tools/testing/selftests/bpf/trace_helpers.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <poll.h>
 #include <unistd.h>
 #include <linux/perf_event.h>
 #include <sys/mman.h>
 #include "trace_helpers.h"
 #include <linux/limits.h>
 #include <libelf.h>
 #include <gelf.h>

 #define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
 #define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"

 #define MAX_SYMS 300000
 static struct ksym syms[MAX_SYMS];
 static int sym_cnt;

 static int ksym_cmp(const void *p1, const void *p2)
 {
 	return ((struct ksym *)p1)->addr - ((struct ksym *)p2)->addr;
 }

 int load_kallsyms_refresh(void)
 {
 	FILE *f;
 	char func[256], buf[256];
 	char symbol;
 	void *addr;
 	int i = 0;

 	sym_cnt = 0;

 	f = fopen("/proc/kallsyms", "r");
 	if (!f)
 		return -ENOENT;

 	while (fgets(buf, sizeof(buf), f)) {
 		if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
 			break;
 		if (!addr)
 			continue;
 		syms[i].addr = (long) addr;
 		syms[i].name = strdup(func);
 		i++;
 	}
 	fclose(f);
 	sym_cnt = i;
 	qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
 	return 0;
 }

 int load_kallsyms(void)
 {
 	/*
 	 * This is called/used from multiplace places,
 	 * load symbols just once.
 	 */
 	if (sym_cnt)
 		return 0;
 	return load_kallsyms_refresh();
 }

 struct ksym *ksym_search(long key)
 {
 	int start = 0, end = sym_cnt;
 	int result;

 	/* kallsyms not loaded. return NULL */
 	if (sym_cnt <= 0)
 		return NULL;

 	while (start < end) {
 		size_t mid = start + (end - start) / 2;

 		result = key - syms[mid].addr;
 		if (result < 0)
 			end = mid;
 		else if (result > 0)
 			start = mid + 1;
 		else
 			return &syms[mid];
 	}

 	if (start >= 1 && syms[start - 1].addr < key &&
 	    key < syms[start].addr)
 		/* valid ksym */
 		return &syms[start - 1];

 	/* out of range. return _stext */
 	return &syms[0];
 }

 long ksym_get_addr(const char *name)
 {
 	int i;

 	for (i = 0; i < sym_cnt; i++) {
 		if (strcmp(syms[i].name, name) == 0)
 			return syms[i].addr;
 	}

 	return 0;
 }

 /* open kallsyms and read symbol addresses on the fly. Without caching all symbols,
  * this is faster than load + find.
  */
 int kallsyms_find(const char *sym, unsigned long long *addr)
 {
 	char type, name[500];
 	unsigned long long value;
 	int err = 0;
 	FILE *f;

 	f = fopen("/proc/kallsyms", "r");
 	if (!f)
 		return -EINVAL;

 	while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) {
 		if (strcmp(name, sym) == 0) {
 			*addr = value;
 			goto out;
 		}
 	}
 	err = -ENOENT;

 out:
 	fclose(f);
 	return err;
 }

 void read_trace_pipe(void)
 {
 	int trace_fd;

 	if (access(TRACEFS_PIPE, F_OK) == 0)
 		trace_fd = open(TRACEFS_PIPE, O_RDONLY, 0);
 	else
 		trace_fd = open(DEBUGFS_PIPE, O_RDONLY, 0);
 	if (trace_fd < 0)
 		return;

 	while (1) {
 		static char buf[4096];
 		ssize_t sz;

 		sz = read(trace_fd, buf, sizeof(buf) - 1);
 		if (sz > 0) {
 			buf[sz] = 0;
 			puts(buf);
 		}
 	}
 }

 ssize_t get_uprobe_offset(const void *addr)
 {
 	size_t start, end, base;
 	char buf[256];
 	bool found = false;
 	FILE *f;

 	f = fopen("/proc/self/maps", "r");
 	if (!f)
 		return -errno;

 	while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &base) == 4) {
 		if (buf[2] == 'x' && (uintptr_t)addr >= start && (uintptr_t)addr < end) {
 			found = true;
 			break;
 		}
 	}

 	fclose(f);

 	if (!found)
 		return -ESRCH;

