linux-kernel - Re: [PATCH v5 1/2] scripts: ftrace - move the sort-processing in ftrace

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Date:   Wed, 1 Dec 2021 16:45:52 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Yinan Liu <yinan@...ux.alibaba.com>
Cc:     peterz@...radead.org, mark-pk.tsai@...iatek.com, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] scripts: ftrace - move the sort-processing in
 ftrace_init to compile time

On Wed,  1 Dec 2021 13:32:06 +0800
Yinan Liu <yinan@...ux.alibaba.com> wrote:

>  
>  #if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
>  /* ORC unwinder only support X86_64 */
> -#include <errno.h>
> -#include <pthread.h>
>  #include <asm/orc_types.h>
>  
>  #define ERRSTR_MAXSZ	256
> @@ -191,7 +198,64 @@ static int compare_extable(const void *a, const void *b)
>  		return 1;
>  	return 0;
>  }
> +#if defined CONFIG_FUNCTION_TRACER

Note, "defined" is best used with parenthesis, but if it's for only a
single define, we usually just use:

#ifdef CONFIG_FUNCTION_TRACER

Same for all he below.

-- Steve


> +struct elf_mcount_loc {
> +	Elf_Ehdr *ehdr;
> +	Elf_Shdr *init_data_sec;
> +	uint_t start_mcount_loc;
> +	uint_t stop_mcount_loc;
> +};
> +
> +/* Sort the addresses stored between __start_mcount_loc to __stop_mcount_loc in vmlinux */
> +static void *sort_mcount_loc(void *arg)
> +{
> +	struct elf_mcount_loc *emloc = (struct elf_mcount_loc *)arg;
> +	uint_t offset = emloc->start_mcount_loc - _r(&(emloc->init_data_sec)->sh_addr)
> +					+ _r(&(emloc->init_data_sec)->sh_offset);
> +	uint_t count = emloc->stop_mcount_loc - emloc->start_mcount_loc;
> +	unsigned char *start_loc = (void *)emloc->ehdr + offset;
> +
> +	qsort(start_loc, count/sizeof(uint_t), sizeof(uint_t), compare_extable);
> +	return NULL;
> +}
> +
> +/* Get the address of __start_mcount_loc and __stop_mcount_loc in System.map */
> +static void get_mcount_loc(uint_t *_start, uint_t *_stop)
> +{
> +	FILE *file_start, *file_stop;
> +	char start_buff[20];
> +	char stop_buff[20];
> +	int len = 0;
> +
> +	file_start = popen(" grep start_mcount System.map | awk '{print $1}' ", "r");
> +	if (!file_start) {
> +		fprintf(stderr, "get start_mcount_loc error!");
> +		return;
> +	}
> +
> +	file_stop = popen(" grep stop_mcount System.map | awk '{print $1}' ", "r");
> +	if (!file_stop) {
> +		fprintf(stderr, "get stop_mcount_loc error!");
> +		pclose(file_start);
> +		return;
> +	}
> +
> +	while (fgets(start_buff, sizeof(start_buff), file_start) != NULL) {
> +		len = strlen(start_buff);
> +		start_buff[len - 1] = '\0';
> +	}
> +	*_start = strtoul(start_buff, NULL, 16);
> +
> +	while (fgets(stop_buff, sizeof(stop_buff), file_stop) != NULL) {
> +		len = strlen(stop_buff);
> +		stop_buff[len - 1] = '\0';
> +	}
> +	*_stop = strtoul(stop_buff, NULL, 16);
>  
> +	pclose(file_start);
> +	pclose(file_stop);
> +}
> +#endif
>  static int do_sort(Elf_Ehdr *ehdr,
>  		   char const *const fname,
>  		   table_sort_t custom_sort)
> @@ -217,6 +281,12 @@ static int do_sort(Elf_Ehdr *ehdr,
>  	int idx;
>  	unsigned int shnum;
>  	unsigned int shstrndx;
> +#if defined CONFIG_FUNCTION_TRACER
> +	struct elf_mcount_loc mstruct;
> +	uint_t _start_mcount_loc = 0;
> +	uint_t _stop_mcount_loc = 0;
> +	pthread_t mcount_sort_thread;
> +#endif
>  #if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
>  	unsigned int orc_ip_size = 0;
>  	unsigned int orc_size = 0;
> @@ -253,6 +323,17 @@ static int do_sort(Elf_Ehdr *ehdr,
>  			symtab_shndx = (Elf32_Word *)((const char *)ehdr +
>  						      _r(&s->sh_offset));
>  
> +#if defined CONFIG_FUNCTION_TRACER
> +		/* locate the .init.data section in vmlinux */
> +		if (!strcmp(secstrings + idx, ".init.data")) {
> +			get_mcount_loc(&_start_mcount_loc, &_stop_mcount_loc);
> +			mstruct.ehdr = ehdr;
> +			mstruct.init_data_sec = s;
> +			mstruct.start_mcount_loc = _start_mcount_loc;
> +			mstruct.stop_mcount_loc = _stop_mcount_loc;
> +		}
> +#endif
> +
>  #if defined(SORTTABLE_64) && defined(UNWINDER_ORC_ENABLED)
>  		/* locate the ORC unwind tables */
>  		if (!strcmp(secstrings + idx, ".orc_unwind_ip")) {
> @@ -294,6 +375,23 @@ static int do_sort(Elf_Ehdr *ehdr,
>  		goto out;
>  	}
>  #endif
> +
> +#if defined CONFIG_FUNCTION_TRACER
> +	if (!mstruct.init_data_sec || !_start_mcount_loc || !_stop_mcount_loc) {
> +		fprintf(stderr,
> +			"incomplete mcount's sort in file: %s\n",
> +			fname);
> +		goto out;
> +	}
> +
> +	/* create thread to sort mcount_loc concurrently */
> +	if (pthread_create(&mcount_sort_thread, NULL, &sort_mcount_loc, &mstruct)) {
> +		fprintf(stderr,
> +			"pthread_create mcount_sort_thread failed '%s': %s\n",
> +			strerror(errno), fname);
> +		goto out;
> +	}
> +#endif
>  	if (!extab_sec) {
>  		fprintf(stderr,	"no __ex_table in file: %s\n", fname);
>  		goto out;
> @@ -376,5 +474,23 @@ static int do_sort(Elf_Ehdr *ehdr,
>  		}
>  	}
>  #endif
> +
> +#if defined CONFIG_FUNCTION_TRACER
> +	if (mcount_sort_thread) {
> +		void *retval = NULL;
> +		/* wait for mcount sort done */
> +		rc = pthread_join(mcount_sort_thread, &retval);
> +		if (rc) {
> +			fprintf(stderr,
> +				"pthread_join failed '%s': %s\n",
> +				strerror(errno), fname);
> +		} else if (retval) {
> +			rc = -1;
> +			fprintf(stderr,
> +				"failed to sort mcount '%s': %s\n",
> +				(char *)retval, fname);
> +		}
> +	}
> +#endif
>  	return rc;
>  }