[PATCH 6/6] dynamic_debug: Add flag for dynamic event tracing
From: Sai Prakash Ranjan <hidden>
Date: 2018-09-08 20:29:07
Also in:
linux-arm-msm, linux-devicetree, lkml
Subsystem:
dynamic debug, generic include/asm header files, library code, the rest · Maintainers:
Jason Baron, Jim Cromie, Arnd Bergmann, Andrew Morton, Linus Torvalds
Debugging a specific driver or subsystem can be a lot easier
if we can trace events specific to that driver or subsystem.
This type of filtering can be achieved using existing
dynamic debug library which provides a way to filter based
on files, functions and modules.
Using this, provide an additional flag 'e' to filter event
tracing to specified input.
For example, tracing all IO read/write can be overwhelming
and of no use when debugging a specific driver or a subsystem.
So switch to dynamic event tracing for register accesses.
Example for tracing register accesses in drivers/soc/qcom/*
and the pstore output is given below:
# dyndbg="file drivers/soc/qcom/* +e" trace_event=io tp_pstore
# reboot -f
# mount -t pstore pstore /sys/fs/pstore
# cat /sys/fs/pstore/event-ramoops-0
io_write: type=writel cpu=1 ts:1423596253 data=0xffff00000d2065a4 caller=qcom_smsm_probe+0x524/0x670
io_write: type=writel cpu=1 ts:1423945889 data=0xffff00000d206608 caller=qcom_smsm_probe+0x524/0x670
Note: Tracing is activated only when flag is enabled either
through command line or through dynamic debug control file.
Signed-off-by: Sai Prakash Ranjan <redacted>
---
include/asm-generic/io-instrumented.h | 28 +++++++++++++++++++++++++--
include/linux/dynamic_debug.h | 1 +
lib/dynamic_debug.c | 1 +
3 files changed, 28 insertions(+), 2 deletions(-)
diff --git a/include/asm-generic/io-instrumented.h b/include/asm-generic/io-instrumented.h
index 7b050e2487ed..023f28571ea3 100644
--- a/include/asm-generic/io-instrumented.h
+++ b/include/asm-generic/io-instrumented.h@@ -2,6 +2,8 @@ #ifndef _ASM_GENERIC_IO_INSTRUMENTED_H #define _ASM_GENERIC_IO_INSTRUMENTED_H +#include <linux/dynamic_debug.h> + #if defined(CONFIG_TRACING_EVENTS_IO) #include <linux/tracepoint-defs.h>
@@ -19,7 +21,7 @@ static inline void do_trace_io_read(const char *type, void *addr) {} #define __raw_write(v, a, _l) ({ \ volatile void __iomem *_a = (a); \ if (io_tracepoint_active(__tracepoint_io_write)) \ - do_trace_io_write(__stringify(write##_l), (void __force *)(_a));\ + dynamic_io_write(__stringify(write##_l), (void __force *)(_a)); \ arch_raw_write##_l((v), _a); \ })
@@ -32,7 +34,7 @@ static inline void do_trace_io_read(const char *type, void *addr) {} _t __a; \ const volatile void __iomem *_a = (a); \ if (io_tracepoint_active(__tracepoint_io_read)) \ - do_trace_io_read(__stringify(read##_l), (void __force *)(_a)); \ + dynamic_io_read(__stringify(read##_l), (void __force *)(_a)); \ __a = arch_raw_read##_l(_a); \ __a; \ })
@@ -42,4 +44,26 @@ static inline void do_trace_io_read(const char *type, void *addr) {} #define __raw_readl(a) __raw_read((a), l, u32) #define __raw_readq(a) __raw_read((a), q, u64) +#if defined(CONFIG_DYNAMIC_DEBUG) && defined(CONFIG_TRACING_EVENTS_IO) +#define dynamic_io_write(type, addr) \ +do { \ + DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, type); \ + if (unlikely(descriptor.flags & _DPRINTK_FLAGS_EVENT)) \ + do_trace_io_write(type, addr); \ +} while (0) + +#define dynamic_io_read(type, addr) \ +do { \ + DEFINE_DYNAMIC_DEBUG_METADATA(descriptor, type); \ + if (unlikely(descriptor.flags & _DPRINTK_FLAGS_EVENT)) \ + do_trace_io_read(type, addr); \ +} while (0) +#elif defined(CONFIG_TRACING_EVENTS_IO) +#define dynamic_io_write(type, addr) do_trace_io_write(type, addr) +#define dynamic_io_read(type, addr) do_trace_io_read(type, addr) +#else +#define dynamic_io_write(type, addr) +#define dynamic_io_read(type, addr) +#endif /* CONFIG_DYNAMIC_DEBUG && CONFIG_TRACING_EVENTS_IO */ + #endif /* _ASM_GENERIC_IO_INSTRUMENTED_H */
diff --git a/include/linux/dynamic_debug.h b/include/linux/dynamic_debug.h
index 2fd8006153c3..14e595c51002 100644
--- a/include/linux/dynamic_debug.h
+++ b/include/linux/dynamic_debug.h@@ -32,6 +32,7 @@ struct _ddebug { #define _DPRINTK_FLAGS_INCL_FUNCNAME (1<<2) #define _DPRINTK_FLAGS_INCL_LINENO (1<<3) #define _DPRINTK_FLAGS_INCL_TID (1<<4) +#define _DPRINTK_FLAGS_EVENT (1<<5) #if defined DEBUG #define _DPRINTK_FLAGS_DEFAULT _DPRINTK_FLAGS_PRINT #else
diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index c7c96bc7654a..694957a8ae54 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c@@ -78,6 +78,7 @@ static inline const char *trim_prefix(const char *path) static struct { unsigned flag:8; char opt_char; } opt_array[] = { { _DPRINTK_FLAGS_PRINT, 'p' }, + { _DPRINTK_FLAGS_EVENT, 'e' }, { _DPRINTK_FLAGS_INCL_MODNAME, 'm' }, { _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' }, { _DPRINTK_FLAGS_INCL_LINENO, 'l' },
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