Alex Bennée <alex.ben...@linaro.org> writes:
> 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.
>
> Cc: Akihiko Odaki <akihiko.od...@daynix.com>
> Based-On: <20231025093128.33116-19-akihiko.od...@daynix.com>
> Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
>
> ---
> vAJB:
>
> Changes for the new API with a simpler glob based "reg" specifier
> which can be specified multiple times.
> +/*
> + * 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) {
> + GPtrArray *registers = g_ptr_array_new();
> +
> + /* For each pattern add the register definitions */
> + for (int p = 0; p < rmatches->len; p++) {
> + g_autoptr(GArray) reg_list =
> + qemu_plugin_find_registers(vcpu_index,
> rmatches->pdata[p]);
> + if (reg_list && reg_list->len) {
> + for (int r = 0; r < reg_list->len; r++) {
> + Register *reg =
> + init_vcpu_register(vcpu_index,
> + &g_array_index(reg_list,
> +
> qemu_plugin_reg_descriptor, r));
> + g_ptr_array_add(registers, reg);
> + }
> + }
> + }
> + cpus[num_cpus].registers = registers;
Note to self:
modified contrib/plugins/execlog.c
@@ -250,6 +250,8 @@ static void vcpu_init(qemu_plugin_id_t id, unsigned int
vcpu_index)
}
}
cpus[num_cpus].registers = registers;
+ } else {
+ cpus[num_cpus].registers = NULL;
}
num_cpus++;
}
> + }
> + 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 +291,18 @@ static void parse_vaddr_match(char *match)
> g_array_append_val(amatches, v);
> }
--
Alex Bennée
Virtualisation Tech Lead @ Linaro
