CoreSight

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6 participants
2569 discussions

Re: [PATCH v2] coresight: prevent deactivate active config while enable the config

by Suzuki K Poulose

Hi Levi On 23/12/2024 18:53, Yeoreum Yun wrote: > While enable active config via cscfg_csdev_enable_active_config(), > active config could be deactivated via configfs' sysfs interface. > This could make UAF issue in below scenario: > > CPU0 CPU1 > (sysfs enable) load module > cscfg_load_config_sets() > activate config. // sysfs > (sys_active_cnt == 1) > ... > cscfg_csdev_enable_active_config() > lock(csdev->cscfg_csdev_lock) > // here load config activate by CPU1 > unlock(csdev->cscfg_csdev_lock) > > deactivate config // sysfs > (sys_activec_cnt == 0) > cscfg_unload_config_sets() > unload module > > // access to config_desc which freed > // while unloading module. > cfs_csdev_enable_config > > To address this, introduce sys_enable_cnt in cscfg_mgr to prevent > deactivate while there is enabled configuration. Thanks for the finding the problem and the detailed description + patch. I have some concerns on the fix, please find it below. > So we have 3 atomic counters now ! cscfg_mgr->sys_active_cnt // Global count config->active_cnt // Per config count, And another one which this one introduces. cscfg_mgr->sys_enable_cnt // ? And config->active_cnt is always ever 0 or 1. i.e., it is not really a reference counter at the moment but it indicates whether it is active or not. Could we not use that for tracking the references on the specific config ? i.e., every time we "enable_active_config" atomic_inc(config->active_cnt) and disable_active_config() always decrements the config. These could be wrapped in cscfg_get() cscfg_put() which would, inc/dec the refcounts and also drop the "module" reference when the active_cnt == 0 > Signed-off-by: Yeoreum Yun <yeoreum.yun(a)arm.com> > --- > from v1 to v2: > - modify commit message. > --- > .../hwtracing/coresight/coresight-etm4x-core.c | 3 +++ > drivers/hwtracing/coresight/coresight-syscfg.c | 18 ++++++++++++++++-- > drivers/hwtracing/coresight/coresight-syscfg.h | 2 ++ > 3 files changed, 21 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c > index 86893115df17..6218ef40acbc 100644 > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c > @@ -986,6 +986,9 @@ static void etm4_disable_sysfs(struct coresight_device *csdev) > smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1); > > raw_spin_unlock(&drvdata->spinlock); > + > + cscfg_csdev_disable_active_config(csdev); This looks like a separate "fix" from what you are trying to address. Please could split this ? Also, would like to hear what Mike has to say about this change. Suzuki > + > cpus_read_unlock(); > > /* > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c > index a70c1454b410..dfa7dcbaf25d 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > @@ -953,7 +953,8 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti > cscfg_mgr->sysfs_active_config = cfg_hash; > } else { > /* disable if matching current value */ > - if (cscfg_mgr->sysfs_active_config == cfg_hash) { > + if (cscfg_mgr->sysfs_active_config == cfg_hash && > + !atomic_read(&cscfg_mgr->sys_enable_cnt)) { > _cscfg_deactivate_config(cfg_hash); > cscfg_mgr->sysfs_active_config = 0; > } else > @@ -1055,6 +1056,12 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > if (!atomic_read(&cscfg_mgr->sys_active_cnt)) > return 0; > > + /* > + * increment sys_enable_cnt first to prevent deactivate the config > + * while enable active config. > + */ > + atomic_inc(&cscfg_mgr->sys_enable_cnt); > + > /* > * Look for matching configuration - set the active configuration > * context if found. > @@ -1098,6 +1105,10 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > } > } > + > + if (!config_csdev_active || err) > + atomic_dec(&cscfg_mgr->sys_enable_cnt); > + > return err; > } > EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config); > @@ -1129,8 +1140,10 @@ void cscfg_csdev_disable_active_config(struct coresight_device *csdev) > if (config_csdev) { > if (!config_csdev->enabled) > config_csdev = NULL; > - else > + else { > config_csdev->enabled = false; > + atomic_dec(&cscfg_mgr->sys_enable_cnt); > + } > } > csdev->active_cscfg_ctxt = NULL; > raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > @@ -1179,6 +1192,7 @@ static int cscfg_create_device(void) > INIT_LIST_HEAD(&cscfg_mgr->config_desc_list); > INIT_LIST_HEAD(&cscfg_mgr->load_order_list); > atomic_set(&cscfg_mgr->sys_active_cnt, 0); > + atomic_set(&cscfg_mgr->sys_enable_cnt, 0); > cscfg_mgr->load_state = CSCFG_NONE; > > /* setup the device */ > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h > index 66e2db890d82..2fc397919985 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.h > +++ b/drivers/hwtracing/coresight/coresight-syscfg.h > @@ -38,6 +38,7 @@ enum cscfg_load_ops { > * @config_desc_list: List of system configuration descriptors to load into registered devices. > * @load_order_list: Ordered list of owners for dynamically loaded configurations. > * @sys_active_cnt: Total number of active config descriptor references. > + * @sys_enable_cnt: Total number of enable of active config descriptor references. > * @cfgfs_subsys: configfs subsystem used to manage configurations. > * @sysfs_active_config:Active config hash used if CoreSight controlled from sysfs. > * @sysfs_active_preset:Active preset index used if CoreSight controlled from sysfs. > @@ -50,6 +51,7 @@ struct cscfg_manager { > struct list_head config_desc_list; > struct list_head load_order_list; > atomic_t sys_active_cnt; > + atomic_t sys_enable_cnt; > struct configfs_subsystem cfgfs_subsys; > u32 sysfs_active_config; > int sysfs_active_preset; > -- > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7} >

