From d593d64f043add170d8ea9cf698449637917dcf9 Mon Sep 17 00:00:00 2001 From: Prasad Sodagudi Date: Wed, 18 May 2022 22:14:14 +0530 Subject: lib: Add register read/write tracing support 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 few 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 Co-developed-by: Sai Prakash Ranjan Signed-off-by: Prasad Sodagudi Signed-off-by: Sai Prakash Ranjan Acked-by: Steven Rostedt (Google) Signed-off-by: Arnd Bergmann --- lib/Kconfig | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'lib/Kconfig') diff --git a/lib/Kconfig b/lib/Kconfig index 6a843639814f..80aeceee88ed 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -118,6 +118,13 @@ config INDIRECT_IOMEM_FALLBACK mmio accesses when the IO memory address is not a registered emulated region. +config TRACE_MMIO_ACCESS + bool "Register read/write tracing" + depends on TRACING && ARCH_HAVE_TRACE_MMIO_ACCESS + help + Create tracepoints for MMIO read/write operations. These trace events + can be used for logging all MMIO read/write operations. + source "lib/crypto/Kconfig" config CRC_CCITT -- cgit v1.2.3-58-ga151