From: Alan Kao <nonerkao@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Palmer Dabbelt <palmer@sifive.com>, Albert Ou <albert@sifive.com>,
Ingo Molnar <mingo@redhat.com>,
Masahiro Yamada <yamada.masahiro@socionext.com>,
Kamil Rytarowski <n54@gmx.com>,
Andrew Morton <akpm@linux-foundation.org>,
patches@groups.riscv.org, linux-kernel@vger.kernel.org,
Alan Kao <alankao@andestech.com>,
Greentime Hu <greentime@andestech.com>
Subject: Re: [PATCH 2/6] riscv/ftrace: Add dynamic function tracer support
Date: Thu, 11 Jan 2018 16:02:57 +0800 [thread overview]
Message-ID: <20180111080255.GA2848@93d8b218059b> (raw)
In-Reply-To: <20180110113643.7622a7d3@vmware.local.home>
On Wed, Jan 10, 2018 at 11:36:43AM -0500, Steven Rostedt wrote:
> On Wed, 10 Jan 2018 15:38:10 +0800
> Alan Kao <nonerkao@gmail.com> wrote:
>
> > +static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target,
> > + bool enable)
> > +{
> > + unsigned int offset = (unsigned int)(target - hook_pos);
> > + unsigned int auipc_call = to_auipc_insn(offset);
> > + unsigned int jalr_call = to_jalr_insn(offset);
> > + unsigned int calls[2] = {auipc_call, jalr_call};
> > + unsigned int nops[2] = {NOP4, NOP4};
> > + int ret = 0;
> > +
> > + /* when ftrace_make_nop is called */
> > + if (!enable)
> > + ret = ftrace_check_current_call(hook_pos, calls);
> > +
> > + if (ret)
> > + goto out;
> > +
> > + /* replace the auipc-jalr pair at once */
> > + ret = probe_kernel_write((void *)hook_pos, enable ? calls : nops,
> > + MCOUNT_INSN_SIZE);
> > + if (ret)
>
> You don't want to return the return of probe_kernel_write() here. For
> ftrace bug to work properly, if a fail to write occurs, you need to
> return -EPERM.
>
> -- Steve
>
Thanks for the correction and the style fix in the previous mail.
These problems will be fixed in the next version patch.
Alan
next prev parent reply other threads:[~2018-01-11 8:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-10 7:38 [PATCH 0/6] Add dynamic ftrace support for RISC-V platforms Alan Kao
2018-01-10 7:38 ` [PATCH 1/6] riscv/ftrace: Add RECORD_MCOUNT support Alan Kao
2018-01-10 7:43 ` [patches] " Christoph Hellwig
2018-01-10 7:54 ` Alan Kao
2018-01-10 7:38 ` [PATCH 2/6] riscv/ftrace: Add dynamic function tracer support Alan Kao
2018-01-10 16:32 ` Steven Rostedt
2018-01-10 16:36 ` Steven Rostedt
2018-01-11 8:02 ` Alan Kao [this message]
2018-01-10 7:38 ` [PATCH 3/6] riscv/ftrace: Add dynamic function graph " Alan Kao
2018-01-10 7:38 ` [PATCH 4/6] riscv/ftrace: Add ARCH_SUPPORTS_FTRACE_OPS support Alan Kao
2018-01-10 7:38 ` [PATCH 5/6] riscv/ftrace: Add DYNAMIC_FTRACE_WITH_REGS support Alan Kao
2018-01-10 7:38 ` [PATCH 6/6] riscv/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support Alan Kao
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