[v2,1/2] elf: Add a way to check if tunable is set (BZ 27069)
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Commit Message
The patch adds two new macros, TUNABLE_GET_DEFAULT and TUNABLE_IS_INITIALIZED,
here the former get the default value with a signature similar to
TUNABLE_GET, while the later returns whether the tunable was set by
the environment variable.
Checked on x86_64-linux-gnu.
---
elf/Versions | 1 +
elf/dl-tunable-types.h | 1 +
elf/dl-tunables.c | 40 ++++++++++++++++++++++++++++++++++++++++
elf/dl-tunables.h | 28 ++++++++++++++++++++++++++++
elf/dl-tunables.list | 1 +
scripts/gen-tunables.awk | 4 ++--
6 files changed, 73 insertions(+), 2 deletions(-)
Comments
LGTM
Reviewed-by: DJ Delorie <dj@redhat.com>
Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:
> diff --git a/elf/Versions b/elf/Versions
> index 4614acea3e..1591031da9 100644
> --- a/elf/Versions
> +++ b/elf/Versions
> @@ -77,6 +77,7 @@ ld {
> _dl_signal_error;
>
> # Set value of a tunable.
> + __tunable_is_initialized;
> __tunable_get_val;
> }
> }
This is in GLIBC_PRIVATE so ok.
> diff --git a/elf/dl-tunable-types.h b/elf/dl-tunable-types.h
> index 62d6d9e629..a2048058fa 100644
> --- a/elf/dl-tunable-types.h
> +++ b/elf/dl-tunable-types.h
> @@ -61,6 +61,7 @@ struct _tunable
> {
> const char name[TUNABLE_NAME_MAX]; /* Internal name of the tunable. */
> tunable_type_t type; /* Data type of the tunable. */
> + const tunable_val_t def; /* The value. */
> tunable_val_t val; /* The value. */
> bool initialized; /* Flag to indicate that the tunable is
> initialized. */
Is this struct part of the ABI between ld.so and libc.so ? It doesn't
look like it to me, so OK.
> diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
> index 83265bc00b..644d21d1b0 100644
> --- a/elf/dl-tunables.c
> +++ b/elf/dl-tunables.c
> @@ -145,6 +145,13 @@ tunable_initialize (tunable_t *cur, const char *strval)
> do_tunable_update_val (cur, &val, NULL, NULL);
> }
>
> +bool
> +__tunable_is_initialized (tunable_id_t id)
> +{
> + return tunable_list[id].initialized;
> +}
> +rtld_hidden_def (__tunable_is_initialized)
> +
Ok.
> @@ -333,6 +340,39 @@ __tunables_print (void)
> }
> }
>
> +void
> +__tunable_get_default (tunable_id_t id, void *valp)
> +{
> + tunable_t *cur = &tunable_list[id];
> +
> + switch (cur->type.type_code)
> + {
> + case TUNABLE_TYPE_UINT_64:
> + {
> + *((uint64_t *) valp) = (uint64_t) cur->def.numval;
Hmmm... doesn't this break the type aliasing rules?
But we do the same thing for __tunable_get_val so OK.
> + break;
> + }
> + case TUNABLE_TYPE_INT_32:
> + {
> + *((int32_t *) valp) = (int32_t) cur->def.numval;
> + break;
> + }
> + case TUNABLE_TYPE_SIZE_T:
> + {
> + *((size_t *) valp) = (size_t) cur->def.numval;
> + break;
> + }
> + case TUNABLE_TYPE_STRING:
> + {
> + *((const char **)valp) = cur->def.strval;
> + break;
> + }
> + default:
> + __builtin_unreachable ();
> + }
> +}
> +rtld_hidden_def (__tunable_get_default)
We don't seem to have a flag that says "no default provided" but if we
assume the templates won't ever provide a default of zero, good enough?
Ok.
> diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
> index 45c191e021..0df4dde24e 100644
> --- a/elf/dl-tunables.h
> +++ b/elf/dl-tunables.h
> @@ -45,18 +45,26 @@ typedef void (*tunable_callback_t) (tunable_val_t *);
>
> extern void __tunables_init (char **);
> extern void __tunables_print (void);
> +extern bool __tunable_is_initialized (tunable_id_t);
Ok.
