From 34c463f37f46abcb2279196def9925e9797e9ede Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Mon, 1 Jun 2020 14:11:32 -0700
Subject: [PATCH] Set tunable value as well as min/max values
Some tunable values and their minimum/maximum values must be determinted
at run-time. Add TUNABLE_SET_WITH_BOUNDS and TUNABLE_SET_WITH_BOUNDS_FULL
to update tunable value together with minimum and maximum values.
__tunable_set_val is updated to set tunable value as well as min/max
values.
---
elf/dl-tunables.c | 17 ++++++++++++-----
elf/dl-tunables.h | 21 +++++++++++++++++++--
manual/README.tunables | 24 ++++++++++++++++++++++--
3 files changed, 53 insertions(+), 9 deletions(-)
@@ -101,12 +101,19 @@ get_next_env (char **envp, char **name, size_t *namelen, char **val,
})
static void
-do_tunable_update_val (tunable_t *cur, const void *valp)
+do_tunable_update_val (tunable_t *cur, const void *valp,
+ const void *minp, const void *maxp)
{
uint64_t val;
if (cur->type.type_code != TUNABLE_TYPE_STRING)
- val = *((int64_t *) valp);
+ {
+ val = *((int64_t *) valp);
+ if (minp)
+ cur->type.min = *((int64_t *) minp);
+ if (maxp)
+ cur->type.max = *((int64_t *) maxp);
+ }
switch (cur->type.type_code)
{
@@ -153,15 +160,15 @@ tunable_initialize (tunable_t *cur, const char *strval)
cur->initialized = true;
valp = strval;
}
- do_tunable_update_val (cur, valp);
+ do_tunable_update_val (cur, valp, NULL, NULL);
}
void
-__tunable_set_val (tunable_id_t id, void *valp)
+__tunable_set_val (tunable_id_t id, void *valp, void *minp, void *maxp)
{
tunable_t *cur = &tunable_list[id];
- do_tunable_update_val (cur, valp);
+ do_tunable_update_val (cur, valp, minp, maxp);
}
#if TUNABLES_FRONTEND == TUNABLES_FRONTEND_valstring
@@ -70,9 +70,10 @@ typedef struct _tunable tunable_t;
extern void __tunables_init (char **);
extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
-extern void __tunable_set_val (tunable_id_t, void *);
+extern void __tunable_set_val (tunable_id_t, void *, void *, void *);
rtld_hidden_proto (__tunables_init)
rtld_hidden_proto (__tunable_get_val)
+rtld_hidden_proto (__tunable_set_val)
/* 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
@@ -82,11 +83,18 @@ rtld_hidden_proto (__tunable_get_val)
TUNABLE_GET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __cb)
# define TUNABLE_SET(__id, __type, __val) \
TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __type, __val)
+# define TUNABLE_SET_WITH_BOUNDS(__id, __type, __val, __min, __max) \
+ TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
+ __type, __val, __min, __max)
#else
# define TUNABLE_GET(__top, __ns, __id, __type, __cb) \
TUNABLE_GET_FULL (__top, __ns, __id, __type, __cb)
# define TUNABLE_SET(__top, __ns, __id, __type, __val) \
TUNABLE_SET_FULL (__top, __ns, __id, __type, __val)
+# define TUNABLE_SET_WITH_BOUNDS(__top, __ns, __id, __type, __val, \
+ __min, __max) \
+ TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __type, __val, \
+ __min, __max)
#endif
/* Get and return a tunable value. If the tunable was set externally and __CB
@@ -103,7 +111,16 @@ rtld_hidden_proto (__tunable_get_val)
# define TUNABLE_SET_FULL(__top, __ns, __id, __type, __val) \
({ \
__tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
- & (__type) {__val}); \
+ & (__type) {__val}, NULL, NULL); \
+})
+
+/* Set a tunable value together with min/max values. */
+# define TUNABLE_SET_WITH_BOUNDS_FULL(__top, __ns, __id, __type, __val, \
+ __min, __max) \
+({ \
+ __tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
+ & (__type) {__val}, & (__type) {__min}, \
+ & (__type) {__max}); \
})
/* Namespace sanity for callback functions. Use this macro to keep the
@@ -67,7 +67,7 @@ The list of allowed attributes are:
non-AT_SECURE subprocesses.
NONE: Read all the time.
-2. Use TUNABLE_GET/TUNABLE_SET to get and set tunables.
+2. Use TUNABLE_GET/TUNABLE_SET/TUNABLE_SET_WITH_BOUNDS to get and set tunables.
3. OPTIONAL: If tunables in a namespace are being used multiple times within a
specific module, set the TUNABLE_NAMESPACE macro to reduce the amount of
@@ -112,9 +112,29 @@ form of the macros as follows:
where 'glibc' is the top namespace, 'cpu' is the tunable namespace and the
remaining arguments are the same as the short form macros.
+The minimum and maximum values can updated together with the tunable value
+using:
+
+ TUNABLE_SET_WITH_BOUNDS (check, int32_t, val, min, max)
+
+where 'check' is the tunable name, 'int32_t' is the C type of the tunable,
+'val' is a value of same type, 'min' and 'max' are the minimum and maximum
+values of the tunable.
+
+To set the minimum and maximum values of tunables in a different namespace
+from that module, use the full form of the macros as follows:
+
+ val = TUNABLE_GET_FULL (glibc, cpu, hwcap_mask, uint64_t, NULL)
+
+ TUNABLE_SET_WITH_BOUNDS_FULL (glibc, cpu, hwcap_mask, uint64_t, val, min, max)
+
+where 'glibc' is the top namespace, 'cpu' is the tunable namespace and the
+remaining arguments are the same as the short form macros.
+
When TUNABLE_NAMESPACE is not defined in a module, TUNABLE_GET is equivalent to
TUNABLE_GET_FULL, so you will need to provide full namespace information for
-both macros. Likewise for TUNABLE_SET and TUNABLE_SET_FULL.
+both macros. Likewise for TUNABLE_SET, TUNABLE_SET_FULL,
+TUNABLE_SET_WITH_BOUNDS and TUNABLE_SET_WITH_BOUNDS_FULL.
** IMPORTANT NOTE **
--
2.26.2