2022-05-18 16:47:17

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 0/9] lib/rwmmio/arm64: Add support to trace register reads/writes

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 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

This series is a follow-up for the series [1] and a recent series [2] making use
of both.

[1] https://lore.kernel.org/lkml/[email protected]/
[2] https://lore.kernel.org/lkml/[email protected]/

Note in v4 version, Arnd suggested to benchmark and compare size with callback
based implementation, please see [3] for more details on that with brief comparison below.


**Inline version with CONFIG_FTRACE=y and CONFIG_TRACE_MMIO_ACCESS=y**
$ size vmlinux
text data bss dec hex filename
23884219 14284468 532568 38701255 24e88c7 vmlinux

**Callback version with CONFIG_FTRACE=y and CONFIG_TRACE_MMIO_ACCESS=y**
$ size vmlinux
text data bss dec hex filename
24108179 14279596 532568 38920343 251e097 vmlinux

$ ./scripts/bloat-o-meter inline-vmlinux callback-vmlinux
add/remove: 8/3 grow/shrink: 4889/89 up/down: 242244/-11564 (230680)
Total: Before=25812612, After=26043292, chg +0.89%

[3] https://lore.kernel.org/lkml/[email protected]/

Changes in v15:
* Fix unnecessary casts (Steve).

Changes in v14:
* Add more description to disabling MMIO traces in geni serial drivers (Steve).

Changes in v13:
* Remove the copyright update as one line change doesn't warrant it (Greg and Lawyers :))
* Update the comment about disabling MMIO traces in geni se and uart drivers.
* Add description for the build time flag to asm-generic/io.h.

Changes in v12:
* Split the generic flag addition patch (Greg).
* Move the flag from makefile to driver .c file (Greg).

Changes in v11:
* Use unsigned long for caller ip and current ip addr (Steven Rostedt).
* Include review tags from Arnd.

Changes in v10:
* Use GENMASK(31, 0) for -Woverflow warning in irqchip tegra driver (Marc).
* Convert ETM4x ARM64 driver to use asm-generic IO memory barriers (Catalin).
* Collect ack from Catalin for arm64 change.

Changes in v9:
* Use TRACE_EVENT_CLASS for rwmmio_write and post_write (Steven Rostedt).

Changes in v8:
* Fix build error reported by kernel test robot.

Changes in v7:
* Use lib/ instead of kernel/trace/ based on review comment by Steven Rostedt.

Changes in v6:
* Implemented suggestions by Arnd Bergmann:
- Use arch independent IO barriers in arm64/asm
- Add ARCH_HAVE_TRACE_MMIO_ACCESS
- Add post read and post write logging support
- Remove tracepoint_active check
* Fix build error reported by kernel test robot.

Changes in v5:
* Move arm64 to use asm-generic provided high level MMIO accessors (Arnd).
* Add inline logging for MMIO relaxed and non-relaxed accessors.
* Move nVHE KVM comment to makefile (Marc).
* Fix overflow warning due to switch to inline accessors instead of macro.
* Modify trace event field to include caller and parent details for more detailed logs.

Changes in v4:
* Drop dynamic debug based filter support since that will be developed later with
the help from Steven (Ftrace maintainer).
* Drop value passed to writel as it is causing hangs when tracing is enabled.
* Code cleanup for trace event as suggested by Steven for earlier version.
* Fixed some build errors reported by 0-day bot.

Changes in v3:
* Create a generic mmio header for instrumented version (Earlier suggested in [1]
by Will Deacon and recently [2] by Greg to have a generic version first).
* Add dynamic debug support to filter out traces which can be very useful for targeted
debugging specific to subsystems or drivers.
* Few modifications to the rwmmio trace event fields to include the mmio width and print
addresses in hex.
* Rewrote commit msg to explain some more about usecases.

Prasad Sodagudi (1):
lib: Add register read/write tracing support

Sai Prakash Ranjan (8):
arm64: io: Use asm-generic high level MMIO accessors
coresight: etm4x: Use asm-generic IO memory barriers
irqchip/tegra: Fix overflow implicit truncation warnings
drm/meson: Fix overflow implicit truncation warnings
KVM: arm64: Add a flag to disable MMIO trace for nVHE KVM
asm-generic/io: Add logging support for MMIO accessors
serial: qcom_geni_serial: Disable MMIO tracing for geni serial
soc: qcom: geni: Disable MMIO tracing for GENI SE

arch/Kconfig | 3 +
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/io.h | 41 ++------
arch/arm64/kvm/hyp/nvhe/Makefile | 7 +-
drivers/gpu/drm/meson/meson_viu.c | 22 ++---
.../coresight/coresight-etm4x-core.c | 8 +-
drivers/hwtracing/coresight/coresight-etm4x.h | 8 +-
drivers/irqchip/irq-tegra.c | 10 +-
drivers/soc/qcom/qcom-geni-se.c | 3 +
drivers/tty/serial/qcom_geni_serial.c | 3 +
include/asm-generic/io.h | 91 ++++++++++++++++-
include/trace/events/rwmmio.h | 97 +++++++++++++++++++
lib/Kconfig | 7 ++
lib/Makefile | 2 +
lib/trace_readwrite.c | 47 +++++++++
15 files changed, 288 insertions(+), 62 deletions(-)
create mode 100644 include/trace/events/rwmmio.h
create mode 100644 lib/trace_readwrite.c

--
2.33.1



2022-05-18 16:47:19

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 1/9] arm64: io: Use asm-generic high level MMIO accessors

Remove custom arm64 MMIO accessors read{b,w,l,q} and their relaxed
versions in support to use asm-generic defined accessors. Also define
one set of IO barriers (ar/bw version) used by asm-generic code to
override the arm64 specific variants.