11 months, 1 week

Re: [PATCH v9 0/7] kvm/coresight: Support exclude guest and exclude host

by James Clark

On 06/01/2025 2:48 pm, Marc Zyngier wrote: > On Mon, 06 Jan 2025 14:24:35 +0000, > James Clark <james.clark(a)linaro.org> wrote: >> >> FEAT_TRF is a Coresight feature that allows trace capture to be >> completely filtered at different exception levels, unlike the existing >> TRCVICTLR controls which may still emit target addresses of branches, >> even if the following trace is filtered. >> >> Without FEAT_TRF, it was possible to start a trace session on a host and >> also collect trace from the guest as TRCVICTLR was never programmed to >> exclude guests (and it could still emit target addresses even if it >> was). >> >> With FEAT_TRF, the current behavior of trace in guests exists depends on >> whether nVHE or VHE are being used. Both of the examples below are from >> the host's point of view, as Coresight isn't accessible from guests. >> This patchset is only relevant to when FEAT_TRF exists, otherwise there >> is no change. >> >> Current behavior: >> >> nVHE/pKVM: >> >> Because the host and the guest are both using TRFCR_EL1, trace will be >> generated in guests depending on the same filter rules the host is >> using. For example if the host is tracing userspace only, then guest >> userspace trace will also be collected. >> >> (This is further limited by whether TRBE is used because an issue >> with TRBE means that it's completely disabled in nVHE guests, but it's >> possible to have other tracing components.) >> >> VHE: >> >> With VHE, the host filters will be in TRFCR_EL2, but the filters in >> TRFCR_EL1 will be active when the guest is running. Because we don't >> write to TRFCR_EL1, guest trace will be completely disabled. >> >> New behavior: >> >> The guest filtering rules from the Perf session are now honored for both >> nVHE and VHE modes. This is done by either writing to TRFCR_EL12 at the >> start of the Perf session and doing nothing else further, or caching the >> guest value and writing it at guest switch for nVHE. In pKVM, trace is >> now be disabled for both protected and unprotected guests. >> >> There is also an optimization where the Coresight drivers pass their >> enabled state to KVM. This means in the common case KVM doesn't have to >> touch any sysregs when the feature isn't in use. >> >> Applies to kvmarm/next (00163be8bb59). > > Can you *PLEASE* stop this absolutely nonsense of posting patches > based on top of random commits? Please look at how we integrate new > developments: they are *always* based on an early -rc tag (usually > -rc3). > > If you depend on other patches, add them to your series and post the > whole thing. > > Thanks, > > M. > Sure, I re-posted it on the latest -rc with a few commits picked up. Thanks James

