accel/tcg/perf.c - qemu - Git at Google

 /*
  * Linux perf perf-<pid>.map and jit-<pid>.dump integration.
  *
  * The jitdump spec can be found at [1].
  *
  * [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/tools/perf/Documentation/jitdump-specification.txt
  *
  * SPDX-License-Identifier: GPL-2.0-or-later
  */

 #include "qemu/osdep.h"
 #include "elf.h"
 #include "exec/exec-all.h"
 #include "qemu/timer.h"
 #include "tcg/tcg.h"

 #include "debuginfo.h"
 #include "perf.h"

 static FILE *safe_fopen_w(const char *path)
 {
     int saved_errno;
     FILE *f;
     int fd;

     /* Delete the old file, if any. */
     unlink(path);

     /* Avoid symlink attacks by using O_CREAT | O_EXCL. */
     fd = open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
     if (fd == -1) {
         return NULL;
     }

     /* Convert fd to FILE*. */
     f = fdopen(fd, "w");
     if (f == NULL) {
         saved_errno = errno;
         close(fd);
         errno = saved_errno;
         return NULL;
     }

     return f;
 }

 static FILE *perfmap;

 void perf_enable_perfmap(void)
 {
     char map_file[32];

     snprintf(map_file, sizeof(map_file), "/tmp/perf-%d.map", getpid());
     perfmap = safe_fopen_w(map_file);
     if (perfmap == NULL) {
         warn_report("Could not open %s: %s, proceeding without perfmap",
                     map_file, strerror(errno));
     }
 }

 /* Get PC and size of code JITed for guest instruction #INSN. */
 static void get_host_pc_size(uintptr_t *host_pc, uint16_t *host_size,
                              const void *start, size_t insn)
 {
     uint16_t start_off = insn ? tcg_ctx->gen_insn_end_off[insn - 1] : 0;

     if (host_pc) {
         *host_pc = (uintptr_t)start + start_off;
     }
     if (host_size) {
         *host_size = tcg_ctx->gen_insn_end_off[insn] - start_off;
     }
 }

 static const char *pretty_symbol(const struct debuginfo_query *q, size_t *len)
 {
     static __thread char buf[64];
     int tmp;

     if (!q->symbol) {
         tmp = snprintf(buf, sizeof(buf), "guest-0x%"PRIx64, q->address);
         if (len) {
             *len = MIN(tmp + 1, sizeof(buf));
         }
         return buf;
     }

     if (!q->offset) {
         if (len) {
             *len = strlen(q->symbol) + 1;
         }
         return q->symbol;
     }

     tmp = snprintf(buf, sizeof(buf), "%s+0x%"PRIx64, q->symbol, q->offset);
     if (len) {
         *len = MIN(tmp + 1, sizeof(buf));
     }
     return buf;
 }

 static void write_perfmap_entry(const void *start, size_t insn,
                                 const struct debuginfo_query *q)
 {
     uint16_t host_size;
     uintptr_t host_pc;

     get_host_pc_size(&host_pc, &host_size, start, insn);
     fprintf(perfmap, "%"PRIxPTR" %"PRIx16" %s\n",
             host_pc, host_size, pretty_symbol(q, NULL));
 }

 static FILE *jitdump;

 #define JITHEADER_MAGIC 0x4A695444
 #define JITHEADER_VERSION 1

 struct jitheader {
     uint32_t magic;
     uint32_t version;
     uint32_t total_size;
     uint32_t elf_mach;
     uint32_t pad1;
     uint32_t pid;
     uint64_t timestamp;
     uint64_t flags;
 };

 enum jit_record_type {
     JIT_CODE_LOAD = 0,
     JIT_CODE_DEBUG_INFO = 2,
 };

 struct jr_prefix {
     uint32_t id;
     uint32_t total_size;
     uint64_t timestamp;
 };

 struct jr_code_load {
     struct jr_prefix p;

     uint32_t pid;
     uint32_t tid;
     uint64_t vma;
     uint64_t code_addr;
     uint64_t code_size;
     uint64_t code_index;
 };

 struct debug_entry {
     uint64_t addr;
     int lineno;
     int discrim;
     const char name[];
 };

 struct jr_code_debug_info {
     struct jr_prefix p;

     uint64_t code_addr;
     uint64_t nr_entry;
     struct debug_entry entries[];
 };

 static uint32_t get_e_machine(void)
 {
     Elf64_Ehdr elf_header;
     FILE *exe;
     size_t n;

