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authorSiddhesh Poyarekar <siddhesh@sourceware.org>2021-02-05 13:18:58 +0530
committerSiddhesh Poyarekar <siddhesh@sourceware.org>2021-02-10 19:08:33 +0530
commit61117bfa1b08ca048e6512c0652c568300fedf6a (patch)
treed752f7a8eec0c3a174c42f73f1e7927616d6d073
parente604a5e4bb61267c58e6b6179209efe74ab5f675 (diff)
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tunables: Simplify TUNABLE_SET interface
The TUNABLE_SET interface took a primitive C type argument, which resulted in inconsistent type conversions internally due to incorrect dereferencing of types, especialy on 32-bit architectures. This change simplifies the TUNABLE setting logic along with the interfaces. Now all numeric tunable values are stored as signed numbers in tunable_num_t, which is intmax_t. All calls to set tunables cast the input value to its primitive type and then to tunable_num_t for storage. This relies on gcc-specific (although I suspect other compilers woul also do the same) unsigned to signed integer conversion semantics, i.e. the bit pattern is conserved. The reverse conversion is guaranteed by the standard.
-rw-r--r--elf/dl-tunable-types.h4
-rw-r--r--elf/dl-tunables.c128
-rw-r--r--elf/dl-tunables.h37
-rw-r--r--manual/README.tunables16
-rw-r--r--sysdeps/unix/sysv/linux/aarch64/cpu-features.c2
-rw-r--r--sysdeps/x86/dl-cacheinfo.h15
6 files changed, 75 insertions, 127 deletions
diff --git a/elf/dl-tunable-types.h b/elf/dl-tunable-types.h
index 3fcc080..626ca33 100644
--- a/elf/dl-tunable-types.h
+++ b/elf/dl-tunable-types.h
@@ -38,8 +38,8 @@ typedef enum
typedef struct
{
tunable_type_code_t type_code;
- int64_t min;
- int64_t max;
+ tunable_num_t min;
+ tunable_num_t max;
} tunable_type_t;
/* Security level for tunables. This decides what to do with individual
diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c
index b1a50b8..a2be9cd 100644
--- a/elf/dl-tunables.c
+++ b/elf/dl-tunables.c
@@ -93,87 +93,45 @@ get_next_env (char **envp, char **name, size_t *namelen, char **val,
return NULL;
}
-#define TUNABLE_SET_VAL_IF_VALID_RANGE(__cur, __val, __type) \
-({ \
- __type min = (__cur)->type.min; \
- __type max = (__cur)->type.max; \
- \
- if ((__type) (__val) >= min && (__type) (__val) <= max) \
- { \
- (__cur)->val.numval = (__val); \
- (__cur)->initialized = true; \
- } \
-})
-
-#define TUNABLE_SET_BOUNDS_IF_VALID(__cur, __minp, __maxp, __type) \
-({ \
- if (__minp != NULL) \
- { \
- /* MIN is specified. */ \
- __type min = *((__type *) __minp); \
- if (__maxp != NULL) \
- { \
- /* Both MIN and MAX are specified. */ \
- __type max = *((__type *) __maxp); \
- if (max >= min \
- && max <= (__cur)->type.max \
- && min >= (__cur)->type.min) \
- { \
- (__cur)->type.min = min; \
- (__cur)->type.max = max; \
- } \
- } \
- else if (min > (__cur)->type.min && min <= (__cur)->type.max) \
- { \
- /* Only MIN is specified. */ \
- (__cur)->type.min = min; \
- } \
- } \
- else if (__maxp != NULL) \
- { \
- /* Only MAX is specified. */ \
- __type max = *((__type *) __maxp); \
- if (max < (__cur)->type.max && max >= (__cur)->type.min) \
- (__cur)->type.max = max; \
- } \
-})
-
static void
-do_tunable_update_val (tunable_t *cur, const void *valp,
- const void *minp, const void *maxp)
+do_tunable_update_val (tunable_t *cur, const tunable_val_t *valp,
+ const tunable_num_t *minp,
+ const tunable_num_t *maxp)
{
- uint64_t val;
+ tunable_num_t val, min, max;
- if (cur->type.type_code != TUNABLE_TYPE_STRING)
- val = *((int64_t *) valp);
+ if (cur->type.type_code == TUNABLE_TYPE_STRING)
+ {
+ cur->val.strval = valp->strval;
+ cur->initialized = true;
+ return;
+ }
- switch (cur->type.type_code)
+ val = valp->numval;
+ min = minp != NULL ? *minp : cur->type.min;
+ max = maxp != NULL ? *maxp : cur->type.max;
+
+ /* We allow only increasingly restrictive bounds. */
+ if (min < cur->type.min)
+ min = cur->type.min;
+
+ if (max > cur->type.max)
+ max = cur->type.max;
+
+ /* Skip both bounds if they're inconsistent. */
+ if (min > max)
{
- case TUNABLE_TYPE_INT_32:
- {
- TUNABLE_SET_BOUNDS_IF_VALID (cur, minp, maxp, int64_t);
- TUNABLE_SET_VAL_IF_VALID_RANGE (cur, val, int64_t);
- break;
- }
- case TUNABLE_TYPE_UINT_64:
- {
