From 7c10cb38ccb86a0e56fff32bb348aa4b34e17e10 Mon Sep 17 00:00:00 2001 From: Ilya Leoshkevich Date: Thu, 12 Jan 2023 16:20:12 +0100 Subject: [PATCH] accel/tcg: Add debuginfo support Add libdw-based functions for loading and querying debuginfo. Load debuginfo from the system and the linux-user loaders. This is useful for the upcoming perf support, which can then put human-readable guest symbols instead of raw guest PCs into perfmap and jitdump files. Signed-off-by: Ilya Leoshkevich Message-Id: <20230112152013.125680-3-iii@linux.ibm.com> Signed-off-by: Richard Henderson --- accel/tcg/debuginfo.c | 96 ++++++++++++++++++++++++++++++++++++++++++ accel/tcg/debuginfo.h | 77 +++++++++++++++++++++++++++++++++ accel/tcg/meson.build | 1 + hw/core/loader.c | 5 +++ linux-user/elfload.c | 3 ++ linux-user/meson.build | 1 + meson.build | 8 ++++ 7 files changed, 191 insertions(+) create mode 100644 accel/tcg/debuginfo.c create mode 100644 accel/tcg/debuginfo.h diff --git a/accel/tcg/debuginfo.c b/accel/tcg/debuginfo.c new file mode 100644 index 0000000000..71c66d04d1 --- /dev/null +++ b/accel/tcg/debuginfo.c @@ -0,0 +1,96 @@ +/* + * Debug information support. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#include "qemu/osdep.h" +#include "qemu/lockable.h" + +#include + +#include "debuginfo.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/accel/tcg/debuginfo.h b/accel/tcg/debuginfo.h new file mode 100644 index 0000000000..7542cfe6e0 --- /dev/null +++ b/accel/tcg/debuginfo.h @@ -0,0 +1,77 @@ +/* + * Debug information support. + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#ifndef ACCEL_TCG_DEBUGINFO_H +#define ACCEL_TCG_DEBUGINFO_H + +/* + * Debuginfo describing a certain address. + */ +struct debuginfo_query { + uint64_t address; /* Input: address. */ + int flags; /* Input: debuginfo subset. */ + const char *symbol; /* Symbol that the address is part of. */ + uint64_t offset; /* Offset from the symbol. */ + const char *file; /* Source file associated with the address. */ + int line; /* Line number in the source file. */ +}; + +/* + * Debuginfo subsets. + */ +#define DEBUGINFO_SYMBOL BIT(1) +#define DEBUGINFO_LINE BIT(2) + +#if defined(CONFIG_TCG) && defined(CONFIG_LIBDW) +/* + * Load debuginfo for the specified guest ELF image. + * Return true on success, false on failure. + */ +void debuginfo_report_elf(const char *name, int fd, uint64_t bias); + +/* + * Take the debuginfo lock. + */ +void debuginfo_lock(void); + +/* + * Fill each on N Qs with the debuginfo about Q->ADDRESS as specified by + * Q->FLAGS: + * + * - DEBUGINFO_SYMBOL: update Q->SYMBOL and Q->OFFSET. If symbol debuginfo is + * missing, then leave them as is. + * - DEBUINFO_LINE: update Q->FILE and Q->LINE. If line debuginfo is missing, + * then leave them as is. + * + * This function must be called under the debuginfo lock. The results can be + * accessed only until the debuginfo lock is released. + */ +void debuginfo_query(struct debuginfo_query *q, size_t n); + +/* + * Release the debuginfo lock. + */ +void debuginfo_unlock(void); +#else +static inline void debuginfo_report_elf(const char *image_name, int image_fd, + uint64_t load_bias) +{ +} + +static inline void debuginfo_lock(void) +{ +} + +static