commit 86f65dffc2396d408beb628f1cad2b8f63e197bd

Author: H.J. Lu <hjl.tools@gmail.com>

Date:   Sun Jul 12 06:04:53 2020 -0700

    ld.so: Add --list-tunables to print tunable values

    Pass --list-tunables to ld.so to print tunables with min and max values.

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Conflicts:

	elf/Makefile

	  (different backporting order)

diff --git a/elf/Makefile b/elf/Makefile

index 3e71939d3234c4c3..aa65ec59f143bccf 100644

--- a/elf/Makefile

+++ b/elf/Makefile

@@ -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))

@@ -1825,6 +1829,13 @@ $(objpfx)tst-glibc-hwcaps-mask.out: \

 # tst-glibc-hwcaps-cache.

 $(objpfx)tst-glibc-hwcaps-cache.out: $(objpfx)tst-glibc-hwcaps

+$(objpfx)list-tunables.out: tst-rtld-list-tunables.sh $(objpfx)ld.so

+	$(SHELL) $< $(objpfx)ld.so '$(test-wrapper-env)' \

+	    '$(run_program_env)' > $(objpfx)/tst-rtld-list-tunables.out

+	cmp tst-rtld-list-tunables.exp \

+	    $(objpfx)/tst-rtld-list-tunables.out > $@; \

+	$(evaluate-test)

+

 tst-dst-static-ENV = LD_LIBRARY_PATH='$$ORIGIN'

 $(objpfx)tst-rtld-help.out: $(objpfx)ld.so

diff --git a/elf/dl-main.h b/elf/dl-main.h

index 566713a0d10cfdb7..9e7b51d8f010e904 100644

--- a/elf/dl-main.h

+++ b/elf/dl-main.h

@@ -63,7 +63,7 @@ struct audit_list

 enum rtld_mode

   {

     rtld_mode_normal, rtld_mode_list, rtld_mode_verify, rtld_mode_trace,

-    rtld_mode_help,

+    rtld_mode_list_tunables, rtld_mode_help,

   };

 /* Aggregated state information extracted from environment variables

diff --git a/elf/dl-tunables.c b/elf/dl-tunables.c

index bbc3679e3564a766..3c84809d44381241 100644

--- a/elf/dl-tunables.c

+++ b/elf/dl-tunables.c

@@ -26,6 +26,7 @@

 #include <sysdep.h>

 #include <fcntl.h>

 #include <ldsodefs.h>

+#include <array_length.h>

 #define TUNABLES_INTERNAL 1

 #include "dl-tunables.h"

@@ -359,6 +360,48 @@ __tunables_init (char **envp)

     }

 }

+void

+__tunables_print (void)

+{

+  for (int i = 0; i < array_length (tunable_list); i++)

+    {

+      const tunable_t *cur = &tunable_list[i];

+      if (cur->type.type_code == TUNABLE_TYPE_STRING

+	  && cur->val.strval == NULL)

+	_dl_printf ("%s:\n", cur->name);

+      else

+	{

+	  _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);

+	      break;

+	    default:

+	      __builtin_unreachable ();

+	    }

+	}

+    }

+}

+

 /* Set the tunable value.  This is called by the module that the tunable exists

    in. */

 void

diff --git a/elf/dl-tunables.h b/elf/dl-tunables.h

index 7f181f3316cd9fc1..f4f2cfaeb9828599 100644

--- a/elf/dl-tunables.h

+++ b/elf/dl-tunables.h

@@ -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 *);

 rtld_hidden_proto (__tunables_init)

+rtld_hidden_proto (__tunables_print)

 rtld_hidden_proto (__tunable_get_val)

 /* Define TUNABLE_GET and TUNABLE_SET in short form if TOP_NAMESPACE and

diff --git a/elf/dl-usage.c b/elf/dl-usage.c

index e22a9c39427187d1..908b4894b3014b2d 100644

--- a/elf/dl-usage.c

+++ b/elf/dl-usage.c

@@ -255,7 +255,12 @@ setting environment variables (which would be inherited by subprocesses).\n\

                         in LIST\n\

   --audit LIST          use objects named in LIST as auditors\n\

   --preload LIST        preload objects named in LIST\n\

-  --argv0 STRING        set argv[0] to STRING before running\n\

+  --argv0 STRING        set argv[0] to STRING before running\n"

+#if HAVE_TUNABLES

+"\

+  --list-tunables       list all tunables with minimum and maximum values\n"

