[RFC PATCH v2 3/3] dynamic_debug: Add support for dynamic register trace
From: Will Deacon <hidden>
Date: 2018-09-06 10:05:13
Also in:
linux-arm-msm, lkml
On Fri, Aug 24, 2018 at 08:15:27PM +0530, Sai Prakash Ranjan wrote:
quoted hunk ↗ jump to hunk
Introduce dynamic debug filtering mechanism to register tracing as dynamic_rtb() which will reduce a lot of overhead otherwise of tracing all the register reads/writes in all files. Now we can just specify the file name or any wildcard pattern as any other dynamic debug facility in bootargs and dynamic rtb will just trace them and the output can be seen in pstore. TODO: Now we use same 'p' flag but will add a separate flag for register trace later. Also add asm-generic/io-instrumented.h file for instrumentation of IO operations such as read/write{b,w,l,q} as per Will's suggestion to not touch arch code and let core generate instrumentation. This can be extended to arm as well later for tracing. Example for tracing all register reads/writes in drivers/soc/qcom/* below: # dyndbg="file drivers/soc/qcom/* +p" in bootargs # reboot -f # mount -t pstore pstore /sys/fs/pstore # cat /sys/fs/pstore/rtb-ramoops-0 [LOGK_WRITE] ts:1373030419 data:ffff00000d5065a4 <ffff00000867cb44> qcom_smsm_probe+0x51c/0x668 [LOGK_WRITE] ts:1373360576 data:ffff00000d506608 <ffff00000867cb44> qcom_smsm_probe+0x51c/0x668 Signed-off-by: Sai Prakash Ranjan <redacted> --- arch/arm64/include/asm/io.h | 26 +++++++++------------- include/asm-generic/io-instrumented.h | 32 +++++++++++++++++++++++++++ include/linux/dynamic_debug.h | 13 +++++++++++ kernel/trace/Kconfig | 1 + 4 files changed, 56 insertions(+), 16 deletions(-) create mode 100644 include/asm-generic/io-instrumented.hdiff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index 35b2e50f17fb..aafd4b0be9f0 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h
The arm64 bits look fine to me, but please can you split them into a separate patch?
quoted hunk ↗ jump to hunk
diff --git a/include/asm-generic/io-instrumented.h b/include/asm-generic/io-instrumented.h new file mode 100644 index 000000000000..ce273742b98c --- /dev/null +++ b/include/asm-generic/io-instrumented.h@@ -0,0 +1,32 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#ifndef _ASM_GENERIC_IO_INSTRUMENTED_H +#define _ASM_GENERIC_IO_INSTRUMENTED_H + +#include <linux/dynamic_debug.h> + +#define __raw_write(v, a, _t) ({ \ + volatile void __iomem *_a = (a); \
Does this actually need to be volatile?
+ dynamic_rtb("LOGK_WRITE", (void __force *)(_a));\
+ arch_raw_write##_t((v), _a); \
+ })
+
+#define __raw_writeb(v, a) __raw_write((v), a, b)
+#define __raw_writew(v, a) __raw_write((v), a, w)
+#define __raw_writel(v, a) __raw_write((v), a, l)
+#define __raw_writeq(v, a) __raw_write((v), a, q)
+
+#define __raw_read(a, _l, _t) ({ \
+ _t __a; \
+ const volatile void __iomem *_a = (const volatile void __iomem *)(a);\Again, can't this just be void __iomem * ?
+ dynamic_rtb("LOGK_READ", (void __force *)(_a)); \
+ __a = arch_raw_read##_l(_a); \
+ __a; \
+ })
+
+#define __raw_readb(a) __raw_read((a), b, u8)
+#define __raw_readw(a) __raw_read((a), w, u16)
+#define __raw_readl(a) __raw_read((a), l, u32)
+#define __raw_readq(a) __raw_read((a), q, u64)
I find the way you've defined the __raw_{read,write} macros quite confusing.
They both have an _t parameter, but it's totally unrelated between the two!
Will