- TUNABLE_SET_BOUNDS_IF_VALID (cur, minp, maxp, uint64_t);
- TUNABLE_SET_VAL_IF_VALID_RANGE (cur, val, uint64_t);
- break;
- }
- case TUNABLE_TYPE_SIZE_T:
- {
- TUNABLE_SET_BOUNDS_IF_VALID (cur, minp, maxp, uint64_t);
- TUNABLE_SET_VAL_IF_VALID_RANGE (cur, val, uint64_t);
- break;
- }
- case TUNABLE_TYPE_STRING:
- {
- cur->val.strval = valp;
- break;
- }
- default:
- __builtin_unreachable ();
+ min = cur->type.min;
+ max = cur->type.max;
+ }
+
+ /* Write everything out if the value and the bounds are valid. */
+ if (min <= val && val <= max)
+ {
+ cur->val.numval = val;
+ cur->type.min = min;
+ cur->type.max = max;
+ cur->initialized = true;
}
}
@@ -182,24 +140,18 @@ do_tunable_update_val (tunable_t *cur, const void *valp,
static void
tunable_initialize (tunable_t *cur, const char *strval)
{
- uint64_t val;
- const void *valp;
+ tunable_val_t val;
if (cur->type.type_code != TUNABLE_TYPE_STRING)
- {
- val = _dl_strtoul (strval, NULL);
- valp = &val;
- }
+ val.numval = (tunable_num_t) _dl_strtoul (strval, NULL);
else
- {
- cur->initialized = true;
- valp = strval;
- }
- do_tunable_update_val (cur, valp, NULL, NULL);
+ val.strval = strval;
+ do_tunable_update_val (cur, &val, NULL, NULL);
}
void
-__tunable_set_val (tunable_id_t id, void *valp, void *minp, void *maxp)
+__tunable_set_val (tunable_id_t id, tunable_val_t *valp, tunable_num_t *minp,
+ tunable_num_t *maxp)
{
tunable_t *cur = &tunable_list[id];
diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h
index 971376b..ba7ae6b 100644
--- a/elf/dl-tunables.h
+++ b/elf/dl-tunables.h
@@ -33,9 +33,11 @@ __tunables_init (char **unused __attribute__ ((unused)))
# include <stddef.h>
# include <stdint.h>
+typedef intmax_t tunable_num_t;
+
typedef union
{
- int64_t numval;
+ tunable_num_t numval;
const char *strval;
} tunable_val_t;
@@ -52,7 +54,8 @@ typedef void (*tunable_callback_t) (tunable_val_t *);
extern void __tunables_init (char **);
extern void __tunables_print (void);
extern void __tunable_get_val (tunable_id_t, void *, tunable_callback_t);
-extern void __tunable_set_val (tunable_id_t, void *, void *, void *);
+extern void __tunable_set_val (tunable_id_t, tunable_val_t *, tunable_num_t *,
+ tunable_num_t *);
rtld_hidden_proto (__tunables_init)
rtld_hidden_proto (__tunables_print)
rtld_hidden_proto (__tunable_get_val)
@@ -64,20 +67,18 @@ rtld_hidden_proto (__tunable_set_val)
#if defined TOP_NAMESPACE && defined TUNABLE_NAMESPACE
# define TUNABLE_GET(__id, __type, __cb) \
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) \
+# define TUNABLE_SET(__id, __val) \
+ TUNABLE_SET_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, __val)
+# define TUNABLE_SET_WITH_BOUNDS(__id, __val, __min, __max) \
TUNABLE_SET_WITH_BOUNDS_FULL (TOP_NAMESPACE, TUNABLE_NAMESPACE, __id, \
- __type, __val, __min, __max)
+ __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)
+# define TUNABLE_SET(__top, __ns, __id, __val) \
+ TUNABLE_SET_FULL (__top, __ns, __id, __val)
+# define TUNABLE_SET_WITH_BOUNDS(__top, __ns, __id, __val, __min, __max) \
+ TUNABLE_SET_WITH_BOUNDS_FULL (__top, __ns, __id, __val, __min, __max)
#endif
/* Get and return a tunable value. If the tunable was set externally and __CB
@@ -91,19 +92,19 @@ rtld_hidden_proto (__tunable_set_val)
})
/* Set a tunable value. */
-# define TUNABLE_SET_FULL(__top, __ns, __id, __type, __val) \
+# define TUNABLE_SET_FULL(__top, __ns, __id, __val) \
({ \
__tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
- & (__type) {__val}, NULL, NULL); \
+ & (tunable_val_t) {.numval = __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) \
+# define TUNABLE_SET_WITH_BOUNDS_FULL(__top, __ns, __id,__val, __min, __max) \
({ \
__tunable_set_val (TUNABLE_ENUM_NAME (__top, __ns, __id), \
- & (__type) {__val}, & (__type) {__min}, \
- & (__type) {__max}); \
+ & (tunable_val_t) {.numval = __val}, \
+ & (tunable_num_t) {__min}, \
+ & (tunable_num_t) {__max}); \
})
/* Namespace sanity for callback functions. Use this macro to keep the
diff --git a/manual/README.tunables b/manual/README.tunables
index d8c768a..605ddd7 100644
--- a/manual/README.tunables
+++ b/manual/README.tunables
@@ -98,17 +98,16 @@ where it can expect the tunable value to be passed in VALP.
