[v4,07/11] qemu-log: new option -dfilter to limit output

When debugging big programs or system emulation sometimes you want both
the verbosity of cpu,exec et all but don't want to generate lots of logs
for unneeded stuff. This patch adds a new option -dfilter which allows
you to specify interesting address ranges in the form:

  -dfilter 0x8000-0x9000,0xffffffc000080000+0x200,...

Then logging code can use the new qemu_log_in_addr_range() function to
decide if it will output logging information for the given range.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

----

v2
  - More clean-ups to the documentation

v3
  - re-base
  - use GArray instead of GList to avoid cache bouncing
  - checkpatch fixes
---
 include/qemu/log.h |  2 ++
 qemu-log.c         | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qemu-options.hx    | 16 +++++++++++++++
 vl.c               |  3 +++
 4 files changed, 78 insertions(+)

Christopher Covington <cov@codeaurora.org> writes:

> Hi Alex,
>
> On 08/03/2015 05:14 AM, Alex Bennée wrote:
>> When debugging big programs or system emulation sometimes you want both
>> the verbosity of cpu,exec et all but don't want to generate lots of logs
>> for unneeded stuff. This patch adds a new option -dfilter which allows
>> you to specify interesting address ranges in the form:
>> 
>>   -dfilter 0x8000-0x9000,0xffffffc000080000+0x200,...
>> 
>> Then logging code can use the new qemu_log_in_addr_range() function to
>> decide if it will output logging information for the given range.
>> 
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>
> My usual flow is to filter based on mode (CurrentEL on AArch64) and PID
> (CONTEXTIDR on AArch64). Do you foresee any problems with adding such
> filters?

I have indeed added such filters on for my own debugging efforts.
However the problem is they are very target focused and I don't want to
pollute the generic code with target specific hacks. I suspect we need
two things:

  - a way to add target specific options to the UI
  - a target agnostic hook which allows additional refinement of the filter

