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Date:   Tue, 3 Jan 2023 22:31:22 +0900
From:   Masami Hiramatsu (Google) <mhiramat@kernel.org>
To:     Song Chen <chensong_2000@189.cn>
Cc:     rostedt@goodmis.org, arnd@arndb.de, linux-kernel@vger.kernel.org,
        linux-trace-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH v5 2/3] kernel/trace: Provide default impelentations
 defined in trace_probe_tmpl.h
Message-Id: <20230103223122.e318f7589e41a92a0f17daf7@kernel.org>
In-Reply-To: <1672382018-18347-1-git-send-email-chensong_2000@189.cn>
References: <1672382018-18347-1-git-send-email-chensong_2000@189.cn>
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On Fri, 30 Dec 2022 14:33:38 +0800
Song Chen <chensong_2000@189.cn> wrote:

> There are 6 function definitions in trace_probe_tmpl.h, they are:
> 
> 1, fetch_store_strlen
> 2, fetch_store_string
> 3, fetch_store_strlen_user
> 4, fetch_store_string_user
> 5, probe_mem_read
> 6, probe_mem_read_user
> 
> Every C file which includes trace_probe_tmpl.h has to implement them,
> otherwise it gets warnings and errors. However, some of them are identical,
> like kprobe and eprobe, as a result, there is a lot redundant code in those
> 2 files.
> 
> This patch would like to provide default behaviors for those functions
> which kprobe and eprobe can share by just including trace_probe_kernel.h
> with trace_probe_tmpl.h together.
> 
> It removes redundant code, increases readability, and more importantly,
> makes it easier to introduce a new feature based on trace probe
> (it's possible).
> 
> Signed-off-by: Song Chen <chensong_2000@189.cn>
> Reported-by: kernel test robot <lkp@intel.com>

This looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>

Thanks!


> 
> ---
> v2:
> 1, reorganize patchset
> 
> v3:
> 1, mark nokprobe_inline for get_event_field
> 2, remove warnings reported from kernel test robot
> 3, fix errors reported from kernel test robot
> 
> v4:
> 1, reset changes in v3(2) and v3(3), they are not reasonable fix.
> 2, fixed errors by adding "#ifdef CONFIG_HAVE_REGS_AND_STACK_ACCESS_API".
> 
> v5:
> 1, move process_fetch_insn to trace_probe_tmpl.h in another patch.
> ---
>  kernel/trace/trace_eprobe.c       | 55 ++-----------------------------
>  kernel/trace/trace_events_synth.c |  6 ++--
>  kernel/trace/trace_kprobe.c       | 54 ------------------------------
>  kernel/trace/trace_probe_kernel.h | 30 +++++++++++++----
>  4 files changed, 29 insertions(+), 116 deletions(-)
> 
> diff --git a/kernel/trace/trace_eprobe.c b/kernel/trace/trace_eprobe.c
> index bdb26eee7a0c..ca5d097eec4f 100644
> --- a/kernel/trace/trace_eprobe.c
> +++ b/kernel/trace/trace_eprobe.c
> @@ -319,7 +319,8 @@ print_eprobe_event(struct trace_iterator *iter, int flags,
>  	return trace_handle_return(s);
>  }
>  
> -static unsigned long get_event_field(struct fetch_insn *code, void *rec)
> +static nokprobe_inline unsigned long
> +get_event_field(struct fetch_insn *code, void *rec)
>  {
>  	struct ftrace_event_field *field = code->data;
>  	unsigned long val;
> @@ -453,58 +454,6 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
>  }
>  NOKPROBE_SYMBOL(process_fetch_insn)
>  
> -/* Return the length of string -- including null terminal byte */
> -static nokprobe_inline int
> -fetch_store_strlen_user(unsigned long addr)
> -{
> -	return kern_fetch_store_strlen_user(addr);
> -}
> -
> -/* Return the length of string -- including null terminal byte */
> -static nokprobe_inline int
> -fetch_store_strlen(unsigned long addr)
> -{
> -	return kern_fetch_store_strlen(addr);
> -}
> -
> -/*
> - * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
> - * with max length and relative data location.
