Re: [PATCHv10 5/6] lib: Add register read/write tracing support

[Sai Prakash Ranjan <quic_saipraka@quicinc.com>]

On 2/24/2022 7:27 PM, Steven Rostedt wrote:
> On Thu, 24 Feb 2022 11:37:07 +0530
> Sai Prakash Ranjan <quic_saipraka@quicinc.com> wrote:
>
>
>> --- /dev/null
>> +++ b/include/trace/events/rwmmio.h
>> @@ -0,0 +1,97 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +/*
>> + * Copyright (c) 2021-2022 Qualcomm Innovation Center, Inc. All rights reserved.
>> + */
>> +#undef TRACE_SYSTEM
>> +#define TRACE_SYSTEM rwmmio
>> +
>> +#if !defined(_TRACE_RWMMIO_H) || defined(TRACE_HEADER_MULTI_READ)
>> +#define _TRACE_RWMMIO_H
>> +
>> +#include <linux/tracepoint.h>
>> +
>> +DECLARE_EVENT_CLASS(rwmmio_rw_template,
>> +
>> +	TP_PROTO(unsigned long caller, u64 val, u8 width, volatile void __iomem *addr),
>> +
>> +	TP_ARGS(caller, val, width, addr),
>> +
>> +	TP_STRUCT__entry(
>> +		__field(u64, caller)
>> +		__field(u64, val)
>> +		__field(u64, addr)
> So caller and addr are both pointers. Why not define them as unsigned long?
> That will save 8 bytes on 32 bit machines.
>
> 		__field(unsigned long, caller)
> 		__field(unsigned long, addr)
> 		__feild(u64, val)
>
> to keep the longs together as on 32 bit, it will be better aligned.
>
> The tracing tools can handle the difference from user space. Even when
> reading trace files from 32 bit architectures on 64 bit machines, and vise
> versa.

Sure, I'll change them to unsigned long. Thanks for the suggestion.

>> +		__field(u8, width)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->caller = caller;
>> +		__entry->val = val;
>> +		__entry->addr = (unsigned long)(void *)addr;
>> +		__entry->width = width;
>> +	),
>> +
>> +	TP_printk("%pS width=%d val=%#llx addr=%#llx",
>> +		(void *)(unsigned long)__entry->caller, __entry->width,
>> +		__entry->val, __entry->addr)
>> +);
>> +
>> +DEFINE_EVENT(rwmmio_rw_template, rwmmio_write,
>> +	TP_PROTO(unsigned long caller, u64 val, u8 width, volatile void __iomem *addr),
>> +	TP_ARGS(caller, val, width, addr)
>> +);
>> +
>> +DEFINE_EVENT(rwmmio_rw_template, rwmmio_post_write,
>> +	TP_PROTO(unsigned long caller, u64 val, u8 width, volatile void __iomem *addr),
>> +	TP_ARGS(caller, val, width, addr)
>> +);
>> +
>> +TRACE_EVENT(rwmmio_read,
>> +
>> +	TP_PROTO(unsigned long caller, u8 width, const volatile void __iomem *addr),
>> +
>> +	TP_ARGS(caller, width, addr),
>> +
>> +	TP_STRUCT__entry(
>> +		__field(u64, caller)
>> +		__field(u64, addr)
> Same here.
>
> -- Steve

Sure.