>
> Thanks,
> Christopher Covington
>
>> v2
>>   - More clean-ups to the documentation
>> 
>> v3
>>   - re-base
>>   - use GArray instead of GList to avoid cache bouncing
>>   - checkpatch fixes
>> ---
>>  include/qemu/log.h |  2 ++
>>  qemu-log.c         | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>  qemu-options.hx    | 16 +++++++++++++++
>>  vl.c               |  3 +++
>>  4 files changed, 78 insertions(+)
>> 
>> diff --git a/include/qemu/log.h b/include/qemu/log.h
>> index b80f8f5..ade1f76 100644
>> --- a/include/qemu/log.h
>> +++ b/include/qemu/log.h
>> @@ -182,6 +182,8 @@ static inline void qemu_set_log(int log_flags)
>>  }
>>  
>>  void qemu_set_log_filename(const char *filename);
>> +void qemu_set_dfilter_ranges(const char *ranges);
>> +bool qemu_log_in_addr_range(uint64_t addr);
>>  int qemu_str_to_log_mask(const char *str);
>>  
>>  /* Print a usage message listing all the valid logging categories
>> diff --git a/qemu-log.c b/qemu-log.c
>> index 77ed7bc..b3ebd3c 100644
>> --- a/qemu-log.c
>> +++ b/qemu-log.c
>> @@ -19,11 +19,13 @@
>>  
>>  #include "qemu-common.h"
>>  #include "qemu/log.h"
>> +#include "qemu/range.h"
>>  
>>  static char *logfilename;
>>  FILE *qemu_logfile;
>>  int qemu_loglevel;
>>  static int log_append = 0;
>> +static GArray *debug_regions;
>>  
>>  void qemu_log(const char *fmt, ...)
>>  {
>> @@ -92,6 +94,61 @@ void qemu_set_log_filename(const char *filename)
>>      qemu_set_log(qemu_loglevel);
>>  }
>>  
>> +/* Returns true if addr is in our debug filter or no filter defined
>> + */
>> +bool qemu_log_in_addr_range(uint64_t addr)
>> +{
>> +    if (debug_regions) {
>> +        int i = 0;
>> +        for (i = 0; i < debug_regions->len; i++) {
>> +            struct Range *range = &g_array_index(debug_regions, Range, i);
>> +            if (addr >= range->begin && addr <= range->end) {
>> +                return true;
>> +            }
>> +        }
>> +        return false;
>> +    } else {
>> +        return true;
>> +    }
>> +}
>> +
>> +
>> +void qemu_set_dfilter_ranges(const char *filter_spec)
>> +{
>> +    gchar **ranges = g_strsplit(filter_spec, ",", 0);
>> +    if (ranges) {
>> +        gchar **next = ranges;
>> +        gchar *r = *next++;
>> +        debug_regions = g_array_sized_new(FALSE, FALSE,
>> +                                          sizeof(Range), g_strv_length(ranges));
>> +        while (r) {
>> +            gchar *delim = g_strrstr(r, "-");
>> +            if (!delim) {
>> +                delim = g_strrstr(r, "+");
>> +            }
>> +            if (delim) {
>> +                struct Range range;
>> +                range.begin = strtoul(r, NULL, 0);
>> +                switch (*delim) {
>> +                case '+':
>> +                    range.end = range.begin + strtoul(delim+1, NULL, 0);
>> +                    break;
>> +                case '-':
>> +                    range.end = strtoul(delim+1, NULL, 0);
>> +                    break;
>> +                default:
>> +                    g_assert_not_reached();
>> +                }
>> +                g_array_append_val(debug_regions, range);
>> +            } else {
>> +                g_error("Bad range specifier in: %s", r);
>> +            }
>> +            r = *next++;
>> +        }
>> +        g_strfreev(ranges);
>> +    }
>> +}
>> +
>>  const QEMULogItem qemu_log_items[] = {
>>      { CPU_LOG_TB_OUT_ASM, "out_asm",
>>        "show generated host assembly code for each compiled TB" },
>> diff --git a/qemu-options.hx b/qemu-options.hx
>> index ae53346..90f0df9 100644
>> --- a/qemu-options.hx
>> +++ b/qemu-options.hx
>> @@ -2987,6 +2987,22 @@ STEXI
>>  Output log in @var{logfile} instead of to stderr
>>  ETEXI
>>  
>> +DEF("dfilter", HAS_ARG, QEMU_OPTION_DFILTER, \
>> +    "-dfilter range,..  filter debug output to range of addresses (useful for -d cpu,exec,etc..)\n",
>> +    QEMU_ARCH_ALL)
>> +STEXI
>> +@item -dfilter @var{range1}[,...]
>> +@findex -dfilter
>> +Filter debug output to that relevant to a range of target addresses. The filter
>> +spec can be either @var{start}-@var{end} or @var{start}+@var{size} where @var{start}
>> +@var{end} and @var{size} are the addresses and sizes required. For example:
>> +@example
>> +    -dfilter 0x8000-0x9000,0xffffffc000080000+0x200
>> +@end example
>> +Will dump output for any code in the 0x1000 sized block starting at 0x8000 and
>> +the 0x200 sized block starting at 0xffffffc000080000.
>> +ETEXI
>> +
>>  DEF("L", HAS_ARG, QEMU_OPTION_L, \
>>      "-L path         set the directory for the BIOS, VGA BIOS and keymaps\n",
>>      QEMU_ARCH_ALL)
>> diff --git a/vl.c b/vl.c
>> index 1d2de4f..05211cf 100644
>> --- a/vl.c
>> +++ b/vl.c
>> @@ -3349,6 +3349,9 @@ int main(int argc, char **argv, char **envp)
>>              case QEMU_OPTION_D:
>>                  log_file = optarg;
>>                  break;
>> +            case QEMU_OPTION_DFILTER:
>> +                qemu_set_dfilter_ranges(optarg);
>> +                break;
>>              case QEMU_OPTION_PERFMAP:
>>                  tb_enable_perfmap();
>>                  break;
>>