Suggested-by: Arnd Bergmann <[email protected]>
Signed-off-by: Sai Prakash Ranjan <[email protected]>
Acked-by: Catalin Marinas <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
---
arch/arm64/include/asm/io.h | 41 ++++++++-----------------------------
1 file changed, 8 insertions(+), 33 deletions(-)

diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
index 7fd836bea7eb..1b436810d779 100644
--- a/arch/arm64/include/asm/io.h
+++ b/arch/arm64/include/asm/io.h
@@ -91,7 +91,7 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
}

/* IO barriers */
-#define __iormb(v) \
+#define __io_ar(v) \
({ \
unsigned long tmp; \
\
@@ -108,39 +108,14 @@ static inline u64 __raw_readq(const volatile void __iomem *addr)
: "memory"); \
})

-#define __io_par(v) __iormb(v)
-#define __iowmb() dma_wmb()
-#define __iomb() dma_mb()
-
-/*
- * Relaxed I/O memory access primitives. These follow the Device memory
- * ordering rules but do not guarantee any ordering relative to Normal memory
- * accesses.
- */
-#define readb_relaxed(c) ({ u8 __r = __raw_readb(c); __r; })
-#define readw_relaxed(c) ({ u16 __r = le16_to_cpu((__force __le16)__raw_readw(c)); __r; })
-#define readl_relaxed(c) ({ u32 __r = le32_to_cpu((__force __le32)__raw_readl(c)); __r; })
-#define readq_relaxed(c) ({ u64 __r = le64_to_cpu((__force __le64)__raw_readq(c)); __r; })
+#define __io_bw() dma_wmb()
+#define __io_br(v)
+#define __io_aw(v)

-#define writeb_relaxed(v,c) ((void)__raw_writeb((v),(c)))
-#define writew_relaxed(v,c) ((void)__raw_writew((__force u16)cpu_to_le16(v),(c)))
-#define writel_relaxed(v,c) ((void)__raw_writel((__force u32)cpu_to_le32(v),(c)))
-#define writeq_relaxed(v,c) ((void)__raw_writeq((__force u64)cpu_to_le64(v),(c)))
-
-/*
- * I/O memory access primitives. Reads are ordered relative to any
- * following Normal memory access. Writes are ordered relative to any prior
- * Normal memory access.
- */
-#define readb(c) ({ u8 __v = readb_relaxed(c); __iormb(__v); __v; })
-#define readw(c) ({ u16 __v = readw_relaxed(c); __iormb(__v); __v; })
-#define readl(c) ({ u32 __v = readl_relaxed(c); __iormb(__v); __v; })
-#define readq(c) ({ u64 __v = readq_relaxed(c); __iormb(__v); __v; })
-
-#define writeb(v,c) ({ __iowmb(); writeb_relaxed((v),(c)); })
-#define writew(v,c) ({ __iowmb(); writew_relaxed((v),(c)); })
-#define writel(v,c) ({ __iowmb(); writel_relaxed((v),(c)); })
-#define writeq(v,c) ({ __iowmb(); writeq_relaxed((v),(c)); })
+/* arm64-specific, don't use in portable drivers */
+#define __iormb(v) __io_ar(v)
+#define __iowmb() __io_bw()
+#define __iomb() dma_mb()

/*
* I/O port access primitives.
--
2.33.1


2022-05-18 16:47:25

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 2/9] coresight: etm4x: Use asm-generic IO memory barriers

Per discussion in [1], it was decided to move to using architecture
independent/asm-generic IO memory barriers to have just one set of
them and deprecate use of arm64 specific IO memory barriers in driver
code. So replace current usage of __io_rmb()/__iowmb() in drivers to
__io_ar()/__io_bw().