11 months, 1 week

[PATCH v10 00/10] kvm/coresight: Support exclude guest and exclude host

by James Clark

FEAT_TRF is a Coresight feature that allows trace capture to be completely filtered at different exception levels, unlike the existing TRCVICTLR controls which may still emit target addresses of branches, even if the following trace is filtered. Without FEAT_TRF, it was possible to start a trace session on a host and also collect trace from the guest as TRCVICTLR was never programmed to exclude guests (and it could still emit target addresses even if it was). With FEAT_TRF, the current behavior of trace in guests exists depends on whether nVHE or VHE are being used. Both of the examples below are from the host's point of view, as Coresight isn't accessible from guests. This patchset is only relevant to when FEAT_TRF exists, otherwise there is no change. Current behavior: nVHE/pKVM: Because the host and the guest are both using TRFCR_EL1, trace will be generated in guests depending on the same filter rules the host is using. For example if the host is tracing userspace only, then guest userspace trace will also be collected. (This is further limited by whether TRBE is used because an issue with TRBE means that it's completely disabled in nVHE guests, but it's possible to have other tracing components.) VHE: With VHE, the host filters will be in TRFCR_EL2, but the filters in TRFCR_EL1 will be active when the guest is running. Because we don't write to TRFCR_EL1, guest trace will be completely disabled. New behavior: The guest filtering rules from the Perf session are now honored for both nVHE and VHE modes. This is done by either writing to TRFCR_EL12 at the start of the Perf session and doing nothing else further, or caching the guest value and writing it at guest switch for nVHE. In pKVM, trace is now be disabled for both protected and unprotected guests. There is also an optimization where the Coresight drivers pass their enabled state to KVM. This means in the common case KVM doesn't have to touch any sysregs when the feature isn't in use. Applies to 6.13-rc6 --- Changes since V9 [9]: * Rebase onto 6.13-rc6 and pickup commit 38131c02a53f ("KVM: arm64: Track presence of SPE/TRBE in kvm_host_data instead of vCPU") to get host_data_set_flag(). Also requires two intertwined parent commits. Changes since V8 [8]: * Rename guest_trfcr_el1 -> trfcr_while_in_guest * Rename GUEST_FILTER -> EL1_TRACING_CONFIGURED * Rename kvm_set_trfcr() -> kvm_tracing_set_el1_configuration() * #include ordering * Reorder Coresight driver to remove need for preempt_disable() to avoid the warning * Force EL1_TRACING_CONFIGURED on for pKVM which drops an additional special case but still disables trace * Change set/clear trfcr to a single function that disables swapping if it has the same value as the host * Make the drain condition a bit clearer with __trace_needs_drain() instead of host trfcr != 0 (Or checking individual E*TRE bits) * Drain is only really required on switch to guest so move it there * Only for pKVM, restore the original behavior for draining whenever trbe is enabled. This prevents hypothetical case where a host has the filters disabled but hasn't drained yet which we had by only looking at host trfcr != 0 Changes since V7 [6]: * Drop SPE changes * Change the interface to be based on intent, i.e kvm_enable_trbe() rather than passing the raw register value * Drop change to re-use vcpu_flags mechanism in favour of [7] * Simplify by using the same switch function to and from guest Changes since V6 [5]: * Implement a better "do nothing" case where both the SPE and Coresight drivers give the enabled state to KVM, allowing some register reads to be dropped. * Move the state and feature flags out of the vCPU into the per-CPU host_debug_state. * Simplify the switch logic by adding a new flag HOST_STATE_SWAP_TRFCR and only storing a single TRFCR value. * Rename vcpu flag macros to a more generic kvm_flag... Changes since V5 [4]: * Sort new sysreg entries by encoding * Add a comment about sorting arch/arm64/tools/sysreg * Warn on preemptible() before calling smp_processor_id() * Pickup tags * Change TRFCR_EL2 from SysregFields to Sysreg because it was only used once Changes since V4 [3]: * Remove all V3 changes that made it work in pKVM and just disable trace there instead * Restore PMU host/hyp state sharing back to how it was (kvm_pmu_update_vcpu_events()) * Simplify some of the duplication in the comments and function docs * Add a WARN_ON_ONCE() if kvm_etm_set_guest_trfcr() is called when the trace filtering feature doesn't exist. * Split sysreg change into a tools update followed by the new register addition Changes since V3: * Create a new shared area to store the host state instead of copying it before each VCPU run * Drop commit that moved SPE and trace registers from host_debug_state into the kvm sysregs array because the guest values were never used * Document kvm_etm_set_guest_trfcr() * Guard kvm_etm_set_guest_trfcr() with a feature check * Drop Mark B and Suzuki's review tags on the sysreg patch because it turned out that broke the Perf build and needed some unconventional changes to fix it (as in: to update the tools copy of the headers in the same commit as the kernel changes) Changes since V2: * Add a new iflag to signify presence of FEAT_TRF and keep the existing TRBE iflag. This fixes the issue where TRBLIMITR_EL1 was being accessed even if TRBE didn't exist * Reword a commit message Changes since V1: * Squashed all the arm64/tools/sysreg changes into the first commit * Add a new commit to move SPE and TRBE regs into the kvm sysreg array * Add a comment above the TRFCR global that it's per host CPU rather than vcpu Changes since nVHE RFC [1]: * Re-write just in terms of the register value to be written for the host and the guest. This removes some logic from the hyp code and a value of kvm_vcpu_arch:trfcr_el1 = 0 no longer means "don't restore". * Remove all the conditional compilation and new files. * Change the kvm_etm_update_vcpu_events macro to a function. * Re-use DEBUG_STATE_SAVE_TRFCR so iflags don't need to be expanded anymore. * Expand the cover letter. Changes since VHE v3 [2]: * Use the same interface as nVHE mode so TRFCR_EL12 is now written by kvm. [1]: https://lore.kernel.org/kvmarm/20230804101317.460697-1-james.clark@arm.com/ [2]: https://lore.kernel.org/kvmarm/20230905102117.2011094-1-james.clark@arm.com/ [3]: https://lore.kernel.org/linux-arm-kernel/20240104162714.1062610-1-james.cla… [4]: https://lore.kernel.org/all/20240220100924.2761706-1-james.clark@arm.com/ [5]: https://lore.kernel.org/linux-arm-kernel/20240226113044.228403-1-james.clar… [6]: https://lore.kernel.org/kvmarm/20241112103717.589952-1-james.clark@linaro.o… [7]: https://lore.kernel.org/kvmarm/20241115224924.2132364-4-oliver.upton@linux.… [8]: https://lore.kernel.org/linux-arm-kernel/20241127100130.1162639-1-james.cla… [9]: https://lore.kernel.org/linux-arm-kernel/20250106142446.628923-1-james.clar… James Clark (7): arm64/sysreg: Add a comment that the sysreg file should be sorted tools: arm64: Update sysreg.h header files arm64/sysreg/tools: Move TRFCR definitions to sysreg coresight: trbe: Remove redundant disable call KVM: arm64: coresight: Give TRBE enabled state to KVM KVM: arm64: Support trace filtering for guests coresight: Pass guest TRFCR value to KVM Oliver Upton (3): KVM: arm64: Drop MDSCR_EL1_DEBUG_MASK KVM: arm64: Get rid of __kvm_get_mdcr_el2() and related warts KVM: arm64: Track presence of SPE/TRBE in kvm_host_data instead of vCPU arch/arm64/include/asm/kvm_asm.h | 5 +- arch/arm64/include/asm/kvm_host.h | 37 +- arch/arm64/include/asm/sysreg.h | 12 - arch/arm64/kvm/arm.c | 5 +- arch/arm64/kvm/debug.c | 94 ++-- arch/arm64/kvm/hyp/nvhe/debug-sr.c | 72 +-- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 6 - arch/arm64/kvm/hyp/vhe/debug-sr.c | 5 - arch/arm64/tools/sysreg | 38 ++ .../coresight/coresight-etm4x-core.c | 49 ++- drivers/hwtracing/coresight/coresight-etm4x.h | 2 +- drivers/hwtracing/coresight/coresight-priv.h | 3 + .../coresight/coresight-self-hosted-trace.h | 9 - drivers/hwtracing/coresight/coresight-trbe.c | 15 +- tools/arch/arm64/include/asm/sysreg.h | 410 +++++++++++++++++- tools/include/linux/kasan-tags.h | 15 + 16 files changed, 626 insertions(+), 151 deletions(-) create mode 100644 tools/include/linux/kasan-tags.h -- 2.34.1

11 months, 1 week

[PATCH v6 0/2] arm64: dts: qcom: sm8450: Add coresight nodes

by Mao Jinlong

Change since V5: 1. Fix the &CPUn vs &cpun issue in device tree file. Change since V4: 1. Use ^ete(-[0-9]+)?$ for the pattern of node name -- comments from Krzysztof Kozlowski <krzk(a)kernel.org> 2. Update commit message --- comments from Rob Herring <robh(a)kernel.org> Change since V3: 1. Use ^ete-[0-9]+$ for the pattern of node name -- comments from Rob Herring Change since V2: 1. Change the name in binding as 'ete'. Change since V1: 1. Remove the pattern match of ETE node name. 2. Update the tmc-etr node name in DT. Mao Jinlong (2): dt-bindings: arm: coresight: Update the pattern of ete node name arm64: dts: qcom: sm8450: Add coresight nodes .../arm/arm,embedded-trace-extension.yaml | 6 +- arch/arm64/boot/dts/qcom/sm8450.dtsi | 726 ++++++++++++++++++ 2 files changed, 729 insertions(+), 3 deletions(-) -- 2.17.1