> +extern void __tunable_get_default (tunable_id_t id, void *valp);
Ok.
> +rtld_hidden_proto (__tunable_is_initialized)
> +rtld_hidden_proto (__tunable_get_default)
Ok.
> /* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
> TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
> tunables within a module. */
> #if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
> +# define TUNABLE_IS_INITIALIZED(__id) \
> + TUNABLE_IS_INITIALIZED_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE, __id)
> +# define TUNABLE_GET_DEFAULT(__id, __type) \
> + TUNABLE_GET_DEFAULT_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE,__id, __type)
> # define TUNABLE_GET(__id, __type, __cb) \
> TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
> # define TUNABLE_SET(__id, __val) \
> @@ -65,6 +73,10 @@ rtld_hidden_proto (__tunable_set_val)
> TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
> __val, __min, __max)
> #else
> +# define TUNABLE_IS_INITIALIZED(__top, __ns, __id) \
> + TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id)
> +# define TUNABLE_GET_DEFAULT(__top, __ns, __type) \
> + TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type)
> # define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
> TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
> # define TUNABLE_SET(__top, __ns, __id, __val) \
> @@ -73,6 +85,22 @@ rtld_hidden_proto (__tunable_set_val)
> TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __val, __min, __max)
> #endif
Ok.
> +/* Return whether the tunable was initialized by the environment variable. */
> +#define TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id) \
> +({ \
> + tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
> + __tunable_is_initialized (id); \
> +})
> +
> +/* Return the default value of the tunable. */
> +#define TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type) \
> +({ \
> + tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
> + __type __ret; \
> + __tunable_get_default (id, &__ret); \
> + __ret; \
> +})
Ok.
> diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
> index 720a8ac49c..1b23fc9473 100644
> --- a/elf/dl-tunables.list
> +++ b/elf/dl-tunables.list
> @@ -20,6 +20,7 @@
> # type: Defaults to STRING
> # minval: Optional minimum acceptable value
> # maxval: Optional maximum acceptable value
> +# default: Optional default value (if not specified it will be 0 or "")
> # env_alias: An alias environment variable
Ok.
> glibc {
> diff --git a/scripts/gen-tunables.awk b/scripts/gen-tunables.awk
> index 1e9d6b534e..9f5336381e 100644
> --- a/scripts/gen-tunables.awk
> +++ b/scripts/gen-tunables.awk
> @@ -163,8 +163,8 @@ END {
> n = indices[2];
> m = indices[3];
> printf (" {TUNABLE_NAME_S(%s, %s, %s)", t, n, m)
> - printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, false, %s},\n",
> - types[t,n,m], minvals[t,n,m], maxvals[t,n,m],
> + printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, {%s}, false, %s},\n",
> + types[t,n,m], minvals[t,n,m], maxvals[t,n,m], default_val[t,n,m],
> default_val[t,n,m], env_alias[t,n,m]);
> }
> print "};"
Ok.
On 28/11/23 18:38, DJ Delorie wrote:
>
> LGTM
> Reviewed-by: DJ Delorie <dj@redhat.com>
>
> Adhemerval Zanella <adhemerval.zanella@linaro.org> writes:
>> diff --git a/elf/Versions b/elf/Versions
>> index 4614acea3e..1591031da9 100644
>> --- a/elf/Versions
>> +++ b/elf/Versions
>> @@ -77,6 +77,7 @@ ld {
>> _dl_signal_error;
>>
>> # Set value of a tunable.
>> + __tunable_is_initialized;
>> __tunable_get_val;
>> }
>> }
>
> This is in GLIBC_PRIVATE so ok.