[1] https://lore.kernel.org/lkml/[email protected]om/

Cc: Mathieu Poirier <[email protected]>
Cc: Suzuki K Poulose <[email protected]>
Signed-off-by: Sai Prakash Ranjan <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
Reviewed-by: Suzuki K Poulose <[email protected]>
---
drivers/hwtracing/coresight/coresight-etm4x-core.c | 8 ++++----
drivers/hwtracing/coresight/coresight-etm4x.h | 8 ++++----
2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index 7f416a12000e..81c0faf45b28 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -98,7 +98,7 @@ u64 etm4x_sysreg_read(u32 offset, bool _relaxed, bool _64bit)
}

if (!_relaxed)
- __iormb(res); /* Imitate the !relaxed I/O helpers */
+ __io_ar(res); /* Imitate the !relaxed I/O helpers */

return res;
}
@@ -106,7 +106,7 @@ u64 etm4x_sysreg_read(u32 offset, bool _relaxed, bool _64bit)
void etm4x_sysreg_write(u64 val, u32 offset, bool _relaxed, bool _64bit)
{
if (!_relaxed)
- __iowmb(); /* Imitate the !relaxed I/O helpers */
+ __io_bw(); /* Imitate the !relaxed I/O helpers */
if (!_64bit)
val &= GENMASK(31, 0);

@@ -130,7 +130,7 @@ static u64 ete_sysreg_read(u32 offset, bool _relaxed, bool _64bit)
}

if (!_relaxed)
- __iormb(res); /* Imitate the !relaxed I/O helpers */
+ __io_ar(res); /* Imitate the !relaxed I/O helpers */

return res;
}
@@ -138,7 +138,7 @@ static u64 ete_sysreg_read(u32 offset, bool _relaxed, bool _64bit)
static void ete_sysreg_write(u64 val, u32 offset, bool _relaxed, bool _64bit)
{
if (!_relaxed)
- __iowmb(); /* Imitate the !relaxed I/O helpers */
+ __io_bw(); /* Imitate the !relaxed I/O helpers */
if (!_64bit)
val &= GENMASK(31, 0);

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 3c4d69b096ca..f54698731582 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -448,14 +448,14 @@
#define etm4x_read32(csa, offset) \
({ \
u32 __val = etm4x_relaxed_read32((csa), (offset)); \
- __iormb(__val); \
+ __io_ar(__val); \
__val; \
})

#define etm4x_read64(csa, offset) \
({ \
u64 __val = etm4x_relaxed_read64((csa), (offset)); \
- __iormb(__val); \
+ __io_ar(__val); \
__val; \
})

@@ -479,13 +479,13 @@

#define etm4x_write32(csa, val, offset) \
do { \
- __iowmb(); \
+ __io_bw(); \
etm4x_relaxed_write32((csa), (val), (offset)); \
} while (0)

#define etm4x_write64(csa, val, offset) \
do { \
- __iowmb(); \
+ __io_bw(); \
etm4x_relaxed_write64((csa), (val), (offset)); \
} while (0)

--
2.33.1


2022-05-18 16:47:26

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 5/9] lib: Add register read/write tracing support

From: Prasad Sodagudi <[email protected]>

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

Signed-off-by: Prasad Sodagudi <[email protected]>
Co-developed-by: Sai Prakash Ranjan <[email protected]>
Signed-off-by: Sai Prakash Ranjan <[email protected]>
---
arch/Kconfig | 3 ++
arch/arm64/Kconfig | 1 +
include/trace/events/rwmmio.h | 97 +++++++++++++++++++++++++++++++++++
lib/Kconfig | 7 +++
lib/Makefile | 2 +
lib/trace_readwrite.c | 47 +++++++++++++++++
6 files changed, 157 insertions(+)
create mode 100644 include/trace/events/rwmmio.h
create mode 100644 lib/trace_readwrite.c

diff --git a/arch/Kconfig b/arch/Kconfig
index 31c4fdc4a4ba..5e7aa17ed609 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -1369,6 +1369,9 @@ config ARCH_HAS_ELFCORE_COMPAT
config ARCH_HAS_PARANOID_L1D_FLUSH
bool

+config ARCH_HAVE_TRACE_MMIO_ACCESS
+ bool
+
config DYNAMIC_SIGFRAME
bool

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 20ea89d9ac2f..926e1a252b6f 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -48,6 +48,7 @@ config ARM64
select ARCH_HAS_ZONE_DMA_SET if EXPERT
select ARCH_HAVE_ELF_PROT
select ARCH_HAVE_NMI_SAFE_CMPXCHG
+ select ARCH_HAVE_TRACE_MMIO_ACCESS
select ARCH_INLINE_READ_LOCK if !PREEMPTION
select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION
select ARCH_INLINE_READ_LOCK_IRQ if !PREEMPTION
diff --git a/include/trace/events/rwmmio.h b/include/trace/events/rwmmio.h
new file mode 100644
index 000000000000..de41159216c1
--- /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(unsigned long, caller)
+ __field(unsigned long, addr)
+ __field(u64, val)
+ __field(u8, width)
+ ),
+
+ TP_fast_assign(
+ __entry->caller = caller;
+ __entry->val = val;
+ __entry->addr = (unsigned long)addr;
+ __entry->width = width;
+ ),
+
+ TP_printk("%pS width=%d val=%#llx addr=%#lx",
+ (void *)__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(unsigned long, caller)
+ __field(unsigned long, addr)
+ __field(u8, width)
+ ),
+
+ TP_fast_assign(
+ __entry->caller = caller;
+ __entry->addr = (unsigned long)addr;
+ __entry->width = width;
+ ),
+
+ TP_printk("%pS width=%d addr=%#lx",
+ (void *)__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(unsigned long, caller)
+ __field(unsigned long, addr)
+ __field(u64, val)
+ __field(u8, width)
+ ),
+
+ TP_fast_assign(
+ __entry->caller = caller;
+ __entry->val = val;
+ __entry->addr = (unsigned long)addr;
+ __entry->width = width;
+ ),
+
+ TP_printk("%pS width=%d val=%#llx addr=%#lx",
+ (void *)__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 087e06b4cdfd..5e2fd075724f 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
diff --git a/lib/Makefile b/lib/Makefile
index 6b9ffc1bd1ee..3df7d24e65d2 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -151,6 +151,8 @@ 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 */
--
2.33.1