11 months, 1 week

Re: [PATCH 1/1] coresight: prevent deactivate active config while enable the config

by Suzuki K Poulose

On 06/01/2025 13:41, Yeo Reum Yun wrote: > Hi Suzuki, > > Sorry this ping was my mistake. > As you said, v2 is the recent one. > You can ignore this. > Thanks, will respond on v2. Also, fyi, your emails not plain text ! Please fix your email client. Suzuki > Thanks! > ------------------------------------------------------------------------ > *보낸 사람:* Suzuki K Poulose <suzuki.poulose(a)arm.com> > *보낸 날짜:* Monday, January 6, 2025 1:37:40 PM > *받는 사람:* Yeo Reum Yun <YeoReum.Yun(a)arm.com>; mike.leach(a)linaro.org > <mike.leach(a)linaro.org>; james.clark(a)linaro.org > <james.clark(a)linaro.org>; alexander.shishkin(a)linux.intel.com > <alexander.shishkin(a)linux.intel.com> > *참조:* coresight(a)lists.linaro.org <coresight(a)lists.linaro.org>; linux- > arm-kernel(a)lists.infradead.org <linux-arm-kernel(a)lists.infradead.org>; > linux-kernel(a)vger.kernel.org <linux-kernel(a)vger.kernel.org>; nd <nd(a)arm.com> > *제목:* Re: [PATCH 1/1] coresight: prevent deactivate active config > while enable the config > Hi Yeo, > > > On 31/12/2024 14:37, Yeo Reum Yun wrote: >> Gentle ping in case of forgotten. >> > > Gentle reminder: Please avoid top posting. > > I thought there is a v2 of this one ? I am now confused. > > Kind regards > Suzuki > >> ________________________________________ >> From: Yeoreum Yun <yeoreum.yun(a)arm.com> >> Sent: 18 December 2024 08:48 >> To: Suzuki Poulose; mike.leach(a)linaro.org; james.clark(a)linaro.org; alexander.shishkin(a)linux.intel.com >> Cc: coresight(a)lists.linaro.org; linux-arm-kernel(a)lists.infradead.org; linux-kernel(a)vger.kernel.org; nd; Yeo Reum Yun >> Subject: [PATCH 1/1] coresight: prevent deactivate active config while enable the config >> >> While enable active config via cscfg_csdev_enable_active_config(), >> active config could be deactivated via configfs' sysfs interface. >> This could make UAF issue in below scenario: >> >> CPU0 CPU1 >> (perf or sysfs enable) load module >> cscfg_load_config_sets() >> activate config. // sysfs >> (sys_active_cnt == 1) >> ... >> cscfg_csdev_enable_active_config() >> lock(csdev->cscfg_csdev_lock) >> // here load config activate by CPU1 >> unlock(csdev->cscfg_csdev_lock) >> >> deactivate config // sysfs >> (sys_activec_cnt == 0) >> cscfg_unload_config_sets() >> unload module >> >> // access to config_desc which freed >> // while unloading module. >> cfs_csdev_enable_config >> >> To address this, introduce sys_enable_cnt in cscfg_mgr to prevent >> deactivate while there is enabled configuration. >> >> Signed-off-by: Yeoreum Yun <yeoreum.yun(a)arm.com> >> --- >> .../hwtracing/coresight/coresight-etm4x-core.c | 3 +++ >> drivers/hwtracing/coresight/coresight-syscfg.c | 18 ++++++++++++++++-- >> drivers/hwtracing/coresight/coresight-syscfg.h | 2 ++ >> 3 files changed, 21 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c >> index 86893115df17..6218ef40acbc 100644 >> --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c >> +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c >> @@ -986,6 +986,9 @@ static void etm4_disable_sysfs(struct coresight_device *csdev) >> smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1); >> >> raw_spin_unlock(&drvdata->spinlock); >> + >> + cscfg_csdev_disable_active_config(csdev); >> + >> cpus_read_unlock(); >> >> /* >> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c >> index a70c1454b410..dfa7dcbaf25d 100644 >> --- a/drivers/hwtracing/coresight/coresight-syscfg.c >> +++ b/drivers/hwtracing/coresight/coresight-syscfg.c >> @@ -953,7 +953,8 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti >> cscfg_mgr->sysfs_active_config = cfg_hash; >> } else { >> /* disable if matching current value */ >> - if (cscfg_mgr->sysfs_active_config == cfg_hash) { >> + if (cscfg_mgr->sysfs_active_config == cfg_hash && >> + !atomic_read(&cscfg_mgr->sys_enable_cnt)) { >> _cscfg_deactivate_config(cfg_hash); >> cscfg_mgr->sysfs_active_config = 0; >> } else >> @@ -1055,6 +1056,12 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, >> if (!atomic_read(&cscfg_mgr->sys_active_cnt)) >> return 0; >> >> + /* >> + * increment sys_enable_cnt first to prevent deactivate the config >> + * while enable active config. >> + */ >> + atomic_inc(&cscfg_mgr->sys_enable_cnt); >> + >> /* >> * Look for matching configuration - set the active configuration >> * context if found. >> @@ -1098,6 +1105,10 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, >> raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); >> } >> } >> + >> + if (!config_csdev_active || err) >> + atomic_dec(&cscfg_mgr->sys_enable_cnt); >> + >> return err; >> } >> EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config); >> @@ -1129,8 +1140,10 @@ void cscfg_csdev_disable_active_config(struct coresight_device *csdev) >> if (config_csdev) { >> if (!config_csdev->enabled) >> config_csdev = NULL; >> - else >> + else { >> config_csdev->enabled = false; >> + atomic_dec(&cscfg_mgr->sys_enable_cnt); >> + } >> } >> csdev->active_cscfg_ctxt = NULL; >> raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); >> @@ -1179,6 +1192,7 @@ static int cscfg_create_device(void) >> INIT_LIST_HEAD(&cscfg_mgr->config_desc_list); >> INIT_LIST_HEAD(&cscfg_mgr->load_order_list); >> atomic_set(&cscfg_mgr->sys_active_cnt, 0); >> + atomic_set(&cscfg_mgr->sys_enable_cnt, 0); >> cscfg_mgr->load_state = CSCFG_NONE; >> >> /* setup the device */ >> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h >> index 66e2db890d82..2fc397919985 100644 >> --- a/drivers/hwtracing/coresight/coresight-syscfg.h >> +++ b/drivers/hwtracing/coresight/coresight-syscfg.h >> @@ -38,6 +38,7 @@ enum cscfg_load_ops { >> * @config_desc_list: List of system configuration descriptors to load into registered devices. >> * @load_order_list: Ordered list of owners for dynamically loaded configurations. >> * @sys_active_cnt: Total number of active config descriptor references. >> + * @sys_enable_cnt: Total number of enable of active config descriptor references. >> * @cfgfs_subsys: configfs subsystem used to manage configurations. >> * @sysfs_active_config:Active config hash used if CoreSight controlled from sysfs. >> * @sysfs_active_preset:Active preset index used if CoreSight controlled from sysfs. >> @@ -50,6 +51,7 @@ struct cscfg_manager { >> struct list_head config_desc_list; >> struct list_head load_order_list; >> atomic_t sys_active_cnt; >> + atomic_t sys_enable_cnt; >> struct configfs_subsystem cfgfs_subsys; >> u32 sysfs_active_config; >> int sysfs_active_preset; >> -- >> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7} >> >