 #if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2

 #define OP_RT_RA_MASK   0xffff0000UL
 #define LIS_R2          0x3c400000UL
 #define ADDIS_R2_R12    0x3c4c0000UL
 #define ADDI_R2_R2      0x38420000UL

 	/*
 	 * A PPC64 ABIv2 function may have a local and a global entry
 	 * point. We need to use the local entry point when patching
 	 * functions, so identify and step over the global entry point
 	 * sequence.
 	 *
 	 * The global entry point sequence is always of the form:
 	 *
 	 * addis r2,r12,XXXX
 	 * addi  r2,r2,XXXX
 	 *
 	 * A linker optimisation may convert the addis to lis:
 	 *
 	 * lis   r2,XXXX
 	 * addi  r2,r2,XXXX
 	 */
 	{
 		const u32 *insn = (const u32 *)(uintptr_t)addr;

 		if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
 		     ((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
 		    ((*(insn + 1) & OP_RT_RA_MASK) == ADDI_R2_R2))
 			return (uintptr_t)(insn + 2) - start + base;
 	}
 #endif
 	return (uintptr_t)addr - start + base;
 }

 ssize_t get_rel_offset(uintptr_t addr)
 {
 	size_t start, end, offset;
 	char buf[256];
 	FILE *f;

 	f = fopen("/proc/self/maps", "r");
 	if (!f)
 		return -errno;

 	while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &offset) == 4) {
 		if (addr >= start && addr < end) {
 			fclose(f);
 			return (size_t)addr - start + offset;
 		}
 	}

 	fclose(f);
 	return -EINVAL;
 }

 static int
 parse_build_id_buf(const void *note_start, Elf32_Word note_size, char *build_id)
 {
 	Elf32_Word note_offs = 0;

 	while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
 		Elf32_Nhdr *nhdr = (Elf32_Nhdr *)(note_start + note_offs);

 		if (nhdr->n_type == 3 && nhdr->n_namesz == sizeof("GNU") &&
 		    !strcmp((char *)(nhdr + 1), "GNU") && nhdr->n_descsz > 0 &&
 		    nhdr->n_descsz <= BPF_BUILD_ID_SIZE) {
 			memcpy(build_id, note_start + note_offs +
 			       ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), nhdr->n_descsz);
 			memset(build_id + nhdr->n_descsz, 0, BPF_BUILD_ID_SIZE - nhdr->n_descsz);
 			return (int) nhdr->n_descsz;
 		}

 		note_offs = note_offs + sizeof(Elf32_Nhdr) +
 			   ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
 	}

 	return -ENOENT;
 }

 /* Reads binary from *path* file and returns it in the *build_id* buffer
  * with *size* which is expected to be at least BPF_BUILD_ID_SIZE bytes.
  * Returns size of build id on success. On error the error value is
  * returned.
  */
 int read_build_id(const char *path, char *build_id, size_t size)
 {
 	int fd, err = -EINVAL;
 	Elf *elf = NULL;
 	GElf_Ehdr ehdr;
 	size_t max, i;

 	if (size < BPF_BUILD_ID_SIZE)
 		return -EINVAL;

 	fd = open(path, O_RDONLY | O_CLOEXEC);
 	if (fd < 0)
 		return -errno;

 	(void)elf_version(EV_CURRENT);

 	elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
 	if (!elf)
 		goto out;
 	if (elf_kind(elf) != ELF_K_ELF)
 		goto out;
 	if (!gelf_getehdr(elf, &ehdr))
 		goto out;

 	for (i = 0; i < ehdr.e_phnum; i++) {
 		GElf_Phdr mem, *phdr;
 		char *data;

 		phdr = gelf_getphdr(elf, i, &mem);
 		if (!phdr)
 			goto out;
 		if (phdr->p_type != PT_NOTE)
 			continue;
 		data = elf_rawfile(elf, &max);
 		if (!data)
 			goto out;
 		if (phdr->p_offset + phdr->p_memsz > max)
 			goto out;
 		err = parse_build_id_buf(data + phdr->p_offset, phdr->p_memsz, build_id);
 		if (err > 0)
 			break;
 	}

 out:
 	if (elf)
 		elf_end(elf);
 	close(fd);
 	return err;
 }
	// SPDX-License-Identifier: GPL-2.0
	#include <ctype.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <assert.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <poll.h>
	#include <unistd.h>
	#include <linux/perf_event.h>
	#include <sys/mman.h>
	#include "trace_helpers.h"
	#include <linux/limits.h>
	#include <libelf.h>
	#include <gelf.h>

