Subject: Re: [PATCH v2 3/6] coresight: configfs: Modify config files to allow userspace use

From: Mathieu Poirier <[email-masked]>
Date: Fri, 28 Jan 2022 11:33:44 -0700

On Tue, Nov 30, 2021 at 10:00:57PM +0000, Mike Leach wrote:
> Update coresight-config.h and the coresight-config-file.c & .h
> to allow use in userspace programs.
> 
> Use __KERNEL__ defines to filter out driver only structures and
> elements so that user space programs can use the descriptor structures.
> 
> Abstract memory allocation in coresight-config-file.c to allow read
> file functions to be run in userspace and kernel drivers.
> 
> Signed-off-by: Mike Leach <[email-masked]>
> ---
>  .../coresight/coresight-config-file.c         | 96 +++++++++++++------
>  .../coresight/coresight-config-file.h         | 33 +++++++
>  .../hwtracing/coresight/coresight-config.h    | 21 ++++
>  3 files changed, 122 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-config-file.c b/drivers/hwtracing/coresight/coresight-config-file.c
> index 3fd001938324..77a64b54280d 100644
> --- a/drivers/hwtracing/coresight/coresight-config-file.c
> +++ b/drivers/hwtracing/coresight/coresight-config-file.c
> @@ -4,10 +4,58 @@
>   * Author: Mike Leach <[email-masked]>
>   */
>  
> -#include "coresight-config.h"
>  #include "coresight-config-file.h"
> +
> +/*
> + * To allow reuse of this source in tools, define memory allocation fns according
> + * to build environment.
> + */
> +
> +#ifdef __KERNEL__
>  #include "coresight-syscfg.h"
>  
> +static void *cscfg_calloc(size_t num, size_t size)
> +{
> +	return devm_kcalloc(cscfg_device(), num, size, GFP_KERNEL);
> +}
> +
> +static char *cscfg_strdup(const char *str)
> +{
> +	return devm_kstrdup(cscfg_device(), str, GFP_KERNEL);
> +}
> +
> +static void *cscfg_zalloc(size_t size)
> +{
> +	return devm_kzalloc(cscfg_device(), size, GFP_KERNEL);
> +}
> +
> +#else
> +
> +#include <stddef.h>
> +#include <string.h>
> +#include <stdlib.h>
> +
> +static void *cscfg_calloc(size_t num, size_t size)
> +{
> +	return calloc(num, size);
> +}
> +
> +static char *cscfg_strdup(const char *str)
> +{
> +	return strdup(str);
> +}
> +
> +static void *cscfg_zalloc(size_t size)
> +{
> +	void *ptr = malloc(size);
> +
> +	if (ptr)
> +		memset(ptr, 0, size);
> +	return ptr;
> +}
> +
> +#endif
> +
>  #define cscfg_extract_u64(val64) {	\
>  	val64 = *(u64 *)(buffer + used); \
>  	used += sizeof(u64); \
> @@ -80,6 +128,7 @@ static int cscfg_file_read_elem_str(const u8 *buffer, const int buflen, int *buf
>  				    struct cscfg_file_elem_str *elem_str)
>  {
>  	int used = *buf_used;
> +	const u8 *str;
>  
>  	if ((buflen - used) < sizeof(u16))
>  		return -EINVAL;
> @@ -89,11 +138,13 @@ static int cscfg_file_read_elem_str(const u8 *buffer, const int buflen, int *buf
>  	if ((buflen - used) < elem_str->str_len)
>  		return -EINVAL;
>  
> +	str = buffer + used;
> +
>  	/* check for 0 termination */
> -	if (buffer[elem_str->str_len - 1] != 0)
> +	if (str[elem_str->str_len - 1] != 0)
>  		return -EINVAL;
>  
> -	elem_str->str = devm_kstrdup(cscfg_device(), (char *)buffer, GFP_KERNEL);
> +	elem_str->str = cscfg_strdup((char *)str);
>  	used += elem_str->str_len;
>  
>  	*buf_used = used;
> @@ -104,14 +155,12 @@ static int cscfg_file_alloc_desc_arrays(struct cscfg_fs_load_descs *desc_arrays,
>  					int nr_features)
>  {
>  	/* arrays are 0 terminated - max of 1 config & nr_features features */
> -	desc_arrays->config_descs = devm_kcalloc(cscfg_device(), 2,
> -						 sizeof(struct cscfg_config_desc *),
> -						 GFP_KERNEL);
> +	desc_arrays->config_descs = cscfg_calloc(2, sizeof(struct cscfg_config_desc *));
>  	if (!desc_arrays->config_descs)
>  		return -ENOMEM;
> -	desc_arrays->feat_descs = devm_kcalloc(cscfg_device(), nr_features + 1,
> -					       sizeof(struct cscfg_feature_desc *),
> -					       GFP_KERNEL);
> +
> +	desc_arrays->feat_descs = cscfg_calloc(nr_features + 1,
> +					       sizeof(struct cscfg_feature_desc *));
>  	if (!desc_arrays->feat_descs)
>  		return -ENOMEM;
>  	return 0;
> @@ -138,8 +187,7 @@ static int cscfg_file_read_elem_config(const u8 *buffer, const int buflen, int *
>  		return 0;
>  
>  	/* we have a config - allocate the descriptor */
> -	config_desc = devm_kzalloc(cscfg_device(), sizeof(struct cscfg_config_desc),
> -				   GFP_KERNEL);
> +	config_desc = cscfg_zalloc(sizeof(struct cscfg_config_desc));
>  	if (!config_desc)
>  		return -ENOMEM;
>  
> @@ -165,8 +213,7 @@ static int cscfg_file_read_elem_config(const u8 *buffer, const int buflen, int *
>  	/* read the array of 64bit presets if present */
>  	nr_preset_vals = config_desc->nr_total_params * config_desc->nr_presets;
>  	if (nr_preset_vals) {
> -		presets = devm_kcalloc(cscfg_device(), nr_preset_vals,
