accel/tcg: Move perf and debuginfo support to tcg/

tcg/ should not depend on accel/tcg/, but perf and debuginfo
support provided by the latter are being used by tcg/tcg.c.

Since that's the only user, move both to tcg/.

Suggested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20231212003837.64090-5-iii@linux.ibm.com>
Message-Id: <20240125054631.78867-5-philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

4 files changed, 483 insertions, 1 deletions

diff --git a/tcg/debuginfo.c b/tcg/debuginfo.c
new file mode 100644
index 0000000000..3753f7ef67
--- /dev/null
+++ b/tcg/debuginfo.c
@@ -0,0 +1,95 @@
+/*
+ * Debug information support.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/lockable.h"
+#include "tcg/debuginfo.h"
+
+#include <elfutils/libdwfl.h>
+
+static QemuMutex lock;
+static Dwfl *dwfl;
+static const Dwfl_Callbacks dwfl_callbacks = {
+    .find_elf = NULL,
+    .find_debuginfo = dwfl_standard_find_debuginfo,
+    .section_address = NULL,
+    .debuginfo_path = NULL,
+};
+
+__attribute__((constructor))
+static void debuginfo_init(void)
+{
+    qemu_mutex_init(&lock);
+}
+
+void debuginfo_report_elf(const char *name, int fd, uint64_t bias)
+{
+    QEMU_LOCK_GUARD(&lock);
+
+    if (dwfl) {
+        dwfl_report_begin_add(dwfl);
+    } else {
+        dwfl = dwfl_begin(&dwfl_callbacks);
+    }
+
+    if (dwfl) {
+        dwfl_report_elf(dwfl, name, name, fd, bias, true);
+        dwfl_report_end(dwfl, NULL, NULL);
+    }
+}
+
+void debuginfo_lock(void)
+{
+    qemu_mutex_lock(&lock);
+}
+
+void debuginfo_query(struct debuginfo_query *q, size_t n)
+{
+    const char *symbol, *file;
+    Dwfl_Module *dwfl_module;
+    Dwfl_Line *dwfl_line;
+    GElf_Off dwfl_offset;
+    GElf_Sym dwfl_sym;
+    size_t i;
+    int line;
+
+    if (!dwfl) {
+        return;
+    }
+
+    for (i = 0; i < n; i++) {
+        dwfl_module = dwfl_addrmodule(dwfl, q[i].address);
+        if (!dwfl_module) {
+            continue;
+        }
+
+        if (q[i].flags & DEBUGINFO_SYMBOL) {
+            symbol = dwfl_module_addrinfo(dwfl_module, q[i].address,
+                                          &dwfl_offset, &dwfl_sym,
+                                          NULL, NULL, NULL);
+            if (symbol) {
+                q[i].symbol = symbol;
+                q[i].offset = dwfl_offset;
+            }
+        }
+
+        if (q[i].flags & DEBUGINFO_LINE) {
+            dwfl_line = dwfl_module_getsrc(dwfl_module, q[i].address);
+            if (dwfl_line) {
+                file = dwfl_lineinfo(dwfl_line, NULL, &line, 0, NULL, NULL);
+                if (file) {
+                    q[i].file = file;
+                    q[i].line = line;
+                }
+            }
+        }
+    }
+}
+
+void debuginfo_unlock(void)
+{
+    qemu_mutex_unlock(&lock);
+}
diff --git a/tcg/meson.build b/tcg/meson.build
index 5afdec1e1a..8251589fd4 100644
--- a/tcg/meson.build
+++ b/tcg/meson.build
@@ -22,6 +22,11 @@ if get_option('tcg_interpreter')
   tcg_ss.add(files('tci.c'))
 endif
 
+tcg_ss.add(when: libdw, if_true: files('debuginfo.c'))
+if host_os == 'linux'
+  tcg_ss.add(files('perf.c'))
+endif
+
 tcg_ss = tcg_ss.apply({})
 
 libtcg_user = static_library('tcg_user',
diff --git a/tcg/perf.c b/tcg/perf.c
new file mode 100644
index 0000000000..412a987d95
--- /dev/null
+++ b/tcg/perf.c
@@ -0,0 +1,382 @@
+/*
+ * 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/target_page.h"
+#include "exec/translation-block.h"
+#include "qemu/timer.h"
+#include "tcg/debuginfo.h"
+#include "tcg/perf.h"
+#include "tcg/tcg.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;
+static size_t perf_marker_size;
+static void *perf_marker = MAP_FAILED;
+
+#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];
+
+    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_size = qemu_real_host_page_size();
+    perf_marker = mmap(NULL, perf_marker_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, start_words;
+    uint64_t *gen_insn_data;
+
+    if (!perfmap && !jitdump) {
+        return;
+    }
+
+    q = g_try_malloc0_n(tb->icount, sizeof(*q));
+    if (!q) {
+        return;
+    }
+
+    debuginfo_lock();
+
+    /* Query debuginfo for each guest instruction. */
+    gen_insn_data = tcg_ctx->gen_insn_data;
+    start_words = tcg_ctx->insn_start_words;
+
+    for (insn = 0; insn < tb->icount; insn++) {
+        /* FIXME: This replicates the restore_state_to_opc() logic. */
+        q[insn].address = gen_insn_data[insn * start_words + 0];
+        if (tb_cflags(tb) & CF_PCREL) {
+            q[insn].address |= (guest_pc & qemu_target_page_mask());
+        }
+        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 (perf_marker != MAP_FAILED) {
+        munmap(perf_marker, perf_marker_size);
+        perf_marker = MAP_FAILED;
+    }
+
+    if (jitdump) {
+        fclose(jitdump);
+        jitdump = NULL;
+    }
+}
diff --git a/tcg/tcg.c b/tcg/tcg.c
index e2c38f6d11..eeff4c1d51 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -55,7 +55,7 @@
 #include "tcg/tcg-ldst.h"
 #include "tcg/tcg-temp-internal.h"
 #include "tcg-internal.h"
-#include "accel/tcg/perf.h"
+#include "tcg/perf.h"
 #ifdef CONFIG_USER_ONLY
 #include "exec/user/guest-base.h"
 #endif