Re: [PATCH dwarves v5 2/2] pahole: Inject kfunc decl tags into BTF

[Jiri Olsa <olsajiri@gmail.com>]

On Fri, Mar 15, 2024 at 01:48:52PM -0600, Daniel Xu wrote:

SNIP

> +static int btf_encoder__tag_kfuncs(struct btf_encoder *encoder)
> +{
> +	const char *filename = encoder->filename;
> +	struct gobuffer btf_kfunc_ranges = {};
> +	struct gobuffer btf_funcs = {};
> +	Elf_Data *symbols = NULL;
> +	Elf_Data *idlist = NULL;
> +	Elf_Scn *symscn = NULL;
> +	int symbols_shndx = -1;
> +	size_t idlist_addr = 0;
> +	int fd = -1, err = -1;
> +	int idlist_shndx = -1;
> +	size_t strtabidx = 0;
> +	Elf_Scn *scn = NULL;
> +	Elf *elf = NULL;
> +	GElf_Shdr shdr;
> +	size_t strndx;
> +	char *secname;
> +	int nr_syms;
> +	int i = 0;
> +
> +	fd = open(filename, O_RDONLY);
> +	if (fd < 0) {
> +		fprintf(stderr, "Cannot open %s\n", filename);
> +		goto out;
> +	}
> +
> +	if (elf_version(EV_CURRENT) == EV_NONE) {
> +		elf_error("Cannot set libelf version");
> +		goto out;
> +	}
> +
> +	elf = elf_begin(fd, ELF_C_READ, NULL);
> +	if (elf == NULL) {
> +		elf_error("Cannot update ELF file");
> +		goto out;
> +	}
> +
> +	/* Locate symbol table and .BTF_ids sections */
> +	if (elf_getshdrstrndx(elf, &strndx) < 0)
> +		goto out;

nit, missing new line

> +	while ((scn = elf_nextscn(elf, scn)) != NULL) {
> +		Elf_Data *data;


Acked/Tested-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

> +
> +		i++;
> +		if (!gelf_getshdr(scn, &shdr)) {
> +			elf_error("Failed to get ELF section(%d) hdr", i);
> +			goto out;
> +		}
> +
> +		secname = elf_strptr(elf, strndx, shdr.sh_name);
> +		if (!secname) {
> +			elf_error("Failed to get ELF section(%d) hdr name", i);
> +			goto out;
> +		}
> +
> +		data = elf_getdata(scn, 0);
> +		if (!data) {
> +			elf_error("Failed to get ELF section(%d) data", i);
> +			goto out;
> +		}
> +
> +		if (shdr.sh_type == SHT_SYMTAB) {
> +			symbols_shndx = i;
> +			symscn = scn;
> +			symbols = data;
> +			strtabidx = shdr.sh_link;
> +		} else if (!strcmp(secname, BTF_IDS_SECTION)) {
> +			idlist_shndx = i;
> +			idlist_addr = shdr.sh_addr;
> +			idlist = data;
> +		}
> +	}

SNIP