From 70eee556b678d1e4cd4ea6742a577b596963fa25 Mon Sep 17 00:00:00 2001
From: Jeff Xie <chongguiguzi@gmail.com>
Date: Sun, 20 Jun 2021 20:01:51 +0800
Subject: riscv: ptrace: add argn syntax
This enables ftrace kprobe events to access kernel function
arguments via $argN syntax.
Signed-off-by: Jeff Xie <huan.xie@suse.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
arch/riscv/include/asm/ptrace.h | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
(limited to 'arch/riscv/include/asm/ptrace.h')
diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
index 09ad4e923510..6ecd461129d2 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)
+{
+ static const int 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 */
--
cgit