[PATCHv8 5/5] asm-generic/io: Add logging support for MMIO accessors

From: Sai Prakash Ranjan
Date: Sun Jan 16 2022 - 22:34:24 EST

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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. Also add a generic flag
(__DISABLE_TRACE_MMIO__) which is used to disable MMIO tracing in nVHE KVM
and if required can be used to disable MMIO tracing for specific drivers.

Signed-off-by: Sai Prakash Ranjan <quic_saipraka@xxxxxxxxxxx>
---
arch/arm64/kvm/hyp/nvhe/Makefile | 7 ++-
include/asm-generic/io.h | 82 ++++++++++++++++++++++++++++++--
2 files changed, 84 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 24b2c2425b38..228d1f8921c3 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
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 7ce93aaf69f8..c9b428657760 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 +62,35 @@
#define __io_par(v) __io_ar(v)
#endif

+#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 +179,11 @@ 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 +194,11 @@ 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 +209,11 @@ 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 +225,11 @@ 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 +239,11 @@ 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 +251,11 @@ 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 +263,11 @@ 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 +276,11 @@ 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 +294,12 @@ 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 +307,12 @@ 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 +320,12 @@ 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 +333,12 @@ 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 +346,9 @@ 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 +356,9 @@ 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 +366,9 @@ 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 +376,9 @@ 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

Next message: Baoquan He: "Re: [PATCH V3] panic: Move panic_print before kmsg dumpers"
Previous message: Sai Prakash Ranjan: "[PATCHv8 4/5] lib: Add register read/write tracing support"
In reply to: Sai Prakash Ranjan: "Re: [PATCHv8 4/5] lib: Add register read/write tracing support"
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