| Message ID | cover.1651139070.git.quic_saipraka@quicinc.com |
|---|---|
| Headers | show |
| Series | lib/rwmmio/arm64: Add support to trace register reads/writes | expand |
On Thu, Apr 28, 2022 at 03:25:30PM +0530, Sai Prakash Ranjan wrote: > Add logging support for MMIO high level accessors such as read{b,w,l,q} > and their relaxed versions to aid in debugging unexpected crashes/hangs > caused by the corresponding MMIO operation. > > Signed-off-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com> > --- > include/asm-generic/io.h | 82 ++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 78 insertions(+), 4 deletions(-) > > diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h > index 7ce93aaf69f8..99090722cb4b 100644 > --- a/include/asm-generic/io.h > +++ b/include/asm-generic/io.h > @@ -10,6 +10,7 @@ > #include <asm/page.h> /* I/O is all done through memory accesses */ > #include <linux/string.h> /* for memset() and memcpy() */ > #include <linux/types.h> > +#include <linux/instruction_pointer.h> > > #ifdef CONFIG_GENERIC_IOMAP > #include <asm-generic/iomap.h> > @@ -61,6 +62,35 @@ > #define __io_par(v) __io_ar(v) > #endif > > +#if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__)) Shouldn't you document __DISABLE_TRACE_MMIO__ somewhere? It's not even in the changelog. Put a big comment above this for what is is for and how to use it. Otherwise you will forget all about this in 6 months :) thanks, greg k-h
On 4/28/2022 4:21 PM, Greg KH wrote: > On Thu, Apr 28, 2022 at 03:25:30PM +0530, Sai Prakash Ranjan wrote: >> Add logging support for MMIO high level accessors such as read{b,w,l,q} >> and their relaxed versions to aid in debugging unexpected crashes/hangs >> caused by the corresponding MMIO operation. >> >> Signed-off-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com> >> --- >> include/asm-generic/io.h | 82 ++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 78 insertions(+), 4 deletions(-) >> >> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h >> index 7ce93aaf69f8..99090722cb4b 100644 >> --- a/include/asm-generic/io.h >> +++ b/include/asm-generic/io.h >> @@ -10,6 +10,7 @@ >> #include <asm/page.h> /* I/O is all done through memory accesses */ >> #include <linux/string.h> /* for memset() and memcpy() */ >> #include <linux/types.h> >> +#include <linux/instruction_pointer.h> >> >> #ifdef CONFIG_GENERIC_IOMAP >> #include <asm-generic/iomap.h> >> @@ -61,6 +62,35 @@ >> #define __io_par(v) __io_ar(v) >> #endif >> >> +#if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__)) > Shouldn't you document __DISABLE_TRACE_MMIO__ somewhere? It's not even > in the changelog. Put a big comment above this for what is is for and > how to use it. Otherwise you will forget all about this in 6 months :) > > thanks, > > greg k-h Didn't you ask me to split the patch to the one actually adding the flag and the one using it. So I have added the description in that patch which adds the flag since we can't add description everywhere we use the flag right :) Thanks, Sai
On 4/28/2022 5:32 PM, Greg KH wrote: > On Thu, Apr 28, 2022 at 04:51:49PM +0530, Sai Prakash Ranjan wrote: >> On 4/28/2022 4:21 PM, Greg KH wrote: >>> On Thu, Apr 28, 2022 at 03:25:30PM +0530, Sai Prakash Ranjan wrote: >>>> Add logging support for MMIO high level accessors such as read{b,w,l,q} >>>> and their relaxed versions to aid in debugging unexpected crashes/hangs >>>> caused by the corresponding MMIO operation. >>>> >>>> Signed-off-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com> >>>> --- >>>> include/asm-generic/io.h | 82 ++++++++++++++++++++++++++++++++++++++-- >>>> 1 file changed, 78 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h >>>> index 7ce93aaf69f8..99090722cb4b 100644 >>>> --- a/include/asm-generic/io.h >>>> +++ b/include/asm-generic/io.h >>>> @@ -10,6 +10,7 @@ >>>> #include <asm/page.h> /* I/O is all done through memory accesses */ >>>> #include <linux/string.h> /* for memset() and memcpy() */ >>>> #include <linux/types.h> >>>> +#include <linux/instruction_pointer.h> >>>> #ifdef CONFIG_GENERIC_IOMAP >>>> #include <asm-generic/iomap.h> >>>> @@ -61,6 +62,35 @@ >>>> #define __io_par(v) __io_ar(v) >>>> #endif >>>> +#if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__)) >>> Shouldn't you document __DISABLE_TRACE_MMIO__ somewhere? It's not even >>> in the changelog. Put a big comment above this for what is is for and >>> how to use it. Otherwise you will forget all about this in 6 months :) >>> >>> thanks, >>> >>> greg k-h >> Didn't you ask me to split the patch to the one actually adding the flag and the one using it. > Yes, and isn't this the commit that adds the flag? Or was that on an > earlier one that I missed? > > Ah, it's in patch 6/9 > > But you should also document it here in the .h file, otherwise the only > place it is described is in some random kvm Makefile that no one will > ever notice :) > > Sure it makes sense, will add it. Thanks, Sai