	#define TRACEFS_PIPE "/sys/kernel/tracing/trace_pipe"
	#define DEBUGFS_PIPE "/sys/kernel/debug/tracing/trace_pipe"

	#define MAX_SYMS 300000
	static struct ksym syms[MAX_SYMS];
	static int sym_cnt;

	static int ksym_cmp(const void p1, const void p2)
	{
	return ((struct ksym )p1)->addr - ((struct ksym )p2)->addr;
	}

	int load_kallsyms_refresh(void)
	{
	FILE *f;
	char func[256], buf[256];
	char symbol;
	void *addr;
	int i = 0;

	sym_cnt = 0;

	f = fopen("/proc/kallsyms", "r");
	if (!f)
	return -ENOENT;

	while (fgets(buf, sizeof(buf), f)) {
	if (sscanf(buf, "%p %c %s", &addr, &symbol, func) != 3)
	break;
	if (!addr)
	continue;
	syms[i].addr = (long) addr;
	syms[i].name = strdup(func);
	i++;
	}
	fclose(f);
	sym_cnt = i;
	qsort(syms, sym_cnt, sizeof(struct ksym), ksym_cmp);
	return 0;
	}

	int load_kallsyms(void)
	{
	/*
	* This is called/used from multiplace places,
	* load symbols just once.
	*/
	if (sym_cnt)
	return 0;
	return load_kallsyms_refresh();
	}

	struct ksym *ksym_search(long key)
	{
	int start = 0, end = sym_cnt;
	int result;

	/* kallsyms not loaded. return NULL */
	if (sym_cnt <= 0)
	return NULL;

	while (start < end) {
	size_t mid = start + (end - start) / 2;

	result = key - syms[mid].addr;
	if (result < 0)
	end = mid;
	else if (result > 0)
	start = mid + 1;
	else
	return &syms[mid];
	}

	if (start >= 1 && syms[start - 1].addr < key &&
	key < syms[start].addr)
	/* valid ksym */
	return &syms[start - 1];

	/* out of range. return _stext */
	return &syms[0];
	}

	long ksym_get_addr(const char *name)
	{
	int i;

	for (i = 0; i < sym_cnt; i++) {
	if (strcmp(syms[i].name, name) == 0)
	return syms[i].addr;
	}

	return 0;
	}

	/* open kallsyms and read symbol addresses on the fly. Without caching all symbols,
	* this is faster than load + find.
	*/
	int kallsyms_find(const char sym, unsigned long long addr)
	{
	char type, name[500];
	unsigned long long value;
	int err = 0;
	FILE *f;

	f = fopen("/proc/kallsyms", "r");
	if (!f)
	return -EINVAL;

	while (fscanf(f, "%llx %c %499s%*[^\n]\n", &value, &type, name) > 0) {
	if (strcmp(name, sym) == 0) {
	*addr = value;
	goto out;
	}
	}
	err = -ENOENT;

	out:
	fclose(f);
	return err;
	}

	void read_trace_pipe(void)
	{
	int trace_fd;

	if (access(TRACEFS_PIPE, F_OK) == 0)
	trace_fd = open(TRACEFS_PIPE, O_RDONLY, 0);
	else
	trace_fd = open(DEBUGFS_PIPE, O_RDONLY, 0);
	if (trace_fd < 0)
	return;

	while (1) {
	static char buf[4096];
	ssize_t sz;

	sz = read(trace_fd, buf, sizeof(buf) - 1);
	if (sz > 0) {
	buf[sz] = 0;
	puts(buf);
	}
	}
	}

	ssize_t get_uprobe_offset(const void *addr)
	{
	size_t start, end, base;
	char buf[256];
	bool found = false;
	FILE *f;

	f = fopen("/proc/self/maps", "r");
	if (!f)
	return -errno;

	while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &base) == 4) {
	if (buf[2] == 'x' && (uintptr_t)addr >= start && (uintptr_t)addr < end) {
	found = true;
	break;
	}
	}

	fclose(f);

	if (!found)
	return -ESRCH;

