Re: [PATCH 3/3] plugins/execlog: add address range matching

[Alex Bennée]

Sven Schnelle <svens@stackframe.org> writes:

> Allow to match memory ranges with the address matches. This
> allows to give a range of adresses like '-dfilter=0-0x400'
> which would only log memory accesses between 0 and 400.
>
> Signed-off-by: Sven Schnelle <svens@stackframe.org>
> ---
>  contrib/plugins/execlog.c | 73 ++++++++++++++++++++++++++++++---------
>  1 file changed, 56 insertions(+), 17 deletions(-)
>
> diff --git a/contrib/plugins/execlog.c b/contrib/plugins/execlog.c
> index c89ebc08b6..b1b2a7baf1 100644
> --- a/contrib/plugins/execlog.c
> +++ b/contrib/plugins/execlog.c
> @@ -44,6 +44,11 @@ static bool disas_assist;
>  static GMutex add_reg_name_lock;
>  static GPtrArray *all_reg_names;
>  
> +struct address_match {
> +    uint64_t low;
> +    uint64_t high;
> +};
> +
>  static CPU *get_cpu(int vcpu_index)
>  {
>      CPU *c;
> @@ -54,11 +59,12 @@ static CPU *get_cpu(int vcpu_index)
>      return c;
>  }
>  
> -static bool match_vaddr(uint64_t vaddr)
> +static bool match_address_range(GArray *match, uint64_t vaddr)
>  {
> -    for (int i = 0; i < dmatches->len; i++) {
> -        uint64_t v = g_array_index(dmatches, uint64_t, i);
> -        if (v == vaddr) {
> +    for (int i = 0; i < match->len; i++) {
> +        struct address_match *m =
> +            g_array_index(match, struct address_match *, i);
> +        if (vaddr >= m->low && vaddr <= m->high) {
>              return true;
>          }
>      }
> @@ -74,9 +80,7 @@ static void vcpu_mem(unsigned int cpu_index, 
> qemu_plugin_meminfo_t info,
>      CPU *c = get_cpu(cpu_index);
>      GString *s = c->last_exec;
>  
> -    /* Find vCPU in array */
> -
> -    if (dmatches && !match_vaddr(vaddr)) {
> +    if (dmatches && !match_address_range(dmatches, vaddr)) {
>          return;
>      }
>      c->log = true;
> @@ -164,8 +168,10 @@ static void vcpu_insn_exec_only_regs(unsigned int 
> cpu_index, void *udata)
>              insn_check_regs(cpu);
>          }
>  
> -        qemu_plugin_outs(cpu->last_exec->str);
> -        qemu_plugin_outs("\n");
> +        if (cpu->log) {
> +            qemu_plugin_outs(cpu->last_exec->str);
> +            qemu_plugin_outs("\n");
> +        }
>      }
>  
>      /* reset */
> @@ -178,7 +184,7 @@ static void vcpu_insn_exec(unsigned int cpu_index, void 
> *udata)
>      CPU *cpu = get_cpu(cpu_index);
>  
>      /* Print previous instruction in cache */
> -    if (cpu->last_exec->len) {
> +    if (cpu->log && cpu->last_exec->len) {
>          qemu_plugin_outs(cpu->last_exec->str);
>          qemu_plugin_outs("\n");
>      }
> @@ -239,8 +245,7 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct 
> qemu_plugin_tb *tb)
>          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) {
> +                if (match_address_range(amatches, insn_vaddr)) {
>                      skip = false;
>                  }
>              }
> @@ -394,6 +399,17 @@ static void vcpu_init(qemu_plugin_id_t id, unsigned int 
> vcpu_index)
>      c->registers = registers_init(vcpu_index);
>  }
>  
> +static void free_matches(GArray *matches)
> +{
> +    if (!matches) {
> +        return;
> +    }
> +
> +    for (int i = 0; i < matches->len; i++) {
> +        g_free(g_array_index(matches, struct address_match *, i));
> +    }
> +}
> +
>  /**
>   * On plugin exit, print last instruction in cache
>   */
> @@ -409,6 +425,9 @@ static void plugin_exit(qemu_plugin_id_t id, void *p)
>          }
>      }
>      g_rw_lock_reader_unlock(&expand_array_lock);
> +
> +    free_matches(amatches);
> +    free_matches(dmatches);
>  }
>  
>  /* Add a match to the array of matches */
> @@ -420,14 +439,34 @@ static void parse_insn_match(char *match)
>      g_ptr_array_add(imatches, g_strdup(match));
>  }
>  
> -static void parse_vaddr_match(GArray **matches, char *match)
> +static void parse_vaddr_match(GArray **matches, char *token)
>  {
> -    uint64_t v = g_ascii_strtoull(match, NULL, 16);
> +    uint64_t low, high;
> +    gchar *endp;
>  
> -    if (!matches) {
> -        *matches = g_array_new(false, true, sizeof(uint64_t));
> +    low = g_ascii_strtoull(token, &endp, 16);
> +    if (endp == token) {
> +        fprintf(stderr, "Invalid address(range) specified: %s\n", token);
> +        return;
> +    }
> +
> +    if (*endp != '-') {
> +        high = low;
> +    } else {
> +        high = g_ascii_strtoull(endp + 1, &endp, 16);
> +        if (endp == token) {
> +            fprintf(stderr, "Invalid address(range) specified: %s\n", token);
> +            return;
> +        }
> +    }
> +
> +    if (!*matches) {
> +        *matches = g_array_new(false, true, sizeof(struct address_match));
>      }
> -    g_array_append_val(*matches, v);
> +    struct address_match *match = g_new(struct address_match, 1);
> +    match->low = low;
> +    match->high = high;
> +    g_array_append_val(*matches, match);

This is almost but not quite qemu_set_dfilter_ranges(). I wonder if it
would be worth a light re-factoring and then exposing the parser as a
helper function?

>  }
>  
>  /*

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro