From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, Siddhesh Poyarekar <siddhesh@sourceware.org>
Cc: Noah Goldstein <goldstein.w.n@gmail.com>
Subject: [PATCH v3 09/19] x86: Use dl-symbol-redir-ifunc.h on cpu-tunables
Date: Mon, 6 Nov 2023 17:25:42 -0300 [thread overview]
Message-ID: <20231106202552.3404059-10-adhemerval.zanella@linaro.org> (raw)
In-Reply-To: <20231106202552.3404059-1-adhemerval.zanella@linaro.org>
The dl-symbol-redir-ifunc.h redirects compiler-generated libcalls to
arch-specific memory implementations to avoid ifunc calls where it is not
yet possible. The memcmp-isa-default-impl.h aims to fix the same issue
by calling the specific memset implementation directly.
Using the memcmp symbol directly allows the compiler to inline the memset
calls (especially because _dl_tunable_set_hwcaps uses constants values),
generating better code.
Checked on x86_64-linux-gnu.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
---
.../i686/multiarch/dl-symbol-redir-ifunc.h | 5 +++
sysdeps/x86/cpu-tunables.c | 39 ++++++-------------
sysdeps/x86_64/memcmp-isa-default-impl.h | 28 -------------
.../x86_64/multiarch/dl-symbol-redir-ifunc.h | 15 +++++++
4 files changed, 32 insertions(+), 55 deletions(-)
delete mode 100644 sysdeps/x86_64/memcmp-isa-default-impl.h
diff --git a/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h
index dee69d19db..220c586bd2 100644
--- a/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h
+++ b/sysdeps/i386/i686/multiarch/dl-symbol-redir-ifunc.h
@@ -19,6 +19,11 @@
#ifndef _DL_IFUNC_GENERIC_H
#define _DL_IFUNC_GENERIC_H
+#ifndef SHARED
+
asm ("memset = __memset_ia32");
+asm ("memcmp = __memcmp_ia32");
+
+#endif /* SHARED */
#endif
diff --git a/sysdeps/x86/cpu-tunables.c b/sysdeps/x86/cpu-tunables.c
index 0d4f328585..5697885226 100644
--- a/sysdeps/x86/cpu-tunables.c
+++ b/sysdeps/x86/cpu-tunables.c
@@ -24,24 +24,11 @@
#include <string.h>
#include <cpu-features.h>
#include <ldsodefs.h>
-
-/* We can't use IFUNC memcmp nor strlen in init_cpu_features from libc.a
- since IFUNC must be set up by init_cpu_features. */
-#if defined USE_MULTIARCH && !defined SHARED
-# ifdef __x86_64__
-/* DEFAULT_MEMCMP by sysdeps/x86_64/memcmp-isa-default-impl.h. */
-# include <sysdeps/x86_64/memcmp-isa-default-impl.h>
-# else
-# define DEFAULT_MEMCMP __memcmp_ia32
-# endif
-extern __typeof (memcmp) DEFAULT_MEMCMP;
-#else
-# define DEFAULT_MEMCMP memcmp
-#endif
+#include <dl-symbol-redir-ifunc.h>
#define CHECK_GLIBC_IFUNC_CPU_OFF(f, cpu_features, name, len) \
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
- if (!DEFAULT_MEMCMP (f, #name, len)) \
+ if (memcmp (f, #name, len) == 0) \
{ \
CPU_FEATURE_UNSET (cpu_features, name) \
break; \
@@ -51,7 +38,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
which isn't available. */
#define CHECK_GLIBC_IFUNC_PREFERRED_OFF(f, cpu_features, name, len) \
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