Thanks,
Sai

>
>> +		__field(u8, width)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->caller = caller;
>> +		__entry->addr = (unsigned long)(void *)addr;
>> +		__entry->width = width;
>> +	),
>> +
>> +	TP_printk("%pS width=%d addr=%#llx",
>> +		 (void *)(unsigned long)__entry->caller, __entry->width, __entry->addr)
>> +);
>> +
>> +TRACE_EVENT(rwmmio_post_read,
>> +
>> +	TP_PROTO(unsigned long caller, u64 val, u8 width, const volatile void __iomem *addr),
>> +
>> +	TP_ARGS(caller, val, width, addr),
>> +
>> +	TP_STRUCT__entry(
>> +		__field(u64, caller)
>> +		__field(u64, val)
>> +		__field(u64, addr)
>> +		__field(u8, width)
>> +	),
>> +
>> +	TP_fast_assign(
>> +		__entry->caller = caller;
>> +		__entry->val = val;
>> +		__entry->addr = (unsigned long)(void *)addr;
>> +		__entry->width = width;
>> +	),
>> +
>> +	TP_printk("%pS width=%d val=%#llx addr=%#llx",
>> +		 (void *)(unsigned long)__entry->caller, __entry->width,
>> +		 __entry->val, __entry->addr)
>> +);
>> +
>> +#endif /* _TRACE_RWMMIO_H */
>> +
>> +#include <trace/define_trace.h>
>> diff --git a/lib/Kconfig b/lib/Kconfig
>> index c80fde816a7e..ea520c315c0f 100644
>> --- a/lib/Kconfig
>> +++ b/lib/Kconfig
>> @@ -119,6 +119,13 @@ 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
>> diff --git a/lib/Makefile b/lib/Makefile
>> index 300f569c626b..43813b0061cd 100644
>> --- a/lib/Makefile
>> +++ b/lib/Makefile
>> @@ -152,6 +152,8 @@ lib-y += logic_pio.o
>>   
>>   lib-$(CONFIG_INDIRECT_IOMEM) += logic_iomem.o
>>   
>> +obj-$(CONFIG_TRACE_MMIO_ACCESS) += trace_readwrite.o
>> +
>>   obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
>>   
>>   obj-$(CONFIG_BTREE) += btree.o
>> diff --git a/lib/trace_readwrite.c b/lib/trace_readwrite.c
>> new file mode 100644
>> index 000000000000..88637038b30c
>> --- /dev/null
>> +++ b/lib/trace_readwrite.c
>> @@ -0,0 +1,47 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Register read and write tracepoints
>> + *
>> + * Copyright (c) 2021-2022 Qualcomm Innovation Center, Inc. All rights reserved.
>> + */
>> +
>> +#include <linux/ftrace.h>
>> +#include <linux/module.h>
>> +#include <asm-generic/io.h>
>> +
>> +#define CREATE_TRACE_POINTS
>> +#include <trace/events/rwmmio.h>
>> +
>> +#ifdef CONFIG_TRACE_MMIO_ACCESS
>> +void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
>> +		    unsigned long caller_addr)
>> +{
>> +	trace_rwmmio_write(caller_addr, val, width, addr);
>> +}
>> +EXPORT_SYMBOL_GPL(log_write_mmio);
>> +EXPORT_TRACEPOINT_SYMBOL_GPL(rwmmio_write);
>> +
>> +void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
>> +			 unsigned long caller_addr)
>> +{
>> +	trace_rwmmio_post_write(caller_addr, val, width, addr);
>> +}
>> +EXPORT_SYMBOL_GPL(log_post_write_mmio);
>> +EXPORT_TRACEPOINT_SYMBOL_GPL(rwmmio_post_write);
>> +
>> +void log_read_mmio(u8 width, const volatile void __iomem *addr,
>> +		   unsigned long caller_addr)
>> +{
>> +	trace_rwmmio_read(caller_addr, width, addr);
>> +}
>> +EXPORT_SYMBOL_GPL(log_read_mmio);
>> +EXPORT_TRACEPOINT_SYMBOL_GPL(rwmmio_read);
>> +
>> +void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
>> +			unsigned long caller_addr)
>> +{
>> +	trace_rwmmio_post_read(caller_addr, val, width, addr);
>> +}
>> +EXPORT_SYMBOL_GPL(log_post_read_mmio);
>> +EXPORT_TRACEPOINT_SYMBOL_GPL(rwmmio_post_read);
>> +#endif /* CONFIG_TRACE_MMIO_ACCESS */