With the new plugin register API we can now track changes to register values. Currently the implementation is fairly dumb which will slow down if a large number of register values are being tracked. This could be improved by only instrumenting instructions which mention registers we are interested in tracking.
Example usage: ./qemu-aarch64 -D plugin.log -d plugin \ -cpu max,sve256=on \ -plugin contrib/plugins/libexeclog.so,reg=sp,reg=z\* \ ./tests/tcg/aarch64-linux-user/sha512-sve will display in the execlog any changes to the stack pointer (sp) and the SVE Z registers. Signed-off-by: Alex Bennée <alex.ben...@linaro.org> Cc: Akihiko Odaki <akihiko.od...@daynix.com> Based-On: <20231025093128.33116-19-akihiko.od...@daynix.com> --- v3 - prefix 0x to register value v2 - we now do the glob-like search in the plugin itself. - fix some erroneous cpus->cpu vAJB: Changes for the new API with a simpler glob based "reg" specifier which can be specified multiple times. --- docs/devel/tcg-plugins.rst | 9 +- contrib/plugins/execlog.c | 189 ++++++++++++++++++++++++++++--------- 2 files changed, 153 insertions(+), 45 deletions(-) diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst index 81dcd43a612..3a0962723d7 100644 --- a/docs/devel/tcg-plugins.rst +++ b/docs/devel/tcg-plugins.rst @@ -497,6 +497,14 @@ arguments if required:: $ qemu-system-arm $(QEMU_ARGS) \ -plugin ./contrib/plugins/libexeclog.so,ifilter=st1w,afilter=0x40001808 -d plugin +This plugin can also dump registers when they change value. Specify the name of the +registers with multiple ``reg`` options. You can also use glob style matching if you wish:: + + $ qemu-system-arm $(QEMU_ARGS) \ + -plugin ./contrib/plugins/libexeclog.so,reg=\*_el2,reg=sp -d plugin + +Be aware that each additional register to check will slow down execution quite considerably. + - contrib/plugins/cache.c Cache modelling plugin that measures the performance of a given L1 cache @@ -583,4 +591,3 @@ The following API is generated from the inline documentation in include the full kernel-doc annotations. .. kernel-doc:: include/qemu/qemu-plugin.h - diff --git a/contrib/plugins/execlog.c b/contrib/plugins/execlog.c index f262e5555eb..c20e88a6941 100644 --- a/contrib/plugins/execlog.c +++ b/contrib/plugins/execlog.c @@ -1,7 +1,7 @@ /* * Copyright (C) 2021, Alexandre Iooss <erdn...@crans.org> * - * Log instruction execution with memory access. + * Log instruction execution with memory access and register changes * * License: GNU GPL, version 2 or later. * See the COPYING file in the top-level directory. @@ -15,30 +15,29 @@ #include <qemu-plugin.h> +typedef struct { + struct qemu_plugin_register *handle; + GByteArray *last; + GByteArray *new; + const char *name; +} Register; + +typedef struct CPU { + /* Store last executed instruction on each vCPU as a GString */ + GString *last_exec; + /* Ptr array of Register */ + GPtrArray *registers; +} CPU; + QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION; -/* Store last executed instruction on each vCPU as a GString */ -static GPtrArray *last_exec; +static CPU *cpus; +static int num_cpus; static GRWLock expand_array_lock; static GPtrArray *imatches; static GArray *amatches; - -/* - * Expand last_exec array. - * - * As we could have multiple threads trying to do this we need to - * serialise the expansion under a lock. - */ -static void expand_last_exec(int cpu_index) -{ - g_rw_lock_writer_lock(&expand_array_lock); - while (cpu_index >= last_exec->len) { - GString *s = g_string_new(NULL); - g_ptr_array_add(last_exec, s); - } - g_rw_lock_writer_unlock(&expand_array_lock); -} +static GPtrArray *rmatches; /** * Add memory read or write information to current instruction log @@ -50,8 +49,8 @@ static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t info, /* Find vCPU in array */ g_rw_lock_reader_lock(&expand_array_lock); - g_assert(cpu_index < last_exec->len); - s = g_ptr_array_index(last_exec, cpu_index); + g_assert(cpu_index < num_cpus); + s = cpus[cpu_index].last_exec; g_rw_lock_reader_unlock(&expand_array_lock); /* Indicate type of memory access */ @@ -77,28 +76,46 @@ static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t info, */ static void vcpu_insn_exec(unsigned int cpu_index, void *udata) { - GString *s; + CPU *cpu; - /* Find or create vCPU in array */ g_rw_lock_reader_lock(&expand_array_lock); - if (cpu_index >= last_exec->len) { - g_rw_lock_reader_unlock(&expand_array_lock); - expand_last_exec(cpu_index); - g_rw_lock_reader_lock(&expand_array_lock); - } - s = g_ptr_array_index(last_exec, cpu_index); + g_assert(cpu_index < num_cpus); + cpu = &cpus[cpu_index]; g_rw_lock_reader_unlock(&expand_array_lock); /* Print previous instruction in cache */ - if (s->len) { - qemu_plugin_outs(s->str); + if (cpu->last_exec->len) { + if (cpu->registers) { + for (int n = 0; n < cpu->registers->len; n++) { + Register *reg = cpu->registers->pdata[n]; + int sz; + + g_byte_array_set_size(reg->new, 