* [PATCH] riscv: ptrace: add argn syntax
@ 2021-06-20 12:01 Jeff Xie
2021-07-06 19:10 ` Palmer Dabbelt
0 siblings, 1 reply; 2+ messages in thread
From: Jeff Xie @ 2021-06-20 12:01 UTC (permalink / raw)
To: oleg
Cc: paul.walmsley, palmer, caou, linux-riscv, linux-kernel,
chongguiguzi, huan.xie
This enables ftrace kprobe events to access kernel function
arguments via $argN syntax.
Signed-off-by: Jeff Xie <huan.xie@suse.com>
---
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/ptrace.h | 31 +++++++++++++++++++++++++++++++
2 files changed, 32 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 18ec0f9bb8d5..f9246a7d0a31 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -88,6 +88,7 @@ config RISCV
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_REGS_AND_STACK_ACCESS_API
+ select HAVE_FUNCTION_ARG_ACCESS_API
select HAVE_STACKPROTECTOR
select HAVE_SYSCALL_TRACEPOINTS
select IRQ_DOMAIN
diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
index 09ad4e923510..fdb59ee405ee 100644
--- a/arch/riscv/include/asm/ptrace.h
+++ b/arch/riscv/include/asm/ptrace.h
@@ -141,6 +141,37 @@ static inline unsigned long regs_get_register(struct pt_regs *regs,
return *(unsigned long *)((unsigned long)regs + offset);
}
+
+/**
+ * regs_get_kernel_argument() - get Nth function argument in kernel
+ * @regs: pt_regs of that context
+ * @n: function argument number (start from 0)
+ *
+ * regs_get_argument() returns @n th argument of the function call.
+ *
+ * Note you can get the parameter correctly if the function has no
+ * more than eight arguments.
+ */
+static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
+ unsigned int n)
+{
+#define NR_REG_ARGUMENTS 8
+ static const unsigned int argument_offs[] = {
+ offsetof(struct pt_regs, a0),
+ offsetof(struct pt_regs, a1),
+ offsetof(struct pt_regs, a2),
+ offsetof(struct pt_regs, a3),
+ offsetof(struct pt_regs, a4),
+ offsetof(struct pt_regs, a5),
+ offsetof(struct pt_regs, a6),
+ offsetof(struct pt_regs, a7),
+ };
+
+ if (n < NR_REG_ARGUMENTS)
+ return regs_get_register(regs, argument_offs[n]);
+ return 0;
+}
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_RISCV_PTRACE_H */
--
2.26.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] riscv: ptrace: add argn syntax
2021-06-20 12:01 [PATCH] riscv: ptrace: add argn syntax Jeff Xie
@ 2021-07-06 19:10 ` Palmer Dabbelt
0 siblings, 0 replies; 2+ messages in thread
From: Palmer Dabbelt @ 2021-07-06 19:10 UTC (permalink / raw)
To: chongguiguzi
Cc: oleg, Paul Walmsley, caou, linux-riscv, linux-kernel,
chongguiguzi, huan.xie
On Sun, 20 Jun 2021 05:01:51 PDT (-0700), chongguiguzi@gmail.com wrote:
> This enables ftrace kprobe events to access kernel function
> arguments via $argN syntax.
>
> Signed-off-by: Jeff Xie <huan.xie@suse.com>
> ---
> arch/riscv/Kconfig | 1 +
> arch/riscv/include/asm/ptrace.h | 31 +++++++++++++++++++++++++++++++
> 2 files changed, 32 insertions(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 18ec0f9bb8d5..f9246a7d0a31 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -88,6 +88,7 @@ config RISCV
> select HAVE_PERF_REGS
> select HAVE_PERF_USER_STACK_DUMP
> select HAVE_REGS_AND_STACK_ACCESS_API
> + select HAVE_FUNCTION_ARG_ACCESS_API
> select HAVE_STACKPROTECTOR
> select HAVE_SYSCALL_TRACEPOINTS
> select IRQ_DOMAIN
> diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
> index 09ad4e923510..fdb59ee405ee 100644
> --- a/arch/riscv/include/asm/ptrace.h
> +++ b/arch/riscv/include/asm/ptrace.h
> @@ -141,6 +141,37 @@ static inline unsigned long regs_get_register(struct pt_regs *regs,
>
> return *(unsigned long *)((unsigned long)regs + offset);
> }
> +
> +/**
> + * regs_get_kernel_argument() - get Nth function argument in kernel
> + * @regs: pt_regs of that context
> + * @n: function argument number (start from 0)
> + *
> + * regs_get_argument() returns @n th argument of the function call.
> + *
> + * Note you can get the parameter correctly if the function has no
> + * more than eight arguments.
> + */
> +static inline unsigned long regs_get_kernel_argument(struct pt_regs *regs,
> + unsigned int n)
> +{
> +#define NR_REG_ARGUMENTS 8
> + static const unsigned int argument_offs[] = {
> + offsetof(struct pt_regs, a0),
> + offsetof(struct pt_regs, a1),
> + offsetof(struct pt_regs, a2),
> + offsetof(struct pt_regs, a3),
> + offsetof(struct pt_regs, a4),
> + offsetof(struct pt_regs, a5),
> + offsetof(struct pt_regs, a6),
> + offsetof(struct pt_regs, a7),
> + };
> +
> + if (n < NR_REG_ARGUMENTS)
> + return regs_get_register(regs, argument_offs[n]);
> + return 0;
> +}
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_RISCV_PTRACE_H */
This is on for-next. I cleaned it up a bit to avoid leaking that
#define.
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