CoreSight January 2025

coresight@lists.linaro.org

8 participants
43 discussions

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} >> >

5 months, 3 weeks

[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

5 months, 3 weeks

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} >

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