11 months, 1 week

[PATCH v9 0/7] kvm/coresight: Support exclude guest and exclude host

by James Clark

FEAT_TRF is a Coresight feature that allows trace capture to be completely filtered at different exception levels, unlike the existing TRCVICTLR controls which may still emit target addresses of branches, even if the following trace is filtered. Without FEAT_TRF, it was possible to start a trace session on a host and also collect trace from the guest as TRCVICTLR was never programmed to exclude guests (and it could still emit target addresses even if it was). With FEAT_TRF, the current behavior of trace in guests exists depends on whether nVHE or VHE are being used. Both of the examples below are from the host's point of view, as Coresight isn't accessible from guests. This patchset is only relevant to when FEAT_TRF exists, otherwise there is no change. Current behavior: nVHE/pKVM: Because the host and the guest are both using TRFCR_EL1, trace will be generated in guests depending on the same filter rules the host is using. For example if the host is tracing userspace only, then guest userspace trace will also be collected. (This is further limited by whether TRBE is used because an issue with TRBE means that it's completely disabled in nVHE guests, but it's possible to have other tracing components.) VHE: With VHE, the host filters will be in TRFCR_EL2, but the filters in TRFCR_EL1 will be active when the guest is running. Because we don't write to TRFCR_EL1, guest trace will be completely disabled. New behavior: The guest filtering rules from the Perf session are now honored for both nVHE and VHE modes. This is done by either writing to TRFCR_EL12 at the start of the Perf session and doing nothing else further, or caching the guest value and writing it at guest switch for nVHE. In pKVM, trace is now be disabled for both protected and unprotected guests. There is also an optimization where the Coresight drivers pass their enabled state to KVM. This means in the common case KVM doesn't have to touch any sysregs when the feature isn't in use. Applies to kvmarm/next (00163be8bb59). --- Changes since V8 [8]: * Rename guest_trfcr_el1 -> trfcr_while_in_guest * Rename GUEST_FILTER -> EL1_TRACING_CONFIGURED * Rename kvm_set_trfcr() -> kvm_tracing_set_el1_configuration() * #include ordering * Reorder Coresight driver to remove need for preempt_disable() to avoid the warning * Force EL1_TRACING_CONFIGURED on for pKVM which drops an additional special case but still disables trace * Change set/clear trfcr to a single function that disables swapping if it has the same value as the host * Make the drain condition a bit clearer with __trace_needs_drain() instead of host trfcr != 0 (Or checking individual E*TRE bits) * Drain is only really required on switch to guest so move it there * Only for pKVM, restore the original behavior for draining whenever trbe is enabled. This prevents hypothetical case where a host has the filters disabled but hasn't drained yet which we had by only looking at host trfcr != 0 Changes since V7 [6]: * Drop SPE changes * Change the interface to be based on intent, i.e kvm_enable_trbe() rather than passing the raw register value * Drop change to re-use vcpu_flags mechanism in favour of [7] * Simplify by using the same switch function to and from guest Changes since V6 [5]: * Implement a better "do nothing" case where both the SPE and Coresight drivers give the enabled state to KVM, allowing some register reads to be dropped. * Move the state and feature flags out of the vCPU into the per-CPU host_debug_state. * Simplify the switch logic by adding a new flag HOST_STATE_SWAP_TRFCR and only storing a single TRFCR value. * Rename vcpu flag macros to a more generic kvm_flag... Changes since V5 [4]: * Sort new sysreg entries by encoding * Add a comment about sorting arch/arm64/tools/sysreg * Warn on preemptible() before calling smp_processor_id() * Pickup tags * Change TRFCR_EL2 from SysregFields to Sysreg because it was only used once Changes since V4 [3]: * Remove all V3 changes that made it work in pKVM and just disable trace there instead * Restore PMU host/hyp state sharing back to how it was (kvm_pmu_update_vcpu_events()) * Simplify some of the duplication in the comments and function docs * Add a WARN_ON_ONCE() if kvm_etm_set_guest_trfcr() is called when the trace filtering feature doesn't exist. * Split sysreg change into a tools update followed by the new register addition Changes since V3: * Create a new shared area to store the host state instead of copying it before each VCPU run * Drop commit that moved SPE and trace registers from host_debug_state into the kvm sysregs array because the guest values were never used * Document kvm_etm_set_guest_trfcr() * Guard kvm_etm_set_guest_trfcr() with a feature check * Drop Mark B and Suzuki's review tags on the sysreg patch because it turned out that broke the Perf build and needed some unconventional changes to fix it (as in: to update the tools copy of the headers in the same commit as the kernel changes) Changes since V2: * Add a new iflag to signify presence of FEAT_TRF and keep the existing TRBE iflag. This fixes the issue where TRBLIMITR_EL1 was being accessed even if TRBE didn't exist * Reword a commit message Changes since V1: * Squashed all the arm64/tools/sysreg changes into the first commit * Add a new commit to move SPE and TRBE regs into the kvm sysreg array * Add a comment above the TRFCR global that it's per host CPU rather than vcpu Changes since nVHE RFC [1]: * Re-write just in terms of the register value to be written for the host and the guest. This removes some logic from the hyp code and a value of kvm_vcpu_arch:trfcr_el1 = 0 no longer means "don't restore". * Remove all the conditional compilation and new files. * Change the kvm_etm_update_vcpu_events macro to a function. * Re-use DEBUG_STATE_SAVE_TRFCR so iflags don't need to be expanded anymore. * Expand the cover letter. Changes since VHE v3 [2]: * Use the same interface as nVHE mode so TRFCR_EL12 is now written by kvm. [1]: https://lore.kernel.org/kvmarm/20230804101317.460697-1-james.clark@arm.com/ [2]: https://lore.kernel.org/kvmarm/20230905102117.2011094-1-james.clark@arm.com/ [3]: https://lore.kernel.org/linux-arm-kernel/20240104162714.1062610-1-james.cla… [4]: https://lore.kernel.org/all/20240220100924.2761706-1-james.clark@arm.com/ [5]: https://lore.kernel.org/linux-arm-kernel/20240226113044.228403-1-james.clar… [6]: https://lore.kernel.org/kvmarm/20241112103717.589952-1-james.clark@linaro.o… [7]: https://lore.kernel.org/kvmarm/20241115224924.2132364-4-oliver.upton@linux.… [8]: https://lore.kernel.org/linux-arm-kernel/20241127100130.1162639-1-james.cla… James Clark (7): arm64/sysreg: Add a comment that the sysreg file should be sorted tools: arm64: Update sysreg.h header files arm64/sysreg/tools: Move TRFCR definitions to sysreg coresight: trbe: Remove redundant disable call KVM: arm64: coresight: Give TRBE enabled state to KVM KVM: arm64: Support trace filtering for guests coresight: Pass guest TRFCR value to KVM arch/arm64/include/asm/kvm_host.h | 11 + arch/arm64/include/asm/sysreg.h | 12 - arch/arm64/kvm/debug.c | 50 ++- arch/arm64/kvm/hyp/nvhe/debug-sr.c | 63 +-- arch/arm64/tools/sysreg | 38 ++ .../coresight/coresight-etm4x-core.c | 49 ++- drivers/hwtracing/coresight/coresight-etm4x.h | 2 +- drivers/hwtracing/coresight/coresight-priv.h | 3 + .../coresight/coresight-self-hosted-trace.h | 9 - drivers/hwtracing/coresight/coresight-trbe.c | 15 +- tools/arch/arm64/include/asm/sysreg.h | 410 +++++++++++++++++- tools/include/linux/kasan-tags.h | 15 + 12 files changed, 599 insertions(+), 78 deletions(-) create mode 100644 tools/include/linux/kasan-tags.h -- 2.34.1