> -				       sizeof(u64), GFP_KERNEL);
> +		presets = cscfg_calloc(nr_preset_vals, sizeof(u64));
>  		if (!presets)
>  			return -ENOMEM;
>  
> @@ -181,10 +228,8 @@ static int cscfg_file_read_elem_config(const u8 *buffer, const int buflen, int *
>  
>  	/* read the array of feature names referenced by the config */
>  	if (config_desc->nr_feat_refs) {
> -		config_desc->feat_ref_names = devm_kcalloc(cscfg_device(),
> -							   config_desc->nr_feat_refs,
> -							   sizeof(char *),
> -							   GFP_KERNEL);
> +		config_desc->feat_ref_names = cscfg_calloc(config_desc->nr_feat_refs,
> +							   sizeof(char *));
>  		if (!config_desc->feat_ref_names)
>  			return -ENOMEM;
>  
> @@ -262,8 +307,7 @@ static int cscfg_file_read_elem_feature(const u8 *buffer, const int buflen, int
>  	u32 val32;
>  
>  	/* allocate the feature descriptor object */
> -	feat_desc = devm_kzalloc(cscfg_device(), sizeof(struct cscfg_feature_desc),
> -				 GFP_KERNEL);
> +	feat_desc = cscfg_zalloc(sizeof(struct cscfg_feature_desc));
>  	if (!feat_desc)
>  		return -ENOMEM;
>  
> @@ -302,10 +346,8 @@ static int cscfg_file_read_elem_feature(const u8 *buffer, const int buflen, int
>  		nr_regs_bytes = ((sizeof(u32) + sizeof(u64)) * feat_desc->nr_regs);
>  		if ((buflen - used) < nr_regs_bytes)
>  			return -EINVAL;
> -		feat_desc->regs_desc = devm_kcalloc(cscfg_device(),
> -						    feat_desc->nr_regs,
> -						    sizeof(struct cscfg_regval_desc),
> -						    GFP_KERNEL);
> +		feat_desc->regs_desc = cscfg_calloc(feat_desc->nr_regs,
> +						    sizeof(struct cscfg_regval_desc));
>  		if (!feat_desc->regs_desc)
>  			return -ENOMEM;
>  
> @@ -319,10 +361,8 @@ static int cscfg_file_read_elem_feature(const u8 *buffer, const int buflen, int
>  
>  	/* parameter descriptors - string + 64 bit value */
>  	if (feat_desc->nr_params) {
> -		feat_desc->params_desc = devm_kcalloc(cscfg_device(),
> -						      feat_desc->nr_params,
> -						      sizeof(struct cscfg_parameter_desc),
> -						      GFP_KERNEL);
> +		feat_desc->params_desc = cscfg_calloc(feat_desc->nr_params,
> +						      sizeof(struct cscfg_parameter_desc));
>  		if (!feat_desc->params_desc)
>  			return -ENOMEM;
>  		for (i = 0; i < feat_desc->nr_params; i++) {
> @@ -399,7 +439,7 @@ int cscfg_file_read_buffer(const u8 *buffer, const int buflen,
>  		if (err)
>  			return err;
>  	}
> -	return used;
> +	return 0;
>  }
>  
>  int cscfg_file_read_buffer_first_name(const u8 *buffer, const int buflen,
> diff --git a/drivers/hwtracing/coresight/coresight-config-file.h b/drivers/hwtracing/coresight/coresight-config-file.h
> index 03899f7d94c9..04c365e5109b 100644
> --- a/drivers/hwtracing/coresight/coresight-config-file.h
> +++ b/drivers/hwtracing/coresight/coresight-config-file.h
> @@ -7,6 +7,39 @@
>  #ifndef _CORESIGHT_CORESIGHT_CONFIG_FILE_H
>  #define _CORESIGHT_CORESIGHT_CONFIG_FILE_H
>  
> +#include <linux/types.h>
> +
> +#ifndef __KERNEL__
> +/*
> + * allow the user space programs to include the coresight config headers
> + * to use the _desc structures, and reuse the read code
> + */
> +#ifndef u8
> +typedef __u8 u8;
> +typedef __u16 u16;
> +typedef __u32 u32;
> +typedef __u64 u64;
> +#endif
> +
> +/* ARRAY SIZE is useful too */
> +#ifndef ARRAY_SIZE
> +#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
> +#endif
> +
> +/* define EINVAL for user space */
> +#ifndef EINVAL
> +#define EINVAL 22
> +#endif
> +
> +#ifndef ENOMEM
> +#define ENOMEM 12
> +#endif
> +
> +#endif
> +
> +#include "coresight-config.h"
> +
> +
>  /*
>   * Structures to represent configuration descriptors in a memory buffer
>   * to serialise to and from files
> diff --git a/drivers/hwtracing/coresight/coresight-config.h b/drivers/hwtracing/coresight/coresight-config.h
> index 770986316bc2..2136393df710 100644
> --- a/drivers/hwtracing/coresight/coresight-config.h
> +++ b/drivers/hwtracing/coresight/coresight-config.h
> @@ -7,7 +7,14 @@
>  #ifndef _CORESIGHT_CORESIGHT_CONFIG_H
>  #define _CORESIGHT_CORESIGHT_CONFIG_H
>  
> +/*
> + * Filter out kernel only portions of the file to allow user space programs
> + * to use the descriptor definitions.
> + */
> +#ifdef __KERNEL__
>  #include <linux/coresight.h>
> +#endif
> +
>  #include <linux/types.h>
>  
>  /* CoreSight Configuration Management - component and system wide configuration */
> @@ -103,14 +110,18 @@ struct cscfg_regval_desc {
>  struct cscfg_feature_desc {
>  	const char *name;
>  	const char *description;
> +#ifdef __KERNEL__
>  	struct list_head item;
> +#endif
>  	u32 match_flags;
>  	int nr_params;
>  	struct cscfg_parameter_desc *params_desc;
>  	int nr_regs;
>  	struct cscfg_regval_desc *regs_desc;
> +#ifdef __KERNEL__
>  	void *load_owner;
>  	struct config_group *fs_group;
> +#endif
>  };