     QEMU_BUILD_BUG_ON(offsetof(Elf32_Ehdr, e_machine) !=
                       offsetof(Elf64_Ehdr, e_machine));

     exe = fopen("/proc/self/exe", "r");
     if (exe == NULL) {
         return EM_NONE;
     }

     n = fread(&elf_header, sizeof(elf_header), 1, exe);
     fclose(exe);
     if (n != 1) {
         return EM_NONE;
     }

     return elf_header.e_machine;
 }

 void perf_enable_jitdump(void)
 {
     struct jitheader header;
     char jitdump_file[32];
     void *perf_marker;

     if (!use_rt_clock) {
         warn_report("CLOCK_MONOTONIC is not available, proceeding without jitdump");
         return;
     }

     snprintf(jitdump_file, sizeof(jitdump_file), "jit-%d.dump", getpid());
     jitdump = safe_fopen_w(jitdump_file);
     if (jitdump == NULL) {
         warn_report("Could not open %s: %s, proceeding without jitdump",
                     jitdump_file, strerror(errno));
         return;
     }

     /*
      * `perf inject` will see that the mapped file name in the corresponding
      * PERF_RECORD_MMAP or PERF_RECORD_MMAP2 event is of the form jit-%d.dump
      * and will process it as a jitdump file.
      */
     perf_marker = mmap(NULL, qemu_real_host_page_size(), PROT_READ | PROT_EXEC,
                        MAP_PRIVATE, fileno(jitdump), 0);
     if (perf_marker == MAP_FAILED) {
         warn_report("Could not map %s: %s, proceeding without jitdump",
                     jitdump_file, strerror(errno));
         fclose(jitdump);
         jitdump = NULL;
         return;
     }

     header.magic = JITHEADER_MAGIC;
     header.version = JITHEADER_VERSION;
     header.total_size = sizeof(header);
     header.elf_mach = get_e_machine();
     header.pad1 = 0;
     header.pid = getpid();
     header.timestamp = get_clock();
     header.flags = 0;
     fwrite(&header, sizeof(header), 1, jitdump);
 }

 void perf_report_prologue(const void *start, size_t size)
 {
     if (perfmap) {
         fprintf(perfmap, "%"PRIxPTR" %zx tcg-prologue-buffer\n",
                 (uintptr_t)start, size);
     }
 }

 /* Write a JIT_CODE_DEBUG_INFO jitdump entry. */
 static void write_jr_code_debug_info(const void *start,
                                      const struct debuginfo_query *q,
                                      size_t icount)
 {
     struct jr_code_debug_info rec;
     struct debug_entry ent;
     uintptr_t host_pc;
     int insn;

     /* Write the header. */
     rec.p.id = JIT_CODE_DEBUG_INFO;
     rec.p.total_size = sizeof(rec) + sizeof(ent) + 1;
     rec.p.timestamp = get_clock();
     rec.code_addr = (uintptr_t)start;
     rec.nr_entry = 1;
     for (insn = 0; insn < icount; insn++) {
         if (q[insn].file) {
             rec.p.total_size += sizeof(ent) + strlen(q[insn].file) + 1;
             rec.nr_entry++;
         }
     }
     fwrite(&rec, sizeof(rec), 1, jitdump);

     /* Write the main debug entries. */
     for (insn = 0; insn < icount; insn++) {
         if (q[insn].file) {
             get_host_pc_size(&host_pc, NULL, start, insn);
             ent.addr = host_pc;
             ent.lineno = q[insn].line;
             ent.discrim = 0;
             fwrite(&ent, sizeof(ent), 1, jitdump);
             fwrite(q[insn].file, strlen(q[insn].file) + 1, 1, jitdump);
         }
     }

     /* Write the trailing debug_entry. */
     ent.addr = (uintptr_t)start + tcg_ctx->gen_insn_end_off[icount - 1];
     ent.lineno = 0;
     ent.discrim = 0;
     fwrite(&ent, sizeof(ent), 1, jitdump);
     fwrite("", 1, 1, jitdump);
 }

