Re: [RFC PATCH 4/5] ftrace: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs

Masami Hiramatsu
2023-08-08T12:10:53Z

On Sat, 5 Aug 2023 23:58:35 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:

> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> Add ftrace_partial_regs() which converts the ftrace_regas to pt_regs.
> If the architecture defines its own ftrace_regs, this copies partial
> registers to pt_regs and returns it. If not, ftrace_regs is the same as
> pt_regs and ftrace_partial_regs() will return ftrace_regs::regs.
>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> ---
> arch/arm64/include/asm/ftrace.h | 11 +++++++++++
> include/linux/ftrace.h | 11 +++++++++++
> 2 files changed, 22 insertions(+)
>
> diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
> index ab158196480c..b108cd6718cf 100644
> --- a/arch/arm64/include/asm/ftrace.h
> +++ b/arch/arm64/include/asm/ftrace.h
> @@ -137,6 +137,17 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs)
> fregs->pc = fregs->lr;
> }
>
> +static __always_inline struct pt_regs *
> +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
> +{
> + memcpy(regs->regs, fregs->regs, sizeof(u64) * 10);
> + regs->sp = fregs->sp;
> + regs->pc = fregs->pc;
> + regs->x[29] = fregs->fp;
> + regs->x[30] = fregs->lr;

Oops, this is regs->regs[29] and regs->regs[30].

Thanks,

> + return regs;
> +}
> +
> int ftrace_regs_query_register_offset(const char *name);
>
> int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index ce156c7704ee..f4fbc493aceb 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -139,6 +139,17 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs
> return arch_ftrace_get_regs(fregs);
> }
>
> +#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \
> + defined(CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS)
> +
> +static __always_inline struct pt_regs *
> +ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
> +{
> + return arch_ftrace_get_regs((struct ftrace_regs *)fregs);
> +}
> +
> +#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_PT_REGS_COMPAT_FTRACE_REGS */
> +
> /*
> * When true, the ftrace_regs_{get,set}_*() functions may be used on fregs.
> * Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.
>

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>