That will quickly become a maintenance nightmare.  I suggest the following:

struct cscfg_feature_desc {
  	struct list_head item;
  	void *load_owner;
  	struct config_group *fs_group;
        struct cscfg_feature_udesc *udesc;
};

struct cscfg_feature_udesc {
        u32 version;
 	const char *name;
  	const char *description;
  	u32 match_flags;
  	int nr_params;
  	struct cscfg_parameter_desc *params_desc;
  	int nr_regs;
  	struct cscfg_regval_desc *regs_desc;
};

Structure cscfg_feature_udesc should likely be under include/uapi/linux/coresight-config.h

>  
>  /**
> @@ -138,16 +149,20 @@ struct cscfg_feature_desc {
>  struct cscfg_config_desc {
>  	const char *name;
>  	const char *description;
> +#ifdef __KERNEL__
>  	struct list_head item;
> +#endif
>  	int nr_feat_refs;
>  	const char **feat_ref_names;
>  	int nr_presets;
>  	int nr_total_params;
>  	const u64 *presets; /* nr_presets * nr_total_params */
> +#ifdef __KERNEL__
>  	struct dev_ext_attribute *event_ea;
>  	atomic_t active_cnt;
>  	void *load_owner;
>  	struct config_group *fs_group;
> +#endif
>  };
>  
>  /**
> @@ -162,11 +177,16 @@ struct cscfg_config_desc {
>   * @feat_descs:		array of feature descriptor pointers.
>   */
>  struct cscfg_fs_load_descs {
> +#ifdef __KERNEL__
>  	void *owner_info;
> +#endif
>  	struct cscfg_config_desc **config_descs;
>  	struct cscfg_feature_desc **feat_descs;
>  };

Same comment as above.

>  
> +/* remainder of header is used by the kernel drivers only */
> +#ifdef __KERNEL__
> +
>  /**
>   * config register instance - part of a loaded feature.
>   *                            maps register values to csdev driver structures
> @@ -274,4 +294,5 @@ void cscfg_csdev_disable_config(struct cscfg_config_csdev *config_csdev);
>  /* reset a feature to default values */
>  void cscfg_reset_feat(struct cscfg_feature_csdev *feat_csdev);
>  
> +#endif /* __KERNEL__ */
>  #endif /* _CORESIGHT_CORESIGHT_CONFIG_H */
> -- 
> 2.17.1
> 

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