 /* Write a JIT_CODE_LOAD jitdump entry. */
 static void write_jr_code_load(const void *start, uint16_t host_size,
                                const struct debuginfo_query *q)
 {
     static uint64_t code_index;
     struct jr_code_load rec;
     const char *symbol;
     size_t symbol_size;

     symbol = pretty_symbol(q, &symbol_size);
     rec.p.id = JIT_CODE_LOAD;
     rec.p.total_size = sizeof(rec) + symbol_size + host_size;
     rec.p.timestamp = get_clock();
     rec.pid = getpid();
     rec.tid = qemu_get_thread_id();
     rec.vma = (uintptr_t)start;
     rec.code_addr = (uintptr_t)start;
     rec.code_size = host_size;
     rec.code_index = code_index++;
     fwrite(&rec, sizeof(rec), 1, jitdump);
     fwrite(symbol, symbol_size, 1, jitdump);
     fwrite(start, host_size, 1, jitdump);
 }

 void perf_report_code(uint64_t guest_pc, TranslationBlock *tb,
                       const void *start)
 {
     struct debuginfo_query *q;
     size_t insn;

     if (!perfmap && !jitdump) {
         return;
     }

     q = g_try_malloc0_n(tb->icount, sizeof(*q));
     if (!q) {
         return;
     }

     debuginfo_lock();

     /* Query debuginfo for each guest instruction. */
     for (insn = 0; insn < tb->icount; insn++) {
         /* FIXME: This replicates the restore_state_to_opc() logic. */
         q[insn].address = tcg_ctx->gen_insn_data[insn][0];
         if (tb_cflags(tb) & CF_PCREL) {
             q[insn].address |= (guest_pc & TARGET_PAGE_MASK);
         } else {
 #if defined(TARGET_I386)
             q[insn].address -= tb->cs_base;
 #endif
         }
         q[insn].flags = DEBUGINFO_SYMBOL | (jitdump ? DEBUGINFO_LINE : 0);
     }
     debuginfo_query(q, tb->icount);

     /* Emit perfmap entries if needed. */
     if (perfmap) {
         flockfile(perfmap);
         for (insn = 0; insn < tb->icount; insn++) {
             write_perfmap_entry(start, insn, &q[insn]);
         }
         funlockfile(perfmap);
     }

     /* Emit jitdump entries if needed. */
     if (jitdump) {
         flockfile(jitdump);
         write_jr_code_debug_info(start, q, tb->icount);
         write_jr_code_load(start, tcg_ctx->gen_insn_end_off[tb->icount - 1],
                            q);
         funlockfile(jitdump);
     }

     debuginfo_unlock();
     g_free(q);
 }

 void perf_exit(void)
 {
     if (perfmap) {
         fclose(perfmap);
         perfmap = NULL;
     }

     if (jitdump) {
         fclose(jitdump);
         jitdump = NULL;
     }
 }
	/*
	* Linux perf perf-<pid>.map and jit-<pid>.dump integration.
	*
	* The jitdump spec can be found at [1].
	*
	* [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/plain/tools/perf/Documentation/jitdump-specification.txt
	*
	* SPDX-License-Identifier: GPL-2.0-or-later
	*/

	#include "qemu/osdep.h"
	#include "elf.h"
	#include "exec/exec-all.h"
	#include "qemu/timer.h"
	#include "tcg/tcg.h"

	#include "debuginfo.h"
	#include "perf.h"

	static FILE safe_fopen_w(const char path)
	{
	int saved_errno;
	FILE *f;
	int fd;

	/* Delete the old file, if any. */
	unlink(path);

	/* Avoid symlink attacks by using O_CREAT \| O_EXCL. */
	fd = open(path, O_RDWR \| O_CREAT \| O_EXCL, S_IRUSR \| S_IWUSR);
	if (fd == -1) {
	return NULL;
	}

	/* Convert fd to FILE. /
	f = fdopen(fd, "w");
	if (f == NULL) {
	saved_errno = errno;
	close(fd);
	errno = saved_errno;
	return NULL;
	}

	return f;
	}

	static FILE *perfmap;

	void perf_enable_perfmap(void)
	{
	char map_file[32];

	snprintf(map_file, sizeof(map_file), "/tmp/perf-%d.map", getpid());
	perfmap = safe_fopen_w(map_file);
	if (perfmap == NULL) {
	warn_report("Could not open %s: %s, proceeding without perfmap",
	map_file, strerror(errno));
	}
	}

	/* Get PC and size of code JITed for guest instruction #INSN. */
	static void get_host_pc_size(uintptr_t host_pc, uint16_t host_size,
	const void *start, size_t insn)
	{
	uint16_t start_off = insn ? tcg_ctx->gen_insn_end_off[insn - 1] : 0;

	if (host_pc) {
	*host_pc = (uintptr_t)start + start_off;
	}
	if (host_size) {
	*host_size = tcg_ctx->gen_insn_end_off[insn] - start_off;
	}
	}

	static const char pretty_symbol(const struct debuginfo_query q, size_t *len)
	{
	static __thread char buf[64];
	int tmp;