- if (!DEFAULT_MEMCMP (f, #name, len)) \
+ if (memcmp (f, #name, len) == 0) \
{ \
cpu_features->preferred[index_arch_##name] \
&= ~bit_arch_##name; \
@@ -62,7 +49,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
#define CHECK_GLIBC_IFUNC_PREFERRED_BOTH(f, cpu_features, name, \
disable, len) \
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
- if (!DEFAULT_MEMCMP (f, #name, len)) \
+ if (memcmp (f, #name, len) == 0) \
{ \
if (disable) \
cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
@@ -76,7 +63,7 @@ extern __typeof (memcmp) DEFAULT_MEMCMP;
#define CHECK_GLIBC_IFUNC_PREFERRED_NEED_BOTH(f, cpu_features, name, \
need, disable, len) \
_Static_assert (sizeof (#name) - 1 == len, #name " != " #len); \
- if (!DEFAULT_MEMCMP (f, #name, len)) \
+ if (memcmp (f, #name, len) == 0) \
{ \
if (disable) \
cpu_features->preferred[index_arch_##name] &= ~bit_arch_##name; \
@@ -177,7 +164,7 @@ TUNABLE_CALLBACK (set_hwcaps) (tunable_val_t *valp)
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, POPCNT, 6);
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_1, 6);
CHECK_GLIBC_IFUNC_CPU_OFF (n, cpu_features, SSE4_2, 6);
- if (!DEFAULT_MEMCMP (n, "XSAVEC", 6))
+ if (memcmp (n, "XSAVEC", 6) == 0)
{
/* Update xsave_state_size to XSAVE state size. */
cpu_features->xsave_state_size
@@ -290,12 +277,11 @@ attribute_hidden
void
TUNABLE_CALLBACK (set_x86_ibt) (tunable_val_t *valp)
{
- if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
+ if (memcmp (valp->strval, "on", sizeof ("on")) == 0)
GL(dl_x86_feature_control).ibt = cet_always_on;
- else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
+ else if (memcmp (valp->strval, "off", sizeof ("off")) == 0)
GL(dl_x86_feature_control).ibt = cet_always_off;
- else if (DEFAULT_MEMCMP (valp->strval, "permissive",
- sizeof ("permissive")) == 0)
+ else if (memcmp (valp->strval, "permissive", sizeof ("permissive")) == 0)
GL(dl_x86_feature_control).ibt = cet_permissive;
}
@@ -303,12 +289,11 @@ attribute_hidden
void
TUNABLE_CALLBACK (set_x86_shstk) (tunable_val_t *valp)
{
- if (DEFAULT_MEMCMP (valp->strval, "on", sizeof ("on")) == 0)
+ if (memcmp (valp->strval, "on", sizeof ("on")) == 0)
GL(dl_x86_feature_control).shstk = cet_always_on;
- else if (DEFAULT_MEMCMP (valp->strval, "off", sizeof ("off")) == 0)
+ else if (memcmp (valp->strval, "off", sizeof ("off")) == 0)
GL(dl_x86_feature_control).shstk = cet_always_off;
- else if (DEFAULT_MEMCMP (valp->strval, "permissive",
- sizeof ("permissive")) == 0)
+ else if (memcmp (valp->strval, "permissive", sizeof ("permissive")) == 0)
GL(dl_x86_feature_control).shstk = cet_permissive;
}
#endif
diff --git a/sysdeps/x86_64/memcmp-isa-default-impl.h b/sysdeps/x86_64/memcmp-isa-default-impl.h
deleted file mode 100644
index 0962e83c3d..0000000000
--- a/sysdeps/x86_64/memcmp-isa-default-impl.h
+++ /dev/null
@@ -1,28 +0,0 @@
-/* Set default memcmp impl based on ISA level.
