@@ -9,6 +9,8 @@ Version 2.33
Major new features:
+* Pass --list-tunables to ld.so to print tunable values.
+
* The mallinfo2 function is added to report statistics as per mallinfo,
but with larger field widths to accurately report values that are
larger than fit in an integer.
@@ -44,6 +44,10 @@ dl-routines += dl-tunables
tunables-type = $(addprefix TUNABLES_FRONTEND_,$(have-tunables))
CPPFLAGS-dl-tunables.c += -DTUNABLES_FRONTEND=$(tunables-type)
+ifeq (yesyes,$(build-shared)$(run-built-tests))
+tests-special += $(objpfx)list-tunables.out
+endif
+
# Make sure that the compiler does not insert any library calls in tunables
# code paths.
ifeq (yes,$(have-loop-to-function))
@@ -1796,3 +1800,7 @@ $(objpfx)tst-tls-ie-dlmopen.out: \
$(objpfx)tst-tls-ie-mod6.so
$(objpfx)tst-tls-surplus: $(libdl)
+
+$(objpfx)list-tunables.out: $(objpfx)ld.so
+ $(objpfx)ld.so --list-tunables > $@; \
+ $(evaluate-test)
@@ -368,6 +368,42 @@ __tunables_init (char **envp)
}
}
+void
+__tunables_print (void)
+{
+ for (int i = 0; i < sizeof (tunable_list) / sizeof (tunable_t); i++)
+ {
+ tunable_t *cur = &tunable_list[i];
+ _dl_printf ("%s: ", cur->name);
+ switch (cur->type.type_code)
+ {
+ case TUNABLE_TYPE_INT_32:
+ _dl_printf ("%d (min: %d, max: %d)\n",
+ (int) cur->val.numval,
+ (int) cur->type.min,
+ (int) cur->type.max);
+ break;
+ case TUNABLE_TYPE_UINT_64:
+ _dl_printf ("0x%lx (min: 0x%lx, max: 0x%lx)\n",
+ (long int) cur->val.numval,
+ (long int) cur->type.min,
+ (long int) cur->type.max);
+ break;
+ case TUNABLE_TYPE_SIZE_T:
+ _dl_printf ("0x%Zx (min: 0x%Zx, max: 0x%Zx)\n",
+ (size_t) cur->val.numval,
+ (size_t) cur->type.min,
+ (size_t) cur->type.max);
+ break;
+ case TUNABLE_TYPE_STRING:
+ _dl_printf ("%s\n", cur->val.strval ? cur->val.strval : "");
+ break;
+ default:
+ __builtin_unreachable ();
+ }
+ }
+}
+
/* Set the tunable value. This is called by the module that the tunable exists
in. */
void
@@ -69,9 +69,11 @@ typedef struct _tunable tunable_t;
# include "dl-tunable-list.h"
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 *);
rtld_hidden_proto (__tunables_init)
+rtld_hidden_proto (__tunables_print)
rtld_hidden_proto (__tunable_get_val)
rtld_hidden_proto (__tunable_set_val)
@@ -48,6 +48,10 @@
#include <array_length.h>
#include <libc-early-init.h>
+#if HAVE_TUNABLES
+# include <dl-tunables.h>
+#endif
+
#include <assert.h>
/* Only enables rtld profiling for architectures which provides non generic
@@ -168,7 +172,7 @@ static void audit_list_add_dynamic_tag (struct audit_list *,
static const char *audit_list_next (struct audit_list *);
/* This is a list of all the modes the dynamic loader can be in. */
-enum mode { normal, list, verify, trace };
+enum mode { normal, list, verify, trace, list_tunables };
/* Process all environments variables the dynamic linker must recognize.