2022-05-18 16:47:45

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 4/9] drm/meson: Fix overflow implicit truncation warnings

Fix -Woverflow warnings for drm/meson driver which is a result
of moving arm64 custom MMIO accessor macros to asm-generic function
implementations giving a bonus type-checking now and uncovering these
overflow warnings.

drivers/gpu/drm/meson/meson_viu.c: In function ‘meson_viu_init’:
drivers/gpu/drm/meson/meson_registers.h:1826:48: error: large integer implicitly truncated to unsigned type [-Werror=overflow]
#define VIU_OSD_BLEND_REORDER(dest, src) ((src) << (dest * 4))
^
drivers/gpu/drm/meson/meson_viu.c:472:18: note: in expansion of macro ‘VIU_OSD_BLEND_REORDER’
writel_relaxed(VIU_OSD_BLEND_REORDER(0, 1) |
^~~~~~~~~~~~~~~~~~~~~

Cc: Arnd Bergmann <[email protected]>
Cc: Neil Armstrong <[email protected]>
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Sai Prakash Ranjan <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
---
drivers/gpu/drm/meson/meson_viu.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/meson/meson_viu.c b/drivers/gpu/drm/meson/meson_viu.c
index 259f3e6bec90..bb7e109534de 100644
--- a/drivers/gpu/drm/meson/meson_viu.c
+++ b/drivers/gpu/drm/meson/meson_viu.c
@@ -469,17 +469,17 @@ void meson_viu_init(struct meson_drm *priv)
priv->io_base + _REG(VD2_IF0_LUMA_FIFO_SIZE));

if (meson_vpu_is_compatible(priv, VPU_COMPATIBLE_G12A)) {
- writel_relaxed(VIU_OSD_BLEND_REORDER(0, 1) |
- VIU_OSD_BLEND_REORDER(1, 0) |
- VIU_OSD_BLEND_REORDER(2, 0) |
- VIU_OSD_BLEND_REORDER(3, 0) |
- VIU_OSD_BLEND_DIN_EN(1) |
- VIU_OSD_BLEND1_DIN3_BYPASS_TO_DOUT1 |
- VIU_OSD_BLEND1_DOUT_BYPASS_TO_BLEND2 |
- VIU_OSD_BLEND_DIN0_BYPASS_TO_DOUT0 |
- VIU_OSD_BLEND_BLEN2_PREMULT_EN(1) |
- VIU_OSD_BLEND_HOLD_LINES(4),
- priv->io_base + _REG(VIU_OSD_BLEND_CTRL));
+ u32 val = (u32)VIU_OSD_BLEND_REORDER(0, 1) |
+ (u32)VIU_OSD_BLEND_REORDER(1, 0) |
+ (u32)VIU_OSD_BLEND_REORDER(2, 0) |
+ (u32)VIU_OSD_BLEND_REORDER(3, 0) |
+ (u32)VIU_OSD_BLEND_DIN_EN(1) |
+ (u32)VIU_OSD_BLEND1_DIN3_BYPASS_TO_DOUT1 |
+ (u32)VIU_OSD_BLEND1_DOUT_BYPASS_TO_BLEND2 |
+ (u32)VIU_OSD_BLEND_DIN0_BYPASS_TO_DOUT0 |
+ (u32)VIU_OSD_BLEND_BLEN2_PREMULT_EN(1) |
+ (u32)VIU_OSD_BLEND_HOLD_LINES(4);
+ writel_relaxed(val, priv->io_base + _REG(VIU_OSD_BLEND_CTRL));

writel_relaxed(OSD_BLEND_PATH_SEL_ENABLE,
priv->io_base + _REG(OSD1_BLEND_SRC_CTRL));
--
2.33.1


2022-05-18 16:51:58

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 3/9] irqchip/tegra: Fix overflow implicit truncation warnings

Fix -Woverflow warnings for tegra irqchip driver which is a result
of moving arm64 custom MMIO accessor macros to asm-generic function
implementations giving a bonus type-checking now and uncovering these
overflow warnings.

