| Message ID | 20240122145610.413836-20-alex.bennee@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | plugin updates (register access) for 9.0 (pre-PR?) | expand |
On 1/22/24 18:56, Alex Bennée wrote: > 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. > > Message-Id: <20240103173349.398526-41-alex.bennee@linaro.org> > Signed-off-by: Alex Bennée <alex.bennee@linaro.org> > Cc: Akihiko Odaki <akihiko.odaki@daynix.com> > Based-On: <20231025093128.33116-19-akihiko.odaki@daynix.com> > > --- > v3 > - just use a GArray for the CPU array > - drop duplicate of cpu_index > --- > docs/devel/tcg-plugins.rst | 17 +- > contrib/plugins/execlog.c | 317 +++++++++++++++++++++++++++++++------ > 2 files changed, 282 insertions(+), 52 deletions(-) > > diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst > index 81dcd43a612..fa7421279f5 100644 > --- a/docs/devel/tcg-plugins.rst > +++ b/docs/devel/tcg-plugins.rst > @@ -497,6 +497,22 @@ 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. You can optimise the number of register > +checks done by using the rdisas option. This will only instrument > +instructions that mention the registers in question in disassembly. > +This is not foolproof as some instructions implicitly change > +instructions. You can use the ifilter to catch these cases: > + > + $ qemu-system-arm $(QEMU_ARGS) \ > + -plugin ./contrib/plugins/libexeclog.so,ifilter=msr,ifilter=blr,reg=x30,reg=\*_el1,rdisas=on > + > - contrib/plugins/cache.c > > Cache modelling plugin that measures the performance of a given L1 cache > @@ -583,4 +599,3 @@ 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..c26664c0ab3 100644 > --- a/contrib/plugins/execlog.c > +++ b/contrib/plugins/execlog.c > @@ -1,7 +1,7 @@ > /* > * Copyright (C) 2021, Alexandre Iooss <erdnaxe@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. > @@ -15,29 +15,40 @@ > > #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 GArray *cpus; > static GRWLock expand_array_lock; > > static GPtrArray *imatches; > static GArray *amatches; > +static GPtrArray *rmatches; > +static bool disas_assist; > +static GMutex add_reg_name_lock; > +static GPtrArray *all_reg_names; > > -/* > - * 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) > +static CPU *get_cpu(int vcpu_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); > + CPU *c; > + g_rw_lock_reader_lock(&expand_array_lock); > + c = &g_array_index(cpus, CPU, vcpu_index); > + g_rw_lock_reader_unlock(&expand_array_lock); > + > + return c; > } > > /** > @@ -46,13 +57,10 @@ static void expand_last_exec(int cpu_index) > static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t info, > uint64_t vaddr, void *udata) > { > - GString *s; > + CPU *c = get_cpu(cpu_index); > + GString *s = c->last_exec; > > /* 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_rw_lock_reader_unlock(&expand_array_lock); > > /* Indicate type of memory access */ > if (qemu_plugin_mem_is_store(info)) { > @@ -73,32 +81,91 @@ static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t info, > } > > /** > - * Log instruction execution > + * Log instruction execution, outputting the last one. > + * > + * vcpu_insn_exec() is a copy and paste of vcpu_insn_exec_with_regs() > + * without the checking of register values when we've attempted to > + * optimise with disas_assist. > */ > -static void vcpu_insn_exec(unsigned int cpu_index, void *udata) > +static void insn_check_regs(int vcpu_index, CPU *cpu) > { > - GString *s; > + for (int n = 0; n < cpu->registers->len; n++) { > + Register *reg = cpu->registers->pdata[n]; > + int sz; > > - /* 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); > + g_byte_array_set_size(reg->new, 0); > + sz = qemu_plugin_read_register(vcpu_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; > + } > + } > +} > + > +/* Log last instruction while checking registers */ > +static void vcpu_insn_exec_with_regs(unsigned int cpu_index, void *udata) > +{ > + CPU *cpu = get_cpu(cpu_index); > + > + /* Print previous instruction in cache */ > + if (cpu->last_exec->len) { > + if (cpu->registers) { > + insn_check_regs(cpu_index, cpu); > + } > + > + 