Since all of them start with `LD_' we are a bit smarter while finding
@@ -1263,9 +1267,27 @@ dl_main (const ElfW(Phdr) *phdr,
_dl_argc -= 2;
_dl_argv += 2;
}
+#if HAVE_TUNABLES
+ else if (! strcmp (_dl_argv[1], "--list-tunables"))
+ {
+ mode = list_tunables;
+
+ ++_dl_skip_args;
+ --_dl_argc;
+ ++_dl_argv;
+ }
+#endif
else
break;
+#if HAVE_TUNABLES
+ if (__builtin_expect (mode, normal) == list_tunables)
+ {
+ __tunables_print ();
+ _exit (0);
+ }
+#endif
+
/* If we have no further argument the program was called incorrectly.
Grant the user some education. */
if (_dl_argc < 2)
@@ -1292,7 +1314,12 @@ of this helper program; chances are you did not intend to run this program.\n\
--inhibit-rpath LIST ignore RUNPATH and RPATH information in object names\n\
in LIST\n\
--audit LIST use objects named in LIST as auditors\n\
- --preload LIST preload objects named in LIST\n");
+ --preload LIST preload objects named in LIST\n"
+#if HAVE_TUNABLES
+"\
+ --list-tunables list all tunables with minimum and maximum values\n"
+#endif
+ );
++_dl_skip_args;
--_dl_argc;
@@ -28,6 +28,43 @@ Finally, the set of tunables available may vary between distributions as
the tunables feature allows distributions to add their own tunables under
their own namespace.
+Passing @option{--list-tunables} to the dynamic loader to print all
+tunables with minimum and maximum values:
+
+@example
+$ /lib64/ld-linux-x86-64.so.2 --list-tunables
+glibc.rtld.nns: 0x4 (min: 0x1, max: 0x10)
+glibc.elision.skip_lock_after_retries: 3 (min: -2147483648, max: 2147483647)
+glibc.malloc.trim_threshold: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.perturb: 0 (min: 0, max: 255)
+glibc.cpu.x86_shared_cache_size: 0x100000 (min: 0x0, max: 0xffffffffffffffff)
+glibc.elision.tries: 3 (min: -2147483648, max: 2147483647)
+glibc.elision.enable: 0 (min: 0, max: 1)
+glibc.cpu.x86_rep_movsb_threshold: 0x800 (min: 0x100, max: 0xffffffffffffffff)
+glibc.malloc.mxfast: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.elision.skip_lock_busy: 3 (min: -2147483648, max: 2147483647)
+glibc.malloc.top_pad: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.cpu.x86_rep_stosb_threshold: 0x800 (min: 0x1, max: 0xffffffffffffffff)
+glibc.cpu.x86_non_temporal_threshold: 0x600000 (min: 0x0, max: 0xffffffffffffffff)
+glibc.cpu.x86_shstk:
+glibc.cpu.hwcap_mask: 0x6 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.mmap_max: 0 (min: -2147483648, max: 2147483647)
+glibc.elision.skip_trylock_internal_abort: 3 (min: -2147483648, max: 2147483647)
+glibc.malloc.tcache_unsorted_limit: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.cpu.x86_ibt:
+glibc.cpu.hwcaps:
+glibc.elision.skip_lock_internal_abort: 3 (min: -2147483648, max: 2147483647)
+glibc.malloc.arena_max: 0x0 (min: 0x1, max: 0xffffffffffffffff)
+glibc.malloc.mmap_threshold: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.cpu.x86_data_cache_size: 0x8000 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.tcache_count: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.arena_test: 0x0 (min: 0x1, max: 0xffffffffffffffff)
+glibc.pthread.mutex_spin_count: 100 (min: 0, max: 32767)
+glibc.rtld.optional_static_tls: 0x200 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.tcache_max: 0x0 (min: 0x0, max: 0xffffffffffffffff)
+glibc.malloc.check: 0 (min: 0, max: 3)
+@end example
+
@menu
* Tunable names:: The structure of a tunable name
* Memory Allocation Tunables:: Tunables in the memory allocation subsystem