drivers/irqchip/irq-tegra.c: In function ‘tegra_ictlr_suspend’:
drivers/irqchip/irq-tegra.c:151:18: warning: large integer implicitly truncated to unsigned type [-Woverflow]
writel_relaxed(~0ul, ictlr + ICTLR_COP_IER_CLR);
^

Cc: Marc Zyngier <[email protected]>
Suggested-by: Marc Zyngier <[email protected]>
Reviewed-by: Arnd Bergmann <[email protected]>
Signed-off-by: Sai Prakash Ranjan <[email protected]>
---
drivers/irqchip/irq-tegra.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/irqchip/irq-tegra.c b/drivers/irqchip/irq-tegra.c
index e1f771c72fc4..ad3e2c1b3c87 100644
--- a/drivers/irqchip/irq-tegra.c
+++ b/drivers/irqchip/irq-tegra.c
@@ -148,10 +148,10 @@ static int tegra_ictlr_suspend(void)
lic->cop_iep[i] = readl_relaxed(ictlr + ICTLR_COP_IEP_CLASS);

/* Disable COP interrupts */
- writel_relaxed(~0ul, ictlr + ICTLR_COP_IER_CLR);
+ writel_relaxed(GENMASK(31, 0), ictlr + ICTLR_COP_IER_CLR);

/* Disable CPU interrupts */
- writel_relaxed(~0ul, ictlr + ICTLR_CPU_IER_CLR);
+ writel_relaxed(GENMASK(31, 0), ictlr + ICTLR_CPU_IER_CLR);

/* Enable the wakeup sources of ictlr */
writel_relaxed(lic->ictlr_wake_mask[i], ictlr + ICTLR_CPU_IER_SET);
@@ -172,12 +172,12 @@ static void tegra_ictlr_resume(void)

writel_relaxed(lic->cpu_iep[i],
ictlr + ICTLR_CPU_IEP_CLASS);
- writel_relaxed(~0ul, ictlr + ICTLR_CPU_IER_CLR);
+ writel_relaxed(GENMASK(31, 0), ictlr + ICTLR_CPU_IER_CLR);
writel_relaxed(lic->cpu_ier[i],
ictlr + ICTLR_CPU_IER_SET);
writel_relaxed(lic->cop_iep[i],
ictlr + ICTLR_COP_IEP_CLASS);
- writel_relaxed(~0ul, ictlr + ICTLR_COP_IER_CLR);
+ writel_relaxed(GENMASK(31, 0), ictlr + ICTLR_COP_IER_CLR);
writel_relaxed(lic->cop_ier[i],
ictlr + ICTLR_COP_IER_SET);
}
@@ -312,7 +312,7 @@ static int __init tegra_ictlr_init(struct device_node *node,
lic->base[i] = base;

/* Disable all interrupts */
- writel_relaxed(~0UL, base + ICTLR_CPU_IER_CLR);
+ writel_relaxed(GENMASK(31, 0), base + ICTLR_CPU_IER_CLR);
/* All interrupts target IRQ */
writel_relaxed(0, base + ICTLR_CPU_IEP_CLASS);

--
2.33.1


2022-05-18 16:52:02

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 8/9] serial: qcom_geni_serial: Disable MMIO tracing for geni serial

Disable MMIO tracing for geni serial driver to prevent excessive
logging. Any access over serial console would involve a lot of
TX and RX register accesses (and few others), so these MMIO
read/write trace events in these drivers cause a lot of unwanted
noise because of the high frequency of such operations and it is
not very useful tracing these events for such drivers.
Given we want to enable these trace events on development devices
(maybe not production devices) where performance also really matters
so that we don't regress other components by wasting CPU cycles and
memory collecting these traces, it makes more sense to disable these
traces from such drivers.

Also another reason to disable these traces would be to prevent
recursive tracing when we display the trace buffer containing
these MMIO trace events since writing onto serial console would
further record MMIO traces.

Cc: Bjorn Andersson <[email protected]>
Signed-off-by: Sai Prakash Ranjan <[email protected]>
---
drivers/tty/serial/qcom_geni_serial.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 1543a6028856..75272585c3c3 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1,6 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2017-2018, The Linux foundation. All rights reserved.

+/* Disable MMIO tracing to prevent excessive logging of unwanted MMIO traces */
+#define __DISABLE_TRACE_MMIO__
+
#include <linux/clk.h>
#include <linux/console.h>
#include <linux/io.h>
--
2.33.1


2022-05-18 16:52:03

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 7/9] asm-generic/io: Add logging support for MMIO accessors

Add logging support for MMIO high level accessors such as read{b,w,l,q}
and their relaxed versions to aid in debugging unexpected crashes/hangs
caused by the corresponding MMIO operation.