	if (!q->symbol) {
	tmp = snprintf(buf, sizeof(buf), "guest-0x%"PRIx64, q->address);
	if (len) {
	*len = MIN(tmp + 1, sizeof(buf));
	}
	return buf;
	}

	if (!q->offset) {
	if (len) {
	*len = strlen(q->symbol) + 1;
	}
	return q->symbol;
	}

	tmp = snprintf(buf, sizeof(buf), "%s+0x%"PRIx64, q->symbol, q->offset);
	if (len) {
	*len = MIN(tmp + 1, sizeof(buf));
	}
	return buf;
	}

	static void write_perfmap_entry(const void *start, size_t insn,
	const struct debuginfo_query *q)
	{
	uint16_t host_size;
	uintptr_t host_pc;

	get_host_pc_size(&host_pc, &host_size, start, insn);
	fprintf(perfmap, "%"PRIxPTR" %"PRIx16" %s\n",
	host_pc, host_size, pretty_symbol(q, NULL));
	}

	static FILE *jitdump;

	#define JITHEADER_MAGIC 0x4A695444
	#define JITHEADER_VERSION 1

	struct jitheader {
	uint32_t magic;
	uint32_t version;
	uint32_t total_size;
	uint32_t elf_mach;
	uint32_t pad1;
	uint32_t pid;
	uint64_t timestamp;
	uint64_t flags;
	};

	enum jit_record_type {
	JIT_CODE_LOAD = 0,
	JIT_CODE_DEBUG_INFO = 2,
	};

	struct jr_prefix {
	uint32_t id;
	uint32_t total_size;
	uint64_t timestamp;
	};

	struct jr_code_load {
	struct jr_prefix p;

	uint32_t pid;
	uint32_t tid;
	uint64_t vma;
	uint64_t code_addr;
	uint64_t code_size;
	uint64_t code_index;
	};

	struct debug_entry {
	uint64_t addr;
	int lineno;
	int discrim;
	const char name[];
	};

	struct jr_code_debug_info {
	struct jr_prefix p;

	uint64_t code_addr;
	uint64_t nr_entry;
	struct debug_entry entries[];
	};

	static uint32_t get_e_machine(void)
	{
	Elf64_Ehdr elf_header;
	FILE *exe;
	size_t n;

	QEMU_BUILD_BUG_ON(offsetof(Elf32_Ehdr, e_machine) !=
	offsetof(Elf64_Ehdr, e_machine));

	exe = fopen("/proc/self/exe", "r");
	if (exe == NULL) {
	return EM_NONE;
	}

	n = fread(&elf_header, sizeof(elf_header), 1, exe);
	fclose(exe);
	if (n != 1) {
	return EM_NONE;
	}

	return elf_header.e_machine;
	}

	void perf_enable_jitdump(void)
	{
	struct jitheader header;
	char jitdump_file[32];
	void *perf_marker;

	if (!use_rt_clock) {
	warn_report("CLOCK_MONOTONIC is not available, proceeding without jitdump");
	return;
	}

	snprintf(jitdump_file, sizeof(jitdump_file), "jit-%d.dump", getpid());
	jitdump = safe_fopen_w(jitdump_file);
	if (jitdump == NULL) {
	warn_report("Could not open %s: %s, proceeding without jitdump",
	jitdump_file, strerror(errno));
	return;
	}

	/*
	* `perf inject` will see that the mapped file name in the corresponding
	* PERF_RECORD_MMAP or PERF_RECORD_MMAP2 event is of the form jit-%d.dump
	* and will process it as a jitdump file.
	*/
	perf_marker = mmap(NULL, qemu_real_host_page_size(), PROT_READ \| PROT_EXEC,
	MAP_PRIVATE, fileno(jitdump), 0);
	if (perf_marker == MAP_FAILED) {
	warn_report("Could not map %s: %s, proceeding without jitdump",
	jitdump_file, strerror(errno));
	fclose(jitdump);
	jitdump = NULL;
	return;
	}

	header.magic = JITHEADER_MAGIC;
	header.version = JITHEADER_VERSION;
	header.total_size = sizeof(header);
	header.elf_mach = get_e_machine();
	header.pad1 = 0;
	header.pid = getpid();
	header.timestamp = get_clock();
	header.flags = 0;
	fwrite(&header, sizeof(header), 1, jitdump);
	}

	void perf_report_prologue(const void *start, size_t size)
	{
	if (perfmap) {
	fprintf(perfmap, "%"PRIxPTR" %zx tcg-prologue-buffer\n",
	(uintptr_t)start, size);
	}
	}