11 months, 1 week

Re: [PATCH 1/1] coresight: prevent deactivate active config while enable the config

by Suzuki K Poulose

Hi Yeo, On 31/12/2024 14:37, Yeo Reum Yun wrote: > Gentle ping in case of forgotten. > Gentle reminder: Please avoid top posting. I thought there is a v2 of this one ? I am now confused. Kind regards Suzuki > ________________________________________ > From: Yeoreum Yun <yeoreum.yun(a)arm.com> > Sent: 18 December 2024 08:48 > To: Suzuki Poulose; mike.leach(a)linaro.org; james.clark(a)linaro.org; alexander.shishkin(a)linux.intel.com > Cc: coresight(a)lists.linaro.org; linux-arm-kernel(a)lists.infradead.org; linux-kernel(a)vger.kernel.org; nd; Yeo Reum Yun > Subject: [PATCH 1/1] coresight: prevent deactivate active config while enable the config > > While enable active config via cscfg_csdev_enable_active_config(), > active config could be deactivated via configfs' sysfs interface. > This could make UAF issue in below scenario: > > CPU0 CPU1 > (perf or sysfs enable) load module > cscfg_load_config_sets() > activate config. // sysfs > (sys_active_cnt == 1) > ... > cscfg_csdev_enable_active_config() > lock(csdev->cscfg_csdev_lock) > // here load config activate by CPU1 > unlock(csdev->cscfg_csdev_lock) > > deactivate config // sysfs > (sys_activec_cnt == 0) > cscfg_unload_config_sets() > unload module > > // access to config_desc which freed > // while unloading module. > cfs_csdev_enable_config > > To address this, introduce sys_enable_cnt in cscfg_mgr to prevent > deactivate while there is enabled configuration. > > Signed-off-by: Yeoreum Yun <yeoreum.yun(a)arm.com> > --- > .../hwtracing/coresight/coresight-etm4x-core.c | 3 +++ > drivers/hwtracing/coresight/coresight-syscfg.c | 18 ++++++++++++++++-- > drivers/hwtracing/coresight/coresight-syscfg.h | 2 ++ > 3 files changed, 21 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c > index 86893115df17..6218ef40acbc 100644 > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c > @@ -986,6 +986,9 @@ static void etm4_disable_sysfs(struct coresight_device *csdev) > smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1); > > raw_spin_unlock(&drvdata->spinlock); > + > + cscfg_csdev_disable_active_config(csdev); > + > cpus_read_unlock(); > > /* > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c > index a70c1454b410..dfa7dcbaf25d 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > @@ -953,7 +953,8 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti > cscfg_mgr->sysfs_active_config = cfg_hash; > } else { > /* disable if matching current value */ > - if (cscfg_mgr->sysfs_active_config == cfg_hash) { > + if (cscfg_mgr->sysfs_active_config == cfg_hash && > + !atomic_read(&cscfg_mgr->sys_enable_cnt)) { > _cscfg_deactivate_config(cfg_hash); > cscfg_mgr->sysfs_active_config = 0; > } else > @@ -1055,6 +1056,12 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > if (!atomic_read(&cscfg_mgr->sys_active_cnt)) > return 0; > > + /* > + * increment sys_enable_cnt first to prevent deactivate the config > + * while enable active config. > + */ > + atomic_inc(&cscfg_mgr->sys_enable_cnt); > + > /* > * Look for matching configuration - set the active configuration > * context if found. > @@ -1098,6 +1105,10 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > } > } > + > + if (!config_csdev_active || err) > + atomic_dec(&cscfg_mgr->sys_enable_cnt); > + > return err; > } > EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config); > @@ -1129,8 +1140,10 @@ void cscfg_csdev_disable_active_config(struct coresight_device *csdev) > if (config_csdev) { > if (!config_csdev->enabled) > config_csdev = NULL; > - else > + else { > config_csdev->enabled = false; > + atomic_dec(&cscfg_mgr->sys_enable_cnt); > + } > } > csdev->active_cscfg_ctxt = NULL; > raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > @@ -1179,6 +1192,7 @@ static int cscfg_create_device(void) > INIT_LIST_HEAD(&cscfg_mgr->config_desc_list); > INIT_LIST_HEAD(&cscfg_mgr->load_order_list); > atomic_set(&cscfg_mgr->sys_active_cnt, 0); > + atomic_set(&cscfg_mgr->sys_enable_cnt, 0); > cscfg_mgr->load_state = CSCFG_NONE; > > /* setup the device */ > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h > index 66e2db890d82..2fc397919985 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.h > +++ b/drivers/hwtracing/coresight/coresight-syscfg.h > @@ -38,6 +38,7 @@ enum cscfg_load_ops { > * @config_desc_list: List of system configuration descriptors to load into registered devices. > * @load_order_list: Ordered list of owners for dynamically loaded configurations. > * @sys_active_cnt: Total number of active config descriptor references. > + * @sys_enable_cnt: Total number of enable of active config descriptor references. > * @cfgfs_subsys: configfs subsystem used to manage configurations. > * @sysfs_active_config:Active config hash used if CoreSight controlled from sysfs. > * @sysfs_active_preset:Active preset index used if CoreSight controlled from sysfs. > @@ -50,6 +51,7 @@ struct cscfg_manager { > struct list_head config_desc_list; > struct list_head load_order_list; > atomic_t sys_active_cnt; > + atomic_t sys_enable_cnt; > struct configfs_subsystem cfgfs_subsys; > u32 sysfs_active_config; > int sysfs_active_preset; > -- > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7} >