Signed-off-by: Sai Prakash Ranjan <[email protected]>
---
include/asm-generic/io.h | 91 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 87 insertions(+), 4 deletions(-)

diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 7ce93aaf69f8..9c5114335a2d 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -10,6 +10,7 @@
#include <asm/page.h> /* I/O is all done through memory accesses */
#include <linux/string.h> /* for memset() and memcpy() */
#include <linux/types.h>
+#include <linux/instruction_pointer.h>

#ifdef CONFIG_GENERIC_IOMAP
#include <asm-generic/iomap.h>
@@ -61,6 +62,44 @@
#define __io_par(v) __io_ar(v)
#endif

+/*
+ * "__DISABLE_TRACE_MMIO__" flag can be used to disable MMIO tracing for
+ * specific kernel drivers in case of excessive/unwanted logging.
+ *
+ * Usage: Add a #define flag at the beginning of the driver file.
+ * Ex: #define __DISABLE_TRACE_MMIO__
+ * #include <...>
+ * ...
+ */
+#if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__))
+#include <linux/tracepoint-defs.h>
+
+DECLARE_TRACEPOINT(rwmmio_write);
+DECLARE_TRACEPOINT(rwmmio_post_write);
+DECLARE_TRACEPOINT(rwmmio_read);
+DECLARE_TRACEPOINT(rwmmio_post_read);
+
+void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
+ unsigned long caller_addr);
+void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
+ unsigned long caller_addr);
+void log_read_mmio(u8 width, const volatile void __iomem *addr,
+ unsigned long caller_addr);
+void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
+ unsigned long caller_addr);
+
+#else
+
+static inline void log_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
+ unsigned long caller_addr) {}
+static inline void log_post_write_mmio(u64 val, u8 width, volatile void __iomem *addr,
+ unsigned long caller_addr) {}
+static inline void log_read_mmio(u8 width, const volatile void __iomem *addr,
+ unsigned long caller_addr) {}
+static inline void log_post_read_mmio(u64 val, u8 width, const volatile void __iomem *addr,
+ unsigned long caller_addr) {}
+
+#endif /* CONFIG_TRACE_MMIO_ACCESS */

/*
* __raw_{read,write}{b,w,l,q}() access memory in native endianness.
@@ -149,9 +188,11 @@ static inline u8 readb(const volatile void __iomem *addr)
{
u8 val;

+ log_read_mmio(8, addr, _THIS_IP_);
__io_br();
val = __raw_readb(addr);
__io_ar(val);
+ log_post_read_mmio(val, 8, addr, _THIS_IP_);
return val;
}
#endif
@@ -162,9 +203,11 @@ static inline u16 readw(const volatile void __iomem *addr)
{
u16 val;

+ log_read_mmio(16, addr, _THIS_IP_);
__io_br();
val = __le16_to_cpu((__le16 __force)__raw_readw(addr));
__io_ar(val);
+ log_post_read_mmio(val, 16, addr, _THIS_IP_);
return val;
}
#endif
@@ -175,9 +218,11 @@ static inline u32 readl(const volatile void __iomem *addr)
{
u32 val;

+ log_read_mmio(32, addr, _THIS_IP_);
__io_br();
val = __le32_to_cpu((__le32 __force)__raw_readl(addr));
__io_ar(val);
+ log_post_read_mmio(val, 32, addr, _THIS_IP_);
return val;
}
#endif
@@ -189,9 +234,11 @@ static inline u64 readq(const volatile void __iomem *addr)
{
u64 val;

+ log_read_mmio(64, addr, _THIS_IP_);
__io_br();
val = __le64_to_cpu(__raw_readq(addr));
__io_ar(val);
+ log_post_read_mmio(val, 64, addr, _THIS_IP_);
return val;
}
#endif
@@ -201,9 +248,11 @@ static inline u64 readq(const volatile void __iomem *addr)
#define writeb writeb
static inline void writeb(u8 value, volatile void __iomem *addr)
{
+ log_write_mmio(value, 8, addr, _THIS_IP_);
__io_bw();
__raw_writeb(value, addr);
__io_aw();
+ log_post_write_mmio(value, 8, addr, _THIS_IP_);
}
#endif

@@ -211,9 +260,11 @@ static inline void writeb(u8 value, volatile void __iomem *addr)
#define writew writew
static inline void writew(u16 value, volatile void __iomem *addr)
{
+ log_write_mmio(value, 16, addr, _THIS_IP_);
__io_bw();
__raw_writew((u16 __force)cpu_to_le16(value), addr);
__io_aw();
+ log_post_write_mmio(value, 16, addr, _THIS_IP_);
}
#endif

@@ -221,9 +272,11 @@ static inline void writew(u16 value, volatile void __iomem *addr)
#define writel writel
static inline void writel(u32 value, volatile void __iomem *addr)
{
+ log_write_mmio(value, 32, addr, _THIS_IP_);
__io_bw();
__raw_writel((u32 __force)__cpu_to_le32(value), addr);
__io_aw();
+ log_post_write_mmio(value, 32, addr, _THIS_IP_);
}
#endif

