From: Steven Rostedt <rostedt@goodmis.org>
To: Alan Kao <nonerkao@gmail.com>
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: Wed, 10 Jan 2018 11:32:34 -0500 [thread overview]
Message-ID: <20180110113234.2fa92920@vmware.local.home> (raw)
In-Reply-To: <20180110073814.32338-3-alankao@andestech.com>
On Wed, 10 Jan 2018 15:38:10 +0800
Alan Kao <nonerkao@gmail.com> wrote:
> +static int ftrace_check_current_call(unsigned long hook_pos,
> + unsigned int *expected)
> +{
> + unsigned int replaced[2];
> + unsigned int nops[2] = {NOP4, NOP4};
> +
> + /* we expect nops at the hook position */
> + if (!expected)
> + expected = nops;
> +
> + /* read the text we want to modify */
> + if (probe_kernel_read(replaced, (void *)hook_pos, MCOUNT_INSN_SIZE))
> + return -EFAULT;
> +
> + /* Make sure it is what we expect it to be */
> + if (replaced[0] != expected[0] || replaced[1] != expected[1]) {
I wonder if we can have a slight enhancement by doing:
if (memcmp(replaced, expected, sizeof(replaced)) != 0) {
-- Steve
> + pr_err("%p: expected (%08x %08x) but get (%08x %08x)",
> + (void *)hook_pos, expected[0], expected[1], replaced[0],
> + replaced[1]);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
next prev parent reply other threads:[~2018-01-10 16:32 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 [this message]
2018-01-10 16:36 ` Steven Rostedt
2018-01-11 8:02 ` Alan Kao
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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