>
>> diff --git a/elf/dl-tunable-types.h b/elf/dl-tunable-types.h
>> index 62d6d9e629..a2048058fa 100644
>> --- a/elf/dl-tunable-types.h
>> +++ b/elf/dl-tunable-types.h
>> @@ -61,6 +61,7 @@ struct _tunable
>> {
>> const char name[TUNABLE_NAME_MAX]; /* Internal name of the tunable. */
>> tunable_type_t type; /* Data type of the tunable. */
>> + const tunable_val_t def; /* The value. */
>> tunable_val_t val; /* The value. */
>> bool initialized; /* Flag to indicate that the tunable is
>> initialized. */
>
> Is this struct part of the ABI between ld.so and libc.so ? It doesn't
> look like it to me, so OK.
I don't think so, libc.so will issue the macros TUNABLES_* that will maps to
tunable_id_t. The tunable_t is used only on dl-tunables.c.
>
>> diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
>> index 83265bc00b..644d21d1b0 100644
>> --- a/elf/dl-tunables.c
>> +++ b/elf/dl-tunables.c
>> @@ -145,6 +145,13 @@ tunable_initialize (tunable_t *cur, const char *strval)
>> do_tunable_update_val (cur, &val, NULL, NULL);
>> }
>>
>> +bool
>> +__tunable_is_initialized (tunable_id_t id)
>> +{
>> + return tunable_list[id].initialized;
>> +}
>> +rtld_hidden_def (__tunable_is_initialized)
>> +
>
> Ok.
>
>> @@ -333,6 +340,39 @@ __tunables_print (void)
>> }
>> }
>>
>> +void
>> +__tunable_get_default (tunable_id_t id, void *valp)
>> +{
>> + tunable_t *cur = &tunable_list[id];
>> +
>> + switch (cur->type.type_code)
>> + {
>> + case TUNABLE_TYPE_UINT_64:
>> + {
>> + *((uint64_t *) valp) = (uint64_t) cur->def.numval;
>
> Hmmm... doesn't this break the type aliasing rules?
>
> But we do the same thing for __tunable_get_val so OK.
Indeed, I will send a patch to fix it.
>
>> + break;
>> + }
>> + case TUNABLE_TYPE_INT_32:
>> + {
>> + *((int32_t *) valp) = (int32_t) cur->def.numval;
>> + break;
>> + }
>> + case TUNABLE_TYPE_SIZE_T:
>> + {
>> + *((size_t *) valp) = (size_t) cur->def.numval;
>> + break;
>> + }
>> + case TUNABLE_TYPE_STRING:
>> + {
>> + *((const char **)valp) = cur->def.strval;
>> + break;
>> + }
>> + default:
>> + __builtin_unreachable ();
>> + }
>> +}
>> +rtld_hidden_def (__tunable_get_default)
>
> We don't seem to have a flag that says "no default provided" but if we
> assume the templates won't ever provide a default of zero, good enough?
Right, but I think it would be easier to add once we actually require it.
>
> Ok.
>
>> diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
>> index 45c191e021..0df4dde24e 100644
>> --- a/elf/dl-tunables.h
>> +++ b/elf/dl-tunables.h
>> @@ -45,18 +45,26 @@ typedef void (*tunable_callback_t) (tunable_val_t *);
>>
>> extern void __tunables_init (char **);
>> extern void __tunables_print (void);
>> +extern bool __tunable_is_initialized (tunable_id_t);
>
> Ok.
>
>> +extern void __tunable_get_default (tunable_id_t id, void *valp);
>
> Ok.
>
>> +rtld_hidden_proto (__tunable_is_initialized)
>> +rtld_hidden_proto (__tunable_get_default)
>
> Ok.
