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Message-ID: <20211116174027.14015dff@gandalf.local.home>
Date: Tue, 16 Nov 2021 17:40:27 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Sai Prakash Ranjan <quic_saipraka@...cinc.com>
Cc: Will Deacon <will@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
<quic_psodagud@...cinc.com>, Marc Zyngier <maz@...nel.org>,
<gregkh@...uxfoundation.org>, <arnd@...db.de>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
<mingo@...hat.com>
Subject: Re: [PATCHv4 2/2] arm64/io: Add a header for mmio access
instrumentation
On Mon, 15 Nov 2021 17:03:30 +0530
Sai Prakash Ranjan <quic_saipraka@...cinc.com> wrote:
> The new generic header mmio-instrumented.h will keep arch code clean
> and separate from instrumented version which traces mmio register
> accesses. This instrumented header is generic and can be used by other
> architectures as well. Also add a generic flag (__DISABLE_TRACE_MMIO__)
> which is used to disable MMIO tracing in nVHE and if required can be
> used to disable tracing for specific drivers.
>
> Signed-off-by: Sai Prakash Ranjan <quic_saipraka@...cinc.com>
> ---
> arch/arm64/include/asm/io.h | 25 ++++-------
> arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
> include/linux/mmio-instrumented.h | 70 +++++++++++++++++++++++++++++++
> 3 files changed, 80 insertions(+), 17 deletions(-)
> create mode 100644 include/linux/mmio-instrumented.h
>
> diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
> index 7fd836bea7eb..a635aaaf81b9 100644
> --- a/arch/arm64/include/asm/io.h
> +++ b/arch/arm64/include/asm/io.h
> @@ -10,6 +10,7 @@
>
> #include <linux/types.h>
> #include <linux/pgtable.h>
> +#include <linux/mmio-instrumented.h>
>
> #include <asm/byteorder.h>
> #include <asm/barrier.h>
> @@ -21,32 +22,27 @@
> /*
> * Generic IO read/write. These perform native-endian accesses.
> */
> -#define __raw_writeb __raw_writeb
> -static inline void __raw_writeb(u8 val, volatile void __iomem *addr)
> +static inline void arch_raw_writeb(u8 val, volatile void __iomem *addr)
> {
> asm volatile("strb %w0, [%1]" : : "rZ" (val), "r" (addr));
> }
>
> -#define __raw_writew __raw_writew
> -static inline void __raw_writew(u16 val, volatile void __iomem *addr)
> +static inline void arch_raw_writew(u16 val, volatile void __iomem *addr)
> {
> asm volatile("strh %w0, [%1]" : : "rZ" (val), "r" (addr));
> }
>
> -#define __raw_writel __raw_writel
> -static __always_inline void __raw_writel(u32 val, volatile void __iomem *addr)
> +static __always_inline void arch_raw_writel(u32 val, volatile void __iomem *addr)
> {
> asm volatile("str %w0, [%1]" : : "rZ" (val), "r" (addr));
> }
>
> -#define __raw_writeq __raw_writeq
> -static inline void __raw_writeq(u64 val, volatile void __iomem *addr)
> +static inline void arch_raw_writeq(u64 val, volatile void __iomem *addr)
> {
> asm volatile("str %x0, [%1]" : : "rZ" (val), "r" (addr));
> }
>
> -#define __raw_readb __raw_readb
> -static inline u8 __raw_readb(const volatile void __iomem *addr)
> +static inline u8 arch_raw_readb(const volatile void __iomem *addr)
> {
> u8 val;
> asm volatile(ALTERNATIVE("ldrb %w0, [%1]",
> @@ -56,8 +52,7 @@ static inline u8 __raw_readb(const volatile void __iomem *addr)
> return val;
> }
>
> -#define __raw_readw __raw_readw
> -static inline u16 __raw_readw(const volatile void __iomem *addr)
> +static inline u16 arch_raw_readw(const volatile void __iomem *addr)
> {
> u16 val;
>
> @@ -68,8 +63,7 @@ static inline u16 __raw_readw(const volatile void __iomem *addr)
> return val;
> }
>
> -#define __raw_readl __raw_readl
> -static __always_inline u32 __raw_readl(const volatile void __iomem *addr)
> +static __always_inline u32 arch_raw_readl(const volatile void __iomem *addr)
> {
> u32 val;
> asm volatile(ALTERNATIVE("ldr %w0, [%1]",
> @@ -79,8 +73,7 @@ static __always_inline u32 __raw_readl(const volatile void __iomem *addr)
> return val;
> }
>
> -#define __raw_readq __raw_readq
> -static inline u64 __raw_readq(const volatile void __iomem *addr)
> +static inline u64 arch_raw_readq(const volatile void __iomem *addr)
Shouldn't the above be done as a separate patch and handle other
architectures that implement __raw_read/write*()?