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(cpu->last_exec, "%u, ", cpu_index); > + g_string_append(cpu->last_exec, (char *)udata); > +} > + > +/* Log last instruction while checking registers, ignore next */ > +static void vcpu_insn_exec_only_regs(unsigned int cpu_index, void *udata) > +{ > + CPU *cpu = get_cpu(cpu_index); > + > + /* Print previous instruction in cache */ > + if (cpu->last_exec->len) { > + if (cpu->registers) { > + insn_check_regs(cpu_index, cpu); > + } > + > + qemu_plugin_outs(cpu->last_exec->str); > + qemu_plugin_outs("\n"); > } > - s = g_ptr_array_index(last_exec, cpu_index); > - g_rw_lock_reader_unlock(&expand_array_lock); > + > + /* reset */ > + cpu->last_exec->len = 0; > +} > + > +/* Log last instruction without checking regs, setup next */ > +static void vcpu_insn_exec(unsigned int cpu_index, void *udata) > +{ > + CPU *cpu = get_cpu(cpu_index); > > /* Print previous instruction in cache */ > - if (s->len) { > - qemu_plugin_outs(s->str); > + if (cpu->last_exec->len) { > + 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(cpu->last_exec, "%u, ", cpu_index); > + g_string_append(cpu->last_exec, (char *)udata); > } > > /** > @@ -111,6 +178,8 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) > { > struct qemu_plugin_insn *insn; > bool skip = (imatches || amatches); > + bool check_regs_this = rmatches; > + bool check_regs_next = false; > > size_t n = qemu_plugin_tb_n_insns(tb); > for (size_t i = 0; i < n; i++) { > @@ -131,7 +200,8 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) > /* > * If we are filtering we better check out if we have any > * hits. The skip "latches" so we can track memory accesses nit: matches > - * after the instruction we care about. > + * after the instruction we care about. Also enable register > + * checking on the next instruction. > */ > if (skip && imatches) { > int j; > @@ -139,6 +209,7 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) > char *m = g_ptr_array_index(imatches, j); > if (g_str_has_prefix(insn_disas, m)) { > skip = false; > + check_regs_next = rmatches; > } > } > } > @@ -153,8 +224,39 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) > } > } > > + /* > + * Check the disassembly to see if a register we care about > + * will be affected by this instruction. This relies on the > + * dissembler doing something sensible for the registers we nit: disassembler > + * care about. > + */ > + if (disas_assist && rmatches) { > + check_regs_next = false; > + gchar *args = g_strstr_len(insn_disas, -1, " "); > + for (int n = 0; n < all_reg_names->len; n++) { > + gchar *reg = g_ptr_array_index(all_reg_names, n); > + if (g_strrstr(args, reg)) { > + check_regs_next = true; > + skip = false; > + } > + } > + } > + > + /* > + * We now have 3 choices: > + * > + * - Log insn > + * - Log insn while checking registers > + * - Don't log this insn but check if last insn changed registers > + */ > + > if (skip) { > - g_free(insn_disas); > + if (check_regs_this) { > + qemu_plugin_register_vcpu_insn_exec_cb(insn, > + vcpu_insn_exec_only_regs, > + QEMU_PLUGIN_CB_R_REGS, > + NULL); > + } > } else { > uint32_t insn_opcode; > insn_opcode = *((uint32_t *)qemu_plugin_insn_data(insn)); > @@ -167,30 +269,125 @@ 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); > + if (check_regs_this) { > + qemu_plugin_register_vcpu_insn_exec_cb( > + insn, vcpu_insn_exec_with_regs, > + QEMU_PLUGIN_CB_R_REGS, > + output); > + } else { > + qemu_plugin_register_vcpu_insn_exec_cb( > + insn, vcpu_insn_exec, > + QEMU_PLUGIN_CB_NO_REGS, > + output); > + } > > /* reset skip */ > skip = (imatches || amatches); > } > > + /* set regs for next */ > + if (disas_assist && rmatches) { > + check_regs_this = check_regs_next; > + } > + > + g_free(insn_disas); > } > } > > +static Register *init_vcpu_register(int vcpu_index, > + qemu_plugin_reg_descriptor *desc) > +{ > + Register *reg = g_new0(Register, 1); > + g_autofree gchar *lower = g_utf8_strdown(desc->name, -1); > + int r; > + > + reg->handle = desc->handle; > + reg->name = g_intern_string(lower); > + 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 GPtrArray *registers_init(int vcpu_index) > +{ > + g_autoptr(GPtrArray) registers = g_ptr_array_new(); > + g_autoptr(GArray) reg_list = qemu_plugin_get_registers(vcpu_index); > + > + if (rmatches && 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]); > + g_autofree gchar *rd_lower = g_utf8_strdown(rd->name, -1); > + if (g_pattern_match_string(pat, rd->name) || > + g_pattern_match_string(pat, rd_lower)) { > + Register *reg = init_vcpu_register(vcpu_index, rd); > + g_ptr_array_add(registers, reg); > + > + /* we need a list of regnames at TB translation time */ > + if (disas_assist) { > + g_mutex_lock(&add_reg_name_lock); > + if (!g_ptr_array_find(all_reg_names, reg->name, NULL)) { > + g_ptr_array_add(all_reg_names, reg->name); > + } > + g_mutex_unlock(&add_reg_name_lock); > + } > + } > + } > + } > + } > + > + return registers->len ? g_steal_pointer(®isters) : NULL; > +} > + > +/* > + * 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) > +{ > + CPU *c; > + > + g_rw_lock_writer_lock(&expand_array_lock); > + if (vcpu_index >= cpus->len) { > + g_array_set_size(cpus, vcpu_index + 1); > + } > + g_rw_lock_writer_unlock(&expand_array_lock); > + > + c = get_cpu(vcpu_index); > + c->last_exec = g_string_new(NULL); > + c->registers = registers_init(vcpu_index); > +} > + > /** > * 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); > + g_rw_lock_reader_lock(&expand_array_lock); > + for (i = 0; i < cpus->len; i++) { > + CPU *c = get_cpu(i); > + if (c->last_exec && c->last_exec->str) { > + qemu_plugin_outs(c->last_exec->str); > qemu_plugin_outs("\n"); > } > } > + g_rw_lock_reader_unlock(&expand_array_lock); > } > > /* Add a match to the array of matches */ > @@ -212,6 +409,18 @@ 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 > */ > @@ -223,11 +432,8 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, > * Initialize dynamic array to cache vCPU instruction. In user mode > * 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_array_sized_new(true, true, sizeof(CPU), > + info->system_emulation ? info->system.max_vcpus : 1); > > for (int i = 0; i < argc; i++) { > char *opt = argv[i]; > @@ -236,13 +442,22 @@ 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 if (g_strcmp0(tokens[0], "rdisas") == 0) { > + if (!qemu_plugin_bool_parse(tokens[0], tokens[1], &disas_assist)) { > + fprintf(stderr, "boolean argument parsing failed: %s\n", opt); > + return -1; > + } > + all_reg_names = g_ptr_array_new(); > } 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); > nit presented inline. In more, you can squash this commit from another series, which fixes warnings added by this change: (https://lore.kernel.org/qemu-devel/20240118032400.3762658-1-pierrick.bouvier@linaro.org/T/#m5674d8f363d2c9f01a5458080a19ad9934cfc453) Besides that, LGTM. Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst index 81dcd43a612..fa7421279f5 100644 --- a/docs/devel/tcg-plugins.rst +++ b/docs/devel/tcg-plugins.rst @@ -497,6 +497,22 @@ 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. You can optimise the number of register +checks done by using the rdisas option. This will only instrument +instructions that mention the registers in question in disassembly. +This is not foolproof as some instructions implicitly change +instructions. You can use the ifilter to catch these cases: + + $ qemu-system-arm $(QEMU_ARGS) \ + -plugin ./contrib/plugins/libexeclog.so,ifilter=msr,ifilter=blr,reg=x30,reg=\*_el1,rdisas=on + - contrib/plugins/cache.c Cache modelling plugin that measures the performance of a given L1 cache @@ -583,4 +599,3 @@ 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..c26664c0ab3 100644 --- a/contrib/plugins/execlog.c +++ b/contrib/plugins/execlog.c @@ -1,7 +1,7 @@ /* * Copyright (C) 2021, Alexandre Iooss <erdnaxe@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. @@ -15,29 +15,40 @@ #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 GArray *cpus; static GRWLock expand_array_lock; static GPtrArray *imatches; static GArray *amatches; +static GPtrArray *rmatches; +static bool disas_assist; +static GMutex add_reg_name_lock; +static GPtrArray *all_reg_names; -/* - * 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) +static CPU *get_cpu(int vcpu_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); + CPU *c; + g_rw_lock_reader_lock(&expand_array_lock); + c = &g_array_index(cpus, CPU, vcpu_index); + g_rw_lock_reader_unlock(&expand_array_lock); + + return c; } /** @@ -46,13 +57,10 @@ static void expand_last_exec(int cpu_index) static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t info, uint64_t vaddr, void *udata) { - GString *s; + CPU *c = get_cpu(cpu_index); + GString *s = c->last_exec; /* 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_rw_lock_reader_unlock(&expand_array_lock); /* Indicate type of memory access */ if (qemu_plugin_mem_is_store(info)) { @@ -73,32 +81,91 @@ static void vcpu_mem(unsigned int cpu_index, qemu_plugin_meminfo_t info, } /** - * Log instruction execution + * Log instruction execution, outputting the last one. + * + * vcpu_insn_exec() is a copy and paste of vcpu_insn_exec_with_regs() + * without the checking of register values when we've attempted to + * optimise with disas_assist. */ -static void vcpu_insn_exec(unsigned int cpu_index, void *udata) +static void insn_check_regs(int vcpu_index, CPU *cpu) { - GString *s; + for (int n = 0; n < cpu->registers->len; n++) { + Register *reg = cpu->registers->pdata[n]; + int sz; - /* 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); + g_byte_array_set_size(reg->new, 0); + sz = qemu_plugin_read_register(vcpu_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; + } + } +} + +/* Log last instruction while checking registers */ +static void vcpu_insn_exec_with_regs(unsigned int cpu_index, void *udata) +{ + CPU *cpu = get_cpu(cpu_index); + + /* Print previous instruction in cache */ + if (cpu->last_exec->len) { + if (cpu->registers) { + insn_check_regs(cpu_index, cpu); + } + + 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(cpu->last_exec, "%u, ", cpu_index); + g_string_append(cpu->last_exec, (char *)udata); +} + +/* Log last instruction while checking registers, ignore next */ +static void vcpu_insn_exec_only_regs(unsigned int cpu_index, void *udata) +{ + CPU *cpu = get_cpu(cpu_index); + + /* Print previous instruction in cache */ + if (cpu->last_exec->len) { + if (cpu->registers) { + insn_check_regs(cpu_index, cpu); + } + + qemu_plugin_outs(cpu->last_exec->str); + qemu_plugin_outs("\n"); } - s = g_ptr_array_index(last_exec, cpu_index); - g_rw_lock_reader_unlock(&expand_array_lock); + + /* reset */ + cpu->last_exec->len = 0; +} + +/* Log last instruction without checking regs, setup next */ +static void vcpu_insn_exec(unsigned int cpu_index, void *udata) +{ + CPU *cpu = get_cpu(cpu_index); /* Print previous instruction in cache */ - if (s->len) { - qemu_plugin_outs(s->str); + if (cpu->last_exec->len) { + 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(cpu->last_exec, "%u, ", cpu_index); + g_string_append(cpu->last_exec, (char *)udata); } /** @@ -111,6 +178,8 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) { struct qemu_plugin_insn *insn; bool skip = (imatches || amatches); + bool check_regs_this = rmatches; + bool check_regs_next = false; size_t n = qemu_plugin_tb_n_insns(tb); for (size_t i = 0; i < n; i++) { @@ -131,7 +200,8 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) /* * If we are filtering we better check out if we have any * hits. The skip "latches" so we can track memory accesses - * after the instruction we care about. + * after the instruction we care about. Also enable register + * checking on the next instruction. */ if (skip && imatches) { int j; @@ -139,6 +209,7 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) char *m = g_ptr_array_index(imatches, j); if (g_str_has_prefix(insn_disas, m)) { skip = false; + check_regs_next = rmatches; } } } @@ -153,8 +224,39 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb) } } + /* + * Check the disassembly to see if a register we care about + * will be affected by this instruction. This relies on the + * dissembler doing something sensible for the registers we + * care about. + */ + if (disas_assist && rmatches) { + check_regs_next = false; + gchar *args = g_strstr_len(insn_disas, -1, " "); + for (int n = 0; n < all_reg_names->len; n++) { + gchar *reg = g_ptr_array_index(all_reg_names, n); + if (g_strrstr(args, reg)) { + check_regs_next = true; + skip = false; + } + } + } + + /* + * We now have 3 choices: + * + * - Log insn + * - Log insn while checking registers + * - Don't log this insn but check if last insn changed registers + */ + if (skip) { - g_free(insn_disas); + if (check_regs_this) { + qemu_plugin_register_vcpu_insn_exec_cb(insn, + vcpu_insn_exec_only_regs, + QEMU_PLUGIN_CB_R_REGS, + NULL); + } } else { uint32_t insn_opcode; insn_opcode = *((uint32_t *)qemu_plugin_insn_data(insn)); @@ -167,30 +269,125 @@ 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); + if (check_regs_this) { + qemu_plugin_register_vcpu_insn_exec_cb( + insn, vcpu_insn_exec_with_regs, + QEMU_PLUGIN_CB_R_REGS, + output); + } else { + qemu_plugin_register_vcpu_insn_exec_cb( + insn, vcpu_insn_exec, + QEMU_PLUGIN_CB_NO_REGS, + output); + } /* reset skip */ skip = (imatches || amatches); } + /* set regs for next */ + if (disas_assist && rmatches) { + check_regs_this = check_regs_next; + } + + g_free(insn_disas); } } +static Register *init_vcpu_register(int vcpu_index, + qemu_plugin_reg_descriptor *desc) +{ + Register *reg = g_new0(Register, 1); + g_autofree gchar *lower = g_utf8_strdown(desc->name, -1); + int r; + + reg->handle = desc->handle; + reg->name = g_intern_string(lower); + 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 GPtrArray *registers_init(int vcpu_index) +{ + g_autoptr(GPtrArray) registers = g_ptr_array_new(); + g_autoptr(GArray) reg_list = qemu_plugin_get_registers(vcpu_index); + + if (rmatches && 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]); + g_autofree gchar *rd_lower = g_utf8_strdown(rd->name, -1); + if (g_pattern_match_string(pat, rd->name) || + g_pattern_match_string(pat, rd_lower)) { + Register *reg = init_vcpu_register(vcpu_index, rd); + g_ptr_array_add(registers, reg); + + /* we need a list of regnames at TB translation time */ + if (disas_assist) { + g_mutex_lock(&add_reg_name_lock); + if (!g_ptr_array_find(all_reg_names, reg->name, NULL)) { + g_ptr_array_add(all_reg_names, reg->name); + } + g_mutex_unlock(&add_reg_name_lock); + } + } + } + } + } + + return registers->len ? g_steal_pointer(®isters) : NULL; +} + +/* + * 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) +{ + CPU *c; + + g_rw_lock_writer_lock(&expand_array_lock); + if (vcpu_index >= cpus->len) { + g_array_set_size(cpus, vcpu_index + 1); + } + g_rw_lock_writer_unlock(&expand_array_lock); + + c = get_cpu(vcpu_index); + c->last_exec = g_string_new(NULL); + c->registers = registers_init(vcpu_index); +} + /** * 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); + g_rw_lock_reader_lock(&expand_array_lock); + for (i = 0; i < cpus->len; i++) { + CPU *c = get_cpu(i); + if (c->last_exec && c->last_exec->str) { + qemu_plugin_outs(c->last_exec->str); qemu_plugin_outs("\n"); } } + g_rw_lock_reader_unlock(&expand_array_lock); } /* Add a match to the array of matches */ @@ -212,6 +409,18 @@ 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 */ @@ -223,11 +432,8 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id, * Initialize dynamic array to cache vCPU instruction. In user mode * 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_array_sized_new(true, true, sizeof(CPU), + info->system_emulation ? info->system.max_vcpus : 1); for (int i = 0; i < argc; i++) { char *opt = argv[i]; @@ -236,13 +442,22 @@ 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 if (g_strcmp0(tokens[0], "rdisas") == 0) { + if (!qemu_plugin_bool_parse(tokens[0], tokens[1], &disas_assist)) { + fprintf(stderr, "boolean argument parsing failed: %s\n", opt); + return -1; + } + all_reg_names = g_ptr_array_new(); } 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);
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. Message-Id: <20240103173349.398526-41-alex.bennee@linaro.org> Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Cc: Akihiko Odaki <akihiko.odaki@daynix.com> Based-On: <20231025093128.33116-19-akihiko.odaki@daynix.com> --- v3 - just use a GArray for the CPU array - drop duplicate of cpu_index --- docs/devel/tcg-plugins.rst | 17 +- contrib/plugins/execlog.c | 317 +++++++++++++++++++++++++++++++------ 2 files changed, 282 insertions(+), 52 deletions(-)