BACKPORT: FROMLIST: tracing: Add register read/write tracing support

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

Bug: 169045115
Change-Id: I54326beb3aeabfc9a57c2de76a916754bdb6fe76
Link: https://lore.kernel.org/lkml/f6d1b9e9d70968b506bdfd1b77129cb751b9df9d.1652891705.git.quic_saipraka@quicinc.com/
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>
Co-developed-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com>
Signed-off-by: Sai Prakash Ranjan <quic_saipraka@quicinc.com>
Signed-off-by: Vamsi Krishna Lanka <quic_vamslank@quicinc.com>

arch/arm64/configs/gki_defconfig

@@ -663,6 +663,7 @@ CONFIG_CRYPTO_LZO=y
 CONFIG_CRYPTO_LZ4=y
 CONFIG_CRYPTO_ZSTD=y
 CONFIG_CRYPTO_ANSI_CPRNG=y
+CONFIG_TRACE_MMIO_ACCESS=y
 CONFIG_XZ_DEC=y
 CONFIG_DMA_RESTRICTED_POOL=y
 CONFIG_DMA_CMA=y
@@ -700,7 +701,6 @@ CONFIG_WQ_WATCHDOG=y
 CONFIG_SCHEDSTATS=y
 # CONFIG_DEBUG_PREEMPT is not set
 CONFIG_BUG_ON_DATA_CORRUPTION=y
-CONFIG_TRACE_MMIO_ACCESS=y
 CONFIG_HIST_TRIGGERS=y
 CONFIG_PID_IN_CONTEXTIDR=y
 # CONFIG_RUNTIME_TESTING_MENU is not set

kernel/trace/Kconfig

@@ -95,13 +95,6 @@ config RING_BUFFER_ALLOW_SWAP
 	 Allow the use of ring_buffer_swap_cpu.
 	 Adds a very slight overhead to tracing when enabled.
 
-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.
-
 config PREEMPTIRQ_TRACEPOINTS
 	bool
 	depends on TRACE_PREEMPT_TOGGLE || TRACE_IRQFLAGS

kernel/trace/Makefile

@@ -98,6 +98,5 @@ obj-$(CONFIG_BOOTTIME_TRACING) += trace_boot.o
 obj-$(CONFIG_FTRACE_RECORD_RECURSION) += trace_recursion_record.o
 
 obj-$(CONFIG_TRACEPOINT_BENCHMARK) += trace_benchmark.o
-obj-$(CONFIG_TRACE_MMIO_ACCESS) += trace_readwrite.o
 
 libftrace-y := ftrace.o

lib/Kconfig

@@ -121,6 +121,13 @@ 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.
+
 config CRC_CCITT
 	tristate "CRC-CCITT functions"
 	help

lib/Makefile

@@ -150,6 +150,8 @@ 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