> - */
> -static nokprobe_inline int
> -fetch_store_string_user(unsigned long addr, void *dest, void *base)
> -{
> -	return kern_fetch_store_string_user(addr, dest, base);
> -}
> -
> -/*
> - * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
> - * length and relative data location.
> - */
> -static nokprobe_inline int
> -fetch_store_string(unsigned long addr, void *dest, void *base)
> -{
> -	return kern_fetch_store_string(addr, dest, base);
> -}
> -
> -static nokprobe_inline int
> -probe_mem_read_user(void *dest, void *src, size_t size)
> -{
> -	const void __user *uaddr =  (__force const void __user *)src;
> -
> -	return copy_from_user_nofault(dest, uaddr, size);
> -}
> -
> -static nokprobe_inline int
> -probe_mem_read(void *dest, void *src, size_t size)
> -{
> -#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> -	if ((unsigned long)src < TASK_SIZE)
> -		return probe_mem_read_user(dest, src, size);
> -#endif
> -	return copy_from_kernel_nofault(dest, src, size);
> -}
> -
>  /* eprobe handler */
>  static inline void
>  __eprobe_trace_func(struct eprobe_data *edata, void *rec)
> diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
> index e310052dc83c..d72916c91e24 100644
> --- a/kernel/trace/trace_events_synth.c
> +++ b/kernel/trace/trace_events_synth.c
> @@ -420,12 +420,12 @@ static unsigned int trace_string(struct synth_trace_event *entry,
>  		data_offset += event->n_u64 * sizeof(u64);
>  		data_offset += data_size;
>  
> -		len = kern_fetch_store_strlen((unsigned long)str_val);
> +		len = fetch_store_strlen((unsigned long)str_val);
>  
>  		data_offset |= len << 16;
>  		*(u32 *)&entry->fields[*n_u64] = data_offset;
>  
> -		ret = kern_fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry);
> +		ret = fetch_store_string((unsigned long)str_val, &entry->fields[*n_u64], entry);
>  
>  		(*n_u64)++;
>  	} else {
> @@ -473,7 +473,7 @@ static notrace void trace_event_raw_event_synth(void *__data,
>  		val_idx = var_ref_idx[field_pos];
>  		str_val = (char *)(long)var_ref_vals[val_idx];
>  
> -		len = kern_fetch_store_strlen((unsigned long)str_val);
> +		len = fetch_store_strlen((unsigned long)str_val);
>  
>  		fields_size += len;
>  	}
> diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
> index a4ffa864dbb7..714fe9c04eb6 100644
> --- a/kernel/trace/trace_kprobe.c
> +++ b/kernel/trace/trace_kprobe.c
> @@ -1218,60 +1218,6 @@ static const struct file_operations kprobe_profile_ops = {
>  	.release        = seq_release,
>  };
>  
> -/* Kprobe specific fetch functions */
> -
> -/* Return the length of string -- including null terminal byte */
> -static nokprobe_inline int
> -fetch_store_strlen_user(unsigned long addr)
> -{
> -	return kern_fetch_store_strlen_user(addr);
> -}
> -
> -/* Return the length of string -- including null terminal byte */
> -static nokprobe_inline int
> -fetch_store_strlen(unsigned long addr)
> -{
> -	return kern_fetch_store_strlen(addr);
> -}
> -
> -/*
> - * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
> - * with max length and relative data location.
> - */
> -static nokprobe_inline int
> -fetch_store_string_user(unsigned long addr, void *dest, void *base)
> -{
> -	return kern_fetch_store_string_user(addr, dest, base);
> -}
> -
> -/*
> - * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
> - * length and relative data location.
