroah-Hartman 2018-01-04 18:23 ` Florian Fainelli 2018-01-04 18:23 ` Florian Fainelli 2018-01-04 23:27 ` Russell King - ARM Linux 2018-01-04 23:27 ` Russell King - ARM Linux 2018-01-05 16:06 ` Greg Kroah-Hartman 2018-01-05 16:06 ` Greg Kroah-Hartman 2018-01-05 16:12 ` Ard Biesheuvel 2018-01-05 16:12 ` Ard Biesheuvel
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