[PATCH v3 3/3] powerpc/xmon: add debugfs entry for xmon

[Pan Xinhui]

在 2017/2/21 09:58, Guilherme G. Piccoli 写道:
> Currently the xmon debugger is set only via kernel boot command-line.
> It's disabled by default, and can be enabled with "xmon=on" on the
> command-line. Also, xmon may be accessed via sysrq mechanism.
> But we cannot enable/disable xmon in runtime, it needs kernel reload.
>
> This patch introduces a debugfs entry for xmon, allowing user to query
> its current state and change it if desired. Basically, the "xmon" file
> to read from/write to is under the debugfs mount point, on powerpc
> directory. It's a simple attribute, value 0 meaning xmon is disabled
> and value 1 the opposite. Writing these states to the file will take
> immediate effect in the debugger.
>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli at linux.vnet.ibm.com>
> ---
> v3: logic improved based in the changes made on patch 1.
>
> v2: dropped the custom parser by using simple attributes [mpe suggestion].
>
>
>  arch/powerpc/xmon/xmon.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index f1fcfa8..764ea62 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -29,6 +29,10 @@
>  #include <linux/nmi.h>
>  #include <linux/ctype.h>
>
> +#ifdef CONFIG_DEBUG_FS
> +#include <linux/debugfs.h>
> +#endif
> +
>  #include <asm/ptrace.h>
>  #include <asm/string.h>
>  #include <asm/prom.h>
> @@ -3275,6 +3279,33 @@ static int __init setup_xmon_sysrq(void)
>  device_initcall(setup_xmon_sysrq);
>  #endif /* CONFIG_MAGIC_SYSRQ */
>
> +#ifdef CONFIG_DEBUG_FS
> +static int xmon_dbgfs_set(void *data, u64 val)
> +{
> +	xmon_off = !val;
xmon_off is really 'off' :)
There is xmon_on

> +	xmon_init(!xmon_off);
> +
> +	return 0;
> +}
> +
> +static int xmon_dbgfs_get(void *data, u64 *val)
> +{
> +	*val = !xmon_off;
> +	return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(xmon_dbgfs_ops, xmon_dbgfs_get,
> +			xmon_dbgfs_set, "%llu\n");
> +
> +static int __init setup_xmon_dbgfs(void)
> +{
> +	debugfs_create_file("xmon", 0600, powerpc_debugfs_root, NULL,
> +				&xmon_dbgfs_ops);
> +	return 0;
> +}
> +device_initcall(setup_xmon_dbgfs);
> +#endif /* CONFIG_DEBUG_FS */
> +
>  static int xmon_early __initdata;
>
>  static int __init early_parse_xmon(char *p)
>