Generic MMIO read/write i.e., __raw_{read,write}{b,l,w,q} accessors are typically used to read/write from/to memory mapped registers and can cause hangs or some undefined behaviour in following cases, * If the access to the register space is unclocked, for example: if there is an access to multimedia(MM) block registers without MM clocks. * If the register space is protected and not set to be accessible from non-secure world, for example: only EL3 (EL: Exception level) access is allowed and any EL2/EL1 access is forbidden. * If xPU(memory/register protection units) is controlling access to certain memory/register space for specific clients. and more... Such cases usually results in instant reboot/SErrors/NOC or interconnect hangs and tracing these register accesses can be very helpful to debug such issues during initial development stages and also in later stages. So use ftrace trace events to log such MMIO register accesses which provides rich feature set such as early enablement of trace events, filtering capability, dumping ftrace logs on console and many more. Sample output: rwmmio_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 val=0xa0d5d addr=0xfffffbfffdbff700 rwmmio_post_write: __qcom_geni_serial_console_write+0x160/0x1e0 width=32 val=0xa0d5d addr=0xfffffbfffdbff700 rwmmio_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 addr=0xfffffbfffdbff610 rwmmio_post_read: qcom_geni_serial_poll_bit+0x94/0x138 width=32 val=0x0 addr=0xfffffbfffdbff610 This series is a follow-up for the series [1] and a recent series [2] making use of both. [1] https://lore.kernel.org/lkml/cover.1536430404.git.saiprakash.ranjan@codeaurora.org/ [2] https://lore.kernel.org/lkml/1604631386-178312-1-git-send-email-psodagud@codeaurora.org/ Note in v4 version, Arnd suggested to benchmark and compare size with callback based implementation, please see [3] for more details on that with brief comparison below. **Inline version with CONFIG_FTRACE=y and CONFIG_TRACE_MMIO_ACCESS=y** $ size vmlinux text data bss dec hex filename 23884219 14284468 532568 38701255 24e88c7 vmlinux **Callback version with CONFIG_FTRACE=y and CONFIG_TRACE_MMIO_ACCESS=y** $ size vmlinux text data bss dec hex filename 24108179 14279596 532568 38920343 251e097 vmlinux $ ./scripts/bloat-o-meter inline-vmlinux callback-vmlinux add/remove: 8/3 grow/shrink: 4889/89 up/down: 242244/-11564 (230680) Total: Before=25812612, After=26043292, chg +0.89% [3] https://lore.kernel.org/lkml/466449a1-36da-aaa9-7e4f-477f36b52c9e@quicinc.com/ Changes in v12: * Split the generic flag addition patch (Greg). * Move the flag from makefile to driver .c file (Greg). Changes in v11: * Use unsigned long for caller ip and current ip addr (Steven Rostedt). * Include review tags from Arnd. Changes in v10: * Use GENMASK(31, 0) for -Woverflow warning in irqchip tegra driver (Marc). * Convert ETM4x ARM64 driver to use asm-generic IO memory barriers (Catalin). * Collect ack from Catalin for arm64 change. Changes in v9: * Use TRACE_EVENT_CLASS for rwmmio_write and post_write (Steven Rostedt). Changes in v8: * Fix build error reported by kernel test robot. Changes in v7: * Use lib/ instead of kernel/trace/ based on review comment by Steven Rostedt. Changes in v6: * Implemented suggestions by Arnd Bergmann: - Use arch independent IO barriers in arm64/asm - Add ARCH_HAVE_TRACE_MMIO_ACCESS - Add post read and post write logging support - Remove tracepoint_active check * Fix build error reported by kernel test robot. Changes in v5: * Move arm64 to use asm-generic provided high level MMIO accessors (Arnd). * Add inline logging for MMIO relaxed and non-relaxed accessors. * Move nVHE KVM comment to makefile (Marc). * Fix overflow warning due to switch to inline accessors instead of macro. * Modify trace event field to include caller and parent details for more detailed logs. Changes in v4: * Drop dynamic debug based filter support since that will be developed later with the help from Steven (Ftrace maintainer). * Drop value passed to writel as it is causing hangs when tracing is enabled. * Code cleanup for trace event as suggested by Steven for earlier version. * Fixed some build errors reported by 0-day bot. Changes in v3: * Create a generic mmio header for instrumented version (Earlier suggested in [1] by Will Deacon and recently [2] by Greg to have a generic version first). * Add dynamic debug support to filter out traces which can be very useful for targeted debugging specific to subsystems or drivers. * Few modifications to the rwmmio trace event fields to include the mmio width and print addresses in hex. * Rewrote commit msg to explain some more about usecases. Prasad Sodagudi (1): lib: Add register read/write tracing support Sai Prakash Ranjan (8): arm64: io: Use asm-generic high level MMIO accessors coresight: etm4x: Use asm-generic IO memory barriers irqchip/tegra: Fix overflow implicit truncation warnings drm/meson: Fix overflow implicit truncation warnings KVM: arm64: Add a flag to disable MMIO trace for nVHE KVM asm-generic/io: Add logging support for MMIO accessors serial: qcom_geni_serial: Disable MMIO tracing for geni serial soc: qcom: geni: Disable MMIO tracing for GENI SE arch/Kconfig | 3 + arch/arm64/Kconfig | 1 + arch/arm64/include/asm/io.h | 41 ++------ arch/arm64/kvm/hyp/nvhe/Makefile | 7 +- drivers/gpu/drm/meson/meson_viu.c | 22 ++--- .../coresight/coresight-etm4x-core.c | 8 +- drivers/hwtracing/coresight/coresight-etm4x.h | 8 +- drivers/irqchip/irq-tegra.c | 10 +- drivers/soc/qcom/qcom-geni-se.c | 8 +- drivers/tty/serial/qcom_geni_serial.c | 8 +- include/asm-generic/io.h | 82 +++++++++++++++- include/trace/events/rwmmio.h | 97 +++++++++++++++++++ lib/Kconfig | 7 ++ lib/Makefile | 2 + lib/trace_readwrite.c | 47 +++++++++ 15 files changed, 287 insertions(+), 64 deletions(-) create mode 100644 include/trace/events/rwmmio.h create mode 100644 lib/trace_readwrite.c