From: Petr Mladek <pmladek@suse.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org,
Masami Hiramatsu <mhiramat@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
live-patching@vger.kernel.org
Subject: Re: [PATCH 3/3 v7] livepatch: Use the default ftrace_ops instead of REGS when ARGS is available
Date: Thu, 19 Nov 2020 12:52:00 +0100 [thread overview]
Message-ID: <X7ZcYIWJEPXW6Z9s@alley> (raw)
In-Reply-To: <20201113171939.455339580@goodmis.org>
On Fri 2020-11-13 12:18:14, Steven Rostedt wrote:
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>
> When CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS is available, the ftrace call
> will be able to set the ip of the calling function. This will improve the
> performance of live kernel patching where it does not need all the regs to
> be stored just to change the instruction pointer.
>
> If all archs that support live kernel patching also support
> HAVE_DYNAMIC_FTRACE_WITH_ARGS, then the architecture specific function
> klp_arch_set_pc() could be made generic.
>
> It is possible that an arch can support HAVE_DYNAMIC_FTRACE_WITH_ARGS but
> not HAVE_DYNAMIC_FTRACE_WITH_REGS and then have access to live patching.
>
> Cc: Josh Poimboeuf <jpoimboe@redhat.com>
> Cc: Jiri Kosina <jikos@kernel.org>
> Cc: live-patching@vger.kernel.org
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Acked-by: Miroslav Benes <mbenes@suse.cz>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> ---
> Changes since v6:
> - Updated to use ftrace_instruction_pointer_set() macro
>
> arch/powerpc/include/asm/livepatch.h | 4 +++-
> arch/s390/include/asm/livepatch.h | 5 ++++-
> arch/x86/include/asm/ftrace.h | 3 +++
> arch/x86/include/asm/livepatch.h | 4 ++--
> arch/x86/kernel/ftrace_64.S | 4 ++++
> include/linux/ftrace.h | 7 +++++++
> kernel/livepatch/Kconfig | 2 +-
> kernel/livepatch/patch.c | 9 +++++----
> 8 files changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/livepatch.h b/arch/powerpc/include/asm/livepatch.h
> index 4a3d5d25fed5..ae25e6e72997 100644
> --- a/arch/powerpc/include/asm/livepatch.h
> +++ b/arch/powerpc/include/asm/livepatch.h
> @@ -12,8 +12,10 @@
> #include <linux/sched/task_stack.h>
>
> #ifdef CONFIG_LIVEPATCH
> -static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
> +static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip)
> {
> + struct pt_regs *regs = ftrace_get_regs(fregs);
Should we check for NULL pointer here?
> +
> regs->nip = ip;
> }
>
> diff --git a/arch/s390/include/asm/livepatch.h b/arch/s390/include/asm/livepatch.h
> index 818612b784cd..d578a8c76676 100644
> --- a/arch/s390/include/asm/livepatch.h
> +++ b/arch/s390/include/asm/livepatch.h
> @@ -11,10 +11,13 @@
> #ifndef ASM_LIVEPATCH_H
> #define ASM_LIVEPATCH_H
>
> +#include <linux/ftrace.h>
> #include <asm/ptrace.h>
>
> -static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip)
> +static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip)
> {
> + struct pt_regs *regs = ftrace_get_regs(fregs);
And here?
> +
> regs->psw.addr = ip;
> }
>
Otherwise, it looks for me.
Best Regards,
Petr
next prev parent reply other threads:[~2020-11-19 11:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20201113171811.288150055@goodmis.org>
2020-11-13 17:18 ` [PATCH 3/3 v7] livepatch: Use the default ftrace_ops instead of REGS when ARGS is available Steven Rostedt
2020-11-19 11:52 ` Petr Mladek [this message]
2020-11-19 14:12 ` Steven Rostedt
2020-11-19 16:07 ` Petr Mladek
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