Tunables in the module can be updated using:
- TUNABLE_SET (check, int32_t, val)
+ TUNABLE_SET (check, val)
-where 'check' is the tunable name, 'int32_t' is the C type of the tunable and
-'val' is a value of same type.
+where 'check' is the tunable name and 'val' is a value of same type.
To get and set 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_FULL (glibc, cpu, hwcap_mask, uint64_t, val)
+ TUNABLE_SET_FULL (glibc, cpu, hwcap_mask, val)
where 'glibc' is the top namespace, 'cpu' is the tunable namespace and the
remaining arguments are the same as the short form macros.
@@ -116,18 +115,17 @@ 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)
+ TUNABLE_SET_WITH_BOUNDS (check, 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.
+where 'check' is the tunable name, '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)
+ TUNABLE_SET_WITH_BOUNDS_FULL (glibc, cpu, hwcap_mask, 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.
diff --git a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
index fe52b63..db6aa35 100644
--- a/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
+++ b/sysdeps/unix/sysv/linux/aarch64/cpu-features.c
@@ -104,7 +104,7 @@ init_cpu_features (struct cpu_features *cpu_features)
cpu_features->mte_state = (GLRO (dl_hwcap2) & HWCAP2_MTE) ? mte_state : 0;
/* If we lack the MTE feature, disable the tunable, since it will
otherwise cause instructions that won't run on this CPU to be used. */
- TUNABLE_SET (glibc, mem, tagging, unsigned, cpu_features->mte_state);
+ TUNABLE_SET (glibc, mem, tagging, cpu_features->mte_state);
# endif
if (cpu_features->mte_state & 2)
diff --git a/sysdeps/x86/dl-cacheinfo.h b/sysdeps/x86/dl-cacheinfo.h
index 374ba82..e5d23e6 100644
--- a/sysdeps/x86/dl-cacheinfo.h
+++ b/sysdeps/x86/dl-cacheinfo.h
@@ -929,17 +929,14 @@ dl_init_cacheinfo (struct cpu_features *cpu_features)
rep_stosb_threshold = TUNABLE_GET (x86_rep_stosb_threshold,
long int, NULL);
- TUNABLE_SET_WITH_BOUNDS (x86_data_cache_size, long int, data,
+ TUNABLE_SET_WITH_BOUNDS (x86_data_cache_size, data, 0, (long int) -1);
+ TUNABLE_SET_WITH_BOUNDS (x86_shared_cache_size, shared, 0, (long int) -1);
+ TUNABLE_SET_WITH_BOUNDS (x86_non_temporal_threshold, non_temporal_threshold,
0, (long int) -1);
- TUNABLE_SET_WITH_BOUNDS (x86_shared_cache_size, long int, shared,
- 0, (long int) -1);
- TUNABLE_SET_WITH_BOUNDS (x86_non_temporal_threshold, long int,
- non_temporal_threshold, 0, (long int) -1);
- TUNABLE_SET_WITH_BOUNDS (x86_rep_movsb_threshold, long int,
- rep_movsb_threshold,
+ TUNABLE_SET_WITH_BOUNDS (x86_rep_movsb_threshold, rep_movsb_threshold,
minimum_rep_movsb_threshold, (long int) -1);
- TUNABLE_SET_WITH_BOUNDS (x86_rep_stosb_threshold, long int,
- rep_stosb_threshold, 1, (long int) -1);
+ TUNABLE_SET_WITH_BOUNDS (x86_rep_stosb_threshold, rep_stosb_threshold, 1,
+ (long int) -1);
#endif
cpu_features->data_cache_size = data;