	/* Write a JIT_CODE_DEBUG_INFO jitdump entry. */
	static void write_jr_code_debug_info(const void *start,
	const struct debuginfo_query *q,
	size_t icount)
	{
	struct jr_code_debug_info rec;
	struct debug_entry ent;
	uintptr_t host_pc;
	int insn;

	/* Write the header. */
	rec.p.id = JIT_CODE_DEBUG_INFO;
	rec.p.total_size = sizeof(rec) + sizeof(ent) + 1;
	rec.p.timestamp = get_clock();
	rec.code_addr = (uintptr_t)start;
	rec.nr_entry = 1;
	for (insn = 0; insn < icount; insn++) {
	if (q[insn].file) {
	rec.p.total_size += sizeof(ent) + strlen(q[insn].file) + 1;
	rec.nr_entry++;
	}
	}
	fwrite(&rec, sizeof(rec), 1, jitdump);

	/* Write the main debug entries. */
	for (insn = 0; insn < icount; insn++) {
	if (q[insn].file) {
	get_host_pc_size(&host_pc, NULL, start, insn);
	ent.addr = host_pc;
	ent.lineno = q[insn].line;
	ent.discrim = 0;
	fwrite(&ent, sizeof(ent), 1, jitdump);
	fwrite(q[insn].file, strlen(q[insn].file) + 1, 1, jitdump);
	}
	}

	/* Write the trailing debug_entry. */
	ent.addr = (uintptr_t)start + tcg_ctx->gen_insn_end_off[icount - 1];
	ent.lineno = 0;
	ent.discrim = 0;
	fwrite(&ent, sizeof(ent), 1, jitdump);
	fwrite("", 1, 1, jitdump);
	}

	/* Write a JIT_CODE_LOAD jitdump entry. */
	static void write_jr_code_load(const void *start, uint16_t host_size,
	const struct debuginfo_query *q)
	{
	static uint64_t code_index;
	struct jr_code_load rec;
	const char *symbol;
	size_t symbol_size;

	symbol = pretty_symbol(q, &symbol_size);
	rec.p.id = JIT_CODE_LOAD;
	rec.p.total_size = sizeof(rec) + symbol_size + host_size;
	rec.p.timestamp = get_clock();
	rec.pid = getpid();
	rec.tid = qemu_get_thread_id();
	rec.vma = (uintptr_t)start;
	rec.code_addr = (uintptr_t)start;
	rec.code_size = host_size;
	rec.code_index = code_index++;
	fwrite(&rec, sizeof(rec), 1, jitdump);
	fwrite(symbol, symbol_size, 1, jitdump);
	fwrite(start, host_size, 1, jitdump);
	}

	void perf_report_code(uint64_t guest_pc, TranslationBlock *tb,
	const void *start)
	{
	struct debuginfo_query *q;
	size_t insn;

	if (!perfmap && !jitdump) {
	return;
	}

	q = g_try_malloc0_n(tb->icount, sizeof(*q));
	if (!q) {
	return;
	}

	debuginfo_lock();

	/* Query debuginfo for each guest instruction. */
	for (insn = 0; insn < tb->icount; insn++) {
	/* FIXME: This replicates the restore_state_to_opc() logic. */
	q[insn].address = tcg_ctx->gen_insn_data[insn][0];
	if (tb_cflags(tb) & CF_PCREL) {
	q[insn].address \|= (guest_pc & TARGET_PAGE_MASK);
	} else {
	#if defined(TARGET_I386)
	q[insn].address -= tb->cs_base;
	#endif
	}
	q[insn].flags = DEBUGINFO_SYMBOL \| (jitdump ? DEBUGINFO_LINE : 0);
	}
	debuginfo_query(q, tb->icount);

	/* Emit perfmap entries if needed. */
	if (perfmap) {
	flockfile(perfmap);
	for (insn = 0; insn < tb->icount; insn++) {
	write_perfmap_entry(start, insn, &q[insn]);
	}
	funlockfile(perfmap);
	}

	/* Emit jitdump entries if needed. */
	if (jitdump) {
	flockfile(jitdump);
	write_jr_code_debug_info(start, q, tb->icount);
	write_jr_code_load(start, tcg_ctx->gen_insn_end_off[tb->icount - 1],
	q);
	funlockfile(jitdump);
	}

	debuginfo_unlock();
	g_free(q);
	}

	void perf_exit(void)
	{
	if (perfmap) {
	fclose(perfmap);
	perfmap = NULL;
	}

	if (jitdump) {
	fclose(jitdump);
	jitdump = NULL;
	}
	}