0); + sz = qemu_plugin_read_register(cpu_index, reg->handle, reg->new); + g_assert(sz == reg->last->len); + + if (memcmp(reg->last->data, reg->new->data, sz)) { + GByteArray *temp = reg->last; + g_string_append_printf(cpu->last_exec, ", %s -> 0x", reg->name); + /* TODO: handle BE properly */ + for (int i = sz; i >= 0; i--) { + g_string_append_printf(cpu->last_exec, "%02x", + reg->new->data[i]); + } + reg->last = reg->new; + reg->new = temp; + } + } + } + + qemu_plugin_outs(cpu->last_exec->str); qemu_plugin_outs("\n"); } /* Store new instruction in cache */ /* vcpu_mem will add memory access information to last_exec */ - g_string_printf(s, "%u, ", cpu_index); - g_string_append(s, (char *)udata); + g_string_printf(cpus[cpu_index].last_exec, "%u, ", cpu_index); + g_string_append(cpus[cpu_index].last_exec, (char *)udata); } /** @@ -167,8 +184,10 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) QEMU_PLUGIN_MEM_RW, NULL); /* Register callback on instruction */ - qemu_plugin_register_vcpu_insn_exec_cb(insn, vcpu_insn_exec, - QEMU_PLUGIN_CB_NO_REGS, output); + qemu_plugin_register_vcpu_insn_exec_cb( + insn, vcpu_insn_exec, + rmatches ? QEMU_PLUGIN_CB_R_REGS : QEMU_PLUGIN_CB_NO_REGS, + output); /* reset skip */ skip = (imatches || amatches); @@ -177,17 +196,86 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) } } +static Register *init_vcpu_register(int vcpu_index, + qemu_plugin_reg_descriptor *desc) +{ + Register *reg = g_new0(Register, 1); + int r; + + reg->handle = desc->handle; + reg->name = g_strdup(desc->name); + reg->last = g_byte_array_new(); + reg->new = g_byte_array_new(); + + /* read the initial value */ + r = qemu_plugin_read_register(vcpu_index, reg->handle, reg->last); + g_assert(r > 0); + return reg; +} + +static registers_init(int vcpu_index) +{ + GPtrArray *registers = g_ptr_array_new(); + g_autoptr(GArray) reg_list = qemu_plugin_get_registers(vcpu_index); + + if (reg_list && reg_list->len) { + /* + * Go through each register in the complete list and + * see if we want to track it. + */ + for (int r = 0; r < reg_list->len; r++) { + qemu_plugin_reg_descriptor *rd = &g_array_index( + reg_list, qemu_plugin_reg_descriptor, r); + for (int p = 0; p < rmatches->len; p++) { + g_autoptr(GPatternSpec) pat = g_pattern_spec_new(rmatches->pdata[p]); + if (g_pattern_match_string(pat, rd->name)) { + Register *reg = init_vcpu_register(vcpu_index, rd); + g_ptr_array_add(registers, reg); + } + } + } + } + cpus[num_cpus].registers = registers; +} + +/* + * Initialise a new vcpu/thread with: + * - last_exec tracking data + * - list of tracked registers + * - initial value of registers + * + * As we could have multiple threads trying to do this we need to + * serialise the expansion under a lock. + */ +static void vcpu_init(qemu_plugin_id_t id, unsigned int vcpu_index) +{ + g_rw_lock_writer_lock(&expand_array_lock); + + if (vcpu_index >= num_cpus) { + cpus = g_realloc_n(cpus, vcpu_index + 1, sizeof(*cpus)); + while (vcpu_index >= num_cpus) { + cpus[num_cpus].last_exec = g_string_new(NULL); + + /* Any registers to track? */ + if (rmatches && rmatches->len) { + registers_init(vcpu_index); + } + num_cpus++; + } + } + + g_rw_lock_writer_unlock(&expand_array_lock); +} + /** * On plugin exit, print last instruction in cache */ static void plugin_exit(qemu_plugin_id_t id, void *p) { guint i; - GString *s; - for (i = 0; i < last_exec->len; i++) { - s = g_ptr_array_index(last_exec, i); - if (s->str) { - qemu_plugin_outs(s->str); + for (i = 0; i < num_cpus; i++) { + if (cpus[i].last_exec->str) { + qemu_plugin_outs(cpus[i].last_exec->str); qemu_plugin_outs("\n"); } } @@ -212,6 +300,18 @@ static void parse_vaddr_match(char *match) g_array_append_val(amatches, v); } +/* + * We have to wait until vCPUs are started before we can check the + * patterns find anything. + */ +static void add_regpat(char *regpat) +{ + if (!rmatches) { + rmatches = g_ptr_array_new(); + } + g_ptr_array_add(rmatches, g_strdup(regpat)); +} + /** * Install the plugin */ @@ -224,9 +324,7 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, * we don't know the size before emulation. */ if (info->system_emulation) { - last_exec = g_ptr_array_sized_new(info->system.max_vcpus); - } else { - last_exec = g_ptr_array_new(); + cpus = g_new(CPU, info->system.max_vcpus); } for (int i = 0; i < argc; i++) { @@ -236,13 +334,16 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, parse_insn_match(tokens[1]); } else if (g_strcmp0(tokens[0], "afilter") == 0) { parse_vaddr_match(tokens[1]); + } else if (g_strcmp0(tokens[0], "reg") == 0) { + add_regpat(tokens[1]); } else { fprintf(stderr, "option parsing failed: %s\n", opt); return -1; } } - /* Register translation block and exit callbacks */ + /* Register init, translation block and exit callbacks */ + qemu_plugin_register_vcpu_init_cb(id, vcpu_init); qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans); qemu_plugin_register_atexit_cb(id, plugin_exit, NULL); -- 2.39.2