	#if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2

	#define OP_RT_RA_MASK 0xffff0000UL
	#define LIS_R2 0x3c400000UL
	#define ADDIS_R2_R12 0x3c4c0000UL
	#define ADDI_R2_R2 0x38420000UL

	/*
	* A PPC64 ABIv2 function may have a local and a global entry
	* point. We need to use the local entry point when patching
	* functions, so identify and step over the global entry point
	* sequence.
	*
	* The global entry point sequence is always of the form:
	*
	* addis r2,r12,XXXX
	* addi r2,r2,XXXX
	*
	* A linker optimisation may convert the addis to lis:
	*
	* lis r2,XXXX
	* addi r2,r2,XXXX
	*/
	{
	const u32 insn = (const u32 )(uintptr_t)addr;

	if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) \|\|
	((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
	((*(insn + 1) & OP_RT_RA_MASK) == ADDI_R2_R2))
	return (uintptr_t)(insn + 2) - start + base;
	}
	#endif
	return (uintptr_t)addr - start + base;
	}

	ssize_t get_rel_offset(uintptr_t addr)
	{
	size_t start, end, offset;
	char buf[256];
	FILE *f;

	f = fopen("/proc/self/maps", "r");
	if (!f)
	return -errno;

	while (fscanf(f, "%zx-%zx %s %zx %*[^\n]\n", &start, &end, buf, &offset) == 4) {
	if (addr >= start && addr < end) {
	fclose(f);
	return (size_t)addr - start + offset;
	}
	}

	fclose(f);
	return -EINVAL;
	}

	static int
	parse_build_id_buf(const void note_start, Elf32_Word note_size, char build_id)
	{
	Elf32_Word note_offs = 0;

	while (note_offs + sizeof(Elf32_Nhdr) < note_size) {
	Elf32_Nhdr nhdr = (Elf32_Nhdr )(note_start + note_offs);

	if (nhdr->n_type == 3 && nhdr->n_namesz == sizeof("GNU") &&
	!strcmp((char *)(nhdr + 1), "GNU") && nhdr->n_descsz > 0 &&
	nhdr->n_descsz <= BPF_BUILD_ID_SIZE) {
	memcpy(build_id, note_start + note_offs +
	ALIGN(sizeof("GNU"), 4) + sizeof(Elf32_Nhdr), nhdr->n_descsz);
	memset(build_id + nhdr->n_descsz, 0, BPF_BUILD_ID_SIZE - nhdr->n_descsz);
	return (int) nhdr->n_descsz;
	}

	note_offs = note_offs + sizeof(Elf32_Nhdr) +
	ALIGN(nhdr->n_namesz, 4) + ALIGN(nhdr->n_descsz, 4);
	}

	return -ENOENT;
	}

	/* Reads binary from path file and returns it in the build_id buffer
	* with size which is expected to be at least BPF_BUILD_ID_SIZE bytes.
	* Returns size of build id on success. On error the error value is
	* returned.
	*/
	int read_build_id(const char path, char build_id, size_t size)
	{
	int fd, err = -EINVAL;
	Elf *elf = NULL;
	GElf_Ehdr ehdr;
	size_t max, i;

	if (size < BPF_BUILD_ID_SIZE)
	return -EINVAL;

	fd = open(path, O_RDONLY \| O_CLOEXEC);
	if (fd < 0)
	return -errno;

	(void)elf_version(EV_CURRENT);

	elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
	if (!elf)
	goto out;
	if (elf_kind(elf) != ELF_K_ELF)
	goto out;
	if (!gelf_getehdr(elf, &ehdr))
	goto out;

	for (i = 0; i < ehdr.e_phnum; i++) {
	GElf_Phdr mem, *phdr;
	char *data;

	phdr = gelf_getphdr(elf, i, &mem);
	if (!phdr)
	goto out;
	if (phdr->p_type != PT_NOTE)
	continue;
	data = elf_rawfile(elf, &max);
	if (!data)
	goto out;
	if (phdr->p_offset + phdr->p_memsz > max)
	goto out;
	err = parse_build_id_buf(data + phdr->p_offset, phdr->p_memsz, build_id);
	if (err > 0)
	break;
	}

	out:
	if (elf)
	elf_end(elf);
	close(fd);
	return err;
	}