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Improve error reporting when handling SystemTap SDT probes 

This patch improves the error reporting when handling SystemTap SDT
probes.  "Handling", in this case, mostly means "parsing".

On gdb/probe.h, only trivial changes on functions' comments in order
to explicitly mention that some of them can throw exceptions.  This is
just to make the API a bit more clear.

On gdb/stap-probe.c, I have s/internal_error/error/ on two functions
that are responsible for parsing specific bits of the probes'
arguments: stap_get_opcode and stap_get_expected_argument_type.  It is
not correct to call internal_error on such situations because it is
not really GDB's fault if the probes have malformed arguments.  I also
improved the error reported on stap_get_expected_argument_type by also
including the probe name on it.

Aside from that, and perhaps most importantly, I added a check on
stap_get_arg to make sure that we don't try to extract an argument
from a probe that has no arguments.  This check issues an
internal_error, because it really means that GDB is doing something it
shouldn't.

Although it can be considered almost trivial, and despite the fact
that I am the maintainer for this part of the code, I am posting this
patch for review.  I will wait a few days, and if nobody has anything
to say, I will go ahead and push it.

gdb/ChangeLog:
2015-09-01  Sergio Durigan Junior  <sergiodj@redhat.com>

	* probe.h (struct probe_ops) <get_probe_argument_count,
	evaluate_probe_argument, enable_probe, disable_probe>: Mention in
	the comment that the function can throw an exception.
	(get_probe_argument_count): Likewise.
	(evaluate_probe_argument): Likewise.
	* stap-probe.c (stap_get_opcode): Call error instead of
	internal_error.
	(stap_get_expected_argument_type): Likewise.  Add argument
	'probe'.  Improve error message by mentioning the probe's name.
	(stap_parse_probe_arguments): Adjust call to
	stap_get_expected_argument_type.
	(stap_get_arg): Add comment.  Assert that 'probe->args_parsed' is
	not zero.  Call internal_error if GDB requests an argument but the
	probe has no arguments.
This commit is contained in:
Sergio Durigan Junior 2015-08-21 18:13:46 -04:00
parent 700190e776
commit f469e8ce11
3 changed files with 53 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
gdb/ChangeLog
View File

@ -1,3 +1,20 @@
2015-09-01 Sergio Durigan Junior <sergiodj@redhat.com>
* probe.h (struct probe_ops) <get_probe_argument_count,
evaluate_probe_argument, enable_probe, disable_probe>: Mention in
the comment that the function can throw an exception.
(get_probe_argument_count): Likewise.
(evaluate_probe_argument): Likewise.
* stap-probe.c (stap_get_opcode): Call error instead of
internal_error.
(stap_get_expected_argument_type): Likewise. Add argument
'probe'. Improve error message by mentioning the probe's name.
(stap_parse_probe_arguments): Adjust call to
stap_get_expected_argument_type.
(stap_get_arg): Add comment. Assert that 'probe->args_parsed' is
not zero. Call internal_error if GDB requests an argument but the
probe has no arguments.
2015-09-01 Pierre-Marie de Rodat <derodat@adacore.com>
* ada-lang.c (ada_resolve_function): Do not ask the user what

20
gdb/probe.h
View File

@ -72,7 +72,8 @@ struct probe_ops
CORE_ADDR (*get_probe_address) (struct probe *probe,
struct objfile *objfile);
/* Return the number of arguments of PROBE. */
/* Return the number of arguments of PROBE. This function can
throw an exception. */
unsigned (*get_probe_argument_count) (struct probe *probe,
struct frame_info *frame);
@ -84,7 +85,8 @@ struct probe_ops
int (*can_evaluate_probe_arguments) (struct probe *probe);
/* Evaluate the Nth argument from the PROBE, returning a value
corresponding to it. The argument number is represented N. */
corresponding to it. The argument number is represented N.
This function can throw an exception. */
struct value *(*evaluate_probe_argument) (struct probe *probe,
unsigned n,
@ -143,13 +145,15 @@ struct probe_ops
/* Enable a probe. The semantics of "enabling" a probe depend on
the specific backend and the field can be NULL in case enabling
probes is not supported. */
probes is not supported. This function can throw an
exception. */
void (*enable_probe) (struct probe *probe);
/* Disable a probe. The semantics of "disabling" a probe depend
on the specific backend and the field can be NULL in case
disabling probes is not supported. */
disabling probes is not supported. This function can throw an
exception. */
void (*disable_probe) (struct probe *probe);
};
@ -266,7 +270,9 @@ extern struct cmd_list_element **info_probes_cmdlist_get (void);
extern CORE_ADDR get_probe_address (struct probe *probe,
struct objfile *objfile);
/* Return the argument count of the specified probe. */
/* Return the argument count of the specified probe.
This function can throw an exception. */
extern unsigned get_probe_argument_count (struct probe *probe,
struct frame_info *frame);
@ -278,7 +284,9 @@ extern unsigned get_probe_argument_count (struct probe *probe,
extern int can_evaluate_probe_arguments (struct probe *probe);
/* Evaluate argument N of the specified probe. N must be between 0
inclusive and get_probe_argument_count exclusive. */
inclusive and get_probe_argument_count exclusive.
This function can throw an exception. */
extern struct value *evaluate_probe_argument (struct probe *probe,
unsigned n,

29
gdb/stap-probe.c
View File

@ -313,9 +313,8 @@ stap_get_opcode (const char **s)
break;
default:
internal_error (__FILE__, __LINE__,
_("Invalid opcode in expression `%s' for SystemTap"
"probe"), *s);
error (_("Invalid opcode in expression `%s' for SystemTap"
"probe"), *s);
}
return op;
@ -326,7 +325,8 @@ stap_get_opcode (const char **s)
static struct type *
stap_get_expected_argument_type (struct gdbarch *gdbarch,
enum stap_arg_bitness b)
enum stap_arg_bitness b,
const struct stap_probe *probe)
{
switch (b)
{
@ -361,8 +361,8 @@ stap_get_expected_argument_type (struct gdbarch *gdbarch,
return builtin_type (gdbarch)->builtin_uint64;
default:
internal_error (__FILE__, __LINE__,
_("Undefined bitness for probe."));
error (_("Undefined bitness for probe '%s'."),
probe->p.name);
break;
}
}
@ -1172,7 +1172,8 @@ stap_parse_probe_arguments (struct stap_probe *probe, struct gdbarch *gdbarch)
else
arg.bitness = STAP_ARG_BITNESS_UNDEFINED;
arg.atype = stap_get_expected_argument_type (gdbarch, arg.bitness);
arg.atype = stap_get_expected_argument_type (gdbarch, arg.bitness,
probe);
expr = stap_parse_argument (&cur, arg.atype, gdbarch);
@ -1278,12 +1279,26 @@ stap_is_operator (const char *op)
return ret;
}
/* Return argument N of probe PROBE.
If the probe's arguments have not been parsed yet, parse them. If
there are no arguments, throw an exception (error). Otherwise,
return the requested argument. */
static struct stap_probe_arg *
stap_get_arg (struct stap_probe *probe, unsigned n, struct gdbarch *gdbarch)
{
if (!probe->args_parsed)
stap_parse_probe_arguments (probe, gdbarch);
gdb_assert (probe->args_parsed);
if (probe->args_u.vec == NULL)
internal_error (__FILE__, __LINE__,
_("Probe '%s' apparently does not have arguments, but \n"
"GDB is requesting its argument number %u anyway. "
"This should not happen. Please report this bug."),
probe->p.name, n);
return VEC_index (stap_probe_arg_s, probe->args_u.vec, n);
}