inline void debuginfo_query(struct debuginfo_query *q, size_t n) +{ +} + +static inline void debuginfo_unlock(void) +{ +} +#endif + +#endif diff --git a/accel/tcg/meson.build b/accel/tcg/meson.build index 75e1dffb4d..55b3b4dd7e 100644 --- a/accel/tcg/meson.build +++ b/accel/tcg/meson.build @@ -12,6 +12,7 @@ tcg_ss.add(files( tcg_ss.add(when: 'CONFIG_USER_ONLY', if_true: files('user-exec.c')) tcg_ss.add(when: 'CONFIG_SOFTMMU', if_false: files('user-exec-stub.c')) tcg_ss.add(when: 'CONFIG_PLUGIN', if_true: [files('plugin-gen.c')]) +tcg_ss.add(when: libdw, if_true: files('debuginfo.c')) specific_ss.add_all(when: 'CONFIG_TCG', if_true: tcg_ss) specific_ss.add(when: ['CONFIG_SOFTMMU', 'CONFIG_TCG'], if_true: files( diff --git a/hw/core/loader.c b/hw/core/loader.c index 0548830733..55dbe2e199 100644 --- a/hw/core/loader.c +++ b/hw/core/loader.c @@ -61,6 +61,7 @@ #include "hw/boards.h" #include "qemu/cutils.h" #include "sysemu/runstate.h" +#include "accel/tcg/debuginfo.h" #include @@ -503,6 +504,10 @@ ssize_t load_elf_ram_sym(const char *filename, clear_lsb, data_swab, as, load_rom, sym_cb); } + if (ret != ELF_LOAD_FAILED) { + debuginfo_report_elf(filename, fd, 0); + } + fail: close(fd); return ret; diff --git a/linux-user/elfload.c b/linux-user/elfload.c index 20894b633f..5928c14dfc 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -19,6 +19,7 @@ #include "qemu/selfmap.h" #include "qapi/error.h" #include "target_signal.h" +#include "accel/tcg/debuginfo.h" #ifdef _ARCH_PPC64 #undef ARCH_DLINFO @@ -3261,6 +3262,8 @@ static void load_elf_image(const char *image_name, int image_fd, load_symbols(ehdr, image_fd, load_bias); } + debuginfo_report_elf(image_name, image_fd, load_bias); + mmap_unlock(); close(image_fd); diff --git a/linux-user/meson.build b/linux-user/meson.build index de4320af05..7171dc60be 100644 --- a/linux-user/meson.build +++ b/linux-user/meson.build @@ -22,6 +22,7 @@ linux_user_ss.add(files( 'uname.c', )) linux_user_ss.add(rt) +linux_user_ss.add(libdw) linux_user_ss.add(when: 'TARGET_HAS_BFLT', if_true: files('flatload.c')) linux_user_ss.add(when: 'TARGET_I386', if_true: files('vm86.c')) diff --git a/meson.build b/meson.build index 5d68a8fd23..6d212f6c8e 100644 --- a/meson.build +++ b/meson.build @@ -1648,6 +1648,12 @@ if libbpf.found() and not cc.links(''' endif endif +# libdw +libdw = dependency('libdw', + method: 'pkg-config', + kwargs: static_kwargs, + required: false) + ################# # config-host.h # ################# @@ -1923,6 +1929,7 @@ config_host_data.set('CONFIG_DBUS_DISPLAY', dbus_display) config_host_data.set('CONFIG_CFI', get_option('cfi')) config_host_data.set('CONFIG_SELINUX', selinux.found()) config_host_data.set('CONFIG_XEN_BACKEND', xen.found()) +config_host_data.set('CONFIG_LIBDW', libdw.found()) if xen.found() # protect from xen.version() having less than three components xen_version = xen.version().split('.') + ['0', '0'] @@ -3976,6 +3983,7 @@ summary_info += {'libudev': libudev} # Dummy dependency, keep .found() summary_info += {'FUSE lseek': fuse_lseek.found()} summary_info += {'selinux': selinux} +summary_info += {'libdw': libdw} summary(summary_info, bool_yn: true, section: 'Dependencies') if not supported_cpus.contains(cpu)