11 months, 1 week

[PATCH v3 0/3] Add support to configure TPDM MCMB subunit

by Mao Jinlong

Introduction of TPDM MCMB(Multi-lane Continuous Multi Bit) subunit MCMB (Multi-lane CMB) is a special form of CMB dataset type. MCMB subunit has the same number and usage of registers as CMB subunit. Just like the CMB subunit, the MCMB subunit must be configured prior to enablement. This series adds support for TPDM to configure the MCMB subunit. Once this series patches are applied properly, the new tpdm nodes for should be observed at the tpdm path /sys/bus/coresight/devices/tpdm* which supports MCMB subunit. All sysfs files of CMB subunit TPDM are included in MCMB subunit TPDM. On this basis, MCMB subunit TPDM will have new sysfs files to select and enable the lane. Changes in V3: 1. Update the date in ABI file. 2. Remove the unrelated change. 3. Correct typo. 4. Move the CMB_CR related definitions together. Changes in V2: 1. Use tdpm_data->cmb instead of (tpdm_has_cmb_dataset(tpdm_data) || tpdm_has_mcmb_dataset(tpdm_data)) for cmb dataset support. 2. Embed mcmb_dataset struct into cmb struct. 3. Update the date and version in sysfs-bus-coresight-devices-tpdm Link: https://patchwork.kernel.org/project/linux-arm-msm/patch/20241105123940.396… Mao Jinlong (1): coresight-tpdm: Add MCMB dataset support Tao Zhang (2): coresight-tpdm: Add support to select lane coresight-tpdm: Add support to enable the lane for MCMB TPDM .../testing/sysfs-bus-coresight-devices-tpdm | 15 +++ drivers/hwtracing/coresight/coresight-tpda.c | 7 +- drivers/hwtracing/coresight/coresight-tpdm.c | 120 +++++++++++++++++- drivers/hwtracing/coresight/coresight-tpdm.h | 33 +++-- 4 files changed, 155 insertions(+), 20 deletions(-) -- 2.17.1

11 months, 3 weeks

Re: [PATCH 1/1] coresight: prevent deactivate active config while enable the config

by James Clark

On 24/12/2024 10:13 am, Yeoreum Yun wrote: > Hi James. >>> diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c >>> index a70c1454b410..dfa7dcbaf25d 100644 >>> --- a/drivers/hwtracing/coresight/coresight-syscfg.c >>> +++ b/drivers/hwtracing/coresight/coresight-syscfg.c >>> @@ -953,7 +953,8 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti >>> cscfg_mgr->sysfs_active_config = cfg_hash; >>> } else { >>> /* disable if matching current value */ >>> - if (cscfg_mgr->sysfs_active_config == cfg_hash) { >>> + if (cscfg_mgr->sysfs_active_config == cfg_hash && >>> + !atomic_read(&cscfg_mgr->sys_enable_cnt)) { >>> _cscfg_deactivate_config(cfg_hash); >> >> So is sys_enable_cnt a global value? If a fix is needed doesn't it need to >> be a per-config refcount? >> >> Say you have two active configs, sys_enable_cnt is now 2, how do you disable >> one without it always skipping here when the other config is enabled? > > Sorry to miss this one!. > Because when one configuration is enabled, > cscfg_mgr->sysfs_active_config becomes !NULL, so it wouldn't happen > there is no two activate configurations. so sys_enable_cnt wouldn't be > 2. > > > Maybe "sys_enabled" is a better name then. Count implies that it can be more than one. And the doc could be updated to say it's only ever 0 or 1. But what about my other point about enabled always being a subset of active? Can we not change "sys_active_cnt" to a more generic "refcount", then both activation and enabling steps increment that same refcount, because they are both technically users of the config. Then you can solve the problem without adding another separate counter. I think that's potentially easier to understand. Although the easiest is just locking every function with the mutex (or a spinlock if it also needs to be used from Perf). Obviously all these atomics are harder to get right than that, and this isn't performance sensitive in any way.