+#endif

+"\

   --help                display this help and exit\n\

   --version             output version information and exit\n\

 \n\

diff --git a/elf/rtld.c b/elf/rtld.c

index 9e09896da078274d..54b621ec5ca014fa 100644

--- a/elf/rtld.c

+++ b/elf/rtld.c

@@ -47,6 +47,7 @@

 #include <libc-early-init.h>

 #include <dl-main.h>

 #include <gnu/lib-names.h>

+#include <dl-tunables.h>

 #include <assert.h>

@@ -1262,6 +1263,16 @@ dl_main (const ElfW(Phdr) *phdr,

 	    _dl_argc -= 2;

 	    _dl_argv += 2;

 	  }

+#if HAVE_TUNABLES

+	else if (! strcmp (_dl_argv[1], "--list-tunables"))

+	  {

+	    state.mode = rtld_mode_list_tunables;

+

+	    ++_dl_skip_args;

+	    --_dl_argc;

+	    ++_dl_argv;

+	  }

+#endif

 	else if (strcmp (_dl_argv[1], "--help") == 0)

 	  {

 	    state.mode = rtld_mode_help;

@@ -1282,6 +1293,14 @@ dl_main (const ElfW(Phdr) *phdr,

 	else

 	  break;

+#if HAVE_TUNABLES

+      if (__glibc_unlikely (state.mode == rtld_mode_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)

diff --git a/elf/tst-rtld-list-tunables.exp b/elf/tst-rtld-list-tunables.exp

new file mode 100644

index 0000000000000000..4f3f7ee4e30a2b42

--- /dev/null

+++ b/elf/tst-rtld-list-tunables.exp

@@ -0,0 +1,14 @@

+glibc.malloc.arena_max: 0x0 (min: 0x1, max: 0x[f]+)

+glibc.malloc.arena_test: 0x0 (min: 0x1, max: 0x[f]+)

+glibc.malloc.check: 0 (min: 0, max: 3)

+glibc.malloc.mmap_max: 0 (min: -2147483648, max: 2147483647)

+glibc.malloc.mmap_threshold: 0x0 (min: 0x0, max: 0x[f]+)

+glibc.malloc.mxfast: 0x0 (min: 0x0, max: 0x[f]+)

+glibc.malloc.perturb: 0 (min: 0, max: 255)

+glibc.malloc.tcache_count: 0x0 (min: 0x0, max: 0x[f]+)

+glibc.malloc.tcache_max: 0x0 (min: 0x0, max: 0x[f]+)

+glibc.malloc.tcache_unsorted_limit: 0x0 (min: 0x0, max: 0x[f]+)

+glibc.malloc.top_pad: 0x0 (min: 0x0, max: 0x[f]+)

+glibc.malloc.trim_threshold: 0x0 (min: 0x0, max: 0x[f]+)

+glibc.rtld.nns: 0x4 (min: 0x1, max: 0x10)

+glibc.rtld.optional_static_tls: 0x200 (min: 0x0, max: 0x[f]+)

diff --git a/elf/tst-rtld-list-tunables.sh b/elf/tst-rtld-list-tunables.sh

new file mode 100755

index 0000000000000000..e7bbdde94952b872

--- /dev/null

+++ b/elf/tst-rtld-list-tunables.sh

@@ -0,0 +1,34 @@

+#!/bin/sh

+# Test for --list-tunables option ld.so.

+# Copyright (C) 2021 Free Software Foundation, Inc.

+# This file is part of the GNU C Library.

+#

+# The GNU C Library is free software; you can redistribute it and/or

+# modify it under the terms of the GNU Lesser General Public

+# License as published by the Free Software Foundation; either

+# version 2.1 of the License, or (at your option) any later version.

+#

+# The GNU C Library is distributed in the hope that it will be useful,

+# but WITHOUT ANY WARRANTY; without even the implied warranty of

+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

+# Lesser General Public License for more details.

+#

+# You should have received a copy of the GNU Lesser General Public

+# License along with the GNU C Library; if not, see

+# <https://www.gnu.org/licenses/>.

+

+set -e

+

+rtld=$1

+test_wrapper_env=$2

+run_program_env=$3

+

+LC_ALL=C

+export LC_ALL

+

+${test_wrapper_env} \

+${run_program_env} \

+$rtld --list-tunables \

+| sort -u \

+| egrep "(rtld|malloc)" \

+| sed -e "s/0xf\+/0x[f]+/"

diff --git a/manual/tunables.texi b/manual/tunables.texi

index 07887981748bc44b..43272cf885d1e3e6 100644

--- a/manual/tunables.texi

+++ b/manual/tunables.texi

@@ -28,6 +28,44 @@ 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.mem.tagging: 0 (min: 0, max: 255)

+glibc.elision.tries: 3 (min: -2147483648, max: 2147483647)

+glibc.elision.enable: 0 (min: 0, max: 1)

+glibc.cpu.x86_rep_movsb_threshold: 0x1000 (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: 0xc0000 (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