Re: [PATCH 04/18] tracing/x86: Add arch_get_func_args() function
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: 2018-02-05 16:33:36
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On Fri, 02 Feb 2018 18:05:02 -0500 Steven Rostedt [off-list ref] wrote:
From: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Add function to get the function arguments from pt_regs.
Can we make it an independent feature in asm/ptrace.h so that
other components (like kprobe-event) share it?
E.g.
static inline unsigned long regs_get_func_arg(struct pt_regs *regs,
unsigned int n)
{
unsigned int offs[] = {
#ifdef CONFIG_X86_64
offsetof(typeof(regs),di),
offsetof(typeof(regs),si),
offsetof(typeof(regs),dx),
offsetof(typeof(regs),cx),
offsetof(typeof(regs),r8),
offsetof(typeof(regs),r9),
#else
offsetof(typeof(regs),ax),
offsetof(typeof(regs),dx),
offsetof(typeof(regs),cx),
#endif
};
if (unlikely(n >= ARRAY_SIZE(offs))
return 0;
return *(unsigned long *)((unsigned long)regs + offs[n]);
}
And HAVE_REGS_GET_FUNC_ARG indicates this is defined on that arch.
Thank you,
quoted hunk ↗ jump to hunk
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- arch/x86/kernel/ftrace.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 01ebcb6f263e..5e845c8cf89d 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c@@ -46,6 +46,34 @@ int ftrace_arch_code_modify_post_process(void) return 0; } +int arch_get_func_args(struct pt_regs *regs, + int start, int end, long *args) +{ +#ifdef CONFIG_X86_64 +# define MAX_ARGS 6 +# define INIT_REGS \ + { regs->di, regs->si, regs->dx, \ + regs->cx, regs->r8, regs->r9 \ + } +#else +# define MAX_ARGS 3 +# define INIT_REGS \ + { regs->ax, regs->dx, regs->cx } +#endif + if (!regs) + return MAX_ARGS; + + { + long pt_args[] = INIT_REGS; + int i; + + for (i = start; i <= end && i < MAX_ARGS; i++) + args[i - start] = pt_args[i]; + + return i - start; + } +} + union ftrace_code_union { char code[MCOUNT_INSN_SIZE]; struct {-- 2.15.1
-- Masami Hiramatsu [off-list ref]