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riscv: ptrace: add argn syntax

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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>
This commit is contained in:
Jeff Xie 2021-06-20 20:01:51 +08:00 committed by Palmer Dabbelt
parent 9eb4fcff22
commit 70eee556b6
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2 changed files with 32 additions and 0 deletions
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1
arch/riscv/Kconfig
View file

@ -90,6 +90,7 @@ 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

31
arch/riscv/include/asm/ptrace.h
View file

@ -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 */