11 months, 3 weeks

Re: [PATCH 1/1] coresight: prevent deactivate active config while enable the config

by James Clark

On 18/12/2024 8:48 am, Yeoreum Yun wrote: > While enable active config via cscfg_csdev_enable_active_config(), > active config could be deactivated via configfs' sysfs interface. > This could make UAF issue in below scenario: > > CPU0 CPU1 > (perf or sysfs enable) load module > cscfg_load_config_sets() > activate config. // sysfs > (sys_active_cnt == 1) > ... > cscfg_csdev_enable_active_config() > lock(csdev->cscfg_csdev_lock) > // here load config activate by CPU1 > unlock(csdev->cscfg_csdev_lock) > > deactivate config // sysfs > (sys_activec_cnt == 0) Assuming the left side does Perf, are there some steps missing? To get to enable_active_config() you first need to pass through etm_setup_aux() -> cscfg_activate_config(). That would also increment sys_active_cnt which would leave it at 2 if there were two concurrent sessions. Then it would end up as 1 here after deactivate, rather than 0. It's not explicitly mentioned in the sequence but I'm assuming the left and right are the same config, but I suppose it could be an issue with different configs too. > cscfg_unload_config_sets() > unload module On the left cscfg_activate_config() also bumps the module refcount, so unload wouldn't cause a UAF here as far as I can see. > > // access to config_desc which freed > // while unloading module. > cfs_csdev_enable_config > > To address this, introduce sys_enable_cnt in cscfg_mgr to prevent > deactivate while there is enabled configuration. > > Signed-off-by: Yeoreum Yun <yeoreum.yun(a)arm.com> > --- > .../hwtracing/coresight/coresight-etm4x-core.c | 3 +++ > drivers/hwtracing/coresight/coresight-syscfg.c | 18 ++++++++++++++++-- > drivers/hwtracing/coresight/coresight-syscfg.h | 2 ++ > 3 files changed, 21 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c > index 86893115df17..6218ef40acbc 100644 > --- a/drivers/hwtracing/coresight/coresight-etm4x-core.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c > @@ -986,6 +986,9 @@ static void etm4_disable_sysfs(struct coresight_device *csdev) > smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1); > > raw_spin_unlock(&drvdata->spinlock); > + > + cscfg_csdev_disable_active_config(csdev); > + > cpus_read_unlock(); > > /* > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c > index a70c1454b410..dfa7dcbaf25d 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.c > +++ b/drivers/hwtracing/coresight/coresight-syscfg.c > @@ -953,7 +953,8 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti > cscfg_mgr->sysfs_active_config = cfg_hash; > } else { > /* disable if matching current value */ > - if (cscfg_mgr->sysfs_active_config == cfg_hash) { > + if (cscfg_mgr->sysfs_active_config == cfg_hash && > + !atomic_read(&cscfg_mgr->sys_enable_cnt)) { > _cscfg_deactivate_config(cfg_hash); So is sys_enable_cnt a global value? If a fix is needed doesn't it need to be a per-config refcount? Say you have two active configs, sys_enable_cnt is now 2, how do you disable one without it always skipping here when the other config is enabled? > cscfg_mgr->sysfs_active_config = 0; > } else > @@ -1055,6 +1056,12 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > if (!atomic_read(&cscfg_mgr->sys_active_cnt)) > return 0; > > + /* > + * increment sys_enable_cnt first to prevent deactivate the config > + * while enable active config. > + */ > + atomic_inc(&cscfg_mgr->sys_enable_cnt); > + > /* > * Look for matching configuration - set the active configuration > * context if found. > @@ -1098,6 +1105,10 @@ int cscfg_csdev_enable_active_config(struct coresight_device *csdev, > raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > } > } > + > + if (!config_csdev_active || err) > + atomic_dec(&cscfg_mgr->sys_enable_cnt); > + > return err; > } > EXPORT_SYMBOL_GPL(cscfg_csdev_enable_active_config); > @@ -1129,8 +1140,10 @@ void cscfg_csdev_disable_active_config(struct coresight_device *csdev) > if (config_csdev) { > if (!config_csdev->enabled) > config_csdev = NULL; > - else > + else { > config_csdev->enabled = false; > + atomic_dec(&cscfg_mgr->sys_enable_cnt); > + } > } > csdev->active_cscfg_ctxt = NULL; > raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags); > @@ -1179,6 +1192,7 @@ static int cscfg_create_device(void) > INIT_LIST_HEAD(&cscfg_mgr->config_desc_list); > INIT_LIST_HEAD(&cscfg_mgr->load_order_list); > atomic_set(&cscfg_mgr->sys_active_cnt, 0); > + atomic_set(&cscfg_mgr->sys_enable_cnt, 0); > cscfg_mgr->load_state = CSCFG_NONE; > > /* setup the device */ > diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h > index 66e2db890d82..2fc397919985 100644 > --- a/drivers/hwtracing/coresight/coresight-syscfg.h > +++ b/drivers/hwtracing/coresight/coresight-syscfg.h > @@ -38,6 +38,7 @@ enum cscfg_load_ops { > * @config_desc_list: List of system configuration descriptors to load into registered devices. > * @load_order_list: Ordered list of owners for dynamically loaded configurations. > * @sys_active_cnt: Total number of active config descriptor references. > + * @sys_enable_cnt: Total number of enable of active config descriptor references. When these are next to each other it makes me wonder why active_cnt isn't enough to prevent unloading? Enabled is always a subset of active, so as long as you gate unloads or modifications on the existing active count it seems fine? > * @cfgfs_subsys: configfs subsystem used to manage configurations. > * @sysfs_active_config:Active config hash used if CoreSight controlled from sysfs. > * @sysfs_active_preset:Active preset index used if CoreSight controlled from sysfs. > @@ -50,6 +51,7 @@ struct cscfg_manager { > struct list_head config_desc_list; > struct list_head load_order_list; > atomic_t sys_active_cnt; > + atomic_t sys_enable_cnt; > struct configfs_subsystem cfgfs_subsys; > u32 sysfs_active_config; > int sysfs_active_preset;

11 months, 3 weeks

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