>
>> /* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
>> TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
>> tunables within a module. */
>> #if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
>> +# define TUNABLE_IS_INITIALIZED(__id) \
>> + TUNABLE_IS_INITIALIZED_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE, __id)
>> +# define TUNABLE_GET_DEFAULT(__id, __type) \
>> + TUNABLE_GET_DEFAULT_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE,__id, __type)
>> # define TUNABLE_GET(__id, __type, __cb) \
>> TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
>> # define TUNABLE_SET(__id, __val) \
>> @@ -65,6 +73,10 @@ rtld_hidden_proto (__tunable_set_val)
>> TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
>> __val, __min, __max)
>> #else
>> +# define TUNABLE_IS_INITIALIZED(__top, __ns, __id) \
>> + TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id)
>> +# define TUNABLE_GET_DEFAULT(__top, __ns, __type) \
>> + TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type)
>> # define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
>> TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
>> # define TUNABLE_SET(__top, __ns, __id, __val) \
>> @@ -73,6 +85,22 @@ rtld_hidden_proto (__tunable_set_val)
>> TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __val, __min, __max)
>> #endif
>
> Ok.
>
>> +/* Return whether the tunable was initialized by the environment variable. */
>> +#define TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id) \
>> +({ \
>> + tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
>> + __tunable_is_initialized (id); \
>> +})
>> +
>> +/* Return the default value of the tunable. */
>> +#define TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type) \
>> +({ \
>> + tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
>> + __type __ret; \
>> + __tunable_get_default (id, &__ret); \
>> + __ret; \
>> +})
>
> Ok.
>
>> diff --git a/elf/dl-tunables.list b/elf/dl-tunables.list
>> index 720a8ac49c..1b23fc9473 100644
>> --- a/elf/dl-tunables.list
>> +++ b/elf/dl-tunables.list
>> @@ -20,6 +20,7 @@
>> # type: Defaults to STRING
>> # minval: Optional minimum acceptable value
>> # maxval: Optional maximum acceptable value
>> +# default: Optional default value (if not specified it will be 0 or "")
>> # env_alias: An alias environment variable
>
> Ok.
>
>> glibc {
>> diff --git a/scripts/gen-tunables.awk b/scripts/gen-tunables.awk
>> index 1e9d6b534e..9f5336381e 100644
>> --- a/scripts/gen-tunables.awk
>> +++ b/scripts/gen-tunables.awk
>> @@ -163,8 +163,8 @@ END {
>> n = indices[2];
>> m = indices[3];
>> printf (" {TUNABLE_NAME_S(%s, %s, %s)", t, n, m)
>> - printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, false, %s},\n",
>> - types[t,n,m], minvals[t,n,m], maxvals[t,n,m],
>> + printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, {%s}, false, %s},\n",
>> + types[t,n,m], minvals[t,n,m], maxvals[t,n,m], default_val[t,n,m],
>> default_val[t,n,m], env_alias[t,n,m]);
>> }
>> print "};"
>
> Ok.
>
@@ -77,6 +77,7 @@ ld {
_dl_signal_error;
# Set value of a tunable.
+ __tunable_is_initialized;
__tunable_get_val;
}
}
@@ -61,6 +61,7 @@ struct _tunable
{
const char name[TUNABLE_NAME_MAX]; /* Internal name of the tunable. */
tunable_type_t type; /* Data type of the tunable. */
+ const tunable_val_t def; /* The value. */
tunable_val_t val; /* The value. */
bool initialized; /* Flag to indicate that the tunable is
initialized. */
@@ -145,6 +145,13 @@ tunable_initialize (tunable_t *cur, const char *strval)
do_tunable_update_val (cur, &val, NULL, NULL);
}
+bool
+__tunable_is_initialized (tunable_id_t id)
+{
+ return tunable_list[id].initialized;
+}
+rtld_hidden_def (__tunable_is_initialized)
+
void
__tunable_set_val (tunable_id_t id, tunable_val_t *valp, tunable_num_t *minp,
tunable_num_t *maxp)
@@ -333,6 +340,39 @@ __tunables_print (void)
}
}
+void
+__tunable_get_default (tunable_id_t id, void *valp)