@@ -232,9 +285,11 @@ static inline void writel(u32 value, volatile void __iomem *addr)
#define writeq writeq
static inline void writeq(u64 value, volatile void __iomem *addr)
{
+ log_write_mmio(value, 64, addr, _THIS_IP_);
__io_bw();
__raw_writeq(__cpu_to_le64(value), addr);
__io_aw();
+ log_post_write_mmio(value, 64, addr, _THIS_IP_);
}
#endif
#endif /* CONFIG_64BIT */
@@ -248,7 +303,12 @@ static inline void writeq(u64 value, volatile void __iomem *addr)
#define readb_relaxed readb_relaxed
static inline u8 readb_relaxed(const volatile void __iomem *addr)
{
- return __raw_readb(addr);
+ u8 val;
+
+ log_read_mmio(8, addr, _THIS_IP_);
+ val = __raw_readb(addr);
+ log_post_read_mmio(val, 8, addr, _THIS_IP_);
+ return val;
}
#endif

@@ -256,7 +316,12 @@ static inline u8 readb_relaxed(const volatile void __iomem *addr)
#define readw_relaxed readw_relaxed
static inline u16 readw_relaxed(const volatile void __iomem *addr)
{
- return __le16_to_cpu(__raw_readw(addr));
+ u16 val;
+
+ log_read_mmio(16, addr, _THIS_IP_);
+ val = __le16_to_cpu(__raw_readw(addr));
+ log_post_read_mmio(val, 16, addr, _THIS_IP_);
+ return val;
}
#endif

@@ -264,7 +329,12 @@ static inline u16 readw_relaxed(const volatile void __iomem *addr)
#define readl_relaxed readl_relaxed
static inline u32 readl_relaxed(const volatile void __iomem *addr)
{
- return __le32_to_cpu(__raw_readl(addr));
+ u32 val;
+
+ log_read_mmio(32, addr, _THIS_IP_);
+ val = __le32_to_cpu(__raw_readl(addr));
+ log_post_read_mmio(val, 32, addr, _THIS_IP_);
+ return val;
}
#endif

@@ -272,7 +342,12 @@ static inline u32 readl_relaxed(const volatile void __iomem *addr)
#define readq_relaxed readq_relaxed
static inline u64 readq_relaxed(const volatile void __iomem *addr)
{
- return __le64_to_cpu(__raw_readq(addr));
+ u64 val;
+
+ log_read_mmio(64, addr, _THIS_IP_);
+ val = __le64_to_cpu(__raw_readq(addr));
+ log_post_read_mmio(val, 64, addr, _THIS_IP_);
+ return val;
}
#endif

@@ -280,7 +355,9 @@ static inline u64 readq_relaxed(const volatile void __iomem *addr)
#define writeb_relaxed writeb_relaxed
static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
{
+ log_write_mmio(value, 8, addr, _THIS_IP_);
__raw_writeb(value, addr);
+ log_post_write_mmio(value, 8, addr, _THIS_IP_);
}
#endif

@@ -288,7 +365,9 @@ static inline void writeb_relaxed(u8 value, volatile void __iomem *addr)
#define writew_relaxed writew_relaxed
static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
{
+ log_write_mmio(value, 16, addr, _THIS_IP_);
__raw_writew(cpu_to_le16(value), addr);
+ log_post_write_mmio(value, 16, addr, _THIS_IP_);
}
#endif

@@ -296,7 +375,9 @@ static inline void writew_relaxed(u16 value, volatile void __iomem *addr)
#define writel_relaxed writel_relaxed
static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
{
+ log_write_mmio(value, 32, addr, _THIS_IP_);
__raw_writel(__cpu_to_le32(value), addr);
+ log_post_write_mmio(value, 32, addr, _THIS_IP_);
}
#endif

@@ -304,7 +385,9 @@ static inline void writel_relaxed(u32 value, volatile void __iomem *addr)
#define writeq_relaxed writeq_relaxed
static inline void writeq_relaxed(u64 value, volatile void __iomem *addr)
{
+ log_write_mmio(value, 64, addr, _THIS_IP_);
__raw_writeq(__cpu_to_le64(value), addr);
+ log_post_write_mmio(value, 64, addr, _THIS_IP_);
}
#endif

--
2.33.1


2022-05-18 16:52:11

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 9/9] soc: qcom: geni: Disable MMIO tracing for GENI SE

Disable MMIO tracing for GENI SE driver to prevent excessive
logging. Any access over serial console would involve a lot of
TX and RX register accesses (and few others), so these MMIO
read/write trace events in these drivers cause a lot of unwanted
noise because of the high frequency of such operations and it is
not very useful tracing these events for such drivers.
Given we want to enable these trace events on development devices
(maybe not production devices) where performance also really
matters so that we don't regress other components by wasting CPU
cycles and memory collecting these traces, it makes more sense to
disable these traces from such drivers.

Also another reason to disable these traces would be to prevent
recursive tracing when we display the trace buffer containing
these MMIO trace events since writing onto serial console would
further record MMIO traces.

Cc: Bjorn Andersson <[email protected]>
Signed-off-by: Sai Prakash Ranjan <[email protected]>
---
drivers/soc/qcom/qcom-geni-se.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c
index 28a8c0dda66c..a0ceeede450f 100644
--- a/drivers/soc/qcom/qcom-geni-se.c
+++ b/drivers/soc/qcom/qcom-geni-se.c
@@ -1,6 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
// Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.

+/* Disable MMIO tracing to prevent excessive logging of unwanted MMIO traces */
+#define __DISABLE_TRACE_MMIO__
+
#include <linux/acpi.h>
#include <linux/clk.h>
#include <linux/slab.h>
--
2.33.1


2022-05-18 16:52:15

by Sai Prakash Ranjan

[permalink] [raw]
Subject: [PATCHv15 6/9] KVM: arm64: Add a flag to disable MMIO trace for nVHE KVM

Add a generic flag (__DISABLE_TRACE_MMIO__) to disable MMIO
tracing in nVHE KVM as the tracepoint and MMIO logging symbols
should not be visible at nVHE KVM as there is no way to execute
them. It can also be used to disable MMIO tracing for specific
drivers.

Signed-off-by: Sai Prakash Ranjan <[email protected]>
---
arch/arm64/kvm/hyp/nvhe/Makefile | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index f9fe4dc21b1f..87d22a18b7a5 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -4,7 +4,12 @@
#

asflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS
-ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS
+
+# Tracepoint and MMIO logging symbols should not be visible at nVHE KVM as
+# there is no way to execute them and any such MMIO access from nVHE KVM
+# will explode instantly (Words of Marc Zyngier). So introduce a generic flag
+# __DISABLE_TRACE_MMIO__ to disable MMIO tracing for nVHE KVM.
+ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS -D__DISABLE_TRACE_MMIO__

hostprogs := gen-hyprel
HOST_EXTRACFLAGS += -I$(objtree)/include
--
2.33.1


2022-05-24 11:46:14

by Sai Prakash Ranjan

[permalink] [raw]
Subject: Re: [PATCHv15 5/9] lib: Add register read/write tracing support

Hi Steve,

On 5/18/2022 10:14 PM, Sai Prakash Ranjan wrote:
> From: Prasad Sodagudi <[email protected]>
>
> 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
>
> Signed-off-by: Prasad Sodagudi <[email protected]>
> Co-developed-by: Sai Prakash Ranjan <[email protected]>
> Signed-off-by: Sai Prakash Ranjan <[email protected]>
> ---
> arch/Kconfig | 3 ++
> arch/arm64/Kconfig | 1 +
> include/trace/events/rwmmio.h | 97 +++++++++++++++++++++++++++++++++++
> lib/Kconfig | 7 +++
> lib/Makefile | 2 +
> lib/trace_readwrite.c | 47 +++++++++++++++++
> 6 files changed, 157 insertions(+)
> create mode 100644 include/trace/events/rwmmio.h
> create mode 100644 lib/trace_readwrite.c

How does this version look?

Thanks,
Sai


2022-06-07 08:29:35

by Sai Prakash Ranjan

[permalink] [raw]
Subject: Re: [PATCHv15 5/9] lib: Add register read/write tracing support

Hi Steve,

On 5/24/2022 9:29 AM, Sai Prakash Ranjan wrote:
> Hi Steve,
>
> On 5/18/2022 10:14 PM, Sai Prakash Ranjan wrote:
>> From: Prasad Sodagudi <[email protected]>
>>
>> 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,
>>
<snip>...
> How does this version look?
>

Gentle ping!!

Thanks,
Sai

2022-06-14 14:51:01

by Steven Rostedt

[permalink] [raw]
Subject: Re: [PATCHv15 5/9] lib: Add register read/write tracing support

On Wed, 18 May 2022 22:14:14 +0530
Sai Prakash Ranjan <[email protected]> wrote:

> From: Prasad Sodagudi <[email protected]>
>
> 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
>
> Signed-off-by: Prasad Sodagudi <[email protected]>
> Co-developed-by: Sai Prakash Ranjan <[email protected]>
> Signed-off-by: Sai Prakash Ranjan <[email protected]>
> ---

From a tracing point of view, I do not see anything wrong with this patch.

Acked-by: Steven Rostedt (Google) <[email protected]>

-- Steve

2022-06-14 15:01:09

by Sai Prakash Ranjan

[permalink] [raw]
Subject: Re: [PATCHv15 5/9] lib: Add register read/write tracing support

On 6/14/2022 8:02 PM, Steven Rostedt wrote:
> On Wed, 18 May 2022 22:14:14 +0530
> Sai Prakash Ranjan <[email protected]> wrote:
>
>> From: Prasad Sodagudi <[email protected]>
>>
>> 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
>>
>> Signed-off-by: Prasad Sodagudi <[email protected]>
>> Co-developed-by: Sai Prakash Ranjan <[email protected]>
>> Signed-off-by: Sai Prakash Ranjan <[email protected]>
>> ---
> From a tracing point of view, I do not see anything wrong with this patch.
>
> Acked-by: Steven Rostedt (Google) <[email protected]>
>
> -- Steve

Thanks Steve.

Hi Arnd, I hope we can take this series in your tree or let me know if anything else is pending?

Thanks,
Sai