> {
> u64 val;
> asm volatile(ALTERNATIVE("ldr %0, [%1]",
> diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
> index c3c11974fa3b..ff56d2165ea9 100644
> --- a/arch/arm64/kvm/hyp/nvhe/Makefile
> +++ b/arch/arm64/kvm/hyp/nvhe/Makefile
> @@ -4,7 +4,7 @@
> #
>
> asflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS
> -ccflags-y := -D__KVM_NVHE_HYPERVISOR__ -D__DISABLE_EXPORTS
> +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/linux/mmio-instrumented.h b/include/linux/mmio-instrumented.h
> new file mode 100644
> index 000000000000..99979c025cc1
> --- /dev/null
> +++ b/include/linux/mmio-instrumented.h
> @@ -0,0 +1,70 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Copyright (c) 2021 Qualcomm Innovation Center, Inc. All rights reserved.
> + */
> +
> +#ifndef _LINUX_MMIO_INSTRUMENTED_H
> +#define _LINUX_MMIO_INSTRUMENTED_H
> +
> +#include <linux/tracepoint-defs.h>
> +
> +/*
> + * Tracepoint and MMIO logging symbols should not be visible at EL2(HYP) as
> + * there is no way to execute them and any such MMIO access from EL2 will
> + * explode instantly (Words of Marc Zyngier). So introduce a generic flag
> + * __DISABLE_TRACE_MMIO__ to disable MMIO tracing in nVHE and other drivers
> + * if required.
> + */
> +#if IS_ENABLED(CONFIG_TRACE_MMIO_ACCESS) && !(defined(__DISABLE_TRACE_MMIO__))
> +DECLARE_TRACEPOINT(rwmmio_write);
> +DECLARE_TRACEPOINT(rwmmio_read);
> +
> +void log_write_mmio(const char *width, volatile void __iomem *addr);
> +void log_read_mmio(const char *width, const volatile void __iomem *addr);
> +
> +#define __raw_write(v, a, _l) ({ \
> + volatile void __iomem *_a = (a); \
> + if (tracepoint_enabled(rwmmio_write)) \
> + log_write_mmio(__stringify(write##_l), _a); \
> + arch_raw_write##_l((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 = (a); \
> + if (tracepoint_enabled(rwmmio_read)) \
> + log_read_mmio(__stringify(read##_l), _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)
> +
> +#else
> +
> +#define __raw_writeb(v, a) arch_raw_writeb(v, a)
> +#define __raw_writew(v, a) arch_raw_writew(v, a)
> +#define __raw_writel(v, a) arch_raw_writel(v, a)
> +#define __raw_writeq(v, a) arch_raw_writeq(v, a)
> +
> +#define __raw_readb(a) arch_raw_readb(a)
> +#define __raw_readw(a) arch_raw_readw(a)
> +#define __raw_readl(a) arch_raw_readl(a)
> +#define __raw_readq(a) arch_raw_readq(a)
> +
> +static inline void log_write_mmio(const char *width,
> + volatile void __iomem *addr) {}
> +static inline void log_read_mmio(const char *width,
> + const volatile void __iomem *addr) {}
The rest from a tracing point of view looks fine, and for that part:
Reviewed-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
-- Steve
> +
> +#endif /* CONFIG_TRACE_MMIO_ACCESS */
> +
> +#endif /* _LINUX_MMIO_INSTRUMENTED_H */
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