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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 <quic_saipraka@quicinc.com> Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org> Signed-off-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com> Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
48 lines
1.3 KiB
C
48 lines
1.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Register read and write tracepoints
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*
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* Copyright (c) 2021-2022 Qualcomm Innovation Center, Inc. All rights reserved.
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*/
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#include <linux/ftrace.h>
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#include <linux/module.h>
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#include <asm-generic/io.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/rwmmio.h>
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#ifdef CONFIG_TRACE_MMIO_ACCESS
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void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
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unsigned long caller_addr)
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{
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trace_rwmmio_write(caller_addr, val, width, addr);
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}
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EXPORT_SYMBOL_GPL(log_write_mmio);
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EXPORT_TRACEPOINT_SYMBOL_GPL(rwmmio_write);
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void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
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unsigned long caller_addr)
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{
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trace_rwmmio_post_write(caller_addr, val, width, addr);
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}
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EXPORT_SYMBOL_GPL(log_post_write_mmio);
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EXPORT_TRACEPOINT_SYMBOL_GPL(rwmmio_post_write);
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void log_read_mmio(u8 width, const volatile void __iomem *addr,
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unsigned long caller_addr)
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{
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trace_rwmmio_read(caller_addr, width, addr);
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}
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EXPORT_SYMBOL_GPL(log_read_mmio);
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EXPORT_TRACEPOINT_SYMBOL_GPL(rwmmio_read);
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void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
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unsigned long caller_addr)
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{
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trace_rwmmio_post_read(caller_addr, val, width, addr);
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}
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EXPORT_SYMBOL_GPL(log_post_read_mmio);
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EXPORT_TRACEPOINT_SYMBOL_GPL(rwmmio_post_read);
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#endif /* CONFIG_TRACE_MMIO_ACCESS */
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