> - */
> -static nokprobe_inline int
> -fetch_store_string(unsigned long addr, void *dest, void *base)
> -{
> -	return kern_fetch_store_string(addr, dest, base);
> -}
> -
> -static nokprobe_inline int
> -probe_mem_read_user(void *dest, void *src, size_t size)
> -{
> -	const void __user *uaddr =  (__force const void __user *)src;
> -
> -	return copy_from_user_nofault(dest, uaddr, size);
> -}
> -
> -static nokprobe_inline int
> -probe_mem_read(void *dest, void *src, size_t size)
> -{
> -#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> -	if ((unsigned long)src < TASK_SIZE)
> -		return probe_mem_read_user(dest, src, size);
> -#endif
> -	return copy_from_kernel_nofault(dest, src, size);
> -}
> -
>  /* Note that we don't verify it, since the code does not come from user space */
>  static int
>  process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
> diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h
> index 77dbd9ff9782..c4e1d4c03a85 100644
> --- a/kernel/trace/trace_probe_kernel.h
> +++ b/kernel/trace/trace_probe_kernel.h
> @@ -12,7 +12,7 @@
>   */
>  /* Return the length of string -- including null terminal byte */
>  static nokprobe_inline int
> -kern_fetch_store_strlen_user(unsigned long addr)
> +fetch_store_strlen_user(unsigned long addr)
>  {
>  	const void __user *uaddr =  (__force const void __user *)addr;
>  	int ret;
> @@ -29,14 +29,14 @@ kern_fetch_store_strlen_user(unsigned long addr)
>  
>  /* Return the length of string -- including null terminal byte */
>  static nokprobe_inline int
> -kern_fetch_store_strlen(unsigned long addr)
> +fetch_store_strlen(unsigned long addr)
>  {
>  	int ret, len = 0;
>  	u8 c;
>  
>  #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
>  	if (addr < TASK_SIZE)
> -		return kern_fetch_store_strlen_user(addr);
> +		return fetch_store_strlen_user(addr);
>  #endif
>  
>  	do {
> @@ -63,7 +63,7 @@ static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void
>   * with max length and relative data location.
>   */
>  static nokprobe_inline int
> -kern_fetch_store_string_user(unsigned long addr, void *dest, void *base)
> +fetch_store_string_user(unsigned long addr, void *dest, void *base)
>  {
>  	const void __user *uaddr =  (__force const void __user *)addr;
>  	int maxlen = get_loc_len(*(u32 *)dest);
> @@ -86,7 +86,7 @@ kern_fetch_store_string_user(unsigned long addr, void *dest, void *base)
>   * length and relative data location.
>   */
>  static nokprobe_inline int
> -kern_fetch_store_string(unsigned long addr, void *dest, void *base)
> +fetch_store_string(unsigned long addr, void *dest, void *base)
>  {
>  	int maxlen = get_loc_len(*(u32 *)dest);
>  	void *__dest;
> @@ -94,7 +94,7 @@ kern_fetch_store_string(unsigned long addr, void *dest, void *base)
>  
>  #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
>  	if ((unsigned long)addr < TASK_SIZE)
> -		return kern_fetch_store_string_user(addr, dest, base);
> +		return fetch_store_string_user(addr, dest, base);
>  #endif
>  
>  	if (unlikely(!maxlen))
> @@ -112,4 +112,22 @@ kern_fetch_store_string(unsigned long addr, void *dest, void *base)
>  	return ret;
>  }
>  
> +static nokprobe_inline int
> +probe_mem_read_user(void *dest, void *src, size_t size)
> +{
> +	const void __user *uaddr =  (__force const void __user *)src;
> +
> +	return copy_from_user_nofault(dest, uaddr, size);
> +}
> +
> +static nokprobe_inline int
> +probe_mem_read(void *dest, void *src, size_t size)
> +{
> +#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> +	if ((unsigned long)src < TASK_SIZE)
> +		return probe_mem_read_user(dest, src, size);
> +#endif
> +	return copy_from_kernel_nofault(dest, src, size);
> +}
> +
>  #endif /* __TRACE_PROBE_KERNEL_H_ */
> -- 
> 2.25.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>