+{
+ tunable_t *cur = &tunable_list[id];
+
+ switch (cur->type.type_code)
+ {
+ case TUNABLE_TYPE_UINT_64:
+ {
+ *((uint64_t *) valp) = (uint64_t) cur->def.numval;
+ break;
+ }
+ case TUNABLE_TYPE_INT_32:
+ {
+ *((int32_t *) valp) = (int32_t) cur->def.numval;
+ break;
+ }
+ case TUNABLE_TYPE_SIZE_T:
+ {
+ *((size_t *) valp) = (size_t) cur->def.numval;
+ break;
+ }
+ case TUNABLE_TYPE_STRING:
+ {
+ *((const char **)valp) = cur->def.strval;
+ break;
+ }
+ default:
+ __builtin_unreachable ();
+ }
+}
+rtld_hidden_def (__tunable_get_default)
+
/* Set the tunable value. This is called by the module that the tunable exists
in. */
void
@@ -45,18 +45,26 @@ typedef void (*tunable_callback_t) (tunable_val_t *);
extern void __tunables_init (char **);
extern void __tunables_print (void);
+extern bool __tunable_is_initialized (tunable_id_t);
extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
extern void __tunable_set_val (tunable_id_t, tunable_val_t *, tunable_num_t *,
tunable_num_t *);
+extern void __tunable_get_default (tunable_id_t id, void *valp);
rtld_hidden_proto (__tunables_init)
rtld_hidden_proto (__tunables_print)
+rtld_hidden_proto (__tunable_is_initialized)
rtld_hidden_proto (__tunable_get_val)
rtld_hidden_proto (__tunable_set_val)
+rtld_hidden_proto (__tunable_get_default)
/* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and
TUNABLE_NAMESPACE are defined. This is useful shorthand to get and set
tunables within a module. */
#if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
+# define TUNABLE_IS_INITIALIZED(__id) \
+ TUNABLE_IS_INITIALIZED_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE, __id)
+# define TUNABLE_GET_DEFAULT(__id, __type) \
+ TUNABLE_GET_DEFAULT_FULL(TOP_NAMESPACE, TUNABLE_NAMESPACE,__id, __type)
# define TUNABLE_GET(__id, __type, __cb) \
TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
# define TUNABLE_SET(__id, __val) \
@@ -65,6 +73,10 @@ rtld_hidden_proto (__tunable_set_val)
TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
__val, __min, __max)
#else
+# define TUNABLE_IS_INITIALIZED(__top, __ns, __id) \
+ TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id)
+# define TUNABLE_GET_DEFAULT(__top, __ns, __type) \
+ TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type)
# define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
# define TUNABLE_SET(__top, __ns, __id, __val) \
@@ -73,6 +85,22 @@ rtld_hidden_proto (__tunable_set_val)
TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __val, __min, __max)
#endif
+/* Return whether the tunable was initialized by the environment variable. */
+#define TUNABLE_IS_INITIALIZED_FULL(__top, __ns, __id) \
+({ \
+ tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
+ __tunable_is_initialized (id); \
+})
+
+/* Return the default value of the tunable. */
+#define TUNABLE_GET_DEFAULT_FULL(__top, __ns, __id, __type) \
+({ \
+ tunable_id_t id = TUNABLE_ENUM_NAME (__top, __ns, __id); \
+ __type __ret; \
+ __tunable_get_default (id, &__ret); \
+ __ret; \
+})
+
/* Get and return a tunable value. If the tunable was set externally and __CB
is defined then call __CB before returning the value. */
#define TUNABLE_GET_FULL(__top, __ns, __id, __type, __cb) \
@@ -20,6 +20,7 @@
# type: Defaults to STRING
# minval: Optional minimum acceptable value
# maxval: Optional maximum acceptable value
+# default: Optional default value (if not specified it will be 0 or "")
# env_alias: An alias environment variable
glibc {
@@ -163,8 +163,8 @@ END {
n = indices[2];
m = indices[3];
printf (" {TUNABLE_NAME_S(%s, %s, %s)", t, n, m)
- printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, false, %s},\n",
- types[t,n,m], minvals[t,n,m], maxvals[t,n,m],
+ printf (", {TUNABLE_TYPE_%s, %s, %s}, {%s}, {%s}, false, %s},\n",
+ types[t,n,m], minvals[t,n,m], maxvals[t,n,m], default_val[t,n,m],
default_val[t,n,m], env_alias[t,n,m]);
}
print "};"