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plugins: extend execlog to filter matches 

Sometimes the whole execlog is just two much so add the ability to
filter by instruction opcode or address.

[AJB: this shows for example

 qemu-system-aarch64 -display none -serial mon:stdio \
   -M virt -cpu max \
   -semihosting-config enable=on \
   -kernel ./tests/tcg/aarch64-softmmu/memory-sve \
   -plugin ./contrib/plugins/libexeclog.so,ifilter=st1w,afilter=0x40001808 -d plugin -D plugin.out

the st1w SVE instruction is not instrumenting its stores.]

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alexandre Iooss <erdnaxe@crans.org>
Cc: Robert Henry <robhenry@microsoft.com>
Cc: Aaron Lindsay <aaron@os.amperecomputing.com>
Message-Id: <20220929114231.583801-36-alex.bennee@linaro.org>
master
Alex Bennée 2022-09-29 12:42:15 +01:00
parent 90bbf9d9db
commit b7855bf65f
2 changed files with 90 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

96
contrib/plugins/execlog.c
View File

@ -20,6 +20,9 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_version = QEMU_PLUGIN_VERSION;
/* Store last executed instruction on each vCPU as a GString */
GArray *last_exec;
static GPtrArray *imatches;
static GArray *amatches;
/**
* Add memory read or write information to current instruction log
*/
@ -85,12 +88,13 @@ static void vcpu_insn_exec(unsigned int cpu_index, void *udata)
static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
{
struct qemu_plugin_insn *insn;
uint64_t insn_vaddr;
uint32_t insn_opcode;
char *insn_disas;
bool skip = (imatches || amatches) ? true : false;
size_t n = qemu_plugin_tb_n_insns(tb);
for (size_t i = 0; i < n; i++) {
char *insn_disas;
uint64_t insn_vaddr;
/*
* `insn` is shared between translations in QEMU, copy needed data here.
* `output` is never freed as it might be used multiple times during
@ -99,20 +103,52 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
* a limitation for CISC architectures.
*/
insn = qemu_plugin_tb_get_insn(tb, i);
insn_vaddr = qemu_plugin_insn_vaddr(insn);
insn_opcode = *((uint32_t *)qemu_plugin_insn_data(insn));
insn_disas = qemu_plugin_insn_disas(insn);
char *output = g_strdup_printf("0x%"PRIx64", 0x%"PRIx32", \"%s\"",
insn_vaddr, insn_opcode, insn_disas);
insn_vaddr = qemu_plugin_insn_vaddr(insn);
/* Register callback on memory read or write */
qemu_plugin_register_vcpu_mem_cb(insn, vcpu_mem,
QEMU_PLUGIN_CB_NO_REGS,
QEMU_PLUGIN_MEM_RW, NULL);
/*
* 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.
*/
if (skip && imatches) {
int j;
for (j = 0; j < imatches->len && skip; j++) {
char *m = g_ptr_array_index(imatches, j);
if (g_str_has_prefix(insn_disas, m)) {
skip = false;
}
}
}
if (skip && amatches) {
int j;
for (j = 0; j < amatches->len && skip; j++) {
uint64_t v = g_array_index(amatches, uint64_t, j);
if (v == insn_vaddr) {
skip = false;
}
}
}
if (skip) {
g_free(insn_disas);
} else {
uint32_t insn_opcode;
insn_opcode = *((uint32_t *)qemu_plugin_insn_data(insn));
char *output = g_strdup_printf("0x%"PRIx64", 0x%"PRIx32", \"%s\"",
insn_vaddr, insn_opcode, insn_disas);
/* Register callback on memory read or write */
qemu_plugin_register_vcpu_mem_cb(insn, vcpu_mem,
QEMU_PLUGIN_CB_NO_REGS,
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);
}
/* Register callback on instruction */
qemu_plugin_register_vcpu_insn_exec_cb(insn, vcpu_insn_exec,
QEMU_PLUGIN_CB_NO_REGS, output);
}
}
@ -132,6 +168,25 @@ static void plugin_exit(qemu_plugin_id_t id, void *p)
}
}
/* Add a match to the array of matches */
static void parse_insn_match(char *match)
{
if (!imatches) {
imatches = g_ptr_array_new();
}
g_ptr_array_add(imatches, match);
}
static void parse_vaddr_match(char *match)
{
uint64_t v = g_ascii_strtoull(match, NULL, 16);
if (!amatches) {
amatches = g_array_new(false, true, sizeof(uint64_t));
}
g_array_append_val(amatches, v);
}
/**
* Install the plugin
*/
@ -145,6 +200,19 @@ QEMU_PLUGIN_EXPORT int qemu_plugin_install(qemu_plugin_id_t id,
*/
last_exec = g_array_new(FALSE, FALSE, sizeof(GString *));
for (int i = 0; i < argc; i++) {
char *opt = argv[i];
g_autofree char **tokens = g_strsplit(opt, "=", 2);
if (g_strcmp0(tokens[0], "ifilter") == 0) {
parse_insn_match(tokens[1]);
} else if (g_strcmp0(tokens[0], "afilter") == 0) {
parse_vaddr_match(tokens[1]);
} else {
fprintf(stderr, "option parsing failed: %s\n", opt);
return -1;
}
}
/* Register translation block and exit callbacks */
qemu_plugin_register_vcpu_tb_trans_cb(id, vcpu_tb_trans);
qemu_plugin_register_atexit_cb(id, plugin_exit, NULL);

9
docs/devel/tcg-plugins.rst
View File

@ -346,7 +346,7 @@ The execlog tool traces executed instructions with memory access. It can be used
for debugging and security analysis purposes.
Please be aware that this will generate a lot of output.
The plugin takes no argument::
The plugin needs default argument::
qemu-system-arm $(QEMU_ARGS) \
-plugin ./contrib/plugins/libexeclog.so -d plugin
@ -364,6 +364,13 @@ which will output an execution trace following this structure::
0, 0xd34, 0xf9c8f000, "bl #0x10c8"
0, 0x10c8, 0xfff96c43, "ldr r3, [r0, #0x44]", load, 0x200000e4, RAM
the output can be filtered to only track certain instructions or
addresses using the `ifilter` or `afilter` options. You can stack the
arguments if required::
qemu-system-arm $(QEMU_ARGS) \
-plugin ./contrib/plugins/libexeclog.so,ifilter=st1w,afilter=0x40001808 -d plugin
- contrib/plugins/cache.c
Cache modelling plugin that measures the performance of a given L1 cache