Yonghong,
The patch looks good to me, but I'll try to read it carefully later.
Just a couple of cosmetic nits for now.
On 11/09, Yonghong Song wrote:
>
> --- a/arch/x86/include/asm/uprobes.h
> +++ b/arch/x86/include/asm/uprobes.h
> @@ -53,6 +53,10 @@ struct arch_uprobe {
> u
Uprobe is a tracing mechanism for userspace programs.
Typical uprobe will incur overhead of two traps.
First trap is caused by replaced trap insn, and
the second trap is to execute the original displaced
insn in user space.
To reduce the overhead, kernel provides hooks
for architectures to emulate
On 11/9/17 5:44 AM, Oleg Nesterov wrote:
On 11/09, Yonghong Song wrote:
This patch extends the emulation to "push "
insns. These insns are typical in the beginning
of the function. For example, bcc
in https://github.com/iovisor/bcc repo provides
tools to measure funclantency, detect memleak,
On 11/09, Yonghong Song wrote:
>
> + if (insn_class == UPROBE_PUSH_INSN) {
> + src_ptr = get_push_reg_ptr(auprobe, regs);
> + reg_width = sizeof_long();
> + sp = regs->sp;
> + if (copy_to_user((void __user *)(sp - reg_width), src_ptr,
> reg_width
On 11/09, Oleg Nesterov wrote:
>
> And. Do you really need ->post_xol() method to emulate "push"? Why we can't
> simply execute it out-of-line if copy_to_user() fails?
>
> branch_post_xol_op() is needed because we can't execute "call" out-of-line,
> we need to restart and try again if copy_to_user(
On 11/09, Yonghong Song wrote:
>
> This patch extends the emulation to "push "
> insns. These insns are typical in the beginning
> of the function. For example, bcc
> in https://github.com/iovisor/bcc repo provides
> tools to measure funclantency, detect memleak, etc.
> The tools will place uprobes
Uprobe is a tracing mechanism for userspace programs.
Typical uprobe will incur overhead of two traps.
First trap is caused by replaced trap insn, and
the second trap is to execute the original displaced
insn in user space.
To reduce the overhead, kernel provides hooks
for architectures to emulate