- Copyright (C) 2022-2023 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/>. */
-
-#include <isa-level.h>
-#if MINIMUM_X86_ISA_LEVEL == 1 || MINIMUM_X86_ISA_LEVEL == 2
-# define DEFAULT_MEMCMP __memcmp_sse2
-#elif MINIMUM_X86_ISA_LEVEL == 3
-# define DEFAULT_MEMCMP __memcmp_avx2_movbe
-#elif MINIMUM_X86_ISA_LEVEL == 4
-# define DEFAULT_MEMCMP __memcmp_evex_movbe
-#else
-# error "Unknown default memcmp implementation"
-#endif
diff --git a/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h b/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
index 3fe73ca1c3..c7d8961bb6 100644
--- a/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
+++ b/sysdeps/x86_64/multiarch/dl-symbol-redir-ifunc.h
@@ -19,6 +19,8 @@
#ifndef _DL_IFUNC_GENERIC_H
#define _DL_IFUNC_GENERIC_H
+#ifndef SHARED
+
#include <isa-level.h>
#if MINIMUM_X86_ISA_LEVEL >= 4
@@ -31,4 +33,17 @@
asm ("memset = " HAVE_MEMSET_IFUNC_GENERIC);
+
+#if MINIMUM_X86_ISA_LEVEL >= 4
+# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_evex_movbe"
+#elif MINIMUM_X86_ISA_LEVEL == 3
+# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_avx2_movbe"
+#else
+# define HAVE_MEMCMP_IFUNC_GENERIC "__memcmp_sse2"
+#endif
+
+asm ("memcmp = " HAVE_MEMCMP_IFUNC_GENERIC);
+
+#endif /* SHARED */
+
#endif
--
2.34.1
next prev parent reply other threads:[~2023-11-06 20:26 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-06 20:25 [PATCH v3 00/19] Improve loader environment variable handling Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 01/19] elf: Remove /etc/suid-debug support Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 02/19] elf: Add GLIBC_TUNABLES to unsecvars Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 03/19] elf: Ignore GLIBC_TUNABLES for setuid/setgid binaries Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 04/19] elf: Add all malloc tunable to unsecvars Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 05/19] elf: Do not process invalid tunable format Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 06/19] elf: Do not parse ill-formatted strings Adhemerval Zanella
2023-11-20 21:48 ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 07/19] elf: Fix _dl_debug_vdprintf to work before self-relocation Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 08/19] elf: Emit warning if tunable is ill-formatted Adhemerval Zanella
2023-11-20 21:50 ` Siddhesh Poyarekar
2023-11-06 20:25 ` Adhemerval Zanella [this message]
2023-11-06 20:25 ` [PATCH v3 10/19] s390: Use dl-symbol-redir-ifunc.h on cpu-tunables Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 11/19] elf: Do not duplicate the GLIBC_TUNABLES string Adhemerval Zanella
2023-11-20 22:44 ` Siddhesh Poyarekar
2023-11-21 18:12 ` Adhemerval Zanella Netto
2023-11-22 11:39 ` Adhemerval Zanella Netto
2023-11-22 12:23 ` Siddhesh Poyarekar
2023-11-22 13:03 ` Adhemerval Zanella Netto
2023-11-22 13:24 ` Siddhesh Poyarekar
2023-11-22 14:13 ` Adhemerval Zanella Netto
2023-11-06 20:25 ` [PATCH v3 12/19] elf: Ignore LD_PROFILE for setuid binaries Adhemerval Zanella
2023-11-20 22:47 ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 13/19] elf: Remove LD_PROFILE for static binaries Adhemerval Zanella
2023-11-20 22:55 ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 14/19] elf: Ignore loader debug env vars for setuid Adhemerval Zanella
2023-11-20 22:57 ` Siddhesh Poyarekar
2023-11-21 18:24 ` Adhemerval Zanella Netto
2023-11-06 20:25 ` [PATCH v3 15/19] elf: Remove any_debug from dl_main_state Adhemerval Zanella
2023-11-20 22:58 ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 16/19] elf: Ignore LD_LIBRARY_PATH and debug env var for setuid for static Adhemerval Zanella
2023-11-20 22:59 ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 17/19] elf: Add comments on how LD_AUDIT and LD_PRELOAD handle __libc_enable_secure Adhemerval Zanella
2023-11-06 20:25 ` [PATCH v3 18/19] elf: Ignore LD_BIND_NOW and LD_BIND_NOT for setuid binaries Adhemerval Zanella
2023-11-20 23:02 ` Siddhesh Poyarekar
2023-11-06 20:25 ` [PATCH v3 19/19] elf: Refactor process_envvars Adhemerval Zanella
2023-11-20 23:09 ` Siddhesh Poyarekar
2023-11-21 19:00 ` Adhemerval Zanella Netto
2023-11-20 23:12 ` [PATCH v3 00/19] Improve loader environment variable handling Siddhesh Poyarekar
2023-11-21 19:37 ` Adhemerval Zanella Netto
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