RE: [PATCH] kprobes: Update examples to target _do_fork

[åæéå / HIRAMATUïMASAMI]

> From: Steve Capper [mailto:steve.capper@xxxxxxxxxx]
> 
> In commit 3033f14ab78c ("clone: support passing tls argument via C
> rather than pt_regs magic"), the kernel calls _do_fork in places where
> it previously called do_fork.
> 
> Unfortunately, the kprobe examples target do_fork; thus no events
> appear to fire when one runs the example modules.
> 
> This commit updates the kprobe example code s.t. _do_fork is targeted
> instead, and the examples work as expected.

Oops, right! I've found it on ftrace-test, but missed on kprobes examples :(

> 
> Signed-off-by: Steve Capper <steve.capper@xxxxxxxxxx>


Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>

Thank you!

> ---
>  samples/kprobes/jprobe_example.c    | 8 ++++----
>  samples/kprobes/kprobe_example.c    | 2 +-
>  samples/kprobes/kretprobe_example.c | 2 +-
>  3 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/samples/kprobes/jprobe_example.c b/samples/kprobes/jprobe_example.c
> index 9119ac6..11dd54b 100644
> --- a/samples/kprobes/jprobe_example.c
> +++ b/samples/kprobes/jprobe_example.c
> @@ -23,9 +23,9 @@
>   */
> 
>  /* Proxy routine having the same arguments as actual do_fork() routine */
> -static long jdo_fork(unsigned long clone_flags, unsigned long stack_start,
> +static long j_do_fork(unsigned long clone_flags, unsigned long stack_start,
>  	      unsigned long stack_size, int __user *parent_tidptr,
> -	      int __user *child_tidptr)
> +	      int __user *child_tidptr, unsigned long tls)
>  {
>  	pr_info("jprobe: clone_flags = 0x%lx, stack_start = 0x%lx "
>  		"stack_size = 0x%lx\n", clone_flags, stack_start, stack_size);
> @@ -36,9 +36,9 @@ static long jdo_fork(unsigned long clone_flags, unsigned long stack_start,
>  }
> 
>  static struct jprobe my_jprobe = {
> -	.entry			= jdo_fork,
> +	.entry			= j_do_fork,
>  	.kp = {
> -		.symbol_name	= "do_fork",
> +		.symbol_name	= "_do_fork",
>  	},
>  };
> 
> diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
> index 51d459c..597e101 100644
> --- a/samples/kprobes/kprobe_example.c
> +++ b/samples/kprobes/kprobe_example.c
> @@ -16,7 +16,7 @@
> 
>  /* For each probe you need to allocate a kprobe structure */
>  static struct kprobe kp = {
> -	.symbol_name	= "do_fork",
> +	.symbol_name	= "_do_fork",
>  };
> 
>  /* kprobe pre_handler: called just before the probed instruction is executed */
> diff --git a/samples/kprobes/kretprobe_example.c b/samples/kprobes/kretprobe_example.c
> index 1041b67..a270535 100644
> --- a/samples/kprobes/kretprobe_example.c
> +++ b/samples/kprobes/kretprobe_example.c
> @@ -25,7 +25,7 @@
>  #include <linux/limits.h>
>  #include <linux/sched.h>
> 
> -static char func_name[NAME_MAX] = "do_fork";
> +static char func_name[NAME_MAX] = "_do_fork";
>  module_param_string(func, func_name, NAME_MAX, S_IRUGO);
>  MODULE_PARM_DESC(func, "Function to kretprobe; this module will report the"
